Two centuries ago, the pioneers of modern empirical research revolutionized Earth science by treating nature as a dynamic, interconnected system—one best understood not through hypotheses alone, but through systematic observation and measurement. "Nature does not answer questions we have not yet asked," as Alexander von Humboldt observed, "it shows us phenomena we must first learn to see as questions."

Yet science today often prioritizes hypothesis-driven research, leaving little room for the unexpected. This lecture explores the tension between discovery and prediction in glaciology, where some of the transformations have emerged not from testing hypotheses, but from exploration, curiosity, and serendipity.

From overlooked data to phenomena no one anticipated, glaciology’s future depends on our willingness to reclaim discovery science—not as a replacement for hypothesis testing, but as its essential counterpart. As Aldous Huxley reminds us, "There are things known and things unknown, and in between are the doors of perception." To address todays and future challenges in Earth science, we must keep those doors open.

How to cite: Eisen, O.: Of Known Unknowns and Unobserved Knowns, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2271, https://doi.org/10.5194/egusphere-egu26-2271, 2026.

Ice shelves, the floating extensions of the Antarctic Ice Sheet, are melted from below by the ocean. Increased ice shelf basal melting is the main mechanism by which Antarctica currently contributes to global sea level rise. As melt rates are sensitive to temperature, salinity, and circulation in tiny pockets of the Southern Ocean, predicting how they might respond to climate change is not straightforward. Projecting future ice shelf melting is at the forefront of coupled Earth system modelling, as most climate and ocean models still do not include ice shelves at all. This talk will summarise my research since 2020 on the future of ice shelf basal melting, focusing on three regions of Antarctica. In the Amundsen Sea, in West Antarctica, relatively warm ocean water already accesses the ice shelves. However, climate change is projected to make these regions warmer still, by increasing the volume of warm water flowing onshore. In contrast, Antarctica’s two largest ice shelves, the Ross and Filchner-Ronne, are currently bathed in cold water and melt rates are stable. However, numerous models predict that with sufficient climate change, these cavities could abruptly flip into a warm state similar to the Amundsen Sea. Sea level rise from Antarctica, therefore, is not all-or-nothing. Ice loss from some regions may already be committed, but in other regions abrupt changes may or may not be triggered, depending on how much the climate warms. Therefore, the trajectory of carbon emissions over the coming century will likely have a large impact on Antarctica’s long-term contribution to sea level rise.

How to cite: Naughten, K.: Ice shelves, the Southern Ocean, and the future, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3134, https://doi.org/10.5194/egusphere-egu26-3134, 2026.

Induced diffusion (ID), an important mechanism of spectral energy transfer due to interacting internal gravity waves (IGWs), plays a significant role in driving turbulent dissipation in the ocean interior. In this study, we revisit the ID mechanism to elucidate its directionality and role in ocean mixing under varying IGW spectral forms, with particular attention to deviations from the standard Garrett-Munk spectrum. The original interpretation of ID as an action diffusion process, as proposed by McComas et al., suggests that ID is inherently bidirectional, with its direction governed by the vertical-wavenumber spectral slope σ of the IGW action spectrum, n ~ m^σ. However, through the direct evaluation of the wave kinetic equation, we reveal a more complete depiction of ID, comprising both a diffusive and a scale-separated transfer rooted in the energy conservation within wave triads. Although the action diffusion may reverse direction depending on the sign of σ (i.e., red or blue spectra), the net transfer consistently leads to a forward energy cascade at the dissipation scale, contributing positively to turbulent dissipation. This supports the viewpoint of ID as a dissipative mechanism in physical oceanography. This study presents a physically grounded overview of ID and offers insights into the specific types of wave-wave interactions responsible for turbulent dissipation.

How to cite: Wu, Y. C. and Pan, Y.: Induced Diffusion of Interacting Internal Gravity Waves, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-221, https://doi.org/10.5194/egusphere-egu26-221, 2026.

A permafrost probability index (PPI) based on rock glacier inventory and machine learning models, including random forest, support vector machine, artificial neural network, and logistic regression, was generated for Kinnaur district, Himachal Pradesh, India. Intact rock glaciers were considered the dependent variable, and elevation, slope, aspect, and potential incoming solar radiation were used as independent variables to generate a spatially distributed, high-resolution permafrost probability index. Daily weather station data and daily multitemporal MODIS satellite data were used to train a linear regression model to predict the annual 0℃ isotherm in the region for the period of 2023-24, aiming to understand potential degradation by overlaying the isotherm on permafrost distribution. The random forest technique produced the best results with an overall accuracy of 89.43%. Seven glacial lakes were identified as located in potentially permafrost-degraded slopes, and the Kashang glacial lake was selected for detailed downstream glacial lake outburst flood process chain modeling based on its size, moraine-dammed proglacial setting, and potential downstream impact. The volume of the lake was estimated to be 8.6 × 10⁶  m³ by extrapolating the contours from overdeepening of the main glacier. Three sources of avalanches were identified based on permafrost degradation and slopes greater than 30 degrees. Subsequently, three scenario-based process chains for glacial lake outburst floods were modeled. We simulate avalanche initialization, displacement wave generation, overtopping, moraine erosion, and downstream flooding. The modelling results revealed that the potential GLOF can cause a peak discharge of 16,167 ms⁻¹, and floodwater can reach the Kashang, where a hydropower is located, within 16 minutes  in the high-magnitude scenario. The findings can give important insights into GLOF hazard mitigation in the valley and can aid as preliminary data for various stakeholders working towards mitigating glacier-related hazards.

Keywords: Permafrost, GLOF, machine learning, r.avaflow, Himalaya

How to cite: Alangadan, A. and Sattar, A.: Glacial lakes in permafrost terrain and downstream hazards, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1083, https://doi.org/10.5194/egusphere-egu26-1083, 2026.

The boreal early-spring of 2024 witnessed unprecedented marine heatwaves across the tropical Atlantic, setting a satellite-era record for basin-averaged marine heatwave intensity. Based on observational and reanalysis datasets and a mixed layer heat budget analysis, we identify three region-specific drivers. In the north (20°N–3°N), the event began in fall 2023 and was maintained by sustained positive shortwave radiation anomalies due to reduced cloudiness. Equatorial warming (3°N–3°S) was primarily driven by wind-driven ocean wave processes, amplified by a shallower mixed layer. In the south (3°S–20°S), the key mechanism was wind-driven mixed layer shoaling. The reduced cloudiness over the northern tropical Atlantic is linked to remote El Niño forcing, and the wind anomalies over the equatorial and southern tropical Atlantic are partly attributable to the concurrent South Atlantic Subtropical Dipole. Our findings clarify the multifaceted origins of such extreme marine heatwaves, offering crucial insights for improving their seasonal prediction.

How to cite: Yang, J.-C., Li, S., Richter, I., Liu, Y., Zhang, Y., Li, Z., and Lin, X.: Primary Factors Driving Extreme 2024 Early-spring Marine Heatwaves in the Tropical Atlantic: Shortwave Radiation and Mixed Layer Depth, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3225, https://doi.org/10.5194/egusphere-egu26-3225, 2026.

Litter pollution has grown to be the most prominent threat to the coastal ecosystems, affecting both the environment and the local communities. An important step towards the mitigation of coastal pollution is the effective monitoring of the issue. The rapid evolution of Remote Sensing has offered many new techniques for the detection of beach litter, and Unmanned Aerial Vehicles (UAVs), especially, have proven to be invaluable tools. In this study, different approaches of beach litter detection are evaluated in order to determine which ones yield the most promising results. The data used were collected in the area of Palio Faliro, Greece and included RGB and Multi-spectral images. For the detection of the litter from the UAV images, two Deep Learning (DL) models were utilized, namely the Mask R-CNN and the YOLOv3. The accuracy of these two DL models in beach litter detection and also explore the potential challenges that may arise while trying to monitor the coastal environment with UAV methods. Our study findings suggest that the combined use of DL methods and UAV imagery can provide a cost-effective and scalable solution in litter detection and can assist relevant decision-making actions. Future work will focus on evaluating different DL methods under other experimental settings as well which will help towards assessing the wider applicability of the combined use of drone imagery and DL approaches in litter detection in coastal areas.

KEYWORDS: Remote Sensing, coastal little, UAVs, drones, deep learning, ACCELERATE project

Acknowledgements 

This study is financially supported by the ACCELERATE MSCA SE program of the European Union’s Horizon research and innovation program under grant agreement No. 101182930

How to cite: Mitsopoulou, C., Petropoulos, G. P., Detsikas, S. E., Lekka, C., Grigoriadis, K., Polychronos, V., Mamagiannou, E.-M., Gkotsikas, C., Chardavellas, K., and Katsou, E.: Litter detection and mapping from the combined use of multispectral UAV imagery and Deep Learning: A case study from Greece, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3528, https://doi.org/10.5194/egusphere-egu26-3528, 2026.

Estuaries represent complex morphodynamic systems where interactions between tides, waves, and sediment processes control coastal stability and its ecological resilience. One such estuary, located along the bank of the Purna River in Navsari District, Gujarat, India, is currently experiencing severe erosion, with nearly two-thirds of the estuarine coastline affected.  Understanding spatio-temporal evolution of key coastal features is essential, including tidal flats, salt marshes, mangrove cover, and anthropogenic infrastructures within the study region. In this study, the coastal features segmentation is performed using the Random Forest on derived Landsat satellite imagery spectral indices spanning 2005–2024. The results indicate that over the past two decades, mangrove cover has increased by more than twofold, particularly near the estuary mouth. In contrast, tidal flat areas exhibited significant spatial variability, while salt marshes showed a considerable decline.

Shoreline change analysis shows extensive coastal erosion with the Net Shoreline Movement (NSM) exceeding 150 m in certain stretches, while the End Point Rate (EPR) ranged from 1.5 to 17 m/year (mean: 9.5 m/year). The analysis further indicates significant accretion in the estuaryward region and pronounced erosion along the seaward coast near its mouth. Further the coupled tide-wave numerical modelling was carried to attribute the observed changes. Overall, the findings highlight the complex interplay between natural coastal processes and anthropogenic pressures in this dynamic estuarine coastal system and provide valuable baseline information for coastal zone management and conservation planning.

Keywords: Estuary Dynamics, Random Forest, Shoreline changes, Tide Modelling, Wave Modelling, Remote Sensing.

How to cite: Makhan, P. K., Goud Lakku, N. K., Behera, M. R., and Vijaya Kumar, S.: Coastal Features Segmentation and Assessing their dynamics Using Machine Learning: Random Forest, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3596, https://doi.org/10.5194/egusphere-egu26-3596, 2026.

The Gulf of Panama is a semi-enclosed tropical basin where coastal processes are driven by a multimodal wave climate with pronounced interannual-to-decadal variability (Vallarino-Castillo, 2026). Offshore wave conditions were characterized at three spectral locations near the Gulf entrance using GLOSWAC-5 spectral data (Portilla-Yandún and Bidlot, 2025), revealing dominant wave systems with distinct directional origins and seasonal variability. A persistent Southern Ocean swell dominates year-round from the south–southwest, while northerly wind-seas associated with the Panama Low-Level Jet prevail during the dry season (December–April). Their opposing directions lead to frequent crossing-sea conditions, particularly along the western Gulf entrance, where partial blocking by the Azuero Peninsula enhances directional spreading. In contrast, more exposed central-eastern locations exhibit consistently multimodal spectra, whereas sheltered eastern areas show reduced northerly wind-sea influence and narrower directional ranges. During the wet season (May–November), additional southerly swell components linked to subtropical trade winds and the Chocó Low-Level Jet reinforce low-frequency energy, while episodic North Pacific swell incursions further increase spectral complexity. Building on these offshore patterns, we analyze how wave systems transform as they propagate across the Gulf’s complex basin geometry.

To resolve coastal wave conditions efficiently, we applied a hybrid spectral downscaling framework across the Gulf. Remote swell was reconstructed using BinWaves (Cagigal et al., 2024), which disaggregates each offshore spectrum into frequency–direction bins and propagates them individually with SWAN, assuming linear wave superposition over the nearshore of the Gulf of Panama, such that nonlinear wave–wave interactions are neglected during propagation. Nearshore spectra are then reassembled using precomputed propagation coefficients that account for coastal geometry. Locally generated seas were reconstructed with HyXSeaSpec, which extracts dominant atmospheric modes via multivariate dimensionality reduction, projects SWAN spectra onto a reduced EOF/PCA space and learns the nonlinear mapping between atmospheric modes and spectral coefficients using radial basis functions (RBFs). During prediction, new wind fields are projected into the reduced space to recover full directional spectra through inverse transforms. The hybrid workflow generates a 3-hourly directional wave spectrum hindcast (1969–2023) that combines remote swell and locally generated wind-sea contributions throughout the basin.

The ongoing nearshore analysis uses the reconstructed spectra to identify dominant variability patterns and coherent wave regimes, assessing how energy is redistributed within the gulf and how nearshore conditions respond to seasonal and interannual atmospheric forcing.

References:

Vallarino-Castillo R, Antolínez JAA, Negro-Valdecantos V, Portilla-Yandún J (2026). “Beyond understanding the role of far-field climate in the Gulf of Panama coastal dynamics: an analysis of long-term and seasonal variability of wave systems”. Climate Dynamics. https://doi.org/10.1007/s00382-025-08007-w

Portilla-Yandún J, Bidlot J-R (2025). “A global ocean spectral wave climate based on ERA-5 data: GLOSWAC-5”. Journal of Geophysical Research: Oceans. https://doi.org/10.1029/2025JC022629

Cagigal, L., Méndez, F.J., Ricondo, A., Gutiérrez-Barceló, D. & Bosserelle, C. (2024). “BinWaves: An additive hybrid method to downscale directional wave spectra to near-shore areas” en Ocean Modelling. 84, 102346.

How to cite: Vallarino-Castillo, R., Bellido, G., Cagigal, L., Negro-Valdecantos, V., Portilla-Yandún, J., Méndez, F., and A. A. Antolínez, J.: Hybrid spectral downscaling and climate-driven variability of multimodal wave systems in the Gulf of Panama, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3616, https://doi.org/10.5194/egusphere-egu26-3616, 2026.

             The variability in the circulation of the Northern Ionian Gyre (NIG) during 1988-2020 is assessed via dynamic-height fields in the upper layer (0-120 m and 0-398 m) derived from the monthly-averaged temperature and salinity fields of the Copernicus reanalysis data. The yearly-averaged dynamic-height fields agree with the corresponding fields of altimetric sea-surface topography used in previous studies that found, at the area of the NIG, a maximum-variability mode in the sea-surface topography of the Ionian Sea. In the present results, the NIG coincides with the area of a) the variability maxima of the dynamic-heights, existing on the standard-deviation (std) maps of the yearly-averaged dynamic heights during 1988-2020, b) the std maxima of the averaged density in the upper layer and c) the std maxima of the averaged salinity in the upper layer; the density-salinity correlation coefficients in the upper-layer within the NIG range from 0.87 to 0.74.

            Moreover, the std maxima of the precipitation fluxes, which have the dominant role on the evaporation-minus-precipitation (E-P) budget, are also located on the NIG area.   The 5-year running-averaged values of yearly E-P and salinity in the upper-layer of the NIG, which filter out the variability in less that ~5-6 years while they preserve the dominant variability in the periodicities (~8-10 years) of the NIG-circulation, have statistically significant correlations ranging from 0.53 for the period 1990-2018 to 0.73 for the period 1997-2018. After ~2005, the two timeseries resemble to each other even more.  In the upper layer, the area to the east-southeast of the NIG has statistically significant correlations in salinity (correlation coefficients: ~0.68-0.8) with the NIG area. This area can feed its higher-salinity signal to the NIG via northward transfer during the cyclonic circulation mode of the NIG.

How to cite: Kontoyiannis, H., Tsiaras, K., Iona, A., and Ballas, D.: The role of the air-sea water fluxes and the lateral influence on salinity in the bimodal circulation variability of the Northern Ionian Gyre in the period 1988-2020, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5203, https://doi.org/10.5194/egusphere-egu26-5203, 2026.

The Karakoram is known for its numerous surge glaciers and associated hazards from ice-dammed lake outburst floods. However, significant discrepancies persist in our understanding of surge trends and flood frequency. Therefore, this study aims to clarify the surge behaviour and related glacial lake outburst flood (GLOF) history for the Kumdan group of glaciers (Chong Kumdan, Kichik Kumdan, and Aktash). The study analysed historical archives, high-resolution satellite imagery, elevation changes derived from digital elevation models (DEMs), and glacier surface velocity from the ITS_LIVE dataset. Based on an in-depth review of historical records and cross-verified with multi-temporal satellite imagery, 16 GLOFs have been documented from this group since 1835, primarily originating from Chong Kumdan and Kichik Kumdan. The Aktash Glacier has surged several times but has not formed any ice-dammed lake due to efficient subglacial drainage, which prevents river blockages. Chong Kumdan and Aktash glaciers exhibit longer active phases (~7-10 years), whereas Kichik Kumdan Glacier shows shorter phases (~2 years). Out of all three Kumdan glaciers, the Chong Kumdan has produced the most devastating floods in 1835, 1926 and 1929. This glacier comprises two tributaries (a and b) and main trunk. Tributary ‘a’ follows a ~77-year surge cycle, and tributary ‘b’ and the main trunk exhibit asynchronous surge records. The surge cycle duration of Kichik Kumdan Glacier decreased from 33 years (1833–1866) to 27 years (1970–1997) due to climate warming. The last GLOFs from Chong Kumdan and Kichik Kumdan occurred in 1934 and 1903, respectively. DEM analysis from 2015 to 2022 reveals thickening in the reservoir areas of Chong Kumdan (~22 m) and Kichik Kumdan (~20 m), suggesting potential future surge but with a low probability of GLOF events. Overall, our study observed a decline in surge-generated GLOFs due to climate warming, reduced mass accumulation and weakening of ice dams. These insights will help downstream communities and risk management authorities better understand future risks and develop effective mitigation strategies.

How to cite: Halder, S. and Bhambri, R.: Impact of climatic warming on glacier surges and associated ice-dammed lake outburst floods in the Eastern Karakoram, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5669, https://doi.org/10.5194/egusphere-egu26-5669, 2026.

How to cite: Bouzaiene, M. and Menna, M.: Development of a Fine-Scale (1/648°) Nested Ocean Forecasting Model for the Tunisian Shelf, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8164, https://doi.org/10.5194/egusphere-egu26-8164, 2026.

Ocean salinity serves as a key indicator of the global water cycle and exerts important controls on oceanic circulation, sea level, and stratification, thereby playing a critical role in marine thermodynamic and dynamic processes. In recent years, salinity variability in the tropical Indian Ocean, particularly its dynamic mechanisms and climatic effects, has attracted growing scientific interest. Using 31 years of satellite observations, in-situ data sets, and model reanalysis data, this study investigates the decadal variability and formation mechanisms of the low salinity tongue in the South Indian Ocean between the equator and 20°S. The results indicate that both the volume and mean salinity of the low-salinity tongue exhibit a quasi-12-year oscillation, which is primarily associated with the Interdecadal Pacific Oscillation (IPO). Further analysis reveals that on decadal timescales, variability in the volume of the upper 50 m low-salinity tongue is mainly driven by local precipitation. Through anomalous atmospheric circulation, sea surface temperature anomalies in the tropical Pacific lead to multi-year precipitation anomalies in the southeastern Indian Ocean, which subsequently alter the westward extension of the surface low-salinity tongue and ultimately govern its volume variability in the upper 50 m. However, in the subsurface layer (50 to 200 m), variability in the volume and average salinity of the low salinity tongue is dominated by freshwater transport associated with the Indonesian Throughflow (ITF). During negative IPO phases, wind anomalies over the tropical Pacific trigger oceanic wave adjustments, which enhance the ITF salinity transport. This process subsequently leads to an expansion of the low salinity tongue and a decrease in its average salinity in the southeastern Indian Ocean. Based on the three-dimensional variability of the low salinity tongue, this study reveals the relationships between the volume and average salinity of the tongue at different depths and local freshwater forcing, as well as salinity transport by the ITF, thereby contributing to an improved understanding of how regional water mass changes respond to long-term climate variability.

How to cite: yanran, P., sun, Q., zhang, Y., zhang, Y., chi, J., and du, Y.: Analysis of the mechanisms underlying the low-frequency variability of the low-salinity tongue in the southeastern Indian Ocean, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10227, https://doi.org/10.5194/egusphere-egu26-10227, 2026.

The rapid expansion of offshore wind energy infrastructure represents a major anthropogenic modification of coastal and marginal seas, yet the physical interactions between monopile foundations, hydrodynamics, and sediment transport remain insufficiently quantified. This study investigates the impact of monopile foundations at the Meerwind offshore wind farm (German Bight, North Sea) on local and regional coastal dynamics. Using a high-resolution coupled wave-current-sediment transport model, we analyze hydrodynamic and sediment processes with mesh refinement of ~2 m near the structures to capture turbulent wake effects.

Our results demonstrate that monopile arrays act as significant sinks for wave energy: monthly mean significant wave heights (Hs) and mid-depth velocities decrease by ~5%, while turbulent kinetic energy increases by up to 70% near the foundations. Dominant westerly wind-driven waves modulate tidal asymmetry on the leeward (eastern) side of the piles, generating asymmetric turbulent wakes and altering bottom shear stress patterns.

Reduced wave-induced bottom stress enhances localized sediment deposition, increasing surface suspended sediment concentration (SSC) while reducing near-bottom loads. On a regional scale, wave attenuation leads to a ~1% decrease in depth-averaged SSC over a 20 km east of the piles. In consequence, the presence of the wind farm reduces the net inflowing sediment flux by ~25% within a 5 km radius during March 2020, linked to a ~2 cm attenuation of Hs.

These findings highlight how large-scale offshore energy infrastructure can reorganize sediment budgets and coastal morphodynamics under changing human activities, providing critical insights for the sustainable management of multi-use ocean spaces. Further work, including additional wind farms and extended simulation periods, is planned to substantiate these initial findings and better quantify cumulative impacts, particularly in light of ongoing erosion challenges in the Wadden Sea under sea-level rise.

How to cite: Hosseini, S. T., Pein, J., Staneva, J., Stanev, E., and Zhang, Y. J.: Influence of Offshore Wind Farm Monopiles on Multi-Scale Hydrodynamics and Sediment Transport in a Wave-Current Environment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10444, https://doi.org/10.5194/egusphere-egu26-10444, 2026.

Effective coastal monitoring and forecasting systems rely on the availability and timeliness of interoperable, standardized, and accessible marine data across observational, modelling and service layers. Fragmented data formats, legacy infrastructures, and non-standardized access mechanisms remain significant barriers to the seamless integration of ocean observations into operational monitoring and forecasting systems and downstream applications.

This study presents the development of a standards-based data workflow designed to enhance interoperability, scalability, and facilitate marine data integration, through the adoption of international standards and best practices. The proposed approach focuses on establishing robust data flows that transform, validate, and harmonize heterogeneous datasets (e.g., in situ near-real-time observations and numerical model outputs) into NetCDF format. Standardized and programmatic access to these datasets is enabled though the OGC API Environmental Data Retrieval protocol, implemented using the pygeoapi platform. By adopting open standards and service-oriented architectures, this framework enables efficient spatio-temporal querying of ocean variables, facilitating their assimilation into forecasting systems, decision-support tools, and customized applications. In parallel, geoportal interfaces were updated to integrate the new OGC API EDR services, ensuring that interoperable data access is available both through machine-to-machine interfaces and user-friendly graphical tools, supporting a broad range of user profiles and promoting citizen involvement and ocean literacy.

By addressing interoperability at the data, service, and user-interface levels, this work demonstrates how standardized data infrastructures are key enablers for improved, scalable, and sustainable coastal monitoring and forecasting capabilities.

How to cite: Dias, T., Videira, C., Lobo, V., Costa, A. C., and Lourenço Baptista, M.: Improving coastal monitoring and forecasting systems through interoperable OGC API EDR-based data services, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11166, https://doi.org/10.5194/egusphere-egu26-11166, 2026.

The South Lhonak Lake (SLL) Glacial Lake Outburst Flood (GLOF) cascade event of 3-4 October 2023 triggered widespread devastation across Sikkim and the downstream region of Bangladesh, causing significant loss of lives and property. The post-disaster research shows that the GLOF event was triggered by a moraine failure, creating tsunami waves in the lake, eventually leading to the breach of the frontal moraine. Despite partial drainage of the lake in the 2023 event, the hazard potential of the lake needs further investigation. This makes it extremely important to continuously monitor the surrounding regions to identify unstable slopes that can potentially fail and impact the lake. The present study utilises a Sentinel-1 Small Baseline Subset (SBAS) workflow performed in the ASF OpenSARLab environment to analyse the condition of the moraines post-SLL disaster. Post-disaster analysis spanning October 2023 to September 2025 reveals continued moraine instability, characterised by an actively deforming zone along the right flank of the failed zone. This region shows a maximum LOS displacement rate of approximately -4 cm yr^-1, with a maximum cumulative LOS displacement reaching around -6 cm in the ascending track and -5 cm in the descending track. The results indicate persistent post-failure deformation and ongoing slope instability in the moraines of South Lhonak. The study provides a critical insight into the temporal behaviour of moraine slopes. This study aimed at strengthening the disaster management strategies by integrating satellite-based deformation monitoring for early warning and risk reduction measures.

How to cite: Verma, U. and Sattar, A.: Monitoring post-GLOF moraine dynamics at South Lhonak lake using satellite radars, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11635, https://doi.org/10.5194/egusphere-egu26-11635, 2026.

Coastal ecosystems are highly vulnerable to nutrient-driven eutrophication from anthropogenic sources such as urbanization, wastewater discharge, and industrial development, among others, which alters their ecosystem services. In order to determine nitrogen sources, the nitrogen isotopic composition (δ¹⁵N) was analyzed in the macroalgae Boodleopsis verticillata and Bostrychia spp., collected between 2014 and 2016 at four localities with different degrees of anthropogenic disturbance: Valencia – Very Low Intervention (MBI-VA), Chucheros – Low Intervention (BAI-CHU), San Pedro – Moderate Intervention (MOI-SP), and Piangüita – High Intervention (ALI-PI) in the Colombian Pacific. The δ¹⁵N values ranged between 0.3 and 2.4‰ in MBI-VA, 1.8 and 3.4‰ in BAI-CHU, 2.3 and 5.5‰ in MOI-SP, and 2.3 and 10.16‰ in ALI-PI. Since the assumptions of normality and homogeneity of variances were not met (p < 0.05), a non-parametric Kruskal–Wallis test was applied, revealing significant differences in δ¹⁵N among localities (p < 0.0001). Dunn’s test indicated that MBI-VA and BAI-CHU differed significantly from MOI-SP and ALI-PI (p < 0.05). Three nitrogen sources were defined: atmospheric deposition, oceanic waters, and wastewater. Both species (B. verticillata andBostrychia spp.) showed a decreasing gradient of atmospheric deposition (87% ± 3% to 52% ± 7% and 82% ± 6% to 21% ± 11%, respectively) from MBI to ALI, in contrast to an increase in oceanic waters (8% ± 4% to 37% ± 13% and 12% ± 7% to 38% ± 21%) and wastewater contributions (5% ± 2% to 12% ± 6% and 7% ± 3% to 41% ± 12%). This pattern was more evident in Bostrychia spp., suggesting greater sensitivity to variations in nitrogen sources. Linear regression between δ¹⁵N and nitrate concentration yielded coefficients of determination of R² = 0.71 for B. verticillata and R² = 0.89for Bostrychia spp., indicating that isotopic variability was explained by nitrate. The potential of macroalgae as bioindicators of anthropogenic intervention in coastal ecosystems of the Colombian Pacific is suggested.

How to cite: Arce-Sánchez, R. S., Medina-Contreras, D., and Sánchez-González, A.:  Use of δ15N and macroalgae as indicators of the level of anthropogenic intervention in the Colombian Pacific., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13664, https://doi.org/10.5194/egusphere-egu26-13664, 2026.

Arctic sea ice plays a critical role in regulating global climate and marine primary production, yet long-term records documenting its natural variability remain sparse in the Pacific sector of the Arctic Ocean. This limitation hampers our ability to establish a regionally coherent understanding of how sea ice responds to climatic and oceanographic forcing on centennial to millennial timescales. Here, we present a new biomarker-based reconstruction of Holocene sea ice and environmental change from the southern Chukchi Sea, north of the Bering Strait.

A 519-cm sediment core (SKQ-VC29) was recovered using a vibracorer and spans the last ~8.6 kyr, based on 17 AMS radiocarbon dates from shells and terrestrial macrofossils. Downcore concentrations of highly branched isoprenoids (HBIs) and sterols were quantified to reconstruct sea-ice conditions, marine productivity, and terrestrial organic matter (OM) inputs. Seasonal sea ice presence is inferred from IP25, a mono-unsaturated HBI produced by sea-ice diatoms, while open-water conditions and phytoplankton productivity are tracked using HBI III, brassicasterol, and dinosterol. These proxies are combined using the PIP25 index to provide a semi-quantitative reconstruction of sea-ice cover. Terrestrial inputs are assessed using vascular-plant sterols (campesterol and β-sitosterol), alongside bulk δ¹³C and C:N ratios.

The record indicates predominantly open-water conditions during the early to mid-Holocene, followed by the reappearance of seasonal sea ice at ~2.5 kyr BP—substantially later than in more northerly Arctic records. This delayed signal suggests that Neoglacial sea-ice expansion in the Pacific Arctic was spatially heterogeneous. Bulk OM proxies and declining β-sitosterol concentrations indicate a progressive reduction in terrestrial OM delivery through the Holocene, while marine productivity remains relatively stable. A pronounced shift at ~4 ka BP marks reduced organic carbon accumulation and broader environmental reorganization.

Together, these results improve spatial coverage of Holocene sea-ice reconstructions in the Pacific Arctic and highlight the complex, regionally variable nature of sea-ice evolution in a climatically sensitive gateway region.

How to cite: Jin, K., de Vernal, A., Pickart, R. S., Chen, M., Otiniano, G., and Porter, T.: Holocene Sea Ice and Organic Matter Dynamics in the Southern Chukchi Sea Revealed by Lipid Biomarkers, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15143, https://doi.org/10.5194/egusphere-egu26-15143, 2026.

Sea ice classification is often a crucial step to predict climatic insights and ensure safe marine navigation. In the last few decades, satellite information has been widely used to classify sea ice in broad areas for practical applications. However, common problems are:

1) Low resolution of satellite images to provide precise classification,

2) High computational need, and

3) Scarcity of general models to discover unknown patterns in the data, especially those that enable free selection of satellite sensors to fit the application at hand.

We propose an explainable unsupervised model to integrate ice-experts’ inputs to models so that the problem of having low-resolution data can be overcome. In other words, the results of the models, given as semantic maps, can be further refined using inputs from ice-experts.

Model explainability and visual interpretation of models serve as tools to talk to’ domain experts. The use of Explainable AI in such vital activities ensures trust and easy detection of error. We present an example from a sea ice classification with Sentinel-1 time-series in the scope of the Horizon 2020 project ExtremeEarth.

A further example from the Horizon Europe project dAIEdge demonstrates the use of these explainable models for ‘on-the-edge’ inference.

How to cite: Dumitru, C. O., Karmakar, C., and Wiehle, S.: Explainable Expert-in-the-loop sea-ice classification with statistical models, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16248, https://doi.org/10.5194/egusphere-egu26-16248, 2026.

Dust in the Arctic is an emerging topic related to climate and environmental impacts. The United Nations (UN) General Assembles and the UN Coalition to Combat Desertification (UNCCD) have reiterated that the global frequency, intensity, and duration of Sand and Dust Storms (SDS) have increased in the last decade and that SDS have natural and human causes that can be exacerbated by desertification, land degradation, drought, biodiversity loss, and climate change. UNCCD and FAO have also highlighted that emerging SDS source areas have been associated with the warming of the Arctic and high latitude regions, the seasonal or permanent drying of inland waters and river deltas, or are following large-scale deforestation and wildfires, or even the ploughing of a single field. Loss of snow cover, retreat of glaciers, and increase in drought intensity due to climate change can lead to surface conditions that increase the likelihood of creation, continuation and expansion of SDS source areas.

Climatic feedback mechanisms and ecosystem impacts related to dust in the Arctic include direct radiative forcing (absorption and scattering), indirect radiative forcing (via clouds and cryosphere), semi-direct effects of dust on meteorological parameters, effects on atmospheric chemistry, as well as impacts on terrestrial, marine, freshwater, and cryosphere ecosystems. Here we give an overview of our recent understanding on dust emissions and their long-range transport routes, deposition, and ecosystem effects in the Arctic as presented in Meinander et al. (2025), part of the series of review papers of the Arctic Council Working Group AMAP (Arctic Monitoring and Assessment Program) and CAFF (Conservation of Arctic Flora and Fauna), where the target audience is the scientific community focusing on the Arctic. Additional audiences include policy advisers and other staff in environmental-related ministries.

We conclude that the multiple mechanisms related to dust emissions, transport and deposition both cool and warm the climate system, with an uncertain net effect. Dust plays a significant role in terrestrial and aquatic ecosystems, e.g., by providing nutrients, and with impacts on the availability of light and water. Due to Arctic warming, HLD dust emissions can be expected to increase. The contributions of LLD and HLD complicates the interpretation of how much different sources contribute to the dust loadings and corresponding temporal and spatial deposition patterns. Another challenge is that low latitude dust source emissions of road and agricultural dust is barely characterized.

Reference:

Meinander O, Uppstu A, Dagsson-Waldhauserova P, Groot Zwaaftink C, Juncher Jørgensen C, Baklanov A, Kristensson A, Massling A and Sofiev M (2025). Dust in the arctic: a brief review of feedbacks and interactions between climate change, aeolian dust and ecosystems. Front. Environ. Sci. Sec. Interdisciplinary Climate Studies, Volume 13 – 2025. doi: 10.3389/fenvs.2025.1536395. CAFF-special issue.

How to cite: Meinander, O., Uppstu, A., Dagsson-Waldhauserova, P., Groot-Zwaaftink, C., Juncher Jørgensen, C., Baklanov, A., Christenson, A., Massling, A., and Sofiev, M.: Dust in the Arctic: feedbacks and interactions between climate change, aeolian dust and ecosystems, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16935, https://doi.org/10.5194/egusphere-egu26-16935, 2026.

Accelerated glacier retreat in the Western Himalaya has led to rapid expansion of glacial lakes and increasing concern over Glacial Lake Outburst Flood (GLOF) hazards. This study presents a basin-scale assessment of glacial lake evolution, potential future lake formation, and GLOF susceptibility in the Chenab Basin, integrating multi-temporal remote sensing, terrain analysis, and probabilistic exposure modelling. A decadal inventory of glacial lakes was developed for five time periods (1990, 2000, 2010, 2020 and 2025) using Landsat and Sentinel-2 imagery, combined with semi-automated extraction and geomorphological classification. Results reveal a consistent increase in both lake number and total area over the last three decades. Potential future glacial lakes were identified using various ice-thickness modeling approach applied to current glacier extents. This analysis presents an inventory of the future glacial lake in the entire basin giving special emphasis to determining the characteristics of the future lake including maximum extent of the future lakes and volume of the future glacial lakes. GLOF susceptibility of existing lakes was evaluated using a multi-criteria framework to identify critical lakes requiring priority monitoring. Downstream exposure was further assessed using the Monte Carlo Least Cost path approach, explicitly accounting for uncertainty in breach location and flood routing parameters to delineate probable impact corridors. The framework provides new insights into evolving cryospheric hazards in the Chenab Basin and demonstrates the utility of combining lake dynamics, future lake potential, susceptibility assessment, and probabilistic exposure analysis for improved GLOF risk prioritization in the Western Himalayas.

How to cite: Das, D. R. and Sattar, A.: Evolution of present and potential future glacial lakes and implications for GLOF hazard in the Chenab Basin, Western Himalaya, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17889, https://doi.org/10.5194/egusphere-egu26-17889, 2026.

Machine learning (ML) remains one of the best approaches for long-term seasonal streamflow forecasting in cold regions owing to its capacity to capture nonlinearity between inputs and outputs, as well as its scalability across hydroclimatic regimes. ML’s main advantage lies in the generalizability of these models when applied to heavily glacierized catchments. In this data-driven study, we mainly utilize the Extreme Gradient Boosting (XGBoost) regression to train and test seasonal streamflow predictions using the LArge-SaMple DAta for Hydrology and Environmental Sciences for Iceland (LamaH-Ice). This new dataset for Iceland, published in 2024 consists of topographic, hydroclimatic, land cover, vegetation, soil, geological, and glaciological attributes that are essential for understanding cryosphere–hydrology processes in cold regions. For more than 100 basins, time series information on meteorological forcings and variables relevant to cold-region hydrology, such as MODIS (Moderate Resolution Imaging Spectroradiometer) snow cover, glacier albedo are also available. The majority of gauged rivers in LamaH-Ice are reported to have minimal human disturbances, making the dataset particularly unique. The XGBoost model demonstrates strong predictive skill across the study basins, as indicated by Kling-Gupta Efficiency (KGE) and Nash-Sutcliffe Efficiency (NSE) metrics exceeding 0.98. Ultimately high-precision streamflow forecasting is needed to track hydrometeorological hazards and to aid our ability to manage water resources in cold regions, which are a source for irrigation and hydropower.

References

Helgason, Hordur Bragi, and Bart Nijssen. “LamaH-Ice: LArge-SaMple DAta for Hydrology and Environmental Sciences for Iceland.” Earth System Science Data, vol. 16, no. 6, 13 June 2024, pp. 2741–2771, doi:10.5194/essd-16-2741-2024. 

Strahlendorff, Mikko, et al. “Forestry Climate Adaptation with HarvesterSeasons Service—a Gradient Boosting Model to Forecast Soil Water Index SWI from a Comprehensive Set of Predictors in Destination Earth.” Frontiers in Remote Sensing, vol. 5, 20 Dec. 2024, doi:10.3389/frsen.2024.1360572.

How to cite: Prakasam, G., Strahlendorff, M., Kröger, A., and Gunnarsson, A.: Machine Learning based Seasonal Streamflow Forecasting in Cold-Region Catchments: Insights from LamaH-Ice dataset, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20743, https://doi.org/10.5194/egusphere-egu26-20743, 2026.

Near-surface water ice in Phlegra Montes, Mars, could support human exploration and settlement. Orbital sounding radar provides strong evidence for the existence of this ice, as does morphology consistent with debris-covered glaciers. Impact excavation of these glacier-like features has exposed ice, visible in HiRISE images, but the distribution and quantity of this ice is uncertain, necessitating further evaluation for its potential to support human exploration. We are developing the Prototype Radar Sounding Experiment for Unveiling the Subsurface (PERSEUS) instrument to study debris-covered glaciers on Earth and Mars, and we propose D-PERSEUS, a mission to study a debris-covered glacier in Phlegra Montes using a drone-based Ground Penetrating Radar like this one. This mission could verify the presence of water ice in-situ and improve characterization of water ice resources, which could serve as exploratory work ahead of a potential Mars Life Explorer mission.

How to cite: Spurling, R., Nerozzi, S., and Aguilar, R.: D-PERSEUS: A Drone Radar Mission to Study a Debris-Covered Glacier on Mars, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21809, https://doi.org/10.5194/egusphere-egu26-21809, 2026.

The dataset with the most spatial coverage for data assimilation of biogeochemical models in operational systems is the satellite-derived data. Nevertheless, variables derived from Remote Sensing Reflectance (RSR), like the sea surface chlorophyll concentration, for regions like coastal areas, can reach big errors if compared with in situ measurements. For this reason, a suggestion with the aim of improving the assimilated results comes from the direct assimilation of Remote Sensing Reflectance, removing the error derived from inferring the biogeochemical variable before assimilating. In this work, we focus on a case study, using the Biogeochemical Flux Model (BFM) merged with a hydrological model, we study the effects of the direct and indirect assimilation of RSR in a region located in the Ligurian Basin of the northwestern Mediterranean Sea.  For both assimilation experiments, the algorithm used was an Error Subspace Kalman Filter. To assess the results, we compared them with climatologies computed with in situ measurements, highlighting the advantages and disadvantages of both approaches. 

How to cite: Soto Lopez, C. E., Lazzari, P., Anselmi, F., and Teruzzi, A.: Indirect assimilation of remote sensing reflectance: case study in the Liguria Sea, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22059, https://doi.org/10.5194/egusphere-egu26-22059, 2026.

In-situ monitoring of calving process from lake-terminating glaciers in the Himalayas remain scarce, despite being a significant component controlling glacier retreat. Acquiring in-situ measurements are challenging due to harsh terrain and extreme weather conditions, which has typically resulted in the use of expensive, state-of-the-art terrestrial observational systems. Such limitation in data acquiring leads to an incomplete understanding of calving-induced glacial mass loss and retreat. In this study, we evaluate the effectiveness of a low-cost Raspberry-Pi based terrestrial photogrammetry system for annual monitoring of calving from lake-terminating glaciers. We tested the proposed system for monitoring calving at lake-terminating Panchinala-B Glacier, Indian Western Himalayas. The photogrammetry system consists of an array of Raspberry-Pi powered time-lapse cameras, which took multi-view stereo images of the glacier front face over a 12-month period between August 2023 and August 2024. The images were processed in a Structure-from-Motion (SfM) workflow to generate two, annually separated, point clouds. The Multiscale Model-to-Model Cloud Comparison (M3C2) distance of the annually separated point clouds yielded a mean terminus position change (retreat) of 0.88 m, with a mean absolute error of (+/-) 5.8 m. Using the above obtained parameters a calving rate and calving mass flux of  16.3 (+/-) 4.29 m/annum and 0.00017 (+/-) 0.000125 Gt/annum respectively can be quantified. Further, numerous environmental and system design-based challenges were encountered, which affected the quality of the obtained calving estimates. These challenges were carefully understood, and we provide further recommendations for the future use of similar low-cost systems for long-term glacier monitoring, which demonstrate good  potential for characterising the magnitude and frequency of calving processes at lake-terminating glaciers.

How to cite: Mandal, S., Taylor, L., Ramsankaran, R., and Quincey, D.: Low-Cost Terrestrial Photogrammetry System for Monitoring Calving from Lake-Terminating Glaciers, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-176, https://doi.org/10.5194/egusphere-egu26-176, 2026.

Field-based seasonal and annual mass-balance observations collected over the past one decade from four benchmark glaciers in the Ladakh region of the western Himalaya, Viz., Pensilungpa, Drang-Drung, Kangrez, and Machoi, indicate a consistent and significant loss of glacier mass across all elevation bands. Mass-balance estimates, obtained from stake networks and snow-pit observations exhibit persistently negative annual values, with enhanced ablation in lower and mid-elevation zones and limited accumulation at higher elevations. The average annual glacier mass balance ranges from −0.4 to −1.4 m w.e. yr⁻¹, with glacier-specific mass balance ranges of −0.8 to −1.4 m w.e. (Pensilungpa), −0.6 to −1.2 m w.e. (Drang-Drung), −0.5 to −1.1 m w.e. (Kangrez), and −0.4 to −0.9 m w.e. (Machoi). Winter accumulation across these four benchmark glaciers ranges from +0.3 to +1.1 m w.e., while summer ablation varies between −0.8 and −2.0 m w.e., reflecting strong altitude-dependent glacier-melt. All glaciers show steep mass-balance gradients, with a pronounced melt in lower ablation zones, and limited but persistent accumulation at higher elevations in the accumulation zones. Drang-Drung and Kangrez exhibit relatively stronger winter mass gains at higher elevations, while Pensilungpa and Machoi display the most intense summer ablation. Although the accumulation zones still gain seasonal mass, but it is not enough to offset the significant ablation as the ablation zones dominate glacier area, causing cumulative negative mass balances. The upward-shifted equilibrium-line altitudes and the dominance of ablation over accumulation indicate the increasing glacier sensitivity to regional warming in the cold desert Ladakh region.

Based on typical uncertainties associated with stake measurements, density sampling, and spatial interpolation of point observation, the uncertainty in annual mass-balance is estimated at ±0.25–0.40 m w.e. yr⁻¹. Despite this uncertainty, the results robustly demonstrate significant glacier mass loss in the  Ladakh region, underscoring enhanced cryospheric vulnerability to climate change and potential impacts on hydrological regimes in the upper Indus basin. These findings are consistent with regional trends in the Himalaya showing accelerated ice loss and rising ELAs, underscoring the growing sensitivity of cold-arid glaciers to climate warming, once considered relatively resilient. Continued mass loss has significant implications for water security, climate adaptation, and glacier hazard risk management across the upper Indus basin.

How to cite: Romshoo, S. A., Lone, B. N., Shah, U. A., Bhat, M., Shah, W., Bhat, M., Shah, W., Yousuf, A., Abdullah, T., Murtaza, K. O., Lone, G., Mir, A., Shah, U., Paul, O., and Romshoo, S.:  Melting Glaciers in the Western Himalaya: Evidence from In-Situ Seasonal and Annual Mass Balance Observations from the Ladakh Himalaya , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-791, https://doi.org/10.5194/egusphere-egu26-791, 2026.

Knowledge of crevasse locations is essential for improving our understanding of glacier dynamics. In addition, accurate information on crevasses is crucial for mountaineering safety and enables reliable route planning. However, large-scale monitoring remains difficult because crevasses vary greatly in appearance and often show low contrast on snow-covered surfaces, limiting the effectiveness of traditional detection methods. Here, we present an automated crevasse-detection approach based on a multi-task neural network trained on high-resolution orthophotos of Austrian alpine glaciers.

The model was developed using 20 cm aerial imagery of glaciers in the Ötztal and Stubai Alps. Through systematic training and validation, the network achieved 86% detection accuracy across independent test sites, demonstrating robust performance in diverse glaciological settings. The multi-task architecture enables simultaneous feature extraction and classification, efficiently handling the complex spectral and textural characteristics of crevassed ice surfaces.

Following successful validation, we applied the method to all glaciated areas in Austria, producing a comprehensive, high-resolution dataset of crevasse locations. We analysed the spatial distribution of crevasses on Austrian glaciers in different mountain regions, including Hohe Tauern, Dachstein, Ötztal, Stubai, Silvretta and Zillertal.  Analysis of this dataset reveals spatial patterns of crevasse distribution and quantitative metrics on variations in crevasse density across slope, elevation, velocity, curvature and aspect.

The crevasse location dataset provides glacier modelers with detailed boundary conditions for glacier modelling and helps mountaineers plan safe routes. This dataset has already been incorporated into recently published hiking maps by the Austrian Alpine Club and demonstrates how machine learning and open data initiatives can bridge glaciological research and practical applications.

How to cite: Baumhoer, C. A., Straßburger, S., Leibrock, S., and Dietz, A.: Large-Scale Detection of Alpine Glacier Crevasses Using Remote Sensing and Deep Learning, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1391, https://doi.org/10.5194/egusphere-egu26-1391, 2026.

Satellite remote sensing has become a cornerstone for monitoring glacier surface velocity and strain rates, with normalized cross-correlation (NCC) techniques widely adopted due to their efficiency and robustness. However, current approaches to quantifying strain-rate uncertainty exhibit substantial limitations. They rely primarily on empirical statistics or classical error-propagation theory, which implicitly assumes spatially independent Gaussian velocity errors and fails to account for the numerical effects introduced by NCC algorithmic parameters and environmental conditions. As a result, strain-rate errors derived from NCC-based velocity fields are poorly characterised at sub-monthly timescales over rapidly evolving glaciers, and technical uncertainties cannot be effectively separated from systematic velocity-field mismatches, limiting the applicability of remote-sensing products in glacier dynamics studies.

We develop a first-principles uncertainty theory by explicitly modelling the fundamental error mechanisms underlying NCC-derived velocity measurements. Building upon the classical error-propagation framework, we combine ordinary differential equations and stochastic process theory to rigorously derive analytical error expressions for two commonly used strain-rate formulations applied to NCC-derived velocity fields: nominal strain rate and logarithmic strain rate. The theory demonstrates that, although the nominal strain-rate error shares a similar mathematical structure with classical error propagation, its coefficients are substantially smaller than those predicted by traditional formulations. In contrast, the logarithmic strain rate (based on the Nye model and Alley grid-based implementation) converges to the true strain rate under normal circumstances, while degenerating to the nominal strain-rate solution in the worst case.

We validate the theoretical predictions using Helheim Glacier, Greenland, as a test case. Surface velocities are extracted from 616 Sentinel-2A/B image pairs with time baselines from 1 to 32 days, followed by statistical analysis of strain-rate errors. Under controlled NCC failure rates, the theoretical model achieves a goodness of fit exceeding R > 0.8, confirming the robustness of the proposed framework.

Our results further reveal a strong dependence of strain-rate error on temporal baseline and pixel distinguishing capacity. For longer baselines (Δt > 18 days over Helheim Glacier), high-strain environments such as shear margins lead to a loss of image similarity, increasing NCC failure rates and inducing systematic velocity-field errors that cause strain-rate overestimation. For shorter baselines (Δt < 10 days), nominal strain rates are strongly limited by pixel distinguishing capacity, producing random non-zero velocity artefacts over stable terrain. Owing to the error attenuation behaviour of logarithmic strain rate, the effective lower bound of usable time baselines is reduced to approximately 3 days, enabling high-temporal-resolution monitoring. Based on the derived error equations, we propose a practical time-baseline selection guideline that constrains random strain-rate errors induced by technical uncertainty, while facilitating the separation of systematic velocity-field errors.

Overall, this work provides an end-to-end uncertainty quantification framework linking remote-sensing techniques to glacier strain-rate products, offering a theoretical foundation for quality control, uncertainty assessment, and data assimilation in next-generation glacier strain-rate monitoring.

How to cite: Zhang, C., Wang, X., and Zhou, Y.: Uncertainty propagation from Sentinel-2A/B-derived velocity to glacier strain rates: a first-principles perspective, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2248, https://doi.org/10.5194/egusphere-egu26-2248, 2026.

The equilibrium-line altitude (ELA) is a key indicator of the climatic limit for glacier sustainability. Monitoring ELA is therefore essential for understanding and projecting glacier change. In practice, however, direct ELA measurements from field surveys (the glaciological method) are available for only a limited number of glaciers because sustained observations require substantial time and labor.

Here, we observe multi-decadal variations in firn-line altitude (FLA) over an Alaskan icefield located near a well-monitored reference glacier with a long-term in situ ELA record, using a time series of L-band SAR imagery from JERS-1, ALOS, ALOS-2, and ALOS-4. We validate the SAR-derived FLA against the in situ ELA record and find that FLA variations closely track the observed ELA changes. This agreement indicates that L-band SAR-based FLA retrieval can serve as a proxy for long-term ELA trends.

To clarify how winter observations differ between frequencies, we compare winter backscatter behavior at C-band and L-band. Winter C-band backscatter is strongly influenced by scattering from seasonal snow cover. By contrast, wintertime dry snow is largely transparent at L-band, and winter L-band SAR therefore primarily reflects surface conditions established at the end of the preceding summer. These results suggest that FLA can be monitored with a single winter L-band SAR acquisition.

How to cite: Arie, K. and Tadono, T.: Firn-Line Monitoring over the Juneau Icefield in Alaska Using SAR Data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2645, https://doi.org/10.5194/egusphere-egu26-2645, 2026.

Glacier ice thickness models are fundamental to studies of glaciology, hydrology, and climatology. They play a key role in estimating ice volume, simulating future glacier evolution, and projecting meltwater runoff changes. However, ice thickness measurements (e.g., ice penetrating radar) only cover about 14% of global glacier area and disparity exists in existing ice thickness models inferred from glacier surface information, making it difficult for glaciologists to accurately simulate and project the future evolution of mountain glaciers and its impact on global sea level change and regional water supply. This study developed a 1.98 km resolution ice thickness model of the West Kunlun glaciers by inverting geophysical data surveyed through an Airbus AS350-B3e helicopter. We analyzed the errors associated with the inversion techniques, evaluated the accuracy of the ice thickness model using ice penetrating radar data, and calculated the ice volume over the surveyed region. Through model comparisons, glacier topographic features not resolvable in previously published models were identified and their potential impacts were analyzed. The ice thickness model developed in this study could provide fundamental data sets for the study of the response of glaciers to climate change and thus contributes to an improved modeling and projection of future evolution of mountain glaciers and its impact on global sea level change and regional water supply.

How to cite: Yang, J. and Shu, Q.: Ice thickness of the West Kunlun glaciers revealed by airborne geophysical survey, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4618, https://doi.org/10.5194/egusphere-egu26-4618, 2026.

Glaciers are crucial components of the Earth's climate system and serve as indicators of climate change. Their substantial mass loss due to global warming significantly contributes to sea-level rise and impacts regional hydrology, downstream ecosystems and settlements. Despite considerable advancements in observational and modeling techniques, accurately quantifying glacier responses to climate change and predicting their future behavior remain complex challenges, particularly in regions characterized by rapidly changing glaciers and complex topography. In this study, we present a spatially resolved time series of annual glacier mass balance and elevation change for the Southern Andes from 2002 to 2025, derived from ASTER digital elevation models (DEMs). All available austral summer-season DEMs were compiled to minimize seasonal bias, and an automated processing workflow was developed to generate elevation change maps for the entire region as well as for individual glaciers. This approach enables consistent, large-scale monitoring without reliance on in-situ measurements, making it particularly valuable for remote and data-scarce regions. Elevation differences were converted to mass balance estimates using density assumptions, allowing both regional-scale assessments and detailed analysis of glacier complexes. Our results reveal pronounced spatial and temporal variability in glacier thinning, including periods of accelerated mass loss and localized heterogeneity linked to topographic and climatic factors. The developed methodology provides a scalable framework for long-term glacier monitoring and contributes to improved understanding of regional cryosphere dynamics and their implications for water resources and sea-level rise.

How to cite: Usoltseva, M., Pail, R., Wendt, A., and Mayer, C.: Two Decades of Glacier Mass Balance in the Southern Andes , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7746, https://doi.org/10.5194/egusphere-egu26-7746, 2026.

Continuous observations of glaciers are critical for measuring climate variability and understanding its consequences for regional water supplies. This study presents a comprehensive assessment of glacier changes in terms of dimension, mass balance and surface velocity in the Gyama Massif, Karzok Range, Ladakh, from 1980 to 2025. In 1980, the Gyama contained 100 glaciers characterized by a mean area of ~0.50 km² (range 0.02–4.77 km²), steep mean surface slopes of ~26° (13–41°), and high mean elevations of ~5,797 m a.s.l. (5,590–6,140 m a.s.l.), indicating predominantly small, steep, high-altitude glacier systems. The glaciers in this region experienced a total deglaciation of ~41% between 1980 and 2025. Mass-balance measurements for 100 glaciers indicate a moderately negative mean mass balance of −0.18 ± 0.10 m w.e. y^-¹ for 2000–2018. Glacier flow velocities (1990–2022) exhibit a statistically significant decreasing trend of −0.13 m y^-¹, corresponding to a ~75% reduction in mean velocity over the 32-year period. The average velocity of all glaciers across the study period was 4.16 m y^-¹. The most pronounced areal losses occurred among the smallest glaciers: those <0.1 km² in 2000 experienced >80–100% area loss, and several glaciers disappeared completely. Glacier fragmentation increased substantially, with the number of discrete glaciers rising from 9 in 2015 to 14 in 2020 and 28 in 2025, reflecting progressive morphological disintegration associated with sustained mass loss.The substantial loss of glacier area across the Gyama Massif, together with progressive mass loss, has led to a marked slowdown in surface ice velocity, highlighting the strong coupling between glacier geometry, mass balance, and ice flow. The consistent glacier decline at very high elevations (mean ~5797 m a.s.l.) further points to the influence of elevation-dependent warming in this Trans-Himalayan region. We recommend sustained high spatio-temporal resolution remote sensing, complemented by targeted field observations, to improve glacier monitoring in this data-sparse high-altitude region. Such integrated approaches are essential for detecting glacier instability and evaluating impacts on regional hydrology and downstream water resources in the Trans-Himalaya.

Keywords: Remote sensing; Mass balance; Glacier velocity; Deglaciation; Glacier fragmentation; Ladakh Himalaya

How to cite: Prajapati, M., Garg, P. K., Mukherjee, S., Guha, S., Tiwari, A., and Taloor, A. K.: Remote sensing insights into fragmentation and decline of glaciers in the Gyama Massif of Karzok, Ladakh (1980-2025), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7945, https://doi.org/10.5194/egusphere-egu26-7945, 2026.

Glacier thermal conditions directly influence ice mechanics, meltwater storage, and drainage, thereby governing glacier stability and hazard potential. Polythermal glaciers, in particular, can create conditions that promote ice break-offs, ice avalanches, water pocket outbursts, and even large-scale glacier detachments. Understanding their distribution is therefore critical for hazard assessment. Yet englacial temperature measurements in the Alps remain sparse and are biased toward high-elevation accumulation areas, while the thermal state of mid- and lower-elevation ablation areas is largely unknown. Extended melt seasons and refreezing of meltwater in cold firn have been associated with warming at high elevations, whereas firn loss at lower elevations may reduce meltwater retention and latent heat input. Modeling studies suggest that this imbalance can lead to cooling in ablation areas, an effect that may be particularly pronounced for very small glaciers, where internal heat production from glacier dynamics is minimal.

Here, we present a new englacial temperature dataset from six small Swiss Alpine glaciers (3000–3800 m a.s.l.), directly addressing the lack of observations in mid- to lower-elevation ablation areas that are poorly constrained by existing measurements. The dataset combines borehole thermometry with ground-penetrating radar surveys. Polythermal conditions were identified in three glaciers, with the cold–temperate transition surface (CTS) occurring at depths of 14–25 m. Below the seasonal surface layer, ice temperatures generally ranged from temperate conditions to –2.1 °C. Two of the glaciers exhibit a recurring pattern in which temperate ice at higher elevations transitions downslope into fully or partially frozen glacier tongues. At the third polythermal site, the CTS was detected at several locations between 17 and 22 m depth, while basal thermal conditions remain partly unresolved. One glacier appears predominantly cold, and at two additional sites, shallow thermistors recorded year-round cold conditions within the seasonal layer, while temperate ice at depth cannot be ruled out. Ground-penetrating radar reflectivity is generally consistent with borehole-derived thermal conditions, characterized by low reflectivity in cold ice and enhanced reflectivity in temperate zones. Our findings suggest that polythermal-type glaciers in the European Alps may be more widespread than previously recognized, with important implications for glacial hazard assessment and for understanding climate-driven changes in smaller Alpine glaciers.

How to cite: Beer, J., Jacquemart, M., Huss, M., Santin, I., Clara Racz, G., Ogier, C., Hösli, L., Moser, R., Irving, J., and Farinotti, D.: Polythermal conditions in small glaciers in the Swiss Alps, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8358, https://doi.org/10.5194/egusphere-egu26-8358, 2026.

Measuring glacier mass change worldwide is essential to document the impact of climate change, understand glacier-related hazards and assess the contribution of the cryosphere to sea-level rise. Over the last two decades, three remote-sensing techniques have been used to measure glacier mass change: digital elevation model (DEM) differencing, altimetry and gravimetry. The Glacier Mass Balance Intercomparison Exercise (GlaMBIE, ESA-funded) aims to compile, homogenize and combine these regional glacier mass change observations.  

One intriguing outcome from the first GlaMBIE phase (2022–24) was a systematic difference of region-wide elevation change measured using ASTER DEM differencing (dDEM) and CryoSat-2 radar altimetry. In most cases, dDEM resulted in more negative values in all glacier regions with an average regional difference of 0.08 ± 0.07 m w.e. yr-1 (The GlaMBIE Team, 2025). The work presented here is part of the second GlaMBIE phase (2025–27). It aims at describing in more detail and understanding the differences between these two techniques. We focus on major Icelandic ice caps as test sites as they present a good coverage for both techniques and are also covered with high resolution, precise dDEM data (e.g., airborne lidar in 2013 and Pléiades in 2020 for Hofsjökull ice cap).  

Our preliminary results indicate that the differences between published ASTER (Hugonnet et al., 2021) and CryoSat-2 (Jakob and Gourmelen, 2023) estimates are also found at ice cap and glacier scale. Next, we plan to compare the methods over the exact same period, and evaluate them using accurate validation data. We will also test the sensitivity to the software used to generate the DEMs, to alternative processing of CryoSat-2 data, and to the post-processing of the data (altimetry and DEMs) to find the key reasons for the systematic difference.

How to cite: Guyez, A., Berthier, E., Jakob, L., Gourmelen, N., Piermattei, L., Webster, C., U. Nussbaumer, S., Zemp, M., M.C. Belart, J., and Jóhannesson, T.: Glacier elevation change estimates: decoding the systematic differences between radar altimetry and DEM differencing, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9325, https://doi.org/10.5194/egusphere-egu26-9325, 2026.

In this study, we present a high temporal resolution (30-minute) multi-view stereo (MVS) photogrammetric dataset capturing the front of the lake-terminating Perito Moreno Glacier during daylight over more than one year. We aim to provide novel data to investigate glacier dynamics, which are strongly affected by climate change and pose increasing risks to ecosystems and human infrastructure. The images for the photogrammetric reconstruction are automatically inspected and prepared to create high-precision 4D (3D + time) point clouds, which are then compared per epoch to detect surface changes along an approx. 300 m wide study reach.

The MVS system comprises eight DSLR cameras and uses 4G connectivity for daily data transfer, aiming for near-real-time monitoring. This has resulted in more than 75,000 images stored on a central server, which allows the calving analysis based on more than 5,000 models. To isolate image regions relevant for the generation of dense clouds with maximum precision across as many epochs as possible, the images are segmented using the artificial intelligence (AI)-based image segmentation model SAM2. The relevant regions are assessed using blur metrics, which identify low contrast caused by harsh glacier conditions, such as moisture or water droplets, thereby reducing the risk of including images of low quality that interfere with image correlation success.

The results of our image pre-processing demonstrate that lighting conditions have the greatest impact on image segmentation performance. In contrast, the final model quality of the 4D point cloud reconstructions, which are based on a multi-epoch multi-imagery (MEMI) strategy, is mostly affected by the presence of adjacent dynamically changing regions, such as floating ice on the lake, highlighting the need for masking these regions. Applying masking further seems to improve the robustness of detecting subtle glacier surface changes, which is essential for pre-failure deformation analysis, providing valuable input for future calving prediction efforts.

The point cloud sequences are analyzed using the Multiscale Model to Model Cloud Comparison (M3C2) algorithm to quantify surface changes. Although calibration parameters of focal length and principal point exhibit temporal variability, a constant calibration strategy is examined to ensure consistent alignment across all epochs, which furthermore enables the observation of glacier flow velocities in both horizontal and vertical directions. Initial results for a test period during a week in summer indicate that a constant calibration does not adversely affect model generation, suggesting that calibration stability may be sufficient under favorable summer conditions, while ongoing analyses will assess the robustness during winter months. Current efforts focus on refining dense cloud quality by separating glacier surfaces from points reconstructed on stable rock areas, which were intentionally retained during point cloud generation to provide stable reference regions for the MEMI workflow.

Our introduced workflow enables the creation of a reliable calving inventory, exceeding the spatio-temporal resolution of conventional glacier monitoring techniques. In a next step, we aim to combine the created calving inventory with associated dynamic parameters, such as glacier velocity, and with environmental variables to support the development of AI-based calving prediction models.

How to cite: Duran Vergara, L. C., Nagathihalli Lokesh, B., Blanch Gorriz, X., and Eltner, A.: 4D Multi-View Stereo Reconstruction for High-Resolution Calving Monitoring of Glacier Perito Moreno: A Basis for Dynamic Analysis and Prediction, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9409, https://doi.org/10.5194/egusphere-egu26-9409, 2026.

The Antarctic Peninsula is among the most rapidly warming regions on Earth and has experienced widespread glacier retreat and acceleration since at least the 1980s, with significant implications for global sea level rise. Glacier change in this region unfolds across a wide range of timescales, spanning from short-lived dynamic events that can trigger persistent adjustments to recurring seasonal variability. However, Earth observation datasets that capture glaciological variables such as ice velocity or calving front dynamics at intra-annual timescales remain scarce. This is largely due to the small size and fast ice flow of Antarctic Peninsula glaciers, combined with complex topography, variable climate, and extreme weather conditions.

Here, we address this observational gap by leveraging a newly developed dataset of sub-seasonal terminus area change records (2013–2023) together with high-resolution satellite-derived ice surface velocity measurements (2014– 2024) to investigate the dynamics of 42 key outlet glaciers on the northern Antarctic Peninsula.

Our results reveal widespread glacier retreat and acceleration, with cumulative ice loss amounting to ~279 km². The majority of this loss (73 %) was observed for glaciers on the eastern Antarctic Peninsula, particularly within the Larsen B embayment, and is attributed to major calving events in early 2022. Although 71 % of the glaciers accelerated over the study period, most eastern glaciers displayed slight trends of slowdown – except for those in the Larsen B embayment, where initial deceleration was followed by abrupt and pronounced velocity increases after the calving events, with some glaciers more than doubling their flow speed. Seasonal analysis further indicates substantial inter-annual variability, with two-thirds of glaciers exhibiting strong seasonal velocity fluctuations, and around half displaying comparable signals in terminus area change.

Overall, the findings demonstrate the persistence of long-term trends of glacier retreat and flow acceleration, while also highlighting substantial spatial and temporal heterogeneity in glacier dynamics across the region, underscoring the need for temporally and spatially detailed monitoring.

How to cite: Leibrock, S., Slater, R. A. W., Hogg, A. E., and Baumhoer, C. A.: Monitoring of Antarctic Peninsula glacier terminus area change and ice surface velocity using dense satellite time series, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9511, https://doi.org/10.5194/egusphere-egu26-9511, 2026.

Mapping of elevation changes across large glacier regions is an essential basis for future IPCC reports. The first Glacier Mass Balance Intercomparison Exercise (GlaMBIE) established a community estimate of global glacier mass change [1]. However, the method of InSAR DEM differencing remains an underrepresented data source in this experiment.

For the second GlaMBIE data contribution, we aim to update our existing DEM Differencing processing pipeline [2]. It will be implemented on the high performance “Terrabyte” platform at the Earth Observation Center (EOC) of DLR. Unlike our previous contribution [2], which relied on targeted acquisitions to cover entire glacier regions, we will exploit the existing TanDEM‑X catalogue. This strategy facilitates future processing of large glacierized regions worldwide.

Recent advances regarding the uncertainty assessment of TanDEM-X DEM Differences will be fully incorporated in this pipeline [3, 4]. Special attention is given to reducing possible biases due to signal penetration. This bias is mitigated by differencing carefully selected TanDEM-X acquisitions from the same season with unchanged SAR geometry, reducing penetration differences between DEMs. Moreover, the relative importance of SAR signal penetration for accurate mass balance measurements also reduces with the length of the observation period.

In this work we will calculate the elevation change of all glacierized regions in Iceland based on available acquisitions in the TanDEM-X catalogue. Because the majority of TanDEM-X data were originally tasked and intended for the TanDEM-X Global DEMs, the final coverage will naturally gravitate towards these acquisitions, however alternative more suitable scenes in the catalogue will be substituted. A penetration-bias-optimized coverage for Iceland is best achieved by targeting the 2013 - 2021 period, with replacement scenes from other times possible.

We will investigate several spatial and temporal extrapolation strategies to fill gaps in Icelandic glacier coverage that must be left intentionally without measurements because the only available scenes are suspected of being affected by signal‑penetration biases.

References

[1]        Zemp, M., Jakob, L., Dussaillant, I., Nussbaumer, S. U., Gourmelen, N., Dubber, S., A, G., Abdullahi, S., Andreassen, L. M., Berthier, E., Bhattacharya, A., Blazquez, A., Boehm Vock, L. F., Bolch, T., Box, J., Braun, M. H., Brun, F., Cicero, E., Colgan, W., … The GlaMBIE Team. (2025). Community estimate of global glacier mass changes from 2000 to 2023. Nature, 1–7. https://doi.org/10.1038/s41586-024-08545-z

[2]        Abdel Jaber, W., Rott, H., Floricioiu, D., Wuite, J., & Miranda, N. (2019). Heterogeneous spatial and temporal pattern of surface elevation change and mass balance of the Patagonian ice fields between 2000 and 2016. The Cryosphere, 13(9), 2511–2535. https://doi.org/10.5194/tc-13-2511-2019

[3]        Hugonnet, R., Brun, F., Berthier, E., Dehecq, A., Mannerfelt, E. S., Eckert, N., & Farinotti, D. (2022). Uncertainty Analysis of Digital Elevation Models by Spatial Inference From Stable Terrain. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 15, 6456–6472. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. https://doi.org/10.1109/JSTARS.2022.3188922

[4]        Li, S., & Hajnsek, I. (2025). Geodetic glacier mass balance in the Karakoram (2011–2019) from TanDEM-X: An InSAR DEM differencing framework. Remote Sensing of Environment, 331, 115023. https://doi.org/10.1016/j.rse.2025.115023

How to cite: Krieger, L., Diaconu, C.-A., Abdullahi, S., Ramanath, S., and Floricioiu, D.: Elevation Change of Icelandic Glaciers from TanDEM‑X DEM Differencing with Penetration‑Bias‑Optimized Scene Selection , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10689, https://doi.org/10.5194/egusphere-egu26-10689, 2026.

Digital elevation models (DEMs) from optical stereo satellite imagery are widely used to quantify glacier elevation change through DEM differencing. However, incomplete spatial coverage and irregular temporal sampling limit the applicability of standard pair-wise DEM differencing over large glaciers, requiring the analysis of multi-temporal DEM time series.

Here, we compare methodological approaches for interpolating optical DEM time series to derive mean glacier elevation change rates using freely available datasets. We exploit SPOT-5 and ArcticDEM as high-resolution complements to the ASTER DEM record. Using the Hofsjökull ice cap (Iceland) as a pilot study, we assess the performance and transferability of a pixel-based Gaussian interpolation approach (Hugonnet et al., 2021) and introduce a computationally efficient elevation-band-based method. Validation is performed against independent elevation datasets, such as LiDAR and Pléiades, and through pairwise DEM differencing. 

Our results show that the elevation-band approach provides reliable estimates of glacier-elevation change under sparse, irregular sampling conditions. Furthermore, with its low computational cost and flexibility, the method is well-suited for regional applications and for extending geodetic glacier mass-balance assessments beyond the ASTER era.

Hugonnet, R., McNabb, R., Berthier, E., Menounos, B., Nuth, C., Girod, L., Farinotti, D., Huss, M., Dussaillant, I., Brun, F. and Kääb, A., 2021. Accelerated global glacier mass loss in the early twenty-first century. Nature, 592(7856), pp.726-731.

How to cite: Webster, C., Ioli, F., Belart, J. M. C., Jóhannesson, T., Berthier, E., Mattea, E., McNabb, R., Treichler, D., Girod, L., Zemp, M., and Piermattei, L.: Comparing approaches for glacier elevation change estimation using optical DEM time series, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11729, https://doi.org/10.5194/egusphere-egu26-11729, 2026.

Mass balance models are typically evaluated using a sparse collection of point measurements on one or more glaciers. Discrete measurements of mass or elevation loss often reflect surface elevation/mass change along centreline ablation stakes. More recent approaches use geodetic data to help constrain these mass balance models, but the infrequent nature of these distributed datasets often precludes an evaluation of how well these models capture important physical properties such as albedo evolution, short-term events such as impurity deposition following wildfire or dust loading, or the importance of heat waves. Here we describe the unique observational dataset for Place Glacier, a small (2 km2) benchmark glacier monitored since 1965. Our dataset includes 62 airborne laser altimetic and 30 hyperspectral surveys from which we derive monthly surface elevation change and optical retrievals (e.g. grain size, albedo and radiative forcing caused by light-absorbing particles-LAPs) during the ablation seasons (2020-2025). These 2-m data are currently being used to assess the performance of distributed surface mass balance models such as COSIPY, GEMB, CROCUS. The dense observational record allows us to perform suitable calibration and validation exercises for each model but also for spaceborne-derived datasets of surface elevation and albedo change. Surface mass balance model performance during the validation period is typically excellent, but significantly degrades when attempting to simulate mass change prior to 2020. Factors which account for this poor pre-2020 performance includes major changes in the extent of firn, late-lying snow and impurity deposition. In addition to elevated flux of LAPs from dry and wet deposition, thinning of firn has elevated surface concentration of LAPs and surface debris thereby darkening the glacier and accelerating mass loss. Work is underway to physically model these important physical processes leading to albedo reduction and attendant glacier mass loss.  

How to cite: Menounos, B. and Viner, N.: Surface elevation change and optical retrieval products to benchmark the next generation of surface mass balance models, Place Glacier, Canada, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11825, https://doi.org/10.5194/egusphere-egu26-11825, 2026.

The Karakoram mountain range is well-known for its numerous surge-type glaciers of which several have recently surged or are currently surging. Analysis of historic satellite images, topographic maps and reports revealed repeat surges for many of the glaciers, partly back to the 19^th century. The observed surges display a great variety of characteristics regarding surge durations, repeat cycles, flow velocities, advance rates and mass transfer patterns. However, surge mechanisms remain speculative, as the thermal and basal conditions of the glaciers are largely unknown.

Along with positive glacier mass balances and decreasing summer temperatures, the enhanced surge activity in this region is one part of the so-called Karakoram Anomaly. It has been speculated that the Karakoram Anomaly might come to an end, as its mass balance part is showing increasingly negative values, i.e. more similar to the glaciers in surrounding mountain ranges. However, dense time-series of freely available satellite images reveal that this is so far not reflected in a diminishing surge activity, which instead continues unabated.

For this study, animations of Sentinel-2 image quicklooks have been used for early detection of upcoming surges and an analysis of surge development over the past ten years in the central Karakoram. While tributary glaciers continued surging according to their surge cycles, also the much larger trunk glaciers (Panmah and Sarpo Laggo) are now surging again and deform or erase the surge marks of previous tributary surges. In 2024/25, at least 15 glaciers were surging in a small region of the Karakoram, two of which were not classified as of surge-type before. Apart from the animations revealing surge front migration and glacier interactions, time series of flow velocities and surface elevations reveal strong differences in surge dynamics among the glaciers. The 10 m resolution of Sentinel-2 is at the edge of providing meaningful velocity data for the 7 smallest glaciers in the sample.

How to cite: Paul, F.: Glacier surging in the Karakoram continues unabated, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12452, https://doi.org/10.5194/egusphere-egu26-12452, 2026.

The surface mass balance (SMB) of glaciers represents a direct link to the local climate and is a key variable in modelling glacier response to climate change. While the SMB is traditionally measured at point locations with ablation stakes or snowpits, recent advances allow estimation of spatially distributed SMB using remotely sensed data of surface elevation change, ice velocity, and ice thickness by solving the mass continuity equation. Such inverse approaches offer a promising alternative to field-based SMB data collection, particularly for model calibration and large-scale assessments. However, SMB inversion approaches vary in spatial coverage, assumptions, and solution strategies as well as in using data of different resolutions and temporal consistency—raising questions about their comparability, performance, and uncertainties.

The Continuity approaches for mass balance Intercomparison eXercise (ContinuIX) is a community effort organized through an IACS Working Group that aims to compare existing continuity approaches for SMB estimation and to deliver clear guidelines and recommendations for future developers and users of SMB products derived from these methods. The first objective of ContinuIX focuses on compiling a benchmark dataset with high-quality, contemporaneous observational data (surface elevation change, velocity, thickness, and in situ SMB), as well as controlled synthetic test cases. The next activities will involve a structured intercomparison experiment using these best possible datasets to assess differences between approaches.

Here, we present progress on the benchmark dataset of phase one, which includes extensive contemporaneous observations of eight glaciers across multiple regions. This dataset may be of value for a wide range of glaciological studies. Additionally, we apply and present first results of mass continuity methods to demonstrate how distributed SMB products can be derived, providing a preview of the types of comparisons envisioned for the next objective of ContinuIX. This presentation is intended not only to share initial results, but also to invite input and discussion from the community as we shape the next steps of ContinuIX. We particularly welcome ideas, feedback, and expressions of interest from potential contributors or users of continuity-derived SMB products.

How to cite: Izeboud, M., Wells, A., Fürst, J. J., Kneib, M., Miles, E., Devaux-Chupin, V., Van Tricht, L., Henning, K., and Zekollari, H.: Exploring contemporaneous observational datasets to derive glacier surface mass balance from continuity approaches (ContinuIX working group), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13647, https://doi.org/10.5194/egusphere-egu26-13647, 2026.

The Arctic is one of the fastest-warming regions in a rapidly warming world. Arctic glaciers are an important contributor to sea level rise, and their increased mass change and retreat has impacts ranging from local-scale ecosystems to regional-scale changes in ocean chemistry and circulation. Longer-term observations, especially of elevation and volume changes, are key for understanding and constraining predictions of future sea level change and other environmental impacts.

Over recent decades, peripheral glaciers in Greenland north of 79° latitude showed fairly steady rates of negative mass balance and small rates of area change, in spite of strongly increased regional warming. In this study, we combine a broad range of remotely sensed imagery and datasets to observe decade-scale changes to peripheral glaciers in the North of Greenland over a 50 year time period. We use historical aerial and declassified satellite imagery as well as Landsat and Sentinel-2 scenes to map glacier area across each decade through a semi-automated approach. To map accumulation area ratio (AAR) for each time period, we apply an albedo threshold approach that has been used to differentiate between snow and bare ice in other regions. Finally, we derive elevation changes using a combinaton of historic aerial and satellite-derived digital elevation models (DEMs) from the 1970s, the ArcticDEM, and ASTER and SPOT-5 derived DEMs to observe elevation and volume changes over the same time period. With the benefit of multiple glacier inventories, we also evaluate the impact of deriving geodetic mass balances from glacier outlines at different points in time.

How to cite: McNabb, R.: Remote sensing of North Greenland glaciers from the 1970s to present, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14880, https://doi.org/10.5194/egusphere-egu26-14880, 2026.

Nine very small glaciers (VSGs) have been identified in the northern Japanese Alps (e.g., Fukui et al., 2018; Arie et al., 2025). These VSGs persist under relatively warm conditions at elevations around 2,000 m, where the mean annual air temperature is approximately 2–3  ℃. Understanding the mechanism that enables their persistence is therefore an important scientific issue. However, long-term mass-balance observations and understanding of the flow mechanisms remain limited.

In this study, the mass balance of eight glaciers and perennial snow patch was observed from the 1960s to 2025, and interannual and seasonal variations in flow velocity were investigated at the Shakushizawa Glacier. The studied glaciers and snow patches―Hakubazawa, Shakushizawa, Kaerazuzawa, Karamatsuzawa, Kakunezato, Komado, Sannomado, Gozenzawa―are located at elevations of 1,700-2,700 m and are characterized by heavy snow accumulation (snow depth: 20-30 m) due to the northwesterly winter monsoon and frequent avalanches.

Cumulative mass balance from the 1960s to the mid-2010s showed only slight gains or losses; however, following the low-snowfall year of 2016, all glaciers and perennial snow patches experienced substantial mass loss by 2025. Meteorological observations (Hakuba AMeDAS) and ERA5 reanalysis data indicate no significant long-term decrease in snowfall since the 1950s, whereas melt amounts estimated using both an energy-balanzsce and a degree-day methods show an increasing trend. These results suggest that the recent acceleration of mass loss is mainly driven by enhanced summer melting associated with rising air temperatures.

Flow observations at the Shakushizawa Glacier show that annual flow velocities exceed those observed at the end of melt season, implying either accelerated internal deformation under heavy winter snow load or enhanced basal sliding during the early melt season. 

How to cite: Takehana, Y., Narama, C., and Arie, K.: Observation of mass balance and flow of very small glaciers in northern Japanese Alps., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17071, https://doi.org/10.5194/egusphere-egu26-17071, 2026.

Glacier surface albedo is an important factor affecting glacier ablation, and it plays a crucial role in understanding glacier health and the surface energy balance. However, its temporal and spatial distribution on glaciers is frequently ignored, entailing the use of constant values in melt models, which can cause inaccurate melt estimates. Glacier albedo changes in the 21^st century remain poorly understood.

Past studies highlight a decrease in glacier albedo between 2001 and 2021 in most regions of the Third Pole. However, the glacier response to climate change in the Karakoram region is not fully understood. A large portion of the glacierized area has shown unusual behavior with respect to global glacier shrinkage, commonly known as the “Karakoram Anomaly”.

In this study, we analyzed, both temporally and spatially, the long-term trend of summer glacier albedo from 1993 to 2025, using Landsat 4/5 TM, 7 EMT+, and 8/9 OLI data from Google Earth Engine database. Our study focuses on the Central Hunza basin, a large basin (2383 km²) in Karakoram (Pakistan), hosting around 280 glaciers. This basin has already shown, on average, an almost balanced mass budget in the period 1973-2009. To ensure focusing only on snow free glacier surface albedo, we masked out snow covered areas by means of the OTSU algorithm and also assessed the Snow Line Altitude, in order to investigate also its variations at the glacier and basin scale. To assure data continuity across sensors with different spectral resolution, we performed a harmonization of the Landsat data.

This study emphasizes the importance of not assuming albedo as a constant, since its long-term variability in the region may not follow global trends. This is particularly relevant as glaciers act as the main hydrological resource in this region.

How to cite: Barbagallo, B., Fugazza, D., and Diolaiuti, G. A.: Long-term variations of glacier albedo from 1993 to 2025 in the Central Hunza basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17333, https://doi.org/10.5194/egusphere-egu26-17333, 2026.

The Pamir Mountains are a key focus of research on the response of glaciers to climate change in High Mountain Asia. They constitute an important mountain water tower that is highly vulnerable to future climatic and environmental change, and they host glaciers that experienced limited but increasing mass loss during 2000-2019. Few studies have constrained mass balance in detail within the region, and these have highlighted strong spatio-temporal variability. Quantification of glacier mass changes and their drivers is challenged by sparse in situ data, strong East-West gradients of temperature and precipitation, and complex glacier processes including debris cover, surging behavior, and collapse features. In this study, we focus on 41 glaciers in the Sangvor region of the western Pamir for 2003-2025 to: i) evaluate the robustness of previous estimates of mass losses for 2000-2019, ii) identify glacier trajectories beyond 2019, and iii) understand the influence of surging glaciers on the observed mass changes. We adopted a stereo image-processing workflow from the Ames Stereo Pipeline and generated DEMs from SPOT5, SPOT6, and Pléiades stereo satellite imagery. Glacier mass balance for each time series was derived using current best practices for DEM co-registration, bias correction, and uncertainty propagation. Additionally, we applied new algorithms for jitter correction, seasonal snow correction based on in-situ data, and a duration-dependent correction scheme for volume-to-mass conversion uncertainties.

Our results provide a time series of high-resolution geodetic surface height changes and glacier mass balance over seven sub-periods spanning 2003 to 2025: -0.19 ± 0.04 m w.e. a^-1 for 2003-2019, -0.63 ± 0.05 m w.e. a^-1 for 2019-2025, and -0.28 ± 0.02 m w.e. a^-1 for the entire period of 2003-2025 for three key intervals. Our 2003-2019 results agree with the mean mass balance measured by ASTER for 2000-2019 (-0.21 m w.e. a^-1) and with the temporal trend. We highlight a sharp mass gain (0.16 ± 0.03 m w.e. a^-1) between 2014 and 2019, followed by a pronounced progressive shift toward negative mass balances. During 2019-2025, characterized by exceptionally warm and dry conditions, the mass balance has been increasingly negative despite higher uncertainty in our annual estimates, reaching its maximum loss of -1.45 (+0.51/-0.19) m w.e. a^-1 in 2024-2025. We also find no statistically significant difference between the mass balance of surging glaciers and the regional mean for the periods of our study. Overall, our results reveal strong temporal variability in glacier mass balance in the region. While long-term mean mass balances agree with previous ASTER-based estimates, our high-resolution geodetic time series resolves their short-term variability, illuminating a complex evolution that includes a marked mass gain for 2014-2019 and a rapid shift toward strongly negative balances thereafter. Comparison with reanalysis data suggests that this variability is more closely linked to precipitation anomalies than to temperature, suggesting a dominant role of mass accumulation and snowfall variability. These results demonstrate the value of high-resolution stereo imagery and motivate extension to the wider Pamir region and can form a new, high-resolution baseline for modelling projections of future glacier changes in the region.

How to cite: Hagiwara, H., Miles, E., Jouberton, A., Muñoz Hermosilla, J., Ren, S., E. Shaw, T., Fiddes, J., Dehecq, A., Hugonnet, R., and Pellicciotti, F.: Glacier mass changes in the Western Pamirs during 2003-2025 from high-resolution stereo satellite images, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17768, https://doi.org/10.5194/egusphere-egu26-17768, 2026.

The Southern Patagonian Icefield, the largest temperate ice body in the Southern Hemisphere, is among the regions with the highest mass-loss rates globally. Most of this mass loss is driven by large, water-terminating outlet glaciers. Their response to climate change, however, is heterogeneous in time and space. For water-terminating glaciers, subglacial topography plays a key role in modulating their response to climate change, yet it remains largely unknown, especially near glacier termini.

We present results from two campaigns in 2022 and 2024, during which we conducted helicopter-borne GPR measurements of three of the largest Argentine outlet glaciers: Glaciar Upsala, Glaciar Viedma, and Glaciar Perito Moreno. Our measurements, covering 232 km of flight tracks, reveal the complex subglacial topography in the lower regions of these glaciers and show bed reflections of up to 800 m depth at Glaciar Upsala. Our data also shows Glaciar Perito Moreno lies on a pronounced subglacial bedrock ridge, which has largely contributed to its past stability.

In addition, we incorporated our measurements into an established ice-thickness reconstruction to derive the basin-wide ice-thickness distribution and, thus, the subglacial topography. Our ice-thickness maps indicate that the three glaciers had a combined ice volume of 831 km³ in the year 2000, which is more than six times the total ice volume of the European Alps combined.

While the rerteat of Glaciar Upsala and Viedma has slowed down, Glaciar Perito Moreno shows increased surface-lowering rates, from 0.34 m a⁻¹ (2000-2019) to 5.5 m a⁻¹ (2019-2024), accompanied by glacier acceleration and frontal retreat. After almost 100 years, the glacier has started to detach from its pinning point. Using a simple numerical model, we show that buoyancy-driven retreat of several kilometres could occur in the near future if lowering rates persist.

How to cite: Koch, M., Sommer, C., Blindow, N., Berkhoff, J., Skvarca, P., Fürst, J., and Braun, M. H.: Mapping bedrock topography and ice thickness distribution of Patagonian outlet glaciers using ground-penetrating radar, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18052, https://doi.org/10.5194/egusphere-egu26-18052, 2026.

Tidewater glaciers in the Arctic and the Antarctic Peninsula are undergoing an unprecedented level of retreat owing to rising temperatures, driven by both ocean-induced melting and atmospheric warming of ice-sheets. Frontal ablation at tidewater glaciers occurs primarily through calving and submarine melting, each of which generates distinct sounds that can be detected using acoustic sensing. Calving generates impulsive transient sounds associated with the impact of the ice on the ocean surface, whereas submarine melting generates a more persistent acoustic signal due to release of pressurized bubbles trapped within the ice. These characteristics provide the opportunity to remotely monitor glacier frontal ablation over a long term using passive acoustics, and complement other modalities of glacial remote sensing. To better understand the physical acoustic variability in glacial bays, we undertook acoustic recordings in tidewater glacier bays in Greenland and the Antarctic Peninsula in 2024-2025 using a long vertical hydrophone array, which allows discrimination of sound emanating from glacier terminus melt. These measurements reveal the directionality of the melt-induced sound field, wide variation in acoustic levels and spatial, temporal and spectral characteristics in the acoustic field in the different glacial bays, and significant contributions from melting ice mélange. These were coupled with conductivity-temperature-depth measurements to understand the effect of thermohaline structure on the melt-induced acoustic field. We investigate the acoustic field characteristics including the directionality, spectrum and coherence, potential links with the water temperature in the bay, and place our findings in the context of earlier passive acoustic studies conducted in Svalbard during 2019-2023, drawing comparisons and contrasts across polar regions. Together, these advance the use of passive acoustics as a tool for long-term, remote monitoring of tidewater glacier ablation.

How to cite: Vishnu, H., Chitre, M., and Hoffmann-Kuhnt, M.: Passive acoustic signatures of frontal ablation at tidewater glaciers in the Antarctic Peninsula and Greenland, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18630, https://doi.org/10.5194/egusphere-egu26-18630, 2026.

Southern Patagonia hosts the largest accumulation of ice in South America. The Patagonian Icefields (PI), situated just north of 52° S, with a highly fragmented glacier outline and a N-S orientation represent the largest glacial system in the region with surface areas of 4,000 and 12,000 km², respectively. A smaller ice cap covers the Cordillera Darwin (CD, 2600 km²) in the south-western part of the Tierra del Fuego main island. The Gran Campo Nevado (GCN, 200 km²) is situated halfway between the Southern Patagonian Icefield and CD. The area of the PI is subject to intense glacial isostatic adjustment (GIA) effects due to its particular rheological setting as response to relatively recent ice-mass loss. These effects include observed bedrock uplift and gravity field changes. Continuous monitoring of the ice loss in Patagonia is key to understanding the impact of ongoing climate change in the southern mid-latitudes and the southeastern Pacific. Previously published mass-balance estimates for the PI agree in an intense ice-mass loss, but indicate a dependence on the analyzed period and the applied method. The GRACE (2002-2017) and GRACE-Follow On (GRACE-FO, since 2018) missions provide an efficient tool for quantifying mass redistribution on Earth from satellite gravimetry data. Richter et al. (2019) developed a method to determine a mass change time series of the PI over the 15-years period of the GRACE mission. By applying a series of corrections, the gravimetric effects of simultaneous mass redistribution processes are removed from the pseudo-observables in order to isolate the target mass-change signal prior to the inversion. We present a new ice-mass change time series extending our estimation of the PI over CD and GCN, and including the GRACE-FO data record over a time span of 22 years. It benefits from improved models used to correct for the gravity effects of GIA, ocean mass redistribution, continental water storage variations, and ice-mass changes of the polar ice sheets and mountain glaciers outside Patagonia. In addition, the effects of major earthquakes in the study region are corrected, and recent InSAR remote-sensing results are incorporated as a priori information on the spatial distribution of ice-mass changes in Southern Patagonia. Our results confirm a steady ice-mass loss with a mean rate of -30 Gt/a and reveal an increase in the mass-loss rate during most recent years, reaching values of about −43 Gt/a.

How to cite: Romero, A., Richter, A., Döhne, T., Horwath, M., Mardewald, E., and Suad Corbetta, F.:  Accelerated ice-mass loss in southern Patagonia observed by satellite gravimetry, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19130, https://doi.org/10.5194/egusphere-egu26-19130, 2026.

Previous studies have mapped end-of-season snowlines (ESS) on glaciers from satellite imagery to find their snowline altitudes (SLA) to use as a proxy for the glacier equilibrium line altitude (ELA). A line is traced along the boundary between snow and ice, then, from a digital elevation model (DEM), elevation values are extracted at regular intervals along the line. The average elevation of these points is taken to be the SLA. While this approach would be advantageous, as it offers a solution to measuring glacier ELAs in remote regions, it is prone to an oversampling bias. Where snow cover is patchy, for example, in shaded areas or where avalanching has occurred, a greater length of line is mapped in order to follow the snow-ice boundary than is required for smoother segments. This is regardless of whether the region contributes a larger area of snow cover or not. Consequently, SLA calculations are prone to oversampling from areas of irregular snow cover. Even when the ESS is mapped accurately and precisely, the SLA value may differ significantly from the true ELA. This poster investigates alternative methods of calculating the SLA from mapped ESSs to reduce bias towards patchy and irregular areas of snow cover.

How to cite: Hallford, M., Rea, B. R., Spagnolo, M., Sam, L., Singh, S., and Mullan, D.: Calculating Snowline Altitudes on Glaciers with Patchy and Irregular Snow Cover Using Satellite Imagery, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19873, https://doi.org/10.5194/egusphere-egu26-19873, 2026.

The Patagonian Andes host the largest glacierized area in the Southern Hemisphere outside Antarctica and play a key role in regional freshwater resources and global sea-level rise. Meltwater discharge from Patagonian glaciers contributes to sea-level rise, while changes in freshwater runoff threaten downstream ecosystems and water availability. In particular, the Northern Patagonian Icefield (NPI), Southern Patagonian Icefield (SPI), and Cordillera Darwin Icefield (CDI) are vast temperate ice bodies and rank among the Earth`s mountain regions with the highest glacier mass-loss rates.

Here, we present new observations of glacier mass change across the Patagonian Andes for the period 2000–2025. We combine multi-mission remote sensing data, including synthetic aperture radar (SAR) digital elevation models (DEMs) from the TanDEM-X mission and satellite altimetry from CryoSat-2 and ICESat-2, to derive glacier-specific and regional geodetic mass changes. In addition, we account for ice mass loss committed by frontal ablation by estimating subaqueous volume change of lake- and marine-terminating glaciers from observed terminus retreat and ice thickness reconstructions.

Comparison with climate observations reveal a region-wide warming trend since the beginning of the 21st century. However, regional glacier mass change exhibits pronounced spatial and temporal heterogeneity. NPI glaciers show a marked acceleration in mass loss after 2013, while at SPI mass loss rates remained comparatively stable until 2019, after which annual mass loss increased to levels similar to the NPI. Similarly, the CDI exhibits a distinct increase in mass loss in recent years, after a short intermediate period of mass loss deceleration. Glacier-specific analyses of surface elevation change and ice flow velocity at major outlet glaciers reveal enhanced surface lowering and increased flow speeds near glacier termini over the past decade, due to intensified dynamic thinning. The observed regional and temporal variability in glacier response is likely linked to previously reported variations in precipitation and snowfall amounts. Overall, annual specific mass loss of the NPI and SPI since 2019 (~ -1.5 m w.e./a) has increased by more than 50% compared to the early 2000s (~ -1.0 m w.e./a).

How to cite: Sommer, C., Koch, M., Temme, F., Warnstedt, A., and Braun, M.: Untangling multi-annual to decadal ice mass loss of glaciers in the Patagonian Andes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20460, https://doi.org/10.5194/egusphere-egu26-20460, 2026.

Cryosphere mainly distributes in polar and high-altitude regions, which includes glaciers, ice sheets, sea ice, lake & river ice, permafrost & sub-sea permafrost, and so on. Under the ongoing climate warming, the cryosphere has been shrinking at an accelerating rate. Most of glaciers retreat and lose their mass loss. The active layer of permafrost deepens and soil temperature rises. All these changes have profoundly altered the regional or even global hydrology and water quality, and further act on the feedbacks to climate change. Besides, the rapid cryospheric changes are also reshaping the terrain and landforms. This is also closely related to the stability of the ecosystem. Meanwhile, cryosphere contains large of chemicals as “pool”, such as carbon, nitrogen, mercury and other pollutants, making it an important linkage for the global biogeochemical cycles, posing potential risks on the cryosphere ecological security.

How to cite: Zhang, Y.: Cryospheric change and ecological security, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1661, https://doi.org/10.5194/egusphere-egu26-1661, 2026.

The melting rate of glaciers in Europe has accelerated continuously since the 1980s and continues today at an unprecedented pace. Such rapid and sustained glacier retreat has important implications for the release of legacy contaminants stored in ice. Since the onset of the Industrial Revolution, atmospheric deposition has led to the accumulation of pollutants, including mercury (Hg)—a highly toxic element with well-documented impacts on ecosystems and human health—within glaciers. Ongoing climate-driven melting can remobilize these long-term contaminant reservoirs.
To investigate this process, we examined Hg accumulation rates (Hg AR) in sediments from two neighboring high-altitude lakes in the French Alps. One lake represents a reference system receiving only atmospheric inputs, while the other is influenced by both atmospheric deposition and meltwater from a shrinking glacier. Comparing the two sedimentary records allowed us to isolate the signal associated with cryospheric change.
In the reference lake, Hg AR is controlled by regional atmospheric Hg emissions and follows the expected anthropogenic pattern, with maxima during World War II and in the 1970s, followed by a steady decline in recent decades. In contrast, the glacier-fed lake shows a steadily increasing Hg AR from the early 1900s to the present, with a doubling of accumulation rates over the past several decades.
Using estimates of glacier volume loss over the last 50 years together with Hg concentrations in glacier ice and cryoconite reported in the literature, we demonstrate that the recent acceleration of Hg AR is consistent with enhanced Hg release driven by glacier shrinkage. These results indicate that glacier melt represents an additional and climate-sensitive source of legacy Hg to downstream aquatic systems, compounding the environmental impacts of cryospheric change alongside pressures such as freshwater scarcity.

How to cite: Mattio, D., Guedron, S., Sabatier, P., Dommergue, A., Martínez Cortizas, A., Rabatel, A., and Angot, H. and the EPOCH ALPS team: The Hidden Threat of Glacier Melt: Rising Mercury Levels in French Alpine Lakes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1802, https://doi.org/10.5194/egusphere-egu26-1802, 2026.

Glaciers are sensitive indicators of climate change, yet only a small number that remain in the Mediterranean region. Of these, most have retreated well into cirques, persisting as small, isolated glaciers or ice patches. The climatic drivers of glacier and snowpack changes across the Mediterranean mountains over the past 75 years are assessed using temperature, precipitation, snow cover, and glacier mass balance data. Summer temperatures in the Mediterranean region have risen dramatically since the 1970s with the average increasing by >1.9 °C by 2024 relative to the 1991–2020 mean. Winter precipitation in the Mediterranean region has shown a slight decline over the last 75 years. From 2019 to 2023, snow cover duration declined across most of the Mediterranean. Regression analysis indicates that the North Atlantic Oscillation (NAO) exerts only a limited influence on glacier mass balance and snowpack variability in the Mediterranean. This is because the dominant control on mass balance change in the Mediterranean is summer temperature rather than precipitation, much more so than further north in Europe where NAO has more influence on glaciers. Despite this strong temperature sensitivity, some Mediterranean glaciers persist due to favourable local topoclimatic conditions. In particular, enhanced snow accumulation from snow avalanching and windblown snow compensates high summer ablation, highlighting the key influence of local topoclimatic conditions on glacier survival in the Mediterranean region. Although Mediterranean glaciers are sustained by high accumulation, they are strongly affected by summer temperature variability, reflecting the broader global pattern whereby warm–wet glaciers show greater temperature sensitivity than cold–dry glaciers. Understanding how glaciers and snowpack respond to climate change in the Mediterranean mountains has relevance beyond this region and provides an important comparison for other mid-latitude regions, such as the Alps, the Caucasus, and the Tibetan Plateau, where glaciers and snowpack are crucial for water supply.

How to cite: Wang, B., Hughes, P., Darvill, C., and Woodward, J.: The impact of climate change on mid-latitude Mediterranean glaciers over the past 75 years, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1956, https://doi.org/10.5194/egusphere-egu26-1956, 2026.

Over the past century, more than two dozen tsunamis with runups greater than 50 m have been reported. Of these, more than half were in the Arctic or subarctic, including the 1958 Lituya Bay megatsunami, which ran up 530 m in elevation. Many of those megatsunamis occurred in deglaciating fjords or valleys, and almost all were triggered by landslides. At 5:26 a.m. local time on 10 August 2025, a large landslide (>64x10⁶ m³) collapsed about one vertical km onto South Sawyer Glacier and into Tracy Arm, a cruise ship-frequented fjord in southeast Alaska. The landslide triggered a megatsunami, which reached an elevation of 481 m up the opposite fjord wall before propagating out of the fjord into Stephens Passage and Endicott Arm to the south. The tsunami was experienced by multiple ships in the vicinity, but due in part to its early morning timing, luckily no deaths or injuries occurred.

The initial rock wedge failure transitioned into a rock avalanche as it traveled down the slope and produced globally observed long-period seismic waves equivalent in size to those of a M5.4 earthquake. The landslide was also preceded by more than 24 hours of microearthquakes attributed to slip along the failure surface, with increasing rate and amplitude until roughly an hour before failure. Long-period monochromatic global seismic signals persisted for over 36 hours. These signals are consistent with a landslide-induced seiche trapped in the fjord, an interpretation further confirmed by tsunami simulations and satellite observations.

The landslide and resulting hazard cascade was enabled by >6 km of retreat of South Sawyer Glacier since 1948, which we statistically attribute to anthropogenic warming. Most recently, the base of the failed slope was fully exposed between late June and early August 2025 when the glacier retreated several hundred metres. A large failure of a slope that had not previously been identified as a hazard, and with no precursory slope deformation, in a fjord with extensive recreational activity (e.g., cruise ships and personal pleasure craft) highlights the near-field risk of landslide tsunamis and underscores the importance of enhanced monitoring and continued research using a variety of tools, including seismic, remote sensing, and in situ monitoring.

How to cite: Shugar, D., Barnhart, K., Berdahl, M., Caplan-Auerbach, J., Ekström, G., Fathian, A., Geertsema, M., Hicks, S., Higman, B., Jensen, E., Karasözen, E., Lynett, P., Lyons, J., Monahan, T., Roe, G., Svennevig, K., Toney, L., Van Wyk de Vries, M., and West, M.: The second highest tsunami ever recorded, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3156, https://doi.org/10.5194/egusphere-egu26-3156, 2026.

The heterogeneous ablation rates of debris-covered glaciers strongly influence mass balance and melt patterns, yet the factors controlling this variability remain poorly understood. To understand this, this study quantifies ablation dynamics across the debris-covered zone of Panchinala A glacier, located in western Himalaya, India, using high-resolution unmanned aerial vehicle (UAV) photogrammetry data. Multi-temporal UAV surveys were conducted during ablation seasons of 2021 and 2022 to generate orthomosaics and digital elevation models (DEMs) at centimeter-scale resolution. Surface velocity was estimated using the More Global Matching algorithm implemented in the Ames Stereo Pipeline and combined with independent ice thickness estimates to compute flux divergence. Flow-corrected Lagrangian surface mass balance (SMB) was estimated using a continuity-equation approach, applying mass conservation under an assumption of constant ice density. During 2021–2022, the ablation area exhibited a mean horizontal velocity of 4.40 m a⁻¹; velocities decreased progressively along-flow toward the glacier front. The mean Lagrangian SMB across the ablation area was -602.6 kg m^-² a^-1 (2021–2022). The result indicates contrasting ablation patterns over ice cliffs and debris covered area. Ice cliffs and adjacent ablation hotspots (10 m buffer) contributed ~50% of total ablation while occupying ≤20% of the ablation area, whereas the remaining debris-covered surface (~80%) accounted for ~50%. These results show that high-resolution datasets are important for accurate surface mass balance estimation and for resolving the spatial heterogeneity of ablation on debris-covered glaciers.

How to cite: Godara, A. and Ramsankaran, R.: Quantifying Ablation Dynamics in the Debris-Covered Zone of Panchinala-A Glacier Using High-Resolution UAV Photogrammetry, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3421, https://doi.org/10.5194/egusphere-egu26-3421, 2026.

Glaciers in the European Alps are retreating and thinning rapidly due to increasing atmospheric temperatures with expected far reaching implications on water availability, biodiversity, and local economy. Given their critical role as freshwater reservoirs and climate indicators, monitoring glacier changes is essential. Uncrewed Aerial Vehicles (UAVs) provide high-resolution, cost-effective observations that bridge the gap between sparse field measurements and coarse satellite data, enabling detailed assessment of glacier surface dynamics. In this study, a UAV- derived high-resolution dataset spanning the years 2017 – 2025 is evaluated to study the frontal spatio-temporal dynamics of the Morteratsch-Pers glacier complex. Surface elevation and surface velocities are derived and combined with reconstructed ice thickness fields (based on radar measurements) to reconstruct the glacier surface mass balance over time. The results are then compared to in-situ stake observations to assess the influence of features such as debris cover and collapsing ice caves, not captured with the local measurements, on frontal retreat patterns.  

How to cite: Henning, K., Van Tricht, L., Izeboud, M., van Breedam, J., Verhaegen, Y., Hoessli, L., Kneib, M., Huybrechts, P., and Zekollari, H.: Quantifying frontal disintegration processes at Morteratsch-Pers glacier complex using high-resolution UAV imagery (2017–2025), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4464, https://doi.org/10.5194/egusphere-egu26-4464, 2026.

We use a three-dimensional time-dependent glacier model that couples higher-order ice flow dynamics with multi-dimensional englacial and supraglacial debris transport to investigate the behavior of debris-covered glaciers and their response to climate change. By applying the model to a synthetic idealized glacier, our simulations allow for multi-dimensional, physically-based and general insights into debris-ice interactions. The model incorporates a melt-modification parameterization based on a synthesis of Østrem curves from previous debris-covered glacier studies, which is coupled to submodules for the spatio-temporal evolution of debris. The debris submodule also includes an off-glacier debris evacuation scheme which allows our simulations to reach a steady state debris mass, while explicitly ensuring debris mass conservation. Results reveal that the presence of a debris cover significantly alters the steady state glacier geometry and dynamics, as well as its climate change response. Debris-covered glaciers in some specific environmental settings are also found to be prone to the formation of stagnant, isolated dead ice bodies during glacier recession. The results highlight the importance of representing a more complete and multi-dimensional set of key debris processes in debris-covered glacier models, including (i) a melt-modification curve that captures melt enhancement for thin debris, (ii) resolving dynamic debris-ice interactions in three dimensions with higher-order ice flow, (iii) explicitly modelling the multi-dimensional, spatio-temporal evolution of a supra- and englacial debris mass, and (iv) a mass-conserving debris off-loading procedure which allows the model to reach steady state. Our main findings therefore emphasize the need to incorporate robust debris modelling in future glacier projections.

How to cite: Verhaegen, Y. and Huybrechts, P.: Coupling debris transport to 3D higher-order ice flow dynamics to model the behavior and climate change response of debris-covered glaciers, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4500, https://doi.org/10.5194/egusphere-egu26-4500, 2026.

Accurate estimation of current and historical glacier area provides crucial information for glacier monitoring and for projecting future glacier change. Despite significant advances in remote sensing, automated glacier delineation techniques still exhibit limited accuracy in debris-covered areas, often requiring time-consuming manual corrections, which are impractical for widespread application. While some regions have rich historical records of glacial development due to ease of access and scientific prioritization, many regions are represented by only a few outlines.

The Himalayas contain many large and heavily debris-covered glaciers, whose retreat and increase in debris coverage could drastically affect the primary source of freshwater for many communities. This vast and important region, however, has very few harmonized and temporally consistent datasets available for scientific use. Existing inventories are generally derived from imagery acquired in different years and exhibit substantial differences in their debris-covered area outlines.

Thus, to improve on these inconsistencies and inaccuracies, we are creating a historical time series spanning the entirety of the Himalayas between 1984 and 2025 with two-year intervals. To overcome the difficulties inherent to debris-covered glacier inclusion, several data sources are used, including optical, infrared, thermal, spectral indices, elevation change rate, surface velocity, and topographic parameters. These data sources are trained on a deep learning network comprised of a pre-trained U-Net with a long short-term memory (LSTM) module, which enhances debris segmentation by introducing historical data to the training process. In addition, the potential benefit of including radar coherence data is evaluated to assess whether glacier outlines produced in recent decades can be further refined.

How to cite: Lutz, K., Wolf, A., and Braun, M.: A historical time series of glacial debris cover change in the Himalayas using multi-source satellite data and deep learning, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6503, https://doi.org/10.5194/egusphere-egu26-6503, 2026.

Tropical Andean glaciers provide an important flux of freshwater to communities living both in high-altitude Cordillera and population centres downstream in countries such as Peru and Bolivia. Glacier recession threatens the sustainability of these water resources, and accurate modelling of future glacier behaviour is required to manage water stress in the region. These models must capture all processes contributing significantly to overall glacier mass budgets. Here we examine supraglacial pond and ice cliff development on three clean-ice glaciers in the Cordillera Vilcanota, Peru and their overall contribution to glacier mass balance. Whilst such features are common and well-studied on debris-covered glaciers, their development on debris-free glaciers has not been examined in detail. We use high-resolution contemporary and historical satellite imagery and repeat drone surveys to examine surface structure and geometry change over three glaciers during 1977–2024. We show how cliff and pond formation is driven by aspect-dependent surface melt of crevasse walls. These features act as ice loss hotspots, which enhance glacier net mass loss by ∼10% despite accounting for <5% glacier surface area. Incorporation of such amplified ice loss processes should be a priority for glacier model advances to achieve more accurate projections of future tropical glacier recession.

How to cite: King, O., Montoya, N., Davies, B., Matthews, T., Vargas, M., Ghuffar, S., Gribbin, T., Perry, B., Rado, M., McNabb, R., Nicholson, L., and Ely, J.: The impact of supraglacial ice cliff and pond formation on debris-free, tropical glacier mass loss, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6845, https://doi.org/10.5194/egusphere-egu26-6845, 2026.

Wave ogives are among the most striking and least studied glacier surface features. They sometimes form at the bottom of icefalls, yet exactly how they form has eluded scientists for decades. On the Gilkey Glacier, below the Vaughan Lewis Icefall in the Juneau Icefield region of Alaska there is a well-developed series of wave ogives. Our study uses geophysical field observations of the Gilkey Glacier ogives combined with satellite data and modeling to better understand the formation process. Satellite-derived DEMs provide ogive amplitudes of 5-8 m and wavelengths of ~130 m. By combining Global Navigation Satellite System (GNSS), satellite, and timelapse camera-derived velocity observations, we found that the Vaughan Lewis Glacier is significantly slower than the Gilkey Glacier (60 m/yr compared to 130 m/yr), and the icefall is exceptionally fast (~2200 m/yr). We used the velocity and ogive characteristics to constrain parameters in a finite-difference numerical model that simulates ogive formation. Using this model, we tested the plausibility of the two formation mechanisms; i) seasonal mass balance variation; and ii) seasonal velocity variation of the lower glacier. Our results suggest that seasonal velocity variation of the lower glacier is the primary driver in wave ogive formation.

How to cite: Ochwat, N., Terleth, Y., Anderson, R. S., Banwell, A., Truffer, M., Hobson, C., Bidwell, S., Neuhauser, E., and Kaltenborn, J.: Wavering Ways Waves Work: Understanding glacier ogive formation using satellite and field observations combined with modelling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6984, https://doi.org/10.5194/egusphere-egu26-6984, 2026.

The Arctic is experiencing rapid climatic warming. The inflow of warm Atlantic Water through the Fram Strait is an additional forcing to the stability of the Arctic cryospheric system, with the Svalbard archipelago being especially sensitive to its primary influence. While recent studies show the “greening” of this region through remote sensing and field observations, this study investigates modern palynological assemblages from fjord surface sediments at 34 different locations in Spitsbergen and Nordaustlandet to explore where this phenomenon is prevalent at an ecosystem scale. Long-distance transported pollen such as Pinus and Betula are consistently identified across fjords, while various and local pollen compositions are observed more in Isfjorden where intensive human activity and substantial retreat of tidewater glaciers have been reported. In addition to herbaceous pollen taxa, shrub pollen including Salix and Dryas is present on the western side of the archipelago more often. During pollen identification, abundant testate amoebae were also detected at most locations. We propose the following explanation on the observed palynological assemblages. Overall, pollen records from the surface fjord sediments reflect terrestrial environmental conditions effectively and spatially. The exposure of newly deglaciated surfaces where soils develop, subsequent ecological succession on these soils facilitates Arctic shrubification. Soil development can be inferred from testate amoebae, and Arctic greening can be detected through local pollen spectra. In our future analysis, the onset of these modern palynological assemblages can be identified through the investigation of fjord long core sediments.

How to cite: Lee, M., Kim, S.-Y., Kim, J.-H., and Byun, E.: Modern palynological assemblages in fjord surface sediments: indicators of Greening Svalbard, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7722, https://doi.org/10.5194/egusphere-egu26-7722, 2026.

In many mountain regions, glaciers constitute an essential freshwater reservoir and represent a critical water supply for downstream populations during droughts. Moreover, glacier mass changes provide a direct and valuable indicator of ongoing climate change. While long-term glacier mass loss is well documented, the drivers of temporal variability in regional glacier mass balance remain poorly constrained, despite their importance for understanding regional glacier–climate interactions.

Satellite gravimetry missions Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) provide direct observations of mass variations at monthly timescales with global coverage over the past two decades. Here, we use GRACE/-FO Level-3 products to estimate glacier mass changes over some regions of the Randolph Glacier Inventory (RGI v6.0) and to investigate their sensitivity to climate variability. Two GRACE/-FO solutions are considered: a solution based on Multichannel Singular Spectrum Analysis (M-SSA), and the SAGSA ensemble solution combining products from multiple processing centers. Signal leakage and separation effects related to the coarse spatial resolution of gravimetry are mitigated using geometry-based approaches, enabling regional mass balance estimates.

Monthly region-wide glacier mass balance are then used to explore relationships with key climate-related drivers, with an initial focus on near-surface air temperature and precipitation derived from the ERA5 reanalysis. This study aims to explore the links between glacier mass variability and climate-related drivers using GRACE/GRACE-FO observations.

How to cite: Gauer, L.-M., Berthier, E., and Blazquez, A.: Assessing glacier mass sensitivity to climate variability using GRACE/-FO, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9610, https://doi.org/10.5194/egusphere-egu26-9610, 2026.

In High Mountain Asia (HMA), glaciers and seasonal snowpacks have seen a widespread decline in the last two decades. However, these changes have been highly heterogeneous: glaciers of the Pamirs and Karakoram have seen positive mass balances in the early 2000s but are now on a trajectory of decline, while moderate and rapid mass loss occurs in the Central Himalayas and southeastern Tibetan Plateau, respectively. To understand these contrasting behaviours, their future trajectory, and their impacts on streamflow, we combine several years of situ observations and climate reanalysis with highly resolved land-surface and ice-flow models. We simulate water fluxes from 1970 to 2100 across three catchments with contrasting climatic settings. The catchments are in the Northwestern Pamirs (Kyzylsu), Central Himalayas (Trambau-Trakarding), and Southeastern Tibetan Plateau (Parlung No.4), spanning elevations from 2100 to 6800 m a.s.l.. 

We simulate the largest mass loss acceleration at Parlung No.4 Glacier, from  -0.10 m w.e. yr-1 in 1970-1999 to -0.80 m w.e. yr-1 in 2000-2023. The limited mass loss at Kyzylsu in 1970-1999 accelerated after 2000, mostly driven by a rapid worsening of glacier health in 2018-2024 (-0.72 m w.e. yr-1). Mass loss remained moderate at Trambau-Trakarding, from -0.39 m w.e. yr-1 in 1970-1999 to -0.30 m w.e. yr-1 in 2000-2023. 

These heterogeneous glacier mass balance patterns were driven by different summer 0°C isotherm changes, and contrasting precipitation decadal variability. Our projections forced with downscaled CMIP6 show that continued warming will expand ablation areas and extend melting into former accumulation areas previously located above the freezing line. On-glacier summer snowfall is projected to decrease by up to 60% by 2100 due to changes in precipitation phase. However, this will largely be offset by increases in snowfall in other seasons, driven by the widespread rise in precipitation projected for HMA. Despite stable accumulation rates, enhanced melt will drive severe glacier volume loss, strongly reducing the likelihood of new prolonged periods of near-stable or positive mass balances seen in our 1970-2020 simulations. 

Glacier retreat, combined with snowline rising to 6000 m a.s.l., will shift meltwater generation to higher elevations, where mass turnover rates will intensify. High-elevation areas will maintain their role as water providers, but with diminished capacity for water storage. We find that the evolving runoff contributions can decouple catchment-scale peak water from glacier-scale peak water. Indeed, substantial increases in rainfall (from 49 ± 22 % at the catchment in the Pamirs to 290 ± 146 % in the southeastern Tibetan Plateau), caused by precipitation phase and amount changes, and relatively stable snowmelt compensate for ice-melt reduction and postpone the timing of maximum runoff. While we find that ice melt nears its peak at Kyzylsu, with considerable uncertainty due to the initial ice volume, we project catchment runoff to continue increasing at all sites until the end of the century. Our results highlight the importance of considering the glacier 'peak water' concept within a catchment or basin hydrological framework.

How to cite: Jouberton, A., Shaw, T., Miles, E., Kneib, M., Fujita, K., and Pellicciotti, F.: Past and future drivers of glacier mass changes in High Mountain Asia and their impacts on catchment hydrology, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10641, https://doi.org/10.5194/egusphere-egu26-10641, 2026.

Glaciers in the Indus are critical water resources, supporting agriculture, hydropower, and livelihoods for hundreds of millions of people downstream, especially during the dry season. Here, we assess changes in the future water availability from melting glaciers in the Indus basin and how this will impact future water scarcity risks. We model the evolution of all glaciers, in the Indus, larger than 0.5km² using the Global Glacier Evolution Model (GloGEM), calibrated with transient snowline altitudes and geodetic mass balance observations. Glacier runoff projections are combined with water demand simulations from the ISIMIP3b dataset on total potential water withdrawal allowing us to explore potential future risks of water scarcity under SSP1-2.6 and SSP5-8.5 scenarios.

We analyse two different scenarios: (i) future changes in glacier runoff with present-day (2001-2020) water demand held constant, (ii) concurrent changes in both future glacier runoff and water demand. Preliminary results show that ongoing glacier mass loss in the Indus basin substantially changes the magnitude and seasonal distribution of glacier runoff. Timing of  peak seasonal ablation is shifted by up to several weeks, and the overall amount of glacier runoff is reduced, which has implications for downstream water availability, particularly during the early and late summer months, when demand is highest. By disentangling the contribution of glacier runoff to water demand, this study aims to quantify the vulnerability of the Indus to future water stress and to identify conditions under which glacier retreat may exacerbate or temporarily mitigate water scarcity. 

How to cite: von der Esch, A., van Tricht, L., Huss, M., van Tiel, M., Kneib, M., Berg, J., and Farinotti, D.: Modelling the Future of Indus Glacier Water Resources: Interactions between Glacier Retreat and Water Demand, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10843, https://doi.org/10.5194/egusphere-egu26-10843, 2026.

Glacier subsurface melt, consisting of englacial and basal melt, is far less understood than surface mass balance. Yet it represents a potentially relevant component of glacier retreat dynamics. Research on subsurface melt has been limited due to scarce observations and incomplete process understanding.

Here, we quantify spatially distributed subsurface melt of Swiss glaciers using a modelling approach, constrained and validated by field observations. To constrain the model, we use field data on energy content of subglacial water and airflow collected at 5 individual glaciers. This included water temperature and discharge measurements of ice-marginal, subglacial, supraglacial and proglacial streams, as well as measurements of melt and air flow inside ice caves. To acquire validation data on subsurface melt rates, vertical ice motion of ablation stakes was measured on the glacier terminus of two glaciers using differential GPS. After correcting for advection and ice flow divergence, residual vertical ice motion was assumed to be equivalent to subsurface melt. The parameterized subsurface melt model is based on sub- and englacial energy exchanges and uses surface mass balance, glacier geometry, catchment topography, and weather data as primary inputs. Subsurface melt is represented through several components: (1) geothermal heat flux, (2) frictional and strain heating, (3) potential energy release from meltwater, (4) advection of energy from ice-marginal and supraglacial streams, and (5) airflow through subglacial channels. To model the spatial distribution of subsurface melt we use spatially distributed surface mass balance, flow routing, and assumptions on energy exchange between subglacial water and ice.

Model results indicate that the dominant contribution to subsurface melt comes from energy input by ice-marginal streams, followed by potential energy release of meltwater. Glacier-wide annual subsurface melt rates averaged across Swiss glaciers are in the order of tens of mm w.e. a^-1, with larger glaciers generally exhibiting higher subsurface melt rates. Spatially, subsurface melt is highest near glacier termini, reflecting the location of ice-marginal stream inflow. A high elevation gradient (potential energy release) and a larger glacier area (larger catchment for ice-marginal streams) were identified as key controls on elevated subsurface melt rates. Validation data were found to be of the same order of magnitude as modelled values at the two respective field sites.

These results demonstrate that subsurface melt can be quantified using a combination of direct field observations and spatially distributed modelling. By providing spatially resolved estimates of subsurface melt for Swiss glaciers, this approach allows subsurface processes to be better understood and explicitly included in glacier evolution models. This constitutes an important step towards a more comprehensive and physically consistent description of glacier mass balance under ongoing climate change.

How to cite: Hösli, L., Huss, M., and Farinotti, D.: Modelling subsurface melt of Swiss glaciers, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11322, https://doi.org/10.5194/egusphere-egu26-11322, 2026.

High Mountain Asia (HMA) provides crucial water resources to more than 1.5 billion people and accurate quantification of high elevation precipitation in this region is essential for understanding the hydrological cycle, patterns of ongoing climatic change, and water resource management. This is particularly the case in high elevation, glacierised catchments where the interplay of cryospheric and atmospheric processes limits our understanding of current and future water resource availability. The role of precipitation and snow accumulation is critical for the health of glaciers which represent both an important freshwater storage and hydrological buffer to drought conditions. In both present-day and future modelling scenarios, precipitation at both macro and local scales generate some of the greatest uncertainties in glacier response to climate, especially across the distinct hydro-climatic regions of HMA.

We leverage precipitation estimates across several regional gridded products with a high spatial (>= 10 km) and temporal (hourly) resolution to explore their discrepancies over glacierised regions of HMA for the period of 2001-2019. Our analyses demonstrate a substantial disagreement between precipitation datasets in terms of i) their annual and seasonal magnitudes, ii) the fraction of precipitation occurring during the summer/monsoon period, iii) the differences of precipitation amounts between decades, iv) the correlation of precipitation amounts to annual mass balances, v) diurnal precipitation frequency and, vi) dependence on elevation and topographic complexity. 

Using the Open Global Glacier Model (OGGM), we demonstrate that the selection of precipitation input data can lead to widely differing interpretations of the role of precipitation as a driver of mass balance variability under a future climate and create substantially different estimations of runoff that exceed the differences due to the choice of climate model.

At catchment scales, the spatial extent and seasonality of precipitation, as well as the representation of specific storm events are all critical for the accurate estimation of glacier energy and mass balance. Fully-physical modelling of well-monitored, glacierised catchments across HMA reveals that the timing of precipitation events can be equally important to the long-term mass balance of glaciers as the monthly amounts of precipitation from different datasets.  

Finally, we discuss the regions of greatest disagreement and highlight further investigations linking precipitation and glacier health under present and future climate.

How to cite: Shaw, T., Jouberton, A., Kneib, M., Miles, E., Niwano, M., Fujita, K., Buri, P., and Pellicciotti, F.: Dataset Discrepancies Dominate Present and Future Precipitation-Glacier Relationships Across High Mountain Asia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11770, https://doi.org/10.5194/egusphere-egu26-11770, 2026.

The Arctic has been warming four times faster than the global mean over the last forty years. In response, the mass loss of glaciers has been accelerating and contributing to global sea-level rise. However, many of the mechanisms of this mass loss process are not well understood, especially the calving dynamics of marine-terminating glaciers, in part due to a lack of high-resolution calving front observations. To address this limitation, we developed a novel automated deep learning framework to automatically detect calving fronts in multimodal satellite imagery, including optical and SAR satellite images from Landsat, Terra-ASTER, Sentinel-2, and Sentinel-1 missions. In total, this provides an approximately four-decade time series of calving dynamics across Arctic glaciers and ice caps. The method was tested and developed initially on the Svalbard archipelago, where we identified widespread calving front retreats during the past four decades, including attribution to climate forcing mechanisms. Here, we have extended the analysis across the entire Arctic to produce a time series that starts in the 1980s with quasi-annual temporal resolution, but achieves sub-monthly sampling from 2014 onward, following the launch of Sentinel-1. This provides both seasonal and inter-annual calving dynamics for almost all marine-terminating glaciers in the Arctic, which have been used to explore and understand the drivers of calving processes.

How to cite: Li, T., Maussion, F., and Bamber, J.: Four decades of pan-Arctic glacier calving fluxes from multimodal satellite imagery, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13133, https://doi.org/10.5194/egusphere-egu26-13133, 2026.

Glacier demise is palpable in mountain regions around the world. This retreat affects marine and terrestrial ecosystems, regional year-around water security as well as increases the risk for mountain hazards. Satellite remote sensing techniques have drawn a sinister picture of increasing rates of ice loss, particularly in the European Alps. There, model projections suggest that glaciers will largely disappear from the mountain landscape by the end of the century. Under most optimistic scenarios with a regional warming below ~3°C, one third of the ice volume can be preserved. Only the larger and more elevated ice bodies will survive. Most glaciers will however disappear. Here, we will redraw this picture combining 3D glacier evolution modelling with systematic data assimilation. In this way, a seamless record of glacier evolution in the European Alps is produced, spanning the time period 2000 to 2100 and considering various climate scenarios.  Its main asset is that no geometric simplifications are applied as typically done in current tools for regional glacier modelling. Together with inverse and ensemble techniques for data assimilation, our approach can directly ingest map products of observed surface velocities as well as the spatial pattern of the observed 2000-2020 elevation change. For our future projections, we exclusively rely on high-resolution regional climate models, better representing the atmospheric conditions over mountainous.

Our results largely corroborate the above-described grim fate for the European glacier population. The retreat is primarily driven by temperature increase rather than precipitation changes.  For the first time, 3D simulations make this retreat tangible in its full extent. Even under the most favourable climatic trajectories, glacier remnants will only survive as isolated ice patches at high altitudes. Like hermits or relicts from the past, they will have largely disappeared from the public perception in Central Europe - at the latest by 2100. We further break down our projections by Alpine sub-regions. We find more pronounced values of relative volume loss in southern and eastern regions (e.g., Rhaetian Alps). Regions with little coverage at present (e.g., Glarus Alps) will virtually become ice-free. Only exception is the French region of the Dauphiné Alps. In general, glaciers in the north-western ranges (Pennine, Bernese, Graian Alps) appear more resilient to future warming – as glacier there can retreat to higher altitudes.

How to cite: Fürst, J. J., Herrmann, O., Groos, A. R., Kc, M., Prasad, V., Sommer, C., and Jouvet, G.: Taking a glimpse into the glacier demise of the European Alps – a 3D portrait, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14057, https://doi.org/10.5194/egusphere-egu26-14057, 2026.

Glacier complexes in the Manaslu region of Nepal Himalaya have been experiencing only moderate mean area losses and geodetic mass balance since the 1970s (~ -0.26 % a^-1, -0.17 ± 0.03 m w.e.a⁻¹. Many debris-covered glacier tongues exhibit large amounts of supra-glacial vegetation and stagnating patterns. Here, we investigate these apparent patterns of stagnation of glacier systems in this area, specifically the prevalent vegetation development and the geomorphological characteristics of debris cover tongues. We use remote sensing-derived surface velocities derived from image cross-correlation (RGDyn open-source package) based on Landsat and Sentinel-2 time series combined with high-resolution declassified Corona imagery and Pléiades. Preliminary results indicate ~8 % supra-glacial vegetation coverage at a regional scale and general glacier slowdown with variable movement rates depending on glacier morphology and debris covered characteristics.

How to cite: Racoviteanu, A. E., Fichant, A., Cusicanqui, D., Glasser, N., Millan, R., Harrison, S., and Robson, B. A.: Vegetated debris-covered glaciers and stagnating patterns in the Manaslu region of Nepal Himalaya, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14771, https://doi.org/10.5194/egusphere-egu26-14771, 2026.

Global glacier mass loss is accelerating, yet considerable spread in projected glacier changes remains due to model structure, forcing, and parameter uncertainty. Most global glacier projections rely on relatively simple models where calibration approaches are essential to constrain uncertainty by using scarce observations. Probabilistic calibration strategies that help with quantifying uncertainities have recently incorporated into a limited number of global glacier models. As a next step, we suggest employing Bayesian data assimilation methods with untapped potential to integrate multi source observations (in-situ, satellite, reanalysis) when calibrating global glacier model projections.

Here, we present a probabilistic calibration framework for the Python Glacier Evolution Model (PyGEM) based on ensemble-based data assimilation. Two data assimilation techniques (PBS and AdaPBS) are used to calibrate mass balance parameters to constrain future projections of glacio-hydrological variables (surface mass balance and runoff) between 2015 and 2100 under four SSP climate scenarios across the Scandinavian region. In this work, we compare our calibration results with commonly used deterministic and probabilistic glacier model calibration algorithms which are already in use in PyGEM. Our probabilistic calibration framework based on data assimilation has the potential to quantify and disentangle uncertainties from climate forcing, model structure, and parameters. Better constrained and uncertainty-aware glacier models increases confidence in projections of future glacier change and their relevant impacts. This work paves the way for producing policy relevant global glacier projections and scenarios with their uncertainty estimates within the ERC-AdG GLACMASS project.

How to cite: Yılmaz, Y. A., Aalstad, K., Guillet, G., Rounce, D., Tober, B., Yang, R., Åkesson, H., and Hock, R.: Probabilistic calibration of glacier projections using data assimilation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14845, https://doi.org/10.5194/egusphere-egu26-14845, 2026.

Glacier mass loss has accelerated globally in recent decades, yet many regional and global glacier models still rely on temperature-index melt formulations that limit physical realism and process attribution. Physics-based approaches, such as surface energy balance (SEB) models, can overcome these limitations but are challenging to apply at regional scales because they require climate forcing resolved at local scales. Global climate models and reanalysis products are known to perform poorly in complex mountainous terrain without downscaling and bias correction. In addition, albedo parameterizations in SEB models typically require calibration against in-situ observations, which are sparse for most glacierized regions.

Here, we evaluate the skill of a physics-based glacier modeling framework designed to reconstruct glacier mass changes with minimal parameter calibration and without downscaling, and with only limited bias correction of climate input data. We first assess a relatively simple SEB model forced by climate variables from the European Centre for Medium-Range Weather Forecasts ERA5 reanalysis. Surface albedo, a key input to the SEB model, is prescribed using a standalone machine-learning model trained on Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations. We show that calibration of selected model parameters—most notably precipitation correction and albedo bias correction—is required for the model to perform well from local to regional scales across western Canada. We then evaluate a more complex SEB formulation using the open-source COupled Snowpack and Ice surface energy and mass balance model in PYthon (COSIPY), with the aim of assessing whether parameter calibration can be further reduced or avoided. We find that neural-network-based albedo estimates substantially improve model performance and that calibration-dependent albedo bias correction is no longer required when Landsat data are used instead of MODIS. In contrast, wind speeds from ERA5 require bias correction to obtain realistic turbulent heat fluxes, highlighting the importance of improving the representation of katabatic winds over glacier surfaces. With these adjustments, the non-calibrated physics-based model performs well in simulating summer mass balance at the glacier scale, provided that snow accumulation at the onset of the melt season is adequately captured. 

How to cite: Radic, V., Phelps, H., and Draeger, C.: Toward Minimally Calibrated Physics-Based Glacier Mass Balance Modeling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15272, https://doi.org/10.5194/egusphere-egu26-15272, 2026.

Understanding how ice caps and glaciers respond to climate change is essential for improving projections of present and future sea-level rise. The Holocene provides a valuable time period for this purpose, as it encompasses long-term ice–climate interactions and a transition from colder to warmer conditions comparable to today. 

Here we investigate the Holocene glacial history of the region presently covered by the Flade Isblink ice cap in northeast Greenland, a remote and high-elevation ice mass that is not directly connected to the Greenland Ice Sheet and is therefore particularly sensitive to climate forcing.

Flade Isblink is situated on the Kronprins Christian Land plateau and drains through fast-flowing outlet glaciers into the Arctic Ocean, storing a substantial volume of freshwater. Its geographic setting makes it an excellent indicator of Arctic climate variability. Here, we focus on identifying which parts of the ice cap survived the Holocene Thermal Maximum and on reconstructing ice extent in regions where geological constraints are sparse.

We use a two-dimensional coupled ice-flow and surface mass balance model implemented in the Ice Sheet and Sea-level System Model (ISSM) to simulate ice evolution from 12.4 ka BP to the present. Time-varying bedrock uplift and relative sea-level change are incorporated through an offline glacial isostatic adjustment (GIA) solution. To account for uncertainties in climate forcing, we run an ensemble of simulations spanning a range of climate scenarios. Model results are evaluated against geomorphological evidence, dated materials, and present-day ice geometry.

How to cite: Bråtner, A., Morlighem, M., Seroussi, H., and Khan, S. A.: Modelling the Holocene evolution of Flade Isblink, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15329, https://doi.org/10.5194/egusphere-egu26-15329, 2026.

In recent decades, an increased frequency of heat waves (HWs) has been detected along the subtropical Andes (SA); however, their impact on the cryosphere has not been assessed in detail. Here we present a multi-scale assessment with the objective of quantifying the impact of HWs on Andean glaciers located in the SA. Sub-daily observations of melt at the Universidad (34°S) and Pichillancahue (39°S) glaciers show that the daily melt rate increases by approximately 25% during HW events compared to the rest of the ablation season. At the annual scale, the relationship is complex. Using seasonal HWs climatologies derived from the ERA5 reanalysis and glacial mass balances available from the World Glacier Monitoring Service (WGMS), it was determined that there is no significant relationship between the number of HW events and the annual mass balance. However, the annual mass balance of the Echaurren Norte Glacier (33°S) showed significant positive correlations (p<0.05) with the number of HW events occurring over the Pacific Ocean, during the spring and summer seasons between 1975 and 2023. Furthermore, the mass balance of the Piloto Este Glacier (33°S) also shows significant positive correlations with the number of HW events in the Pacific during spring and summer between 1979 and 2002. These correlations would indicate the importance of the higher evaporation rate during HW events, with the consequent contribution of moisture to the atmosphere, contributing to precipitation and snow accumulation on glaciers during synoptic events occurring over the Andes. The above is consistent with the fact that glaciers in the central Andes of Chile and Argentina are more sensitive to precipitation variability, as well as its relationship with the El Niño-Southern Oscillation (ENSO). While melt rates increase during HW events, the forcing  of evaporation rates during HW events over the Pacific would generate a greater impact on the annual glacier mass balance. This finding, from a glaciological perspective, calls for further investigation into the role of HW events over the oceans as drivers of evaporation and their transport and circulation mechanisms. This work is funded by the FONDECYT Iniciación Project 11240379.

How to cite: Bravo, C., Gonzalez-Reyes, A., Bozkurt, D., and Cisternas, S.: Heat wave events and the response of glaciers in the subtropical Andes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15852, https://doi.org/10.5194/egusphere-egu26-15852, 2026.

The cryosphere is experiencing rapid decline due to climate change, with 25-54% mass loss of the world’s glaciers predicted over the next century. These changes have far-reaching implications including impacts on local geohazards, regional freshwater availability, global sea-level rise, and downstream nutrient supply. Though many studies have examined the physical processes associated with glacier change, we still lack a complete understanding of the associated geochemical consequences. This is especially important to constrain as glaciated catchments are important sources of lithogenic nutrients due to mechanical and chemical weathering, and meltwater transport in turn influencing downstream ecosystems.

To better constrain the effects of subglacial weathering on glacial runoff chemistry, water and ice samples were collected at Storglaciären and Isfallsglaciären, two polythermal glaciers in the Tarfala Valley, Arctic Sweden in the summers of 2024 and 2025. These glaciers have experienced dramatic thinning and retreat for the past century, with this trend recently accelerating. Water temperature, conductivity, pH and other parameters were measured in situ. Samples were analyzed for major and trace ion concentrations, total carbon, and stable water isotopes. These are the first reported geochemical measurements of this kind for the reference glacier Storglaciären.

Aqueous geochemistry results indicate that chemical weathering of the bedrock is likely driven by a combination of both carbonic (H₂CO₃) and sulfuric (H₂SO₄) acid dissolution, resulting in major cations (e.g., Ca, Mg), Si, and Fe being released from subglacial sediment. Solute concentrations are highest at the cold-based ice margins, indicating increased dissolution of Fe- and Mg-rich bedrock in these areas. Concentrations of sulfate are also highest under the cold ice, most likely due to increased FeS₂ oxidation at the cold-based margins of the glacier.

These results indicate that heterogeneous oxidation most likely drives acidic weathering in the subglacial environment, and that this process appears to be more effective in the more stable, cold-based margins of the glacier where residence times of sediment are longer. Localized silica precipitation is more prevalent in the warm-based portions dominated by subglacial meltwater, glacial sliding, and seasonal flushing of sediment and water. These results suggest that there may be detectable differences in alteration processes between cold- and warm-based glacial thermal portions of ice sheets and glaciers, that these differences are detectable in local meltwaters, and that significant amounts of solutes are generated by subglacial alteration processes and transported to lower elevation Arctic ecosystems. It is imperative that future studies include repeat meltwater monitoring at these rapidly changing systems to understand the ongoing effects of climate change on glacial water chemistry and downstream nutrient supply.

How to cite: Rutledge, A., Havig, J., Horgan, B., Salvatore, M., De Anda, C., and Marrs, I.: Meltwater chemistry at two rapidly retreating Arctic Sweden glaciers: Implications for downstream nutrient supply in a warming climate, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15904, https://doi.org/10.5194/egusphere-egu26-15904, 2026.

The Svalbard archipelago (76-81N) is undergoing increased warming compared to the global mean, which has major implications for freshwater runoff into the oceans from seasonal snow and glaciers. Quantifying changes of freshwater runoff  requires close integration of observations and process-based models.

Here, we use land-surface and ice-flow modelling in combination with satellite and in-situ observations, to simulate runoff from the Bayelva catchment, Svalbard (~30 km2, ~54% glacier cover), for the period 1991–2100. Runoff from seasonal snow and glaciers is simulated using the land surface model CRYOGRID, which includes a coupled energy balance-snow/firn model. Historical simulations (1991–2024) are forced by downscaled CARRA reanalysis data and evaluated against in situ measurements and geodetic mass balance observations. Future simulations (2024–2100) are driven by temperature and precipitation trends derived from CORDEX projections under the RCP4.5 and RCP8.5 scenarios.

To account for feedbacks between surface mass balance and glacier geometry, the runoff simulations are coupled to the 3D glacier evolution model IGM. Sentinel-1 surface velocity observations are used to constrain glacier sliding, while observed surface elevation changes are used to evaluate simulated thickness changes and in situ ice-thickness measurements to evaluate the initial glacier geometry.

For continued warming, glacier melt will intensify, thus increasing runoff, but at a later stage, the reduction of glacier area due to retreat will offset this effect, giving rise to a peak in glacier runoff. The simulations indicate that runoff from the Bayelva catchment is likely to peak within the next two decades. Under the RCP8.5 scenario, both glaciers within the Bayelva catchment, Austre and Vestre Brøggerbreen, are projected to largely disappear by 2100, resulting in a transition from glacier-dominated to snow-dominated runoff.

How to cite: Schuler, T. V., Schmidt, L. S., Revheim, M. K., and Westermann, S.: Changes in glacier runoff in a warming Arctic: simulations from the Bayelva catchment, Svalbard, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16470, https://doi.org/10.5194/egusphere-egu26-16470, 2026.

Cryokarst processes such as ice cliffs, ponds and collapsed subglacial cavities have been recognized to substantially enhance surface ablation on debris covered glacier surfaces. Existing flow models for debris covered glaciers, however, still largely ignore their effects, thereby limiting the related predictions and understanding of dynamic feedbacks. We propose here a process based conceptual framework that dynamically simulates the melt enhancing effect along the glacier and can be coupled to a flow-model.

We approximate the enhancing effect of cryokarst through a state variable of ice cliff area density (ICAD) and which is simulated over time and space along the glacier surface through production, advection and reduction. The production of ICAD is assumed to be driven by the processes of meltwater incision, pondsand crevassing through extensional flow; ICAD is then advected at the surface by ice-flow. Reduction in ICAD is simulated through a typical decay timescale related to debris redistribution and burial and, for crevasses, through compressional flow. The drainage of supraglacial streams to the glacier bed under tensile strain rates or through cut-and-closure allows to remove supraglacial discharge, thereby stopping ice-cliff production from supraglacial channel incision. In addition, ICAD growth from full thickness collapse of non-pressurized subglacial channel voids is parametrized through subglacial stream discharge and a threshold in ice overburden pressure. The parametrizations of the above processes are based on variables that are directly available in flow models for debris covered glaciers and encompass ice thickness, surface slope, flow speed, debris thickness and surface ablation. This framework of modelling ICAD evolution is coupled to a flowline model for debris covered glaciers that dynamically tracks debris thickness and then uses ICAD to incorporate melt enhancement relative to clean ice. The effects of including cryokarst processes and the related feedbacks are then investigated for a synthetic debris covered glacier geometry. Modelling results indicate an enhancement of glacier decay in a warming world and are compared to observed relationships of ice cliff area density to variables such as flow speed, surface slope and debris thickness.

How to cite: Vieli, A., Hardmeier, F., Miles, E., Kneib, M., and Banjeree, A.: Towards a physically based framework of cryokarst evolution for dynamic modelling of debris covered glaciers, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16695, https://doi.org/10.5194/egusphere-egu26-16695, 2026.

Glaciers distinct from the ice sheets in Greenland and Antarctica are experiencing accelerating retreat. Consequently, landscapes so-far hidden beneath the ice will emerge, yet their characteristics are poorly constrained by existing observations and models. At the same time, the subglacial topography itself controls retreat patterns and magnitudes. Hence, an improved representation of the glacier bed is key for improved future projections of glacier evolution. Here, we present a physically plausible map of subglacial topography for all >200,000 glaciers in the world, called Topography of a Deglaciated Earth (TOPO-DE). The map is constrained by an inverse modeling approach that relies on the higher-order Instructed Glacier Model (IGM), a wealth of surface observations, and automatic Bayesian calibration against thickness observations. We find a global glacier volume of 149±29 × 10³ km³ (316±61 mm sea level equivalent) and a mean glacier thickness of 212 m. While the global total is consistent with previous work, regionally variable discrepancies highlight the differences between this study and previous reconstructions based on shallow ice-flow physics. The landscapes beneath the ice are characterized by a large potential to host future lakes, quantified as a combined potential lake volume of >3,000 km³, or 2% of the global glacier volume, and a potential areal lake coverage of the presently ice-covered lands of 6%. We show where previous studies produced unphysical bed features and compare that to solutions of our model. Our freely-available bed product offers new insights into landscapes emerging after glacier retreat and can serve as an input for future projections of glacier change and its consequences.

How to cite: Frank, T., van Pelt, W., Rounce, D., Jouvet, G., and Hock, R.: Beneath the ice: Unravelling the Topography of a Deglaciated Earth (TOPO-DE), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16948, https://doi.org/10.5194/egusphere-egu26-16948, 2026.

Glaciers in Patagonia and Tierra del Fuego remain among the least studied worldwide, despite experiencing pronounced mass loss over recent decades. Many glaciers in this region terminate in lakes or the ocean, making their evolution dependent on mass balance both directly controlled by climatic forcing at the glacier surface as well as dynamically controlled at the ice front. Recent studies demonstrate that warming air temperatures have increased surface melt rates significantly, suggesting climatic changes as the main driver for the observed losses. Climatically driven thinning can, however, trigger ice-dynamic instabilities, potentially amplifying glacier retreat.

To improve our understanding of the interaction of both components, climatic mass balance and glacier dynamics, we aim to establish a comprehensive modelling framework for Schiaparelli Glacier in Tierra del Fuego. Schiaparelli Glacier terminates in a proglacial lake that formed after recession in the 1940s. Ice thickness reconstructions reveal a potential overdeepening near the glacier front, which may lead to a self-accelerating ice-dynamic retreat once the glacier retreats into deeper water. This setting, combined with the availability of more than a decade of glaciological, meteorological and hydrological in-situ observations, makes Schiaparelli Glacier an attractive and exciting research target.

The aim of this study is to set up a modelling framework to simulate the evolution of Schiaparelli Glacier in the past and future, covering the Little Ice Age to the end of the 21^st century. To do so, we will rely on the FROST framework (“Framework for assimilating Remote-sensing Observations for Surface mass balance Tuning”), which applies an Ensemble Kalman Filter to calibrate glacier-specific surface mass balance parameters using remote sensing observations. FROST is coupled to the Instructed Glacier Model (IGM) to capture the glacier dynamics. We further upgrade the surface mass balance scheme from a basic temperature-index model to a simplified energy balance model that explicitly accounts for solar radiation. Past glacier extents derived from moraine and tree-ring dating are used to validate the reconstructed glacier evolution of Schiaparelli Glacier.

How to cite: Temme, F., Berkhoff, J., Herrmann, O., Langhamer, L., Tabone, I., Jaña, R., and Fürst, J.: From the Little Ice Age to the future: modelling the evolution of Schiaparelli Glacier, Tierra del Fuego, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17201, https://doi.org/10.5194/egusphere-egu26-17201, 2026.

Supraglacial debris partially covers more than 40% of Earth’s glaciers (excluding Antarctica) and, where present, acts as a major controlling factor for glacier melt. It can enhance melt when the layer is thin by reducing surface albedo (increasing the net radiative flux) and it reduces melt when it is thick by insulating the ice from the atmosphere (dampening the conductive heat flux). Accurately simulating the spatio-temporal evolution of debris over a glacier is still a challenge, because of diverse debris sources and mechanisms of transport on and within the ice that affect long-term debris cover evolution. Previous studies have investigated the evolution of debris from geomorphological and historical data or from debris-tracking ice dynamics modelling. These approaches, however, often do not capture the transient ice melt-debris thickness relationship under a changing climate. To date, no attempt has been made to couple the century-scale evolution of debris extent and thickness with a full surface energy-balance model to evaluate debris-melt feedbacks and assess their impacts on catchment-scale runoff generation.

We apply a distributed land surface-energy balance model to simulate the glacier evolution and surface hydrology of the Aletschgletscher catchment (including glaciated and ice-free areas) in the Swiss Alps from 1900 to 2023. We incorporate the evolution of supraglacial debris, constrained using historical topographic maps and recent debris thickness measurements. We evaluate the impact that time-evolving debris-cover extent and thickness has on the glacier mass balance and hydrology. We also compare results for Grosser Aletsch and Oberaletsch to demonstrate that increasing catchment debris cover influences catchment response to climate and glacier change.

Our results show that the contribution of sub-debris melt to runoff varied substantially over the last century. The catchment-wide sub-debris melt contribution increased until ~1945, then declined until today. However, trends differed between subcatchments. In the sparsely debris-covered Grosser Aletschgletscher, sub-debris melt reached its peak around 1940 (25–30% of total ice melt) before decreasing until present (same pattern as the entire catchment). In contrast, the highly debris-covered Oberaletsch shows a continuous increase, with recent values reaching 40–50% without a clear peak. The catchment trend is primarily explained by the evolution of debris cover on Grosser Aletschgletscher, combined with climate factors. Periods of expanding debris extent (~1910–1930 and ~1940–1965) initially increased the sub-debris melt contribution by enlarging the area where melt is enhanced by thin debris. Once debris area stabilised and average thickness increased (post-~1965), the stronger insulating effect reduced its relative contribution. An early rapid thinning of debris (~1910–1920) further enhanced early melt. Furthermore, climate warming has raised the 0°C isotherm, increasing melt in debris-free areas and thereby relatively reducing the proportion of melt occurring under debris. Therefore, the sub-debris melt contribution is affected by the combination between debris evolution and climate change. In a world with darkening glaciers, it is essential for glacio-hydrological models to consider evolving debris extent and thickness, and to incorporate feedbacks related to these changes, which substantially impact the surface energy balance, in order to accurately project future runoff from these catchments.

How to cite: Melo-Velasco, V., Shaw, T., McCarthy, M., Fyffe, C., Miles, E., Muñoz Hermosilla, J. M., Fontrodona-Bach, A., Gantayat, P., Jouberton, A., and Pellicciotti, F.: Glacio-hydrological modelling of the Aletschgletscher catchment with evolving supraglacial debris since 1900, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17501, https://doi.org/10.5194/egusphere-egu26-17501, 2026.

The Arctic is increasingly influenced by extreme events both in environmental forcing, and in the response in the cryosphere. Still, the mechanisms linking short-lived events in the different component of the Arctic system (atmosphere, land ice, ocean and sea ice) remain poorly understood. Within the  ESA-funded ARCTEX project we use a range of EO datasets and model outputs to identify extreme events and their impact on three different ice caps/ glaciers in the Arctic: The Flade Isblink and Austfonna ice caps and Nioghalvfjerdsfjorden outlet glacier.

Here, we present our findings over the Flade Isblink Ice cap in Northeastern Greenland. We present a comprehensive suite of EO-derived data sets over and around the ice cap, and wavelet analysis to identify extreme events, periodicity and regime shifts in these time series. One finding is the surge of Marsk Stig Bræ, which was initiated after 2021, and the subsequent response in the surface topography of the ice cap. We examine the potential drivers and consequences of this surge, with particular emphasis on the possible coupling between glacier dynamics, the drainage of a nearby subglacial lake, sea ice variability and ocean temperatures. Using a multi-sensor Earth Observation approach combined with regional climate model output, we analyse the temporal evolution of ice velocity, surface elevation, meltwater production, and subglacial hydrology from 2011 to 2025. This study demonstrates the value of integrated, high-temporal-resolution EO datasets for resolving rapid cryospheric change.

How to cite: Sandberg Sørensen, L., Scanlan, K., Fredensborg, R., Andersen, N., Arildsen, R., Kirby, J., and Kruse, M.: Drivers and impacts of extreme events on Flade Isblink ice cap., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17756, https://doi.org/10.5194/egusphere-egu26-17756, 2026.

Debris-covered glaciers influence the regional hydrological cycle by modulating glacier melt processes. One important control on melt variability on debris-covered glaciers are ice cliffs, which have been identified as melt hotspots, exhibiting ablation rates that far exceed those of the surrounding debris-covered area. As a result, they contribute disproportionately to total glacier mass loss. However, their dynamics and contribution to overall ablation have been quantified for only a few glaciers, mainly in the Himalaya. Quantifying and parameterizing ice cliff dynamics, including modelling frameworks, is needed to reliably project the future evolution of debris-covered glaciers in different mountain regions, as well as their water supply.

The aim of this study is to quantify ice cliff melt and backwasting rates in alpine settings, to generate a reference dataset for ice cliff model applications and to assess their relative contribution to total ablation. Ablation and dynamics of four ice cliffs were measured between 26 August and 19 September 2025 at the Kanderfirn. The Kanderfirn, a valley glacier in the Swiss Alps, was selected for this study as the tongue comprises both debris-covered and debris-free areas and, thus, enables the study of different ablation processes at the same site. Four ice cliffs representing the four cardinal orientations were selected to assess differences in melt and backwasting rates related to the ice cliff orientation, which are discussed in the literature. In total, eight stakes were installed at the four ice cliffs, with one stake drilled into the bare ice face of each cliff and a corresponding stake placed in the debris-covered area immediately above each cliff, to quantify the vertical, tangential and sub-debris melt rates as well as horizontal backwasting rates. Eleven additional stakes were installed at sites with varying debris thickness. Moreover, repeated UAV surveys were carried out to generate digital elevation models for the investigation of the geometric evolution of the ice cliffs over a one-month period. Finally, a surface energy-balance model was applied to model ice cliff and sub-debris ablation using the UAV-based digital elevation model and meteorological data from on- and off-glacier weather stations.

The in-situ results show clear contrasts in melt rates between ice cliff faces and the surrounding debris-covered area, as well as variability among ice cliffs with different orientations, including differences in backwasting rates. Two separate estimates of apparent vertical melt rate are derived from tangential melt measurements as well as from backwasting and sub-debris melt, combined with the slope angle. The close agreement between both results indicates consistent field measurements. The measurements and modelling provide valuable insights into the ablation and dynamics of ice cliffs on an Alpine glacier.

How to cite: Kogel, A. C., Zöller, A., Mayer, C., and Groos, A. R.: Ablation and dynamics of four ice cliffs on the partially debris-covered glacier tongue of Kanderfirn, Swiss Alps, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18086, https://doi.org/10.5194/egusphere-egu26-18086, 2026.

Debris-covered glaciers play an important role in alpine hydrology, yet the origin and transport pathways of debris within the glacier remain difficult to constrain. This is a major limitation in glacier evolution models, many of which have tended to ignore debris transient effects, especially for assessment of catchment hydrological processes. Supraglacial debris coverage is an integrated signal of debris supply, climate forcing, glacier geometry and debris physical properties, all of which vary in time, resulting in a complex inverse problem for model-based reconstructions.

Here, we apply the Instructed Glacier Model (IGM) with a newly implemented Lagrangian debris transport module combined with an ensemble of climate forcing, to explore constraints on debris input at Oberaletsch Glacier in the Swiss Alps. This framework allows debris particles to be tracked within a dynamically evolving glacier geometry and enables a likelihood-based assessment of inferred debris source regions across the ensemble. Rather than seeking a unique reconstruction, we identify spatially persistent and statistically robust seeding areas that are compatible with the observed historical evolution of debris extent derived from debris-cover maps for 1965, 1985, 1995, 2000, 2010 and 2015. These areas are identified by tracing debris particles backward from their final positions within the observed debris-covered zone to their upstream seeding locations.

Our results show that our inverse filtering strategy effectively identifies potential debris input zones that are primarily controlled by glacier dynamics and geometry. Notably, including or excluding the effect of debris on surface mass balance does not significantly alter the reconstructed debris extent in the ablation zone, highlighting the dominant role of ice flow in shaping supraglacial debris patterns at glacier scale. The reconstructed debris input patterns allow us to reproduce the observed historical evolution of debris extent and glacier geometry with good agreement. Debris extent matching between simulations and observations reaches around 80%, while the percentage of the total particles ending up in the target debris area remains above 70%. Ongoing work addresses the reconstruction of debris thickness, which is sensitive to both the debris weight (i.e. the assigned debris volume) prescribed for each particle and, crucially, the climatic forcing, requiring an iterative approach to capture the full transient characteristics of the glacier debris cover.

This study demonstrates that ensemble-based Lagrangian modelling provides a powerful framework to constrain debris input to glaciers. By explicitly coupling debris transport to the evolving glacier dynamics, this approach opens new perspectives for interpreting present-day debris cover and for projecting the future evolution of debris-covered glaciers under changing climatic conditions.

How to cite: Muñoz-Hermosilla, J. M., Miles, E., McCarthy, M., Melo Velasco, V., Hardmeier, F., Gantayat, P., Fontrodona-Bach, A., Jouvet, G., and Pellicciotti, F.: Constraining debris input to Oberaletsch Glacier using ensemble-based Lagrangian modelling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19367, https://doi.org/10.5194/egusphere-egu26-19367, 2026.

Recent climate warming has increased the extent of debris cover on mountain glaciers. A thicker debris cover tends to shield the glacier surface from melting whereas a thinner/ patchy debris cover can amplify surface melting, with consequences for glacier dynamics and evolution. Most modelling studies that have estimated glacier evolution at a regional scale either a) do not consider the impact of debris cover at all or, b) assume a temporally static debris cover. Some major advances have been achieved in a recent study that accounted for the impact of evolving debris cover on future evolution of glaciers with an aerial extent > 1 km2 in High Mountain Asia; however, limitations remained related to the parameterised relationships between debris cover area and thickness changes. Alternatively, debris-explicit ice flow models exist, but are not suitable for  regional or global scales due to the data inputs and spin-up period. As such, a gap exists for an approach to model dynamic debris that is physics-based but simple to implement in large-scale glacier models.

To address this gap, we present a 1D numerical ice-flow model based on the Shallow Ice Approximation (SIA) that  includes coupled sub-modules which explicitly evolve the debris cover and thickness using principles of mass conservation and a degree day approach for estimating surface mass balance. It uses freely available data namely ERA-5 daily data of temperature and precipitation, glacier geodetic mass balances, historic satellite-derived supraglacial debris cover, glacier surface elevation and glacier surface velocities as inputs. The debris extent/thickness module is easily calibrated; dependent on the mass balance parameters and does not lead to the problem of equifinality of parameter sets.

We demonstrate the model over four debris-covered glaciers located in  the Central European Alps (Oberaletsch, Zmutt, Pasterze and Miage glaciers), where present-day debris thickness data are available. Results from the historic simulations show that the model was able to estimate the distribution of debris thickness within an RMSE ~ 0.07 m. In addition to that, the modelled evolution of the debris cover area fraction (i.e., the fraction of the glacier area covered by debris in a 10-m surface elevation band) was also in good agreement with that measured with maximum RMSE of ~8% per elevation band. The future evolution of these glaciers was carried out by forcing the ice-flow model with CMIP6 derived SSP2-4.5 and SSP5-8.5 climate scenarios, and highlighting the process of tongue detachment from headwall mass supply areas in the 21st century. Future simulations revealed that these test glaciers would be nearly completely covered with debris by the end of the 21st century with debris thicknesses becoming at least twice as compared to the present state. In addition to that, these glaciers are also expected to break into fragments with the tongues getting detached from the main glacier.  Overall, the coupled model is easy to apply, computationally fast and is currently being used to study the impact of an evolving debris cover on glacier evolution, in the Central European Alps, under different climate scenarios.

How to cite: Gantayat, P., Miles, E. S., Jouberton, A., Manuel Munoz, J., Melo Velasco, V., Fontrodona Bach, A., McCarthy, M., and Pellicciotti, F.: Modelling the impact of an evolving supraglacial debris cover on the future evolution of glaciers in a changing climate, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19772, https://doi.org/10.5194/egusphere-egu26-19772, 2026.

In High Mountain Asia (HMA), glacier meltwater plays a critical role in regulating seasonal river discharge and supporting water availability for populations living in mountainous and downstream regions. Observed acceleration in glacier mass loss over recent decades, together with projected future warming and changes in precipitation, is expected to modify the timing and magnitude of meltwater contributions, with significant implications for regional water security, sustainable development, and glacier-related hazards. To quantify glacier responses to climate change under different emission scenarios, we model glacier evolution across diverse climatic settings in HMA, including the Central Karakoram, Tibetan Plateau, and Central Himalaya. We use a MOno-Layer Higher-Order ice-flow model within the Ice-sheet and Sea-level System Model on an unstructured triangular finite-element mesh, locally refined at high spatial resolution (30–500 m) based on present-day observed surface velocities. We use a nonlinear Budd friction law and the basal friction coefficients are inferred using surface velocity observations from 2022. Surface mass balance (SMB) is computed using a temperature-index method that explicitly accounts for debris cover effects. The SMB model is calibrated against geodetic mass-balance estimates derived from stereo imagery (2000–2020) and validated using satellite altimetry observations (2003–2023). We simulate the glacier evolution from 2000 to 2100 under SSP1-2.5, SSP2-4.5, SSP3-7.0, and SSP5-8.5 using climate forcing from five global climate models (GCMs). Based on ensemble of all five GCMs, glaciers are projected to loose 10 ± 16% (SSP1-2.5) to 98 ± 2% (SSP5-8.5) of their mass by 2100, relative to 2000 across the regions. Among all studied region Monumaha Ice field and Purogangri Ice Cap on Tibetan Plateau exhibit a maximum mass loss of up to 70 ± 22 to 98 ± 2%. We find that on individual glaciers mass change debris cover play an important role, particularly in Central Karakoram region where debris cover delayed the mass loss by 15% by the end of 2100. One of the major takeaways for our study is that compared to earlier studies based on flowline models, our estimates show that glacier mass change differs significantly

How to cite: Hassan, M., Kayastha, R. B., Cheng, G., Chand, M. B., and Hassan, J.: Modeling Glacier Evolution Across Different Climatic Regions of High Mountain Asia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21674, https://doi.org/10.5194/egusphere-egu26-21674, 2026.

Debris on glacier surfaces has a strong effect on glacier melt and is currently expanding and thickening due to climate change. Several studies have applied coupled debris-ice dynamic modelling in order to simulate the evolution of debris-covered glaciers. However, many aspects within these dynamic systems remain poorly constrained, as data is scarce and processes are complex and interdependent. So far, most approaches focused on the simulation of the debris layer in the ablation area, but preceding processes of debris supply through gravitational processes and englacial debris transport are often represented based on simple assumptions or limited measurements and with unknown uncertainties. In this study, we address this issue by investigating how changes in the spatial distribution of debris supply affect down-glacier debris transport and debris cover.

For this, we apply a novel 3-dimensional coupled debris-ice dynamics model, implemented within the Instructed Glacier Model (IGM), that uses particle tracking to model englacial and supraglacial debris transport. In this approach, particles need to be seeded to initialize their entry into the glacier system. This involves the development of a framework to decide where and at what rate we seed these particles. We test several approaches and implement a scheme that automatically generates seeding locations based on local topography. In our experiments, we find that small differences in along-flow seeding location can have a strong impact on englacial transport paths, debris cover extent, and finally glacier extent. This reasserts the need to better constrain debris supply as an important part of the process chain if we want other aspects to be accurately represented in models.

How to cite: Hardmeier, F., Miles, E., Muñoz-Hermosilla, J. M., Jouvet, G., and Vieli, A.: The effect of debris supply on glacier evolution: sensitivities and challenges, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21688, https://doi.org/10.5194/egusphere-egu26-21688, 2026.

Debris-covered glaciers have been widely recognized in glacier runoff contributions and ice-rock disasters. It showed that debris-covered glaciers occupy about 27% glacierized region in the Central Himalayas. However, the delineation of debris-covered glaciers is still the bottleneck, which leads to high uncertainties in glacier change deteriorating our understanding of the hazard cascade from the collapse of rock and ice. Therefore, it is vital to provide the definitive margins of the debris-covered ice.

Here, we put forward a suitable method to locate the debris-covered glacier terminus of the Middle-West Rongbuk glacier based on multi-temporal surface elevation change data pairs from multi-source remote sensing data (such as DEM differencing, ICESat-2 laser altimetry, and InSAR technology). According to the DDh indicator (the difference in Dh), the debris-covered glacier terminus is determined. In addition, the glacial movement velocity generated from Sentinel-1 images was also used to verify the determined terminus outline of the debris-covered glacier. Our results showed that, from 1974 to 2025, the terminus of the debris-covered Rongbuk Glacier continuously migrated to higher elevations, rising from about 5240±20 m in the 1970s to 5290±20 m in the 2000s, then upward further to 5400±50 m after the 2010s. Over the past 48 years, the cumulative upward shift was approximately 160 m.

How to cite: Ye, Q., Ali, N., Ghimire, K., Wang, J., and Zhu, L.: Identifing the debris-covered terminus for the Middle-West Rongbuk Glacier at the Mt. Everest in the Central Himalayas, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22641, https://doi.org/10.5194/egusphere-egu26-22641, 2026.

The Pyrenees range is the most southern European region with active glaciers and rock glaciers. In the current climate change context, their depth, extent and viability are rapidly declining. Even though they are usually located in high-elevation and remote areas, their dynamics can affect human settlements and activities. Mapping and monitoring these ice bodies will provide more information about their past, present and future evolution.

Remote sensing data provides extensive information, especially in rough mountainous areas and inaccessible or distant regions. Differential and Multitemporal interferometry (DInSAR and MT-InSAR) has been extensively proven to be a valuable tool to detect ground deformations, but also works to provide insightful results over glacial and periglacial environments. Since many authors have found SAR data useful in this context, there is a scarcity of works that exploit the high spatial and temporal resolution of X-band dense constellations such as COSMO-SkyMed. On the other hand, this kind of ice bodies are usually located over low satellite-visibility areas (related to shadow and layover effects), increasing the importance of alternative information, such as that provided by in-situ (GNSS) or near-remote sensing (UAV).

This work compares coverture and displacement results from Sentinel-1 C-band (both DInSAR and MT-InSAR) and COSMO-SkyMed X-band data. MT-InSAR results from EGMS revealed low coverage due to geometrical and snow-cover issues, while DInSAR results from both constellations provide better coverage results. UAV flights over the glacier allowed perfect coverage and high spatial resolution, but lacked in temporal resolution. Lastly, a GNSS measurement grid was redeployed over the glacier and will provide displacement data for future campaigns and for comparison with previous campaigns in the 90s. Combining data from UAV flights, three-dimensional displacement is estimated and compared with InSAR results, after projection in the Line of Sight (LOS), with the InSAR displacements. This work is part of JDC2023-052719-I, financed by MCIU/AEI/10.13039/501100011033 y and FSE+.

How to cite: Ezquerro, P., Revuelto, J., López-Vinielles, J., Izagirre, E., Domínguez Aguilar, P., Bandrés, J., Rojas Heredia, F., Monserrat, O., and López Moreno, J. I.: Monitoring Argualas rock glacier dynamics combining InSAR, GNSS and UAV data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22830, https://doi.org/10.5194/egusphere-egu26-22830, 2026.

The onset and potentially time-transgressive latitudinal development of Northern Hemisphere glaciations during the Plio-Quaternary represents a key component of global late Cenozoic climate dynamics. The timing of the earliest Alpine glaciations has been debated since the pioneering work of A. Penck and E. Brückner at the beginning of the 20^th century. Over the past three decades, cosmogenic nuclide burial dating has provided absolute ages on glacial and fluvioglacial sedimentary deposits in the Alpine forelands, progressively refining the chronology of early glaciations as methodological advances have emerged and as the number of analyzed samples has increased. Recent syntheses from the northern Alpine foreland (Deckenschotter) and the Ivrea amphitheater indicate that piedmont glacier lobes developed between 1.2 and 0.8 Ma, suggesting that the first extensive Alpine-wide glaciations occurred during the Mid-Pleistocene Transition. However, reconstructions based solely on surface deposits are strongly affected by preservation biases, as repeated glaciations may have eroded older sedimentary archives. As a result, Early Pleistocene surface records may have been largely removed by subsequent, more extensive glaciations.

Karst systems provide an alternative archive for early glaciations. During glacial periods, glaciers in contact with karst conduits inject detrital material (allochthonous or autochthonous) into subsurface voids, where sediments can be preserved for several million years. These buried deposits can be dated using in situ cosmogenic nuclides such as ²⁶Al–¹⁰Be in quartz. Prior to this study, very few geochronological and sedimentological data existed for such ancient glacio-karst deposits (i.e. Early Pleistocene). New ²⁶Al–¹⁰Be burial ages obtained from 20 detrital endokarst sediment samples (sands and pebbles) in the western to central Alps (Vercors, Chartreuse, Haut-Giffre and Bernese Alps), together with a synthesis of existing dating in the central Alps, allow the first spatio-temporal reconstruction of glacial sediment injections into the Alpine karst. Consistent with surface records, the burial ages reveal major glacial sediment injections into the karst around 0.8 Ma, at the end of the Mid-Pleistocene Transition. However, the data also point to a much earlier phase of widespread injections around 2 Ma. These early injections occurred both in high-elevation (>2500 m) headwater karst systems and in peripheral karst networks bordering the major Alpine valleys along the mountain front, demonstrating that widespread early glaciations affected the entire Alpine chain around 2 Ma. Because Alpine valleys were less deeply incised during the Early Pleistocene, glacier geometries differed significantly from those of Middle and Late Pleistocene glaciations, with thinner and potentially less extensive ice bodies. These earliest Alpine glaciations are contemporaneous with major advances of the Eurasian and North American ice sheets, consistent with extensive Northern Hemisphere glaciations at that time, predating the intensification of glaciations initiated at the Mid-Pleistocene Transition. Ultimately, this study highlights the potential of mountain karst systems as long-term archives for reconstructing Quaternary climate transitions.

How to cite: Mai Yung Sen, V., Valla, P., Jaillet, S., Robert, X., Rolland, Y., Borreguero, M., Carcaillet, J., Pons-Branchu, E., Crouzet, C., and Bruguier, O.: Early Alpine glaciations at ca. 2 Ma revealed by 26Al–10Be burial dating of endokarst sediments in the western–central European Alps, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-461, https://doi.org/10.5194/egusphere-egu26-461, 2026.

The west-central Keewatin region of northern Canada preserves a rich record of former ice sheets and their impact on the landscape. The diverse assemblage of glacial landforms in the region reflects spatial variations in glacial modification driven by changes in basal thermal regime, subglacial hydrology, and ice-flow dynamics, all of which are key to reconstructing the history and behaviour of palaeo-ice sheets. Resolving how these landforms relate to changes in basal regime and glacial modification requires integrated datasets such as geomorphological mapping and to provide the robust reconstructions needed for climate and ice-sheet models.

Our work aims to provide both a qualitative and quantitative assessment of glacial landscape modification in the west-central Keewatin region of the Northwest Territories and mainland Nunavut using two independent proxies: geomorphic mapping and cosmogenic nuclide concentrations. We used the ArcticDEM and Landsat 8 imagery to remotely map This new inventory of landforms, integrated with existing mapping, provides a qualitative assessment of glacial landsystems and landscape modification across the Keewatin region. As a quantitative proxy for glacial modification from the last glacial period(s), we collected 10 bedrock and 7 boulder samples for cosmogenic ¹⁰Be measurement along a north-south transect east of Dubawnt Lake, Nunavut. The sample transect was informed by glacial geomorphic mapping and was selected to test field-based predictions of the degree of landscape modification from the previous glaciation(s). The northern portion of the transect contains high concentrations of streamlined landforms associated with the onset zone of the Dubawnt Ice stream, inferred to be a region of high glacial modification. In contrast, the southern end of the transect contains lower concentrations of streamlined features, flow sets with contrasting orientations, and cross-cutting striations, suggesting a higher degree of landscape preservation during the last glaciation(s). Preliminary ¹⁰Be results broadly confirm our initial assessment of glacial modification along our transect, revealing slightly higher concentrations of ¹⁰Be in the south (less modification) and decreasing ¹⁰Be concentrations towards the north (more modification). Both bedrock and boulder samples follow this trend, however, our results show that in both low- and high-modification landsystems, some samples retain significant nuclide inheritance, including some boulders which suggests transport from a less modified landscape. Combining qualitative and quantitative approaches to evaluate glacial modification associated with specific landform assemblages informs our understanding of the basal thermal conditions of palaeo-ice sheets, the distribution of which informs our understanding of ice sheet evolution through space and time. Furthermore, the identification of streamlined features into palaeo-flow sets supports potential mineral exploration by helping to determine glacial transport directions and dispersal patterns. However, our results show the concentrations of cosmogenic nuclides vary within individual landsystems, suggesting that glacial modification varied through time and can be influenced by multiple factors (e.g., subglacial thermal conditions, topography, glacio-isostatic adjustment, lake development) that remain to be quantified.  

How to cite: Crowell, C., Kelley, S., Brouard, E., Campbell, J., and Gosse, J.: Using digital mapping and cosmogenic 10Be to assess glacial landscape modification in west-central Keewatin, Arctic Canada , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-822, https://doi.org/10.5194/egusphere-egu26-822, 2026.

Understanding temperature variability during the Holocene is critical for constraining baselines of natural climate variability. Temperate mountain glacier extent is limited most significantly by summer air temperature, thus geological records of past glacier length changes represent a useful proxy for this climatic variable. Iceland’s maritime glaciers with their high sensitivity to temperature and precipitation changes serve as robust indicators of climate variability in the North Atlantic region. Previous reconstructions of Iceland’s Holocene glacier and climate history have relied primarily on marine sediment cores, terrestrial geomorphological evidence, and glaciological modelling. These proxies highlight a correlation between glacier fluctuations and regional climate variability and suggest notable glacier retreats during early and mid-Holocene warm periods.

Here, we present cosmogenic chlorine-36 measurements from four outlet glaciers of the Vatnajöküll ice cap in Iceland that test and further constrain the occurrence of past glacier minima during the Holocene. Unlike the more commonly used method of cosmogenic surface exposure dating of moraines, which constrains the timing of past glacier advances, our application targets the remnant cosmogenic signals of prehistoric exposure events preserved in freshly exposed proglacial surfaces. Our data thus tests for the occurrence and constrains the duration of past glacier retreat events and, thereby, warmer times during the Holocene. Our results support the hypothesis that Icelandic glaciers were smaller than present for several millennia during the Holocene and when combined with existing datasets of Icelandic climate, our new results allow us to reconstruct both glacier advance and retreat through the Holocene.

How to cite: de Campo, A., Eaves, S., Norton, K., Wilcken, K., Fülöp, R.-H., Simon, K., Silvia, C., Lane, T., and Jackson, M.: Cosmogenic chlorine-36 constraints on Holocene glacier change in Iceland, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1360, https://doi.org/10.5194/egusphere-egu26-1360, 2026.

For over 100 years, from school textbook to research, glacially sculpted landforms called drumlins have been considered asymmetrical, tear-drop shaped. Recent work has securely demonstrated that, in the absence of bedrock, this asymmetry is measurable but tiny – non-existent to visual inspection.  High-resolution DEMs and a novel application of statistics to flow-sets demonstrate that a well-studied a Swedish site exhibits a transition from asymmetrical bedrock-cored drumlins to symmetrical till-cored ones within just a few 10s of m of till. We believe that this is the first direct observational constraint upon the thickness of till required to effectively decouple flowing ice from rough bedrock topography.  Understanding where till lubrication has the potential to speed up ice flow has large implications for modelling current ice sheets and Antarctic deglaciation, so we are hoping for ideas of how to best assess this last part.

How to cite: Hillier, J. K., Smith, M., Dowling, T., Spagnolo, M., Maclachlan, J., and Martin, C.: Symmetrical till-cored drumlins highlight where past ice sheets flowed faster, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2751, https://doi.org/10.5194/egusphere-egu26-2751, 2026.

The possibility of a continuous, kilometre-thick Arctic Ocean ice shelf in the geological past has long intrigued scientists. Yet, fundamental questions surrounding the architecture, timing, and oceanic and climatic consequences of such an ice shelf remain unresolved. A pan-Arctic glaciation model has been inferred primarily from glacial landforms identified on seafloor bathymetric highs and continental shelves, as well as from geochemical proxies found in marine sediment cores.

Subsequent chronological analyses of sediment cores from these eroded regions have suggested that this pan-Arctic Ocean ice shelf developed during Marine Isotope Stage (MIS) 6, approximately 140,000 to 160,000 years ago. In contrast, more recent evidence from the eastern Fram Strait suggests the persistence of marginal sea-ice conditions and recurrent phytoplankton spring blooms across several glacial-interglacial cycles over the last 750,000 years. Nevertheless, an exception appears to occur during MIS 16, a glacial interval between ~670,000 and 620,000 years ago that remains relatively understudied in the Arctic Ocean. During this period, biomarkers indicative of sea ice and primary productivity, and planktic foraminifera are either absent or occur in extremely low concentrations in sediment cores from both the Arctic-Atlantic Gateway and the Nordic Seas. Although the full spatial extent of glacial ice during MIS 16 remains uncertain, it is thought to have rivalled that of the Last Glacial Maximum (LGM) in terms of ice volume. In this study, we present new geomorphological evidence supported by sediment core chronologies for significant Greenland ice sheet expansion during the end of the Mid Pleistocene Transitoin (MPT). The discovery of record-deep ploughmarks, in combination with a grounding zone wedge (GZW) at approximately 800 meters water depth on the Morris Jesup Rise, northeast Greenland, suggests that the Greenland/Innuitian Ice Sheet grew sufficiently to form an ice shelf extending into the central Arctic Ocean – implying an "Antarctification" of Greenland during this extreme glacial phase.

How to cite: Knies, J., Patton, H., Giertzuch, P.-L., and De Schepper, S. and the i2B Arctic Ocean Expedition 2025 Science Party: New evidence for Greenland ice sheet expansion beyond its present shelf break during the Mid-Pleistocene Transition  , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3417, https://doi.org/10.5194/egusphere-egu26-3417, 2026.

During the Late Palaeozoic Ice Age (LPIA; ~360–260 Ma), southern Africa formed part of Gondwana and experienced repeated episodes of continental glaciation. These glacial events left an extensive sedimentological and geomorphological record. In several regions, modern topography partially reflects this inherited glacial relief, providing rare insights into pre-Quaternary ice-sheet dynamics, basal processes, and ice–substrate interactions. Despite their scientific importance, many LPIA glacial pavements in southern Africa remain poorly documented and understudied. Numerous key outcrops are increasingly threatened by natural erosion, flooding, agricultural practices, and industrial development. In addition, access is often restricted because many pavements occur on private farmland or in remote areas, limiting systematic field investigation. To date, most known glacial pavements have not been digitally mapped or analysed at high spatial resolution. 

Here we apply integrated aerial and close-range photogrammetry, combined with detailed sedimentological analysis, to document seven representative Late Palaeozoic glacial outcrops in the Northern Cape Region in South Africa. High-resolution digital outcrop models are complemented by field-based sedimentological observations. Together, these approaches provide a robust framework for interpreting glacial dynamics and depositional environments. The resulting digital and sedimentological datasets form a reproducible archive that supports quantitative analysis, virtual access, and long-term preservation of vulnerable geological heritage sites. Our results demonstrate the potential of combining digital documentation with in-depth sedimentological analysis to advance the study of ancient glacial landscapes and to preserve critical pre-Quaternary cryospheric records for future research.

How to cite: Wohlschlägl, R., Mejías Osorio, P., Busfield, M., Haberer, P., Smith, A., and Le Heron, D.: Chasing pavements: New insights from Late Palaeozoic glacial outcrops in South Africa, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4936, https://doi.org/10.5194/egusphere-egu26-4936, 2026.

In Arctic Canada and Northeast Greenland, previous studies have found several high-elevation occurrences of marine and/or fluvial sediments of Pliocene-early Pleistocene age. In Arctic Canada, the deposits include the marine strata of the Hvitland beds on Ellesmere Island (up to ~130 m a.s.l.; Fyles et al., 1998), the marine deposits on Meighen Island (up to ~100 m a.s.l.; Fyles et al., 1991), as well as several sites with fluvial deposits, including the unconsolidated braided river deposits found on Banks Island (up to ~130 m a.s.l.; e.g., Fyles et al., 1994), Prince Patrick Island (up to ~200 m a.s.l.; Fyles, 1990), and on the high terraces of Ellesmere Island (up to ~600 m a.s.l.; Fyles, 1989) – all assumed to have be deposited prior to the carving of the deep fjord systems seen in the regions today. In Northeast Greenland, the sediment deposits include the marine Kap København (up to ~230 m; Funder et al., 1984) and Lodin Elv Formations (up to 62 m a.s.l.; Feyling-Hansen et al., 1983), assumed to have been deposited ca. 2-2.5 Ma. Previous work has studied these deposits in detail to constrain their fauna and age, their stratigraphic relationships, as well as their implications for past climates in the Arctic. However, particularly the current high elevation of the marine deposits can also put time constraints on surface uplift in these regions (e.g., Pedersen et al., 2019). Here we explore these constraints in the context of erosion driven flexural isostatic uplift associated with glacial erosion and fjord formation, allowing us to constrain the incision of the fjord systems in time, with the potential to also constrain the timing and rates of glacial erosion.

Feyling-Hanssen, R.W., Funder, S., Petersen, K.S., 1983, The Lodin Elv Formation: A Plio-Pleistocene occurrence in Greenland. Bulletin of the Geological Society of Denmark 31, 81-106.

Funder, S., Bennike, O., Mogensen, G.S., Noe-Nygaard, B., Pedersen, S.A.S., Petersen, K.S., 1984. The Kap København Formation, a late Cainozoic sedimentary sequence in North Greenland. Grønlands Geologiske Undersøgelse, 120, 9–18.

Fyles, J.G., 1989: High terrace sediments probably of Neogene age, west-central Ellesmere Island, Northwest Territories; in Current Research, Part D; Geological Survey of Canada, Paper 89-1 D, p. 101-104.

Fyles, J.G., 1990. Beaufort Formation (Late Tertiary) as seen from Prince Patrick Island, Arctic Canada. Arctic 43, 393-403.

Fyles, J.G., Marincovich, L., Jr., Matthews, J.V., Jr., Barendregt, R., 1991. Unique mollusc find in the Beaufort Formation (Pliocene) on Meighen Island, Arctic Canada; in Current Research, Part B; Geological Survey of Canada, Paper 91-1 B, 105-112.

Fyles, J.G., Hills, L.V., Matthews, J.V., Barendregt, R., Baker, J., Irving, E., Jetté, H., 1994. Ballast Brook and Beaufort Formations (late Tertiary) on Northern Banks Island, Arctic Canada. Quaternary International 22–23, 141-171.

Pedersen, V.K., Larsen, N.K., Egholm, D.L., 2019. The timing of fjord formation and early glaciations in North and Northeast Greenland. Geol­ogy 47, 682–686.

How to cite: Pedersen, V. K., Brand, C., Krog Larsen, N., and Folmer Damsgård, J.: Constraining fjord formation and isostatic uplift in Arctic Canada and Northeast Greenland using Pliocene-early Pleistocene sediment deposits, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6359, https://doi.org/10.5194/egusphere-egu26-6359, 2026.

The Quaternary glacial history of Siberia is uncertain, with several competing reconstructions existing in the published literature. This uncertainty is driven by seemingly incomplete and inconsistent records of glacial geomorphology and a patchy record of chronometric data. To address this, we have compiled previously published glacial geomorphological maps and chronometric data to establish what empirical data for former glaciations exist across Siberia. We also use these data to test the currently published glacial reconstructions to determine which, if any, reconstruction can be best underpinned by current empirical evidence. In turn, we will attempt to reconcile the competing reconstructions into coherent glaciation scenarios for the Quaternary stadials or highlight where palaeo-glaciological research is needed.

Here, we present version-1 of the SIBERICE database, a compilation of all previously published glacial geomorphology, chronometric data, and glacial reconstructions published up to 1 January 2026. The SIBERICE database is a Geographic Information System (GIS) database that make data readily accessible, including information published in often overlooked Russian-language journal articles.

How to cite: Boyes, B., Barr, I., Oien, R., Szuman, I., Winsborrow, M., and Margold, M.: SIBERICE v1: a database of Quaternary glacial reconstructions, glacial geomorphology, and chronometric data in Siberia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9053, https://doi.org/10.5194/egusphere-egu26-9053, 2026.

The nature of the subglacial environment is a key part of glacier dynamics. Studies from modern glaciers have revealed there is a continuum in subglacial fluvial behaviour associated with a soft-bed, from channelised to distributed. How is this continuum preserved within the sedimentary record and what is the relationship between fluvioglacial sediments and flutes?  Classically eskers are associated with channelized drainage, whilst the sedimentary remains of ‘canals’, ‘subglacial meltwater corridors’ and murtoos may reflect the distributed system. Stratified lenses within till are common and have been given numerous interpretations, either reflecting preglacial sediments that have been incorporated into the till by deformation, or penecontemporaneous sedimentation with the till. We use data from instrumented modern glaciers and Quaternary sections to illustrate the nature and rate of subglacial behaviour associated with soft-bedded glaciers.

How to cite: Hart, J. and Martinez, K.: Soft-bed distributed subglacial sedimentology, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9543, https://doi.org/10.5194/egusphere-egu26-9543, 2026.

The East Antarctic Ice Sheet (EAIS) contribution for future global sea level rise and climate change is source of uncertainty, and it appears essential to reconstruct its past fluctuations. Previous works reveal geomorphic and chronological evidence that the ice sheet extended to the continental shelf break during LGM (Last Glacial Maximum; ~20 ka). However, still little is known about its response to the major climate and oceanic transitions following the LGM. In this study, we reconstruct (1) a chronology of ice-sheet fluctuations, (2) ice-sheet past erosion efficiency and (3) ice-sheet thinning during the late-Pleistocene to Holocene time-period, in Terre Adélie (East Antarctica). Newly obtained exposure ages for coupled ¹⁰Be-²⁶Al support a scenario of glacial fluctuations at global, regional and local scales. Inland nunataks reveal some long-term exposure with apparent exposure ages ~150 ka, while coastal areas record a past ice-sheet thinning after ~20 ka. Ages measured on erratic boulders of Archipel Pointe Géologie record the final episode of a regional deglaciation around ~15 ka. Slightly inland, in Lacroix sector, erratic boulders record a more recent local ice-sheet oscillations around ~1.5 ka. In contrast, exposure ages obtained on glacially-polished bedrock are characterised by spatially-variable inheritance, suggesting that past ice sheet retreat history is characterised by variations in erosion efficiency. Finally, our results also suggest some potential previous geomorphological inheritance from the hot Pliocene phase.

How to cite: Rolland, Y., Péan, M., Valla, P., Duclaux, G., Braucher, R., Jomelli, V., Favier, V., Schimmelpfennig, I., Crosta, X., Etourneau, J., and Louis, M.: Reconstructing Plio-Quaternary fluctuations of the East Antarctic Ice Sheet in Terre Adélie inferred from cosmogenic nuclides (10Be-26Al) in glacially-polished bedrock, morainic boulders and nunataks , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10117, https://doi.org/10.5194/egusphere-egu26-10117, 2026.

Glacial forefields host abundant information regarding the sedimentary processes associated with glacier dynamics. Transport pathways and sediment deposition can be characterized by investigating the landforms and sediments found in these areas. One such area is the Vernagtferner forefield in the Austrian Alps, which contrasts with other surrounding glaciers due to the presence of a large surface covered by flutes. These flutes can reach up to 250 m in length and have been continuously exposed over the past decades as the glacier recedes, but have not been researched recently. Since this glacier has been regularly studied (with records from as early as 1601) and it has been linked to surging episodes in the past, there are plenty of questions to be answered related to its current behavior. Here we present the results of sedimentological observations, as well as geomorphological mapping and statistics based on fieldwork, historical, and uncrewed aerial vehicle imagery. We highlight aspects of the glacial forefield and the contrast between what can be seen in 2023-2024 and snapshots from the past 50 years. In a changing climate, understanding how rapid glacial recession affects the deposition of sediments and the parameters that govern them will be useful in deciphering glacial dynamics and contrasting them with the paleorecord. 

How to cite: Mejías Osorio, P., Wohlschlägl, R., Karbacher, S., Vandyk, T., Davies, B. J., Grasemann, B., and Le Heron, D. P.: Vernagtferner flute field findings, Austrian Alps, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10565, https://doi.org/10.5194/egusphere-egu26-10565, 2026.

Reconstructions of Antarctica's past ice-sheet evolution remain poorly constrained due to sparse, spatially discontinuous proxies, limiting accurate projections of its future sea-level contribution. Here we present a novel isochronally-constrained reconstruction of Dronning Maud Land (DML), East Antarctica spanning the last interglacial-glacial cycle (~130 kyr), integrating extensive radar-derived internal reflection horizons (IRHs) with PISM ice-sheet simulations.

IRHs preserve continuous records of past accumulation, flow, and basal conditions, providing unprecedented spatiotemporal constraints for model validation. Our ensemble simulations indicate that DML’s sea-level potential change between interglacial and glacial states is comparable to, and likely larger than, the contribution of all modern mountain glaciers, and show that variations in geothermal flux alone can substantially alter sea-level projections. These results provide physical modelling context of East Antarctica's ice history, reveal DML's role in Last Interglacial sea-level rise, and highlight persistent parameterization uncertainties limiting future projections.

How to cite: Višnjević, V., Bodart, J., Hermant, A., Spezia, E., Wirths, C., and Sutter, J.: Modelling the evolution of Dronning Maud Land, Antarctica across the last interglacial-glacial cycle – insights from isochrone modelling., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11727, https://doi.org/10.5194/egusphere-egu26-11727, 2026.

Throughout the Quaternary, cyclical variations in global ice volume are recorded by benthic marine δ¹⁸O fluctuations. This signal is dominated by the waxing and waning of Northern Hemisphere ice sheets, particularly the Laurentide Ice Sheet (LIS) in North America, which builds periodically into the largest of all ice sheets on Earth. At such times, the LIS advanced southward into the American Midwest where glacial deposits emplaced prior to Marine Isotope Stage (MIS) 6 are known from just a handful of securely-dated sites. Consequently, current understandings of LIS extent and volume through time are incomplete and poorly constrained.

Here, we focus on tills bearing putative pre-MIS 6 depositional ages along the southern and southwestern margins of the LIS. We combine single-grain sedimentary provenance analyses with cosmogenic ¹⁰Be-²⁶Al burial dating in an aim to better resolve till chronology and provenance, using P-PINI and CosmoChron numerical models to calculate burial ages.

Building on existing magneto-, tephro-, and lithostratigraphic correlations, our new burial ages will significantly improve knowledge of the timing and extent of the LIS and its sediment source areas feeding different ice sheet sectors along the southern and southwestern margins. Our findings will improve reconstructions of LIS configurations through time, and yield new insights into Early–Middle Pleistocene global ice volume variability linked directly to the terrestrial record.

How to cite: Bertels, R., Wagner, K., Ylä-Mella, L., Stoker, B. J., Jansen, J. D., and Margold, M.: Constraining Early and Middle Pleistocene Laurentide Ice Sheet advances with 10Be-26Al burial dating, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11797, https://doi.org/10.5194/egusphere-egu26-11797, 2026.

Glacially derived, marine sediments preserve a record of the timing, extent, and dynamics of shelf glaciation. In addition, these deposits can provide constraints on glacial erosion rates and offer insights into landscape evolution. However, in Greenland, the total offshore volume of glacially derived sediments remains poorly constrained due to an uneven distribution of offshore seismic surveys and a lack of dating constraints. To address this, we present a first quantification of Quaternary glacial sediment thicknesses around Greenland, combining interpretations of available marine seismic data with age constraints where scientific boreholes are available and a neural network approach. We train the neural network using the seismic-derived thicknesses, along with several parameters related to glacial and geomorphological features. This approach allows us to predict Quaternary sediment thicknesses in regions with sparse data coverage, thereby constraining the total volumes of deposition. Our estimates reveal regional variations in glacial deposition volumes and sediment thicknesses around Greenland. On the southern and parts of the northern Greenlandic continental slope, Quaternary sediments are thin, whereas in west and east Greenland, larger sediment deposits have led to a greater shelf progradation throughout the Quaternary. These patterns demonstrate a diverse influence of (paleo-)climatic, oceanographic, and orographic processes on glacial dynamics and the source-to-sink sediment transport. Finally, we compare our estimates of Quaternary offshore deposition with estimates of onshore glacial erosion inferred from paleo-topographic reconstructions and erosion potentials of the present ice sheet, based on ice sliding velocities. This provides insights into the temporal and spatial variability of erosion around Greenland, advancing our understanding of the long-term landscape evolution in glaciated regions.

How to cite: Brand, C., Elger, J., Andresen, K. J., Hansen, T. M., Poulsen, V. S., Pérez, L. F., Fox, M., Böttner, C., Knutz, P., Damsgård, J. F., and Pedersen, V. K.: From source to sink: Quantifying Quaternary erosion from offshore deposits associated with the Greenland Ice Sheet, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12234, https://doi.org/10.5194/egusphere-egu26-12234, 2026.

Understanding the processes at glacier beds is crucial as they regulate ice flow, basal sediment dynamics, and meltwater routing, which collectively control glacier stability and response to climate change. Flute fields are a vital archive of subglacial processes, widespread in both terrestrial and marine glacial environments, whereby sediments are fashioned subglacially into lineations at different scales. The assemblages are highly variable in both environments, yet models to explain this are outstanding, and aspects of preservational bias are rarely entertained. Integrating observations from modern Alpine forefields (Austria) with exceptionally preserved Late Ordovician and Late Paleozoic examples in Africa and Arabia, we interrogate terrestrial and glaciomarine flute fields. Flutes, megaflutes, and diamictons occur in both settings, but architecture is strongly context-dependent. Terrestrial flutes degrade rapidly under surface meltwater and rainfall, whereas marine flute fields are commonly preserved beneath fine-grained shales, recording stacked lobate sediments with superimposed mega-scale glacial lineations, metre-scale flutes, and centimetre-scale soft-sediment striae. Oversteepened subaqueous flutes collapse laterally, forming fan-shaped deposits, and lateral margins exhibit scalloped surfaces that record focused subglacial meltwater discharge. We propose a conceptual model in which metre- and centimetre-scale lobes act as miniature grounding zone wedges, forming through simultaneous deposition and shearing beneath tidewater glaciers. This framework reveals how subglacial processes are recorded in preserved landforms and demonstrates that integrating modern and ancient records is essential to understanding glacier–bed interactions.

How to cite: Le Heron, D., Busfield, M., Mejías Osorio, P., Smith, B., Tofaif, S., and Wohlschlägl, R.: The formation of flute fields in glacial environments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12657, https://doi.org/10.5194/egusphere-egu26-12657, 2026.

The existence of glacial cycles in the Alps was proposed as early as the first half of the 19th century following the observation of numerous direct traces left by glaciers in lower parts of alpine valleys. However, the influence of glacial-interglacial cycles on sediment transfer from the internal source zone to the peripheral mountain range is only now being re-investigated in the context of the recent “Source to sink” approach.

The study, part of the DYMODU project (2023–2026), a collaboration between the CNRS and the RGF focuses on new geological, geomorphological and geochronological investigations undergone in the Laragne-Montéglin depression and along the Middle Durance (western Alps, France). The DYMODU project aims at deciphering the role of glacial-interglacial cycles in both the landscape organization of alpine valleys and the evolution of routing systems during the Quaternary. The sediment pile shows a characteristic sedimentary motif repeated four times, indicating a succession of four aggradation-incision cycles. The sedimentary motif records a period of aggradation during which a several tens of metres thick conglomerate fills one or more palaeo-valleys, affecting the underlying units. This conglomerate is topped by glaciogenic deposits (ground till, morainic vallum), then incised by one or more palaeo-valleys affecting the entire sedimentary series, often down to the underlying sediments before the onset of the aggradation phase of the next cycle begins, and fills these palaeo-valleys.

To confirm the integration of these cycles into the Quaternary evolution of the area, preliminary dating was carried out on various sedimentary morphostructures using Optically Stimulated Luminescence dating (OSL), Electron Spin Resonance dating (ESR) and Cosmogenic Nuclides (CN).

In this contribution, we will present the sedimentary pattern of a typical sequence. We will attempt to deconvolute the signals of the general Alpine uplift, the lithospheric flexure due to glaciation, and the glacio-isostatic rebound during deglaciation. This will enable us to discuss the interdependencies between climate and tectonics for valley glacier systems and the forcings that influenced sediment routing during the Upper Pleistocene in the Alps.

How to cite: Dervis, V., Nutz, A., Rizza, M., Braucher, R., Dietrich, P., and Tissoux, H.: Glacial-interglacial cycles in the Western Alps (Middle Durance Valley, France): sedimentary evolution and responses of continental surfaces, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12949, https://doi.org/10.5194/egusphere-egu26-12949, 2026.

In this study, we integrate marine geophysical datasets and analyses of four marine sediment cores to reconstruct the deglaciation and paleoenvironmental development of the Ardencaple Fjord and the adjacent cross-shelf trough in Northeast Greenland. Although recent studies have presented isochron-based reconstructions of the circum-Greenland ice margin since the last deglaciation, crucial knowledge gaps regarding the timing and dynamics of ice retreat still exist, particularly in offshore Northeast Greenland, where former glaciated trough systems hosted fast-flowing ice.

Our preliminary results indicate fast retreat dynamics of the ice based on observations of glacial lineation morphologies on the seabed, while sedimentological data enable spatiotemporal reconstructions of grounding line positions and floating ice margins. A preliminary chronological framework constraining the ice retreat across the core sites is based on radiocarbon dates, supplemented by paleomagnetic secular variation records. Our reconstruction further allows us to assess benthic ecosystem responses to deglaciation, contributing to the current evaluation of benthic foraminifera as a proxy for identifying stages of deglaciation in marine sediments around Greenland.

How to cite: Ramsgaard Stoltenberg, M., Kristensen, K., Böttner, C., López-Quirós, A., Davies, J., Girard, J., Detlef, H., St‐Onge, G., Pearce, C., and Seidenkrantz, M.-S.: Deglaciation of the Ardencaple Fjord and adjacent shelf environment, Northeast Greenland, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14137, https://doi.org/10.5194/egusphere-egu26-14137, 2026.

Marine geophysical data and sediment cores were collected from the continental shelf and slope offshore of SE Greenland during cruise SD041 of the UK research vessel the RRS Sir David Attenborough in 2024. The cruise collected a range of geological, geophysical, oceanographic and biological data. The cruise was part of the ‘Kang-Glac’ project, the aim of which is to investigate the response of the Greenland Ice Sheet to ocean warming during the last 11,700 years. Marine geophysical data and radiocarbon-dated sediment cores provide a clear record of an extensive Greenland Ice Sheet which expanded and retreated across the continental shelf offshore of SE Greenland during, and following, the last glacial maximum. An ancestral Kangerlussuaq Glacier flowed along Kangerlussuaq Trough, a cross shelf bathymetric trough which extends from the mouth of Kangerlussuaq Fiord to the edge of the continental shelf, where it terminates in a trough-mouth fan. Streamlined subglacial bedforms record convergent ice flow into the trough. Sediment cores from along the trough recovered subglacial tills recording a grounded ice sheet. The tills are overlain by a range of deglacial, glacimarine facies recording ice sheet retreat by melting and iceberg calving. A suite of new radiocarbon dates were obtained on foraminifera and shells from the deglacial facies in a transect of cores extending from the trough-mouth fan to the inner shelf. The dates constrain the timing of initial retreat from the outer shelf and allow the position of the grounding-line to be tracked during retreat. The new radiocarbon dates significantly improve the offshore temporal constraints on the post-LGM deglaciation for this sector of the Greenland Ice Sheet and, allied with core sedimentology and foraminferal assemblage data, allow assessment of the role of ocean warming in driving retreat of the ancestral Kangerlussuaq Glacier.

How to cite: O'Cofaigh, C., Hunt, M., Lloyd, J., Hogan, K., Snowman Andresen, C., Larter, R., and Roberts, D.: Deglaciation of the ancestral Kangerlussuaq Glacier from the continental shelf offshore of SE Greenland following the LGM, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14254, https://doi.org/10.5194/egusphere-egu26-14254, 2026.

Reconstructions of Northern Hemisphere ice sheets throughout the Quaternary are central to interpreting past variations in sea level, ocean-atmospheric circulation, and climate. Yet, terrestrial records of the earliest glaciations are fragmentary and anchored principally to relative chronostratigraphic frameworks, limiting direct comparison with more continuous marine archives. Here, we present new dating and sedimentary provenance constraints, motivating reassessment of the early history of the Eurasian Ice Sheet (EIS) and its role within the evolving Pleistocene climate system.

Cosmogenic ²⁶Al-¹⁰Be burial dating of key glacigenic deposits from northwest and central Europe reveals that extensive EIS advances occurred repeatedly during the Early Pleistocene, beginning as early as ~2.35 million years ago (Ma), and substantially predating the traditionally inferred onset of lowland glaciation during marine isotope stages (MIS) 16–12 (~0.65–0.45 Ma). Detrital zircon U-Pb fingerprinting of these deposits indicates that successive EIS advances transported sediment from the Fennoscandian Shield into the North Sea Basin and the North European Plain, implying that ice flow pathways through the Baltic Depression were established already in the Early Pleistocene and the Baltic (Eridanos) River System had terminated by at least ~1.5 Ma.

Our revised chronologies highlight that the most extensive EIS configurations formed prior to the Middle Pleistocene Transition, and within the context of apparent low-amplitude glacial cycles of the ‘41-kyr world.’ When integrated with independent geochronologic evidence from North America, these findings (within uncertainties) point to broadly synchronous Early–Middle Pleistocene expansions of the major Northern Hemisphere ice sheets. Such early attainment of continental-scale ice sheets may help to reconcile available terrestrial evidence with emerging reconstructions of significant glacial sea-level lowstands prior to the dominance of ~100-thousand year glacial cycles.

More generally, this synthesis calls for re-examination of long-standing European Quaternary stratigraphic frameworks and suggests that Eurasian glaciation may have played an important role in reorganizing continental drainage, modulating freshwater delivery to the North Atlantic, and influencing ocean-atmospheric circulation throughout the Early–Middle Pleistocene.

How to cite: Wagner, K., Ylä-Mella, L., Margold, M., Faurschou Knudsen, M., and D. Jansen, J.: Two million years of the Eurasian Ice Sheet, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14737, https://doi.org/10.5194/egusphere-egu26-14737, 2026.

Many tens of ice rises exist at the marine margins of the Antarctic Ice Sheet.  Isle-type ice rises in particular are those where an ice shelf is pinned to an underlying submarine bank.  Recent and ongoing studies show that Ross Bank, on the middle continental shelf of central Ross Sea, was the former site of an important Ross Ice Shelf ice rise during the advance and retreat of the West Antarctic Ice Sheet (WAIS) in the last glacial cycle.  Ross Bank is a broad and anomalously shallow water platform whose crest rises to 150 m water depth. Despite its importance as a buttressing site, little is known about how, when and why such submarine banks formed. Here, we use a grid of seismic data acquired during expedition NBP2301/2 to reconstruct how Ross Bank morphology evolved.  Our seismic-based correlations and mapping show that Ross Bank overlies the western flank of the Central High, a large basement horst created during the rifting of Ross Sea.  Seismic correlation to lithologic and chronologic control at IODP expedition 374 sites U1521 and U1522 indicates that thick grounding zone wedges were deposited at the site of Ross Bank during the early Miocene.  Intermittent advance of erosive ice streams deeply eroded those wedges and produced approximately 400 meters of relief at Ross Bank prior to the middle Miocene.  The complete absence of middle Miocene strata at Ross Bank suggests significant intervals of subglacial erosion associated with glacial stages of the Middle Miocene Shift.  In the time since, relatively minor aggradation on the crest of Ross Bank occurred during parts of the late Miocene, Pliocene and Pleistocene. Our analyses make the case that a shallow submarine area existed at Ross Bank since the middle Miocene.  The bank would have been the site of ice rises that influenced the advance and retreat of the WAIS in central Ross Sea over the past 14 Myr.

How to cite: Weber, W. and Bart, P.: The case for Ross Bank ice rises since the middle Miocene, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15366, https://doi.org/10.5194/egusphere-egu26-15366, 2026.

GLAC3 is the first history matching of every last glacial cycle ice sheet. It therefore includes North American, Greenlandic, Icelandic,
Eurasian, Tibetan, Patagonian, and Antarctic components. Instead of determining a non-robust "optimal" chronology, history matching aims
to "bound reality" with robust assessment of both proxy data and model (both parametric and structural) uncertainties. For the four major ice
sheets, this entails Bayesian artificial neural network emulation of the glaciological model predictions to enable adequate Markov Chain
Monte Carlo sampling of chronologies. The history matching is against a large set of geophysical (such as relative sea level and marine
limit), geological (cosmogenic exposure and C14 ages), and glaciological (such as present-day ice surface velocity) constraints.

Aside from being a product of history matching, GLAC3 has two additional unique features. Firstly, it is the only available
deglacial, let alone full glacial cycle, global set of chronologies from glaciological modelling, using the Glacial Systems Model
(GSM) with hybrid shallow ice and shallow shelf ice dynamic. This enables physical resolution of ice sheets, ice streams, ice shelves,
and grounding line migration. As such, GLAC3 is subject to glaciological constraints such as borehole temperature profiles that
non-glaciological reconstructions can't resolve. Secondly, the glaciologically modelling is self-consistently coupled with full
visco-elastic glacio-isostatic adjustment enabling joint history matching of ice history and regional earth viscosity.

The presentation will focus on the relative phasing of each ice sheet, rates of mass gain and loss, and rates of ice margin migration. This
will be compared against both far-field relative sea level records as well as the results of fully coupled ice and climate modelling of the
last glacial cycle with LCice (LOVECLIM + GSM).

How to cite: Tarasov, L., Dalton, A., Dyke, A., Geng, M., Goffin, A., Hughes, A., Lecavalier, B., Mangerud, J., Milne, G., Svendsen, J.-I., and Woodroffe, S.: GLAC3 rates and phasing: the first joint history matching of global last glacial cycle ice sheet evolution and regional earth rheology, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15518, https://doi.org/10.5194/egusphere-egu26-15518, 2026.

Reconstructing the precise timing and geometry of the British-Irish Ice Sheet (BIIS) is critical for understanding the sensitivity of the North Atlantic climate system to abrupt perturbations. We present preliminary results from a cosmogenic beryllium-10 (¹⁰Be) surface-exposure chronology of glacial deposits in the Gaddagh valley, situated on the northern flank of the McGillycuddy’s Reeks, southwest Ireland. Our geomorphological and chronological transect reveals a detailed history of deglaciation and ice-margin fluctuations since the Late Pleistocene.

Initial results indicate that high-elevation areas (300–350 m asl) adjacent to the main valley were ice-free by ~28 ka (n=2), suggesting an earlier onset of local thinning than previously modelled. The prominent "Hag’s Tooth Moraine”, the primary geomorphological feature in the valley, appears to represent a culmination during the Last Glacial Maximum (LGM). Following this peak, the deposition of a barely preserved subdued moraine impounded Loch Callee at ~19 ka (n=3), marking a significant phase of ice retreat at the onset of Termination 1. The final pulse of glacial activity is recorded 200 m higher in the catchment by a complex of five latero-frontal moraines. These landforms mark the former extent of a small cirque glacier, with the final abandonment of these positions occurring at ~12.7 ka (n=3).

Thus far, our findings implicate the following. First, the data do not support a complete ice cover over the McGillycuddy’s Reeks during the LGM as previously proposed; instead, we suggest that ice was topographically restricted to the main valleys, with the front of the Gaddah glacier not below 150 m asl. Second, our chronology indicates that terminal deglaciation occurred during a period traditionally associated with relatively cold climate conditions. This pattern of glacier recession during inferred year-round cold climate aligns with recent ¹⁰Be chronologies from Scotland (Bromley et al., 2018, 2023), central East Greenland (Kelly et al., 2025), southernmost Greenland (Carlson et al., 2021) and Norway (Putnam et al., 2023; Wittmeier et al., 2020), which demonstrate glacier shrinkage during the Younger Dryas. These results contribute to the ongoing discussion about glacier extension in the area and the evolving paradigm of North Atlantic climate dynamics, emphasizing the role of summer temperature as the primary driver of glacial mass balance during millennial-scale stadials.

How to cite: Rodriguez, P. and Bromley, G.: Lateglacial deglaciation of the McGillycuddy’s Reeks, SW Ireland through 10Be surface-exposure dating of glacial deposits in the Gaddah Valley: Implications for late glacial climate variability., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15730, https://doi.org/10.5194/egusphere-egu26-15730, 2026.

The East Antarctic Ice Sheet is showing evidence of mass loss, particularly near its coastal margin in the Wilkes and Aurora Subglacial Basins, and at Denman Glacier. Quantitative satellite observations indicate significant grounding line retreat at these sites, suggesting potential vulnerability to Marine Ice Sheet Instability. Reconstructions of past ice sheet behaviour using cosmogenic exposure dating can provide robust geological constraints on prior ice sheet thinning. This helps us assess whether contemporary thinning and retreat is unprecedented, while also establishing a geologically constrained precedent for ice-sheet behaviour and sensitivity to which projections can be compared.

Here we present the first reconstruction of Holocene thinning of Scott Glacier, East Antarctica, located 56 km east of Denman Glacier. Scott Glacier is currently stable, pinned by subglacial topography, though is projected to retreat into the Denman trough, and ultimately contribute to the instability of the Denman-Scott System. Together, the Denman and Scott Glacier could contribute up to 1.5 m to global sea level rise if fully deglaciated. To examine its past behaviour, we collected 11 bedrock and erratic samples over an elevation transect at Grace Rocks (-66.421S, 100.508E), an ice-free nunatak adjacent to the modern-day grounding line. Exposure ages were then derived from measured cosmogenic Berilyum-10 and in-situ Carbon-14 concentrations. Together, they provide consistent evidence for rapid thinning during the early-Holocene, with estimates suggesting a maximum thinning rate of ~1 m/yr, comparable to thinning observed in parts of the ice sheet today. This thinning history provides robust geological constraints on the past behaviour and sensitivity of Scott Glacier, and a baseline from which to assess its contemporary and projected retreat and vulnerability.

We also derive projections of ice elevation change at Scott Glacier from simulations with the Ice-sheet and Sea-level System Model (ISSM). Projections show thinning rates exceeding 2 m/yr over the next two centuries across the Denman-Scott region, with an average thinning rate of 0.65 m/yr at Grace Rocks projected until 2085. While there are uncertainties associated with these models, the rates and sensitivity we established from the early-Holocene geological record suggest that modelled changes of this magnitude are plausible, and that despite contemporary stability, Scott Glacier is at risk of contributing significantly to regional icesheet instability and sea level rise in coming decades to centuries.

How to cite: Port, C., Jones, R., Mackintosh, A., Tielidze, L., Fulop, R., Wilcken, K., Pelle, T., White, D., and O'Connor, J.: Evidence and implications of rapid early-Holocene thinning of Scott Glacier, East Antarctica, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16257, https://doi.org/10.5194/egusphere-egu26-16257, 2026.

Fjord landscapes along the margins of past and present ice sheets testify to the significant long-term erosive power of large outlet glaciers. Yet, our understanding of the rates and processes of subglacial erosion and sediment transport beneath ice sheets remains incomplete. Quantifying these processes is crucial for reconstructing past ice dynamics, estimating sediment fluxes to the ocean, and understanding long-term landscape evolution.

Greenland’s narrow, steep-sided fjords act as natural sediment traps, preserving erosion products delivered by large outlet glaciers during deglaciation. These fjord sediments constitute a valuable constraint on past erosion rates and glacial sediment fluxes when combined with ice catchment areas and retreat histories in a source-to-sink framework. However, most Greenlandic fjords remain unmapped in terms of sediment thickness because sediment cores rarely penetrate deeply and seismic data acquisition is sparse. In contrast, accurate bathymetric data are increasingly available for many fjords. We use a geomorphological approach to estimate sediment infill volumes based on fjord cross-sectional profiles, where deviations from the expected U-shape and the slope of the sidewalls are used to infer sediment thickness.

We quantify fjord infill volumes for several fjords and use these to estimate average catchment-wide erosion rates. The timing of deposition (starting when the ice retreated into the fjord) is constrained by available deglaciation models. To further explore the temporal and spatial variability of subglacial erosion, we employ a coupled ice-flow and erosion model (iSOSIA), driven by paleoclimate forcing, to simulate erosion beneath marine-terminating outlet glaciers during the last deglaciation (~21–0 ka BP). Modeled sediment outputs are compared with our estimates of sediment volumes and accumulation rates from sediment cores to calibrate the model erosion parameters.

Our results indicate that average deglacial erosion rates are largely independent of catchment size but vary significantly through time and space within ice-sheet catchments. Rates can exceed 10 mm yr⁻¹ for topographically steered, fast-flowing outlet glaciers, while much lower rates (<0.1 mm yr⁻¹) occur in slower-flowing interior regions with slow-moving ice. Quantifying and linking offshore sediment volumes with numerical modeling provides an opportunity to constrain subglacial erosion rates, sediment transport and ice-sheet reconstructions. This work demonstrates the value of integrating glaciological modeling with marine sediment archives to refine erosion estimates and improve predictions of future sediment fluxes under continued ice-sheet retreat.

How to cite: Damsgård, J., Brand, C., Jungdal-Olesen, G., and Pedersen, V.: Constraining subglacial erosion in Greenland using estimates of fjord sediment volumes and ice-flow modeling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16822, https://doi.org/10.5194/egusphere-egu26-16822, 2026.

Accurate reconstructions of past ice sheet dynamics are essential for constraining ice sheet sensitivity to climate forcing and projecting future sea-level rise in a warming climate. The British-Irish Ice Sheet (BIIS) during the Last Glacial Maximum presents a critical test case, and yet, reconstructions of its southern margin across Ireland differ fundamentally in both extent and timing.
 
Earlier geomorphic mapping-based models proposed an ice-free corridor across southern Ireland during the last glacial period. In contrast, more recent offshore and near-shore sediment-based reconstructions propose a maximum BIIS extent covering the entire island and extending to the continental shelf edge, requiring an ice sheet thick enough to override most Irish mountain ranges. This interpretation conflicts with evidence for localized mountain glaciation in the same time period in areas like the Wicklows Mountains, which would have been impossible under a thick ice sheet. The scarcity of reliable terrestrial geochronological control points (e.g., cosmogenic exposure ages, OSL, ¹⁴C) in southern Ireland significantly contributes to these uncertainties, thus limiting the accuracy of reconstructions of BIIS expansion and retreat.
 
This project aims to resolve these contradictions by providing robust chronological control on the position of the BIIS margin in the south of Ireland. We conducted sampling campaigns in three critical locations: the Wicklow Mountains, the Comeragh Mountains, and the Kerry Peninsula. Our sampling strategy targeted boulders at multiple elevations and aspects to capture both the timing and geometry of ice cover. We present preliminary ¹⁰Be surface-exposure ages from erratic boulders in the Comeragh Mountains (maximum elevation 792 m), sampled on transects from the northern, eastern, southern, and western slopes.
 
These chronological constraints will refine deglaciation scenarios for the BIIS southern margin, in turn improving our understanding of regional landscape evolution, and provide empirical data for testing ice sheet models under past climate conditions similar to future warming scenarios.

How to cite: Mariotti, A., Dulfer, H., Jackson, M., and Kelley, S. E.: Dynamics of the British-Irish Ice Sheet in the South of Ireland., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18150, https://doi.org/10.5194/egusphere-egu26-18150, 2026.

How to cite: Romé, Y., Gregoire, L., Gandy, N., Patterson, V., and Ely, J.: Using reconstructed ice streams to calibrate a coupled climate-ice-sheet model of the North American Ice Sheet Complex during the Last Glacial Maximum , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20495, https://doi.org/10.5194/egusphere-egu26-20495, 2026.

Whilst our understanding of the past ice-sheet extent of the Amundsen Sea sector at the Last Glacial Maximum (LGM) is relatively well known, the subsequent retreat (and potential re-advance) of Pine Island and Thwaites glaciers during the Holocene is contrastingly less understood. Some studies conducted across its neighbouring catchments, such as the Weddell and Ross Sea sectors, indicate that the grounding line may have retreated beyond its current position, and then subsequently re-advanced primarily due to isostatic rebound and stabilisation around pinning points. Over the Amundsen Sea sector, contrasting evidence suggests that non-linear changes in inland ice-sheet cover may have occurred, but little evidence exists for large changes affecting the continuous and gradual retreat of the grounding line from the LGM to its current position today. Here, we employ the three-dimensional PISM ice-sheet model to reconstruct the evolution of this sector since the LGM. We first explore the full parameter space using a Latin Hypercube Sampling method, and further constrain our best sets of simulations using extensive and newly available isochronal surfaces imaged by radars and dated at several snapshots throughout the last ~20 thousand years. We show that isochrones are essential for assessing the transient evolution of paleo simulations, particularly in off-divide areas of the ice sheet, and discuss how different geothermal heat-flux and SMB datasets impact the transient evolution of this sensitive sector.

How to cite: Bodart, J. A., Sutter, J. C. R., Young, D. A., Blankenship, D. D., Višnjević, V., Hermant, A., and Spezia, E.: Holocene evolution of the Amundsen Sea sector from three-dimensional modelling constrained by extensive ice-penetrating radar isochrones, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20734, https://doi.org/10.5194/egusphere-egu26-20734, 2026.

The British-Irish Ice Sheet (BIIS) is one of the best-constrained paleo-ice sheets in the world, with detailed geomorphological and geochronological data constraining margins and retreat patterns. Despite this, the thickness of this former ice sheet remains uncertain. High elevation locations offer potential for constraining former ice sheet thickness; however, a lack of glacial erosion due to cold-based ice cover of mountain summits limits the use of single isotope cosmogenic exposure dating, as inherited nuclides commonly yield ages older than the last glaciation from mountain top landscapes. As such, landscapes that experienced cold-based ice cover and those at relatively high elevations are underrepresented in glacial reconstructions, both for the BIIS and globally, thus negatively affecting their ability to serve as training datasets for numerical models used to reconstruct paleo-ice masses. Here, we use paired ¹⁰Be/¹⁴C extracted from bedrock and boulder samples in high-elevation locations across Scotland and Ireland. Our multi-nuclide approach uses one long-lived nuclide, ¹⁰Be, and one short-lived nuclide, ¹⁴C, allowing for an examination of two questions: 1) What is the vertical pattern of deglaciation across the BIIS? 2) Did mountaintops exist as nunataks during the last glaciation? To address these questions, we collected samples from one site in Scotland (Cairngorm Mountains) and four Irish mountains (Dublin, Wicklow, and Mourne Mountains, as well as Mt. Brandon in Dingle) for paired ¹⁰Be and ¹⁴C analysis, yielding 22 new pairs of exposure ages. At four of our study sites, ¹⁰Be results yield exposure ages preceding the LGM, indicative of a lack of erosion during the last glaciation or prolonged exposure. Our ¹⁴C results show concentrations at or near secular equilibrium at three of those sites, indicating either exposure during the last glaciation or a period of glaciation too short for inherited ¹⁴C to decay. These results provide insight into ice-mass thinning and the spatial pattern of glacial erosion, allowing for a more holistic view of cryospheric change in the region in response to a changing climate.

How to cite: Kelley, S. E., Crowell, C., Lifton, N., and Pendleton, S.: IN SITU COSMOGENIC 10Be AND 14C: A WINDOW INTO PAST ICE SHEET THICKNESS IN SCOTLAND AND IRELAND, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20850, https://doi.org/10.5194/egusphere-egu26-20850, 2026.

Recognising the global importance and vulnerability of mountain glaciers, the United Nations General Assembly declared 2025 the International Year of Glaciers’ Preservation, highlighting the critical role of glaciers in the hydrological cycle and the growing societal risks associated with their rapid decline. These concerns are well founded: glaciers worldwide are retreating rapidly, yet projections have traditionally focused on changes in mass and area rather than on the fate of individual glaciers.

Here, we quantify the future evolution of the global number of glaciers and introduce the concept of peak glacier extinction: the year in which the largest number of individual glaciers is projected to disappear. Using three global glacier models and the Randolph Glacier Inventory v6.0, we project the fate of more than 200,000 glaciers worldwide under four policy-relevant global warming scenarios by 2100 (+1.5 °C, +2.0 °C, +2.7 °C and +4.0 °C relative to pre-industrial levels). A glacier is classified as extinct when its area falls below 0.01 km² or its remaining volume declines to less than 1% of its initial value.

Across all scenarios, we identify a pronounced mid-century peak in glacier extinction. Under a +1.5 °C pathway, this peak occurs around 2041, with approximately 2,000 glaciers disappearing per year, whereas under a +4.0 °C scenario it shifts to the mid-2050s and intensifies to nearly 4,000 glacier extinctions annually. Regional differences reflect contrasts in glacier size distributions and climatic conditions. Our results highlight the urgency of ambitious climate action. Whether the world faces the loss of 2,000 or 4,000 glaciers per year by mid-century, and whether roughly 20,000 or 100,000 glaciers remain by the end of the century, will be determined by near-term policy and societal choices made today.

How to cite: Van Tricht, L., Zekollari, H., Huss, M., Rounce, D., Schuster, L., Aguayo, R., Schmitt, P., Maussion, F., Tober, B., and Farinotti, D.: Peak glacier extinction in the mid-twenty-first century, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2716, https://doi.org/10.5194/egusphere-egu26-2716, 2026.

The demise of glaciers in the European Alps appears inevitable. The remaining question is the rate of ice loss and the timing of complete disappearance. This is particularly important for local water resource management and hazard assessment. Answering this requires glacier models that can robustly project glacier evolution over the coming decades. With the Instructed Glacier Model (IGM), an important tool for such projections has been made available, enabling computationally efficient modeling of glaciers as three-dimensional objects.

The remaining task is to accurately calibrate the glacier model. Fortunately, major advances in remote sensing provide an unprecedented amount of satellite observations that can be used for calibration on regional to global scale, even in remote areas without in-situ observations. The Framework for assimilating Remote-sensing Observations for Surface mass balance Tuning (FROST) utilizes a global elevation change product to infer equilibrium line altitudes and surface mass balance gradients. We tested the framework on 409 individual glaciers in the European Alps that were larger than 1 km² at the beginning of the century and evaluated the results against in situ measurements and end-of-summer snow line altitudes. The results show that the calibrated equilibrium line altitudes agree well with the snow line altitudes, while the surface mass balance gradients differ from glaciological measurements. This discrepancy is partially explained by the presence of small glaciers, which challenge gradient-based surface mass balance models, and by uncertainties of observation that lead to inaccurately modelled glacier flow. The first regional application of FROST shows promising results, provides meaningful insights and reveals challenges  for glacier projections in central Europe.

How to cite: Herrmann, O., Prasad, V., Zöller, A., Groos, A. R., Cook, S., Sommer, C., and Fürst, J. J.: FROST in the European Alps – Implementing a data assimilation framework for calibration of surface mass balance models., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5383, https://doi.org/10.5194/egusphere-egu26-5383, 2026.

In this contribution, we will demonstrate the first prototype of the Svalbard cryosphere digital twin (SvalbardDT v1; https://svalbarddt.org/), which is a Digital Twin Component of ESAs Digital Twin Earth (DTE). An environmental digital twin observes a physical entity (i.e. the cryosphere), fuses multi-modal observations together, then generates what if scenarios to improve human decision-making. In this way, there are two-way flows of information (i.e. data) between the physical and digital assets. In Svalbard, where rates of warming are six times faster than the global average, digital twins have the potential to be used by researchers to analyse trends in the cryosphere, by local communities to improve navigation, and by policy-makers to improve decision-making. Furthermore, Svalbard is considered a ‘super site’ of in situ observations in a pan-Arctic context owing to the permanent infrastructure and long history of international scientific collaboration on the archipelago, hence it is a prime location to develop Arctic digital twin technology. Here, we will provide a demonstration of the capabilities of SvalbardDT version 1 as a new tool for monitoring Svalbard’s cryosphere in the 21^st century (2010-present), the underlying architecture, and the next steps towards full operationalisation.

SvalbardDT represents a digital twin of Svalbard’s cryosphere covering glaciers, snow and sea ice observed through a combination of Earth Observation data sets and reanalysis data products. These data products are multi-modal i.e. they are collected at different resolutions, scales and time/spatial periods. SvalbardDT fine-tunes a deep learning foundational model to ingest the relevant data products and harmonise them into a 4D data cube describing the data set variable, x-dimension, y-dimension, and its changes over time. This produces weekly to monthly data cubes describing ~21 parameters. SvalbardDT focuses on the application of two case studies which are accessed through an online dashboard: (1) exploring the current state of cryosphere conditions in Svalbard to simulate terrestrial and marine navigation routes across the archipelago; and (2) forecast extreme Rain on Snow and Ice (ROSI) events using an AI foundation model. The associated toolboxes help to improve our understanding of the interconnecting processes shaping glaciers and ice caps across Svalbard.

How to cite: Harcourt, W. D., Fotheringham, M., Leontidis, G., Durrant, A., Morris, A., Malnes, E., Ricker, R., Luckman, A., Van Pelt, W., Pohjola, V., Jakob, L., and Gourmelen, N.: Monitoring and forecasting the state of Svalbard’s cryosphere using a digital twin (SvalbardDT), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5777, https://doi.org/10.5194/egusphere-egu26-5777, 2026.

Glaciers are currently losing mass at unprecedented rates. These losses are often attributed to past climate forcing. However, a substantial share of glacier volume loss reflects the delayed adjustment of glacier geometry to past climate conditions. This lag arises because glacier geometry can evolve only as fast as ice can flow and surface mass balance can add or remove ice, making glacier change a continual race to adapt to changing climatic conditions.

In this study, we globally quantify the fraction of glacier volume loss that is committed to past climate forcing, relative to losses driven by concurrent climate conditions. Using the Open Global Glacier Model (OGGM), we decompose volume loss over the preceding decade for reference years. Each period is simulated twice: once forced by the climate of the reference period and once with the climate from a preceding period. This allows us to isolate the fraction of volume loss attributable to committed adjustment. Preliminary results indicate that of the 4.5% global glacier volume loss between 2000 and 2019, approximately 90% would also have occurred under the climate conditions of 2000–2010 alone, and nearly half can be attributed to climate conditions from 1990–2000.

Our results provide a new perspective on the evolving balance between glacier geometry and climate forcing, enabling a clearer interpretation of recent glacier change and its underlying drivers.

How to cite: Ponds, M., Aguayo, R., and Zekollari, H.: Lagged glacier response to past climate forcing and its role in recent volume loss, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7409, https://doi.org/10.5194/egusphere-egu26-7409, 2026.

Glacier surface mass balance observations are highly heterogeneous, with point glaciological measurements spanning decadal timescales being limited to a few well-monitored regions, while geodetic observations are available globally with a multi-annual baseline and almost full glacier coverage. Existing surface mass balance modelling approaches can only calibrate their parameters for individual glaciers or regions with available observations. This often implies that a big part of the available observations per glacier (generally glaciological data) cannot be exploited for calibration since they play the role of independent data for validation. There is a need to move towards flexible surface mass balance models, capable of leveraging in a coherent fashion both glaciological and remote sensing data.

To address this challenge, we introduce a new version of MassBalanceMachine, a neural network-based model that predicts monthly surface mass balance using topographical features and monthly climate forcing as inputs. The pointwise nature of the model, combined with the global availability of input features thanks to OGGM and ERA5, enables the implementation of custom loss functions to train the model. This loss function allows the model to align with both glaciological measurements and geodetic mass balance observations over multiple decades.

By leveraging the interannual variability and point-wise nature from glaciological data and correcting long term biases with geodetic data, MassBalanceMachine can generate reliable high-resolution monthly mass balance predictions for unmonitored glaciers, and correct existing predictions where previous training strategies are known to fail, e.g. in the Alps. This approach exploits data from data-rich sparse regions to make predictions for other unmonitored regions or glaciers, offering a scalable solution for global glacier mass balance estimation.

How to cite: Gossard, A., Bolibar, J., van der Meer, M., and Hauknes Sjursen, K.: One mass balance model to rule them all: joint assimilation of remote sensing and glaciological data into MassBalanceMachine, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11039, https://doi.org/10.5194/egusphere-egu26-11039, 2026.

Warm atmospheric conditions promote the rise of local microclimates over mountain glaciers and the generation of cool katabatic winds. These “Glacier winds” act to reinforce a shallow boundary layer above melting snow and ice in the summer months, mediating their response to temperature fluctuations in the wider mountain domain. Recent observational studies have highlighted the magnitude to which these temperature fluctuations over glaciers are decoupled from broader temperature changes, promoting cooling that can slow down melting. Nevertheless, they have largely drawn upon individual glacier case studies with little broader quantification of its scale and relevance for glaciers response to climate change.

We compiled meteorological observations from > 350 on-glacier automatic weather station records from >60 glaciers around the world over the past three decades. We contrast the air temperature conditions on-glacier with local, off-glacier weather station records to find that above-ice air temperatures warms ~0.73°C on average for every 1°C change in the surrounding mountain atmosphere. Using a combination of available meteorological and topographical data for each glacier in our dataset, we build a statistical model to estimate the magnitude of cooling over mountain glaciers globally. A global estimate of near-surface cooling over mountain glaciers based upon ERA5-Land climatologies for 2000-2022 reveals stark regional variability in how glaciers ‘feel’ temperature warming in the mountains. We demonstrate that larger glaciers in warmer and more humid environments maintain stronger and more persistent glacier winds that promote greater localised cooling. In contrast, on small, fragmenting glaciers in drier environments, especially those where exposure to synoptic winds or increased debris cover is common, glacier winds and localised cooling are limited.  

We leverage ensemble climate estimates from socio-economic pathway SSP2-4.5 and SSP5-8.5 scenarios of sixth phase of the Coupled Model Intercomparison Project (CMIP6) as well as published estimates of glacier volume loss until 2100 to provide a first estimate of the expected future glacier cooling under a warmer climate. While glacier winds are expected to increase near-surface cooling under a warmer climate of the 2030’s and 2040’s in several glacier regions of the world, widespread glacier retreat will limit the development of these glacier winds and, ‘recouple’ temperature variability over glaciers to their surroundings and thus enhance the sensitivity of glaciers to broader climatic warming in the latter half of the 21st century. In the European Alps, it is estimated that the period of maximised glacier katabatic wind development has already passed, signalling the expected demise of cooler meteorological conditions there.

How to cite: Shaw, T., Miles, E., McCarthy, M., Buri, P., Guyennon, N., Salerno, F., Carturan, L., Brock, B., and Pellicciotti, F.: Cool no More! Mountain Glaciers Recouple to Atmospheric Warming over the Twenty-First Century, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11494, https://doi.org/10.5194/egusphere-egu26-11494, 2026.

The Fluctuations of Glaciers (FoG) database is the outcome of 130 years of coordinated international glacier monitoring. It is curated by the World Glacier Monitoring Service (WGMS) and regularly updated with observations submitted by a worldwide network of scientific collaborators. Glacier mass, elevation, and length change observations (1535–2025) are complemented by an inventory of glacier-related events (e.g., surges, lake outbursts, and ice avalanches). We will explain the data integration process and evaluate the spatial, temporal, and climatic coverage of the observations.

We will also highlight many enhancements to the database, including structured authorship and bibliographic metadata for each observation, a near-complete full-text archive of all cited literature, glacier names in multiple languages and scripts, the outline used to derive each glacier-wide elevation change, and a representative outline for each in-situ mass change series.

Finally, we will present an annual estimate of global glacier mass loss from 1976 through the 2025 hydrological year. Since 2025, the WGMS combines the latest in-situ mass change observations and remotely-sensed elevation change observations in FoG to calculate a mass-change time series for every glacier on Earth (separate from the Greenland and Antarctic ice sheets) and corresponding regional and global totals.

How to cite: Welty, E. and the WGMS Network: Global glacier change observations (1535–2025) and mass loss (1976–2025), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11914, https://doi.org/10.5194/egusphere-egu26-11914, 2026.

Meltwater from High Mountain Asia (HMA) provides water resources to large downstream populations of central, southern and eastern Asia. Recent decades have seen critical changes in the health of the high mountain cryosphere of the region, which poses risks to those dependent upon its water supply. Glaciers of HMA have been observed to change mass at varying rates regionally, likely caused by a combination of heterogeneous climate change and region-specific glacier sensitivities. Regional studies on glacier sensitivities have been limited by computational power to rely on degree day models with higher dependence on calibration and equifinality issues. The same computational limits and data availability have limited energy balance studies to short periods, localised domains or coarsely resolved glacier regions. Explicit representation of glacier specific hypsometry and surface characteristics allows the inclusion of non-linear sensitivity of mass balance with elevation, as well as the inclusion of effects of debris cover. Here we provide a new regional picture of HMA glacier sensitivity to climate using a physically-based high resolution energy and mass balance model (Tethys & Chloris).

We run the model for 50 glaciers in each glacier subregion of HMA, chosen to be representative in terms of glacier area, median elevation, debris area and mean debris thickness. Each glacier is modelled using a clustering of points to discretise its surface, where the number of points is optimised depending on glacier size. We first build a baseline of glacier response to present climate (2000-2010) by forcing the model with bias-corrected hourly ERA5-Land data. For the bias correction, a precipitation factor and temperature bias is optimised for each glacier so that model results match against remotely sensed observations of glacier mass balance, snow line altitude and surface albedo.

To determine glacier sensitivities and their drivers, we perturb temperature and precipitation annually to quantify the mass balance changes at the glacier and regional scale. Further experiments perturbing seasonal climatic signals reveal the relevance and relative impacts of temperature and precipitation changes for regions previously identified as experiencing anomalous mass balance behaviour, such as the Pamir-Karakoram. We analyse the contribution of the main energy fluxes and melt components to the glacier-wide mass balance and quantify the relative influence of precipitation solid fraction and sublimation under these different climate perturbation scenarios. We study the sensitivity of the accumulation area ratio and the glacier equilibrium line altitude as indicators of the regional patterns in glacier health, its year-to-year variability and susceptibility to abrupt shifts under climatic extremes. With this, we identify and explain which regions may be most susceptible to future climate change signals, with an unprecedented attribution to the underlying glacier characteristics and changes in physical processes.

How to cite: Tumarkin, E., Shaw, T., Jouberton, A., Ren, S., and Pellicciotti, F.: Energy and mass balance sensitivities of glaciers to climate across High Mountain Asia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12522, https://doi.org/10.5194/egusphere-egu26-12522, 2026.

The accelerating loss of glacier mass is disrupting local ecosystems, reshaping hydrological regimes, increasing the likelihood of glacier-related hazards, and undermining the resilience of dependent communities. Quantifying annual glacier mass balance remains challenging because existing estimates rely on either sparse in situ and remote sensing observations or process-based models, each with inherent limitations. Observational approaches, while consistent at global scales, exhibit large regional variations. In contrast, modelling frameworks provide complete spatiotemporal fields but are typically deterministic, sensitive to calibration data, and constrained by assumptions that may overlook key energy balance drivers. Through our approach, we combine the strengths of models and various observational methods in a Bayesian neural network framework. Specifically, we use a Bayesian Neural Field architecture that is first pre-trained on fixed-geometry annual mass balance outputs from the Open Global Glacier Model (OGGM) and then finetuned using multimodal observations available at different spatial and temporal scales. The model uses static glacier characteristics and near-surface climate variables as predictors. We demonstrate through a blocked testing strategy that our framework can fill gaps for glaciers with missing or highly uncertain mass balance records as well as reconstruct meaningful long-term time series. In summary, this approach provides a scalable, uncertainty-aware method for generating spatially and temporally complete annual glacier mass balance estimates.

How to cite: Anilkumar, R., Bamber, J., Maussion, F., and Zemp, M.: Reconstructing Annual Global Glacier Mass Balance using Bayesian Neural Fields, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13047, https://doi.org/10.5194/egusphere-egu26-13047, 2026.

With the availability of open-access satellite imagery and derived products from open-source tools, global studies of glaciers have become increasingly manageable. Many studies have used these global datasets to delineate spatial and temporal variations in glacier mass balance and dynamics. This has highlighted the effects of seasonal fluctuations and climatic trends on glaciers and has aided the identification of glacier surges. Here we focus on the often-neglected effects volcanoes may have on glacier mass balance and dynamics. First, we analyse the elevation distribution of the world’s glaciers with respect to their proximity to volcanoes and find that there is measurable evidence of the negative mass-balance effect volcanoes have on nearby glaciers. Second, we use the ITS_LIVE glacier velocity dataset along with the new TICOI regularisation and signal decomposition to identify velocity anomalies on glaciers located around volcanoes. This allows us to discern both short-lived velocity anomalies as well as long-term trends and variations in seasonal patterns. We identify multiple velocity anomalies, many of which correlate with climatic trends or weather events, others with surges, but some stand out as volcanically induced. We demonstrate examples of what effect various volcanic processes such as geothermal activity, mass wasting events, unrest, and pre-eruptive activity can have on glacier velocity.

How to cite: Unnsteinsson, T., Spagnolo, M., Rea, B., Girona, T., Barr, I., and Mullan, D.: Feeling the heat: global detection of volcanic effects on glacier mass balance and dynamics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14408, https://doi.org/10.5194/egusphere-egu26-14408, 2026.

Glacier thermal structure exerts a strong control on ice dynamics, yet it remains poorly characterized at the global scale. Despite its influence on glacier flow and, consequently, on melt and sea-level projections, thermal structure is typically neglected in large-scale glacier models. This omission stems from the fact that current methods of determining thermal structure require extensive field observations or computationally expensive modelling, resulting in only dozens of glaciers having well-defined thermal structures. In this work, we developed and applied a proxy-based approach to estimate the major heat sources (meltwater refreezing and strain heating) and transport mechanisms (advection and diffusion) in the heat transfer equation, which shapes glacier thermal structure. Proxies derived from publicly available observations and model output are calculated for glaciers in RGI-01 (Alaska) and RGI-07 (Svalbard and Jan Mayen). This framework enables a rapid regional assessment of thermal characteristics without requiring coupled thermomechanical modelling.

Across both Alaska and Svalbard, meltwater refreezing is the dominant heat source for 73% of glaciers, while diffusion dominates heat transport for 75% of glaciers. Note that this model only considers refreezing in the accumulation area, and 21% of these glaciers do not have an accumulation area. The majority (76%) of glaciers exhibit warmer accumulation-area ice transported toward cooler ablation areas. When examined by proxy rank, the most common pattern (47% of glaciers) is characterized by refreezing as the dominant heat source over strain heating, and vertical diffusion over horizontal advection as the primary transport mechanism. This pattern represents 25% of glacierized area, corresponding primarily to smaller glaciers (<10 km) scattered across Alaska, but found across sizes in Svalbard. Large Alaskan glaciers (39% of glacierized area), have a proxy pattern where refreezing dominates strong strain heating, while horizontal advection exceeds vertical diffusion. In Svalbard, this pattern is almost absent (<1% of glaciers). Comparing the proxy rank patterns of all glaciers in Alaska and Svalbard with those of glaciers with known thermal structures provides a correlation-based interpretation of the proxy results. For example, we found that the calculated proxy pattern for known temperate glaciers is characterized by dominant refreezing and advection, whereas known cold glaciers exhibit the pattern characterized by dominant refreezing over strain heating and diffusion over advection. Furthermore, a number of large glaciers on the continental side of the St. Elias Mountains in Alaska exhibit a proxy pattern distinct from those associated with well-established thermal structures in the region.

This work presents a way to calculate heat-source and transport-mechanism proxies as a practical means of estimating glacier thermal characteristics for any RGI region with sufficient input data. The resulting proxy distributions provide new insight into spatial patterns of heat generation and transfer in glaciers at the regional scale and establish a baseline for evaluating thermal responses to climate change. Moreover, these results can serve as comparative datasets for emerging emulator-based, regional-scale thermal modelling.

How to cite: Martinez Gracey, D., Flowers, G., and Jacquemart, M.: A proxy-based method of estimating glacier heat sources and transport mechanisms to map thermal processes at a regional scale, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14679, https://doi.org/10.5194/egusphere-egu26-14679, 2026.

Glaciers in the southern Andes are retreating rapidly because of ongoing climate warming. This process is reshaping the mountainous landscape and promoting the formation of new glacial lakes. Therefore, quantifying glacier ice thickness and subglacial topography is vitally important for assessing future water resources and glacier-retreat hazard. Of particular interest are bed over-deepening that will fill with water once they become ice-free. Such water bodies are potentially trigger sites for devasting Glacial Lake Outburst Floods (GLOF). However, estimates of ice thickness at the regional scale in the southern Andes remain uncertain due to the scarcity of in situ data on current glacier thickness as well as strong climatic and topographic gradients.

Here, we present a regional reconstruction of glacier ice thickness and subglacial topography for the entire Southern Andes, systematically constrained by the extensive archive of ground-penetrating radar measurements available for the region. Ice thickness is reconstructed, assuming perfect plasticity. Apart from direct measurements, we use glacier retreat and observe elevation changes to constrain the reconstruction. The resultant thickness map shows latitudinal contrasts in glacier geometry, with thin ice bodies in the desert Andes and substantially thicker ice masses in Patagonia.

We estimate a total volume of glacial ice of 5,960.6 km³ in the Southern Andes, equivalent to a global sea-level rise of 15.1 mm, with more than 95% of this volume concentrated in Patagonia, particularly in the two vast icefields there. By removing the modeled ice cover, we determine the subglacial topography and identify more than 6,000 overdeepenings that represent potential sites for future glacial lake formation. For each potential lake, we estimate its area, depth, and volume, yielding a total potential lake volume of approximately 177.6 km³ across the Southern Andes, with most of this volume concentrated in Patagonia (171.18 km³).

Our results provide a new measurement-informed, database for assessing future glacier evolution, freshwater storage, and emerging GLOF hazards in the Andes, providing critical information for climate adaptation and risk management in high-mountain regions

How to cite: Berkhoff, J. A., Farías-Barahona, D., Iribarren-Anacona, P., Sommer, C., Schaefer, M., Rodriguez, J. L., Uribe, J., and Fürst, J. J.: Unveiling the subglacial landscape in the Southern Andes shows an abundance of future glacial lakes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15350, https://doi.org/10.5194/egusphere-egu26-15350, 2026.

The European Alps have experienced massive glacier loss over the last decade, and 50% of all glaciers are expected to disappear even under current climate conditions by 2050. Glacier retreat, rapid meltwater production and damming, debustressing, and accelerated release of sediment massively increase the natural hazards in the region. The decline of glaciated areas in alpine regions directly impacts water reservoirs, tourist infrastructure, and alpine communities; therefore, precise quantification of rates of glacier retreat at a regional scale are paramount for foreseen prevention and mitigation plans.

The location and extent of mountain glaciers are conditioned by two independent factors: topography and climatic conditions. In this contribution, we explore the glacier changes over the last decade in two contrasting regions: (i) the drier and colder Ötztal Alps, host of the largest glaciers in Austria, and (ii) the wetter/warmer Zillertal Alps. Our aim is to decipher the key factors controlling glacier retreat at the regional scale. We used photogrammetric reconstruction of high-resolution aerial imagery at a 20cm resolution to (i) manually map the glacier extent in 2009/2010 and 2022 for 87 glaciers in the Zillertal and 48 glaciers in the Ötztal. The manual mapping was supported by stereographic visualizations for a precise photo-interpretation of glacier boundaries, (ii) quantify glacier retreat for each glacier in terms of relative area change (km²) and geodetic mass balance (m w.e.a^-1), and (iii) calculate morphometric parameters such as slope and slope orientation. Finally, we contrasted ERA5 precipitation and temperature data with the findings.

This study presents a unique compilation of glacier extents and geodetic mass balance over 202 km² of the Ötztal and 184 km^² of the Zillertal Alps from 2009 to 2022. Despite the contrasting morphological and climatic characteristics, glaciers in both mountain ranges retreat at similar rates. These findings demonstrate the dominant climatic control on glacier loss in the Eastern Alps and suggest that, under current climatic conditions, glacier morphology plays a minor role at the regional scale. 

How to cite: Barbosa, N., Mayer, C., Jubanski, J., Münzer, U., Siegert, F., and Krautblatter, M.: Alpine glacier response to increasing temperature between 2009 and 2022. Insights from photogrammetric analysis in the Ötztal and Zillertal Alps (AT)., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18021, https://doi.org/10.5194/egusphere-egu26-18021, 2026.

Glacier mass balance is a key indicator of climate change and a central driver of glacier evolution, yet most glaciers worldwide lack long-term in-situ measurements. For estimating glacier mass balance, data-driven models offer a complementary pathway to traditional numerical approaches by learning empirical relationships between climate forcing, topography, and mass balance directly from observations. Here, we develop a recurrent neural network based on a Long Short-Term Memory (LSTM) architecture within the Mass Balance Machine (MBM) framework and evaluate its ability to predict seasonal and annual point surface mass balance across the Swiss Alps. MBM is trained on 30'000 point observations from 30 glaciers and tested on eight glaciers excluded from training to assess spatial generalization. MBM predicts both winter and annual mass balance with high accuracy on unseen glaciers, and its recurrent structure provides a clear advantage by allowing the model to learn temporal dependencies, which improves the representation of seasons with strong accumulation or ablation. Beyond point predictions, MBM produces spatially distributed mass balance maps that closely resemble reference products directly derived from in-situ data, capture elevation-dependent gradients, and yield glacier-wide mass changes consistent with the differencing of repeated terrain models. Monthly outputs further show that the model captures the seasonal transition from winter accumulation to summer ablation and its dependence on elevation with realistic timing and magnitude. These results indicate that a recurrent neural network approach can recover key characteristics of glacier mass balance dynamics from sparse in-situ observations and that the learned relationships are transferable across glaciers with distinct meteorological and topographic settings. The demonstrated generalization skill and suitability for transfer learning highlight the potential of MBM for predicting glacier mass balance in regions with limited or no direct measurements.

How to cite: van der Meer, M., Zekollari, H., Gossard, A., Hauknes Sjursen, K., Bolibar, J., Huss, M., and Farinotti, D.: Glacier mass balance modeling using a Long Short-Term Memory network, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20051, https://doi.org/10.5194/egusphere-egu26-20051, 2026.

Snow cover variability in high-altitude Himalayan river basins plays a critical role in regulating regional hydrology, water availability, and climate-cryosphere interactions. Understanding its temporal behaviour is particularly important for snow-fed basins such as the Budhi Gandaki Basin, Nepal, where seasonal meltwater significantly influences downstream flow regimes. Previous studies often overlooked detailed monthly-scale time series analysis and robust trend diagnostics of snow cover variability. In this study, we investigate the temporal dynamics of monthly snow cover area in the Budhi Gandaki Basin (area: 3857.85 km²) using continuous observations from 2020 to 2024 using the Moderate Resolution Imaging Spectroradiometer (MODIS) 8-day snow cover products (MOD10A2) with 500 m resolution. A comprehensive time-series framework was applied, incorporating descriptive statistics, linear trend analysis, seasonal climatology, anomaly assessment, and non-parametric trend detection. The MOD10A2 snow cover composites were spatially averaged over the basin and temporally aggregated to monthly resolution using a proportional day-overlap weighting scheme to estimate basin-averaged monthly snow covered area (SCA). Monthly snow cover data were then transformed into a continuous time series to evaluate overall variability and long-term behaviour. Seasonal characteristics were quantified through monthly climatology and interannual variability using mean and standard deviation metrics. Trend significance was examined using the Mann-Kendall test, while the magnitude of change was estimated using Sen’s slope. Results reveal a mean snow cover index of 0.56 with substantial variability showing a standard deviation of 0.16 snow cover fraction (SCF), indicating pronounced seasonal and interannual fluctuations. Monthly climatology shows maximum snow cover during winter months, peaking in February (mean: 0.762 SCF) and January (mean: 0.756 SCF), while minimum values occur during the summer monsoon period, particularly in July (mean: 0.424 SCF) and June (mean: 0.426 SCF). Linear trend analysis indicates a gradual declining tendency in snow cover at a rate of -0.0024 SCF per month. However, the Mann-Kendall test yields a Z statistic of -1.77 with a p-value of 0.076, suggesting that the observed decreasing trend is not statistically significant at the 95% confidence level. Anomaly analysis further highlights episodic deviations from the climatological mean, with maximum positive and negative anomalies of +0.204 SCF and -0.162 SCF, respectively, reflecting short-term climate-driven variability. Overall, the findings indicate a weak but persistent declining tendency in snow cover, modulated strongly by seasonal and interannual variability rather than a statistically significant long-term trend. This study provides an improved understanding of snow cover dynamics in the Budhi Gandaki Basin and offers valuable insights for hydrological modeling, climate impact assessments, and sustainable water resource management in snow-fed Himalayan river systems.

Keywords: Snow cover variability; Time series analysis; Himalayan river basin; Seasonal climatology; Trend detection

How to cite: Tiwari, H., Thakur, A. K., and Garg, R. D.: Temporal Variability and Trend Analysis of Monthly Snow Cover in a Himalayan river basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2219, https://doi.org/10.5194/egusphere-egu26-2219, 2026.

Seasonal snow cover in high mountain regions plays an important role in river flow hydrographs, water availability and land atmosphere interactions. In the Western Himalaya, mapping snow cover accurately is difficult due to frequent cloud cover, steep terrain, strong shadow effects and confusion between snow, clouds and bright rocky surfaces in satellite images. The study shows that these issues are clearly observed in the Western Himalayas, where the lack of sufficient ground reference data further limits the use of fully supervised classification methods. To address these challenges, the objective of the present study is to develop a snow cover mapping framework that leverages self-supervised learning for robust feature representation from satellite remote sensing data in the Western Himalaya. The method focuses on learning useful snow related features directly from large volumes of unlabelled satellite images, reducing the need for extensive manually labelled training data. Multi temporal optical satellite images are used so that the model can learn stable snow patterns across different seasons, illumination conditions and surface states. A convolutional neural network is trained using a contrastive self-supervised learning strategy, where different augmented versions of the same image patch are treated as similar samples, while patches from different locations are treated as dissimilar. The self-supervised encoder is coupled with a lightweight decoder in an encoder-decoder segmentation architecture, enabling pixel wise snow mapping while preserving spatial detail under limited supervision. Simple data augmentations, such as brightness changes, contrast adjustments and random cropping are applied to improve the model’s ability to recognize snow under varying conditions while preserving its key spectral and spatial characteristics. After self-supervised pretraining, the learned feature representations are fine tuned for snow and non-snow classification using a limited set of labelled samples derived from reference snow products and manual interpretation. This greatly reduces the dependence on large labelled datasets compared to conventional supervised learning methods. Snow cover maps are generated for different seasons and elevation zones to examine spatial and temporal variability of snow distribution across the basin. The results are compared with traditional index based methods, such as Normalized Difference Snow Index (NDSI) thresholding, especially in areas affected by clouds, shadows and mixed land cover. The study shows that the self-supervised learning provides a practical and reliable framework for snow cover mapping in data scarce and high altitude regions. The methodological framework developed in this study can be utilized for other basins also to have improved understanding of snow cover dynamics.

Keywords: Snow cover; self-supervised learning; remote sensing; Himalaya

How to cite: Thakur, V., Keshari, A. K., and Tak, S.: Monitoring of Spatio-Temporal Snow Cover using AI Based Self-Supervised Learning in Data Scarce Himalayan River Catchment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3445, https://doi.org/10.5194/egusphere-egu26-3445, 2026.

Water management represents a critical challenge for the mining industry, as large volumes of surface water must be controlled and treated during operations to ensure the stability of geotechnical structures and protect the environment. This extends beyond the operational phase, as it is essential to ensure the physical stability of tailings storage facilities and to limit the potential transport of contaminants on reclaimed mine sites. The water balance of tailings storage facilities is regulated by surface water management and often treatment infrastructures. In addition, the water balance is also closely linked to the performance of several engineered cover systems used to reclaim tailings storage facilities. Because tailings storage facilities generally occupy large areas, snow accumulation in winter and rapid melting in spring generate substantial volumes of meltwater within a short period. Thus, the spring freshet is a critical phase for water inventory control, from operation to post-reclamation. In this context, developing tailored monitoring tools is essential to ensure effective spring water management on tailings storage facilities.

This work aims to develop a high spatial resolution drone-based sensing approach for semi-real-time monitoring of the snow water balance in tailings storage facilities during snowmelt. This study is based on the results of several drone-based Structure-from-Motion photogrammetry and LiDAR surveys conducted during snowmelt on a reclaimed tailings storage facility. The site presents two major challenges for these sensing techniques: a flat, featureless area prone to oversaturated whites when covered with snow, and sections of dense low vegetation that reduce LiDAR signal penetration and hinder the generation of accurate digital elevation models. The accuracy and precision of the two remote sensing technologies to evaluate the snow depth were assessed based on manual measurements and conventional GNSS surveys. The impact of the reconstruction software/algorithms and parameters, as well as the number of ground control points (between 3 and 21) used in the reconstructions, on accuracy was also assessed. Finally, a preliminary snow-water equivalent model was developed and integrated within the data processing scheme to provide the changes of snow-water equivalent during snowmelt. Results show that LiDAR is the most accurate and reliable approach to monitor the snow depth. Photogrammetry-derived digital elevation models resulted in an error up to 66 cm. The quality and accuracy of photogrammetric surveys depend on the number of ground control points, the reconstruction algorithm used, and the absence of aerotriangulation tie points in certain areas. A snow-water equivalent model was integrated with LiDAR-derived snow depth data to characterize the temporal evolution of the tailings storage facility water balance during snowmelt. This presents an incremental improvement towards effective spring-water management on tailings storage facilities.

How to cite: Boulanger-Martel, V. and Blatter, N.: Potential of LiDAR and Structure-from-Motion Photogrammetry for High-Resolution Monitoring of Snowmelt Water Balance in Tailings Storage Facilities, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8352, https://doi.org/10.5194/egusphere-egu26-8352, 2026.

Snow is the only component of the water cycle that does not have a dedicated earth observation mission. Snow impacts many sectors like the health and well-being of communities, the economy, and sustains ecosystems. Snow also contributes to many costly hazards like floods, droughts, and avalanches. The current lack of information on how much water is stored as snow (snow water equivalent, SWE), and how it varies in space and time, limits the hydrological, climate, and weather services provided by Environment and Climate Change Canada (ECCC). To address this knowledge gap, ECCC, the Canadian Space Agency (CSA) and Natural Resources Canada (NRCan) are working in partnership to advance the scientific and technical readiness for a Ku-band synthetic aperture radar (SAR) mission presently named the ‘Terrestrial Snow Mass Mission’ – TSMM. An observing concept capable of providing dual-polarization (VV/VH), moderate resolution (500 m), wide swath (~250 km), and high duty cycle (~25% SAR-on time) Ku-band radar measurements at two frequencies (13.5; 17.25 GHz) is under development. This Canadian radar mission will provide weekly coverage of the northern hemisphere with Ku-band SAR data, and coupled with modeled data in the Canadian Land Data Assimilation System (CaLDAS), will provide daily snow water equivalent data, to assist hydrological applications and decision-making. It has been proven that Ku-Band backscatter measurements are sensitive to SWE through the volume scattering of the signal by the snow microstructure. Radar measurements are also well known to be able to discriminate between wet and dry snow conditions.

In this presentation, we will review recent progress at ECCC (supported by the mission science team and the international snow community). Key areas of ongoing development include:
(1) The Ku-band radar SWE retrieval algorithm proof of concept, based on the use of physical snow modeling to provide initial estimates of snow microstructure which can effectively parameterize forward model simulations for prediction of snow volume scattering.
(2) Improvements to radiative transfer modelling codes to improve computation efficiency.
(3) Improvements to physical snow modeling in the Canadian land surface model Soil Vegetation Snow version 2 (SVS2).
(4) Development of the capability for direct assimilation of Ku-band backscatter into environmental prediction systems at ECCC.
(5) Segmentation of wet from dry snow based on the time evolution of radar backscatter.

Testbed experiments in which snow physical modeling, SWE retrievals, and data assimilation are analyzed collectively are currently under development. These experiments will be facilitated by the TSMM simulator and will incorporate outputs from SVS2 and are supported by airborne and ground-based Ku-band radar measurements from national and international academic partners. 

How to cite: Montpetit, B., Derksen, C., Vionnet, V., Carrera, M., Meloche, J., Leroux, N., and Bergeron, J.: Updates on advancements of the Terrestrial Snow Mass Mission, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8577, https://doi.org/10.5194/egusphere-egu26-8577, 2026.

Abstract: Snow is a critical component of the cryosphere, exhibiting substantial variations in both spatial and temporal dimensions. Accurately capturing the dynamic characteristics of seasonal snow cover is essential for predicting snowmelt runoff, monitoring hydrological cycle, and conducting climate change analysis. Optical satellite remote sensing has proven to be an effective tool for monitoring global and regional snow cover. However, existing fractional snow cover (FSC) data derived from optical imagery often encounters challenges, including large-scale spatial gaps caused by cloud cover and shadows. Meanwhile, passive microwave data, although valuable, typically possess lower spatial resolution, rendering them inadequate for detecting snow cover dynamics under complex surface conditions. In this study, we employed a fractional snow cover fusion estimation method to generate high-resolution (1 km) spatiotemporally continuous FSC estimation datasets for the Tibetan Plateau region from the years 2008 to 2021, regardless of weather conditions. The accuracy of the FSC data was systematically evaluated over the study period, demonstrating excellent consistency with independent datasets, including Landsat-derived FSC (total 20 scenes; RMSE = 0.092–0.193; R = 0.83–0.946) and ground-based snow observations (Approximately 70,000 site records; Overall Accuracy = 0.95; Kappa = 0.95). Furthermore, the FSC datasets produced by this method exhibits superior performance in accurately capturing the complex daily snow cover dynamics compared to other FSC datasets(Overall Accuracy: 0.95 vs. 0.91 vs. 0.85). In conclusion, the daily FSC maps of the Tibetan Plateau generated from 2008 to 2021 using data fusion methods in this study offer high accuracy and complete spatiotemporal coverage. These FSC datasets hold substantial value for climate projections, hydrological studies, and water management at both global and regional scales.

Fig.1 Spatial Distribution of Snow Cover (1 km) for daily FSC data over the Tibetan Plateau from 2008 to 2021. The dates are shown at the bottom of the subplots. The blank areas denote missing values due to various reasons. The range of snow cover variation is from 0 to 1, where 0 indicates no snow cover and 1 indicates full snow cover.

Table.1 Summary of accuracy metrics for the 1km daily fractional snow cover data over the Tibetan Plateau using 10 Landsat scenes FSC data as the reference data.

How to cite: Sun, T. and He, T.: Mapping 1 km Fractional Snow Cover from Passive Microwave Brightness Temperature Data and MODIS Snow Cover Product over The Tibetan Plateau, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10752, https://doi.org/10.5194/egusphere-egu26-10752, 2026.

Reliable information on snow cover dynamics is essential for water resource management, climate impact assessments, and ecological studies. In mountainous regions, where spatial variability is high and long-term observations are limited, satellite-based snow products often present the primary source of information. However, their performance is constrained in complex terrain by cloud cover, coarse spatial resolution, and data gaps. Therefore, the validation of satellite-derived snow cover data is crucial for reducing uncertainty. In this study, we employed a low-cost, ground-based time-lapse camera to monitor snow cover (SC) and to support the validation, gap-filling, and improved reliability of satellite-derived snow cover products.

Time-lapse photography was obtained using a camera trap installed at the Skalnaté Pleso Observatory in the High Tatra Mountains (Slovakia). The camera captured daily images of a south-eastern slope during four snow seasons (2021/22–2024/25). An automated image-processing workflow was applied to derive snow cover percentage from the photographs, including horizon-based image alignment, masking of non-relevant areas, and automatic snow classification based on blue-band intensity thresholds. The resulting camera-derived SC was compared with satellite-based fractional snow cover (FSC) from Sentinel-2 products (Fractional Snow Cover and Gap-filled Fractional Snow Cover marked as S_FSC and S_GFSC) and MODIS products (MOD10 and MYD10 marked as M_TERRA_FSC and M_AQUA_FSC) within the camera’s field of view.

The analysis revealed substantial differences in data availability between ground-based and satellite observations, with time-lapse photography providing more continuous records during periods of frequent cloud cover. Camera-derived SC captured short-term snow accumulation and melt dynamics that were often missed or temporally smoothed in satellite products. Relative to camera observations, Sentinel products overestimated SC by 11.3 % (S_GFSC) and 9.1 % (S_FSC), whereas MODIS products underestimated SC by -9.5 % (M_AQUA_FSC) and -7.7 % (M_TERRA_FSC). 

Data gaps in satellite products were addressed using a Random Forest machine-learning approach trained on SC derived from terrestrial time-lapse photography. To avoid sensor-mixing biases, separate models were trained for each Sentinel-2 and MODIS product. By integrating local meteorological variables such as daily air temperature, precipitation, snow depth, and global radiation, the models were able to capture the non-linear nature of snow dynamics. Our study demonstrates that combining time-lapse photography with satellite products and in situ meteorological measurements enables more accurate reconstruction of snow cover dynamics, particularly in periods of rapid snow accumulation and melt in alpine environments.

Acknowledgement: This study was funded by the project VEGA 2/0048/25.

How to cite: Krempaský, J., Lukasová, V., Mrekaj, I., Onderka, M., and Varšová, S.: Machine Learning–Based Gap-Filling of Satellite Snow Products Using Time-Lapse Photography and Meteorological Data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10848, https://doi.org/10.5194/egusphere-egu26-10848, 2026.

Mineral dust is produced as a by-product when mining for metals such as iron and rare-earth elements. Around mines in the Arctic and Subarctic, this dust is transported by wind and deposited on the snow surface, contaminating the seasonal snowpack. The presence of mine dust darkens the snow surface, resulting in a lower snowpack albedo. Due to their lowered albedo, seasonal snowpacks that contain mine dust experience accelerated melting. Nordic countries, including Sweden, are showing an increasing interest in the expansion of mining activities due to increasing demand for metals to use in technology and a desire to produce raw materials within Europe. The Kirunavaara mine in the Swedish Arctic is Europe’s largest iron mine, and is an accordingly large source of mineral dust, which spreads around the adjacent town of Kiruna and the surrounding areas.

One possible approach to quantify mine dust contamination of the seasonal snowpack is using optical remote sensing. The change in spectral reflectance of the contaminated snow surface is used to infer optical properties and the concentration of mine dust in the surface snow. Spectral indices and radiative transfer modelling are applied to the spectral reflectance data to retrieve dust concentrations. We have measured dust concentrations in snow around Kiruna during spring 2025, and measured reflectance of the affected snow surfaces. Snow darkening in Kiruna occurs predominantly in the area located downwind from the mine where dust concentrations in snow are highest. Dust loadings in surface snow around Kiruna reach over 2000ppm, with associated snow broadband albedo values as low as 0.3 in the most heavily contaminated areas. There is a clear relationship between broadband albedo and mine dust concentrations in the surface snow. However, the spectral signatures of the contaminated snow surface show that iron mine dust darkens the snow relatively evenly across all wavelengths of visible light. Combined with the high dust loading, this even darkening effect means that previously established spectral indices for minerals dust in snow are not applicable in the case of iron dust contamination, and an approach tailored specifically to this type of dust is required.

How to cite: Taveirne, M., Zdanowicz, C., Langlois, A., Di Mauro, B., Traversa, G., and Hagermann, A.: Measuring mine dust contamination of snow in northern Sweden using optical remote sensing, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12080, https://doi.org/10.5194/egusphere-egu26-12080, 2026.

The COOL project, funded by the Italian Space Agency (ASI), focuses on the development of an advanced, modular Level-2 (L2) processor for the PRISMA Second-Generation (PRISMA-SG) hyperspectral mission. The processor is designed to generate high-quality L2 products, including surface reflectance, water vapor content, and aerosol optical thickness, while addressing the unique challenges introduced by the off-nadir acquisition geometry of the PRISMA-SG sensor.

The processor builds upon state-of-the-art radiative transfer modeling and integrates physics-based atmospheric and topographic correction algorithms based on the MODTRAN6 model. The processing chain is derived and extended from previous work (Santini & Palombo, 2019; Palombo & Santini, 2020; Santini & Palombo, 2022), and incorporates second-order effects, such as adjacency corrections and topographic illumination variations. These algorithms are carefully adapted to the spectral, spatial, and viewing geometry characteristics of PRISMA-SG, aiming to achieve or exceed a Scientific Readiness Level (SRL) of 6.

Validation of the processor relies on both simulated datasets and in-situ measurements over dedicated calibration and validation (CAL/VAL) sites established within the COOL project. Top-of-atmosphere (TOA) radiance signals are simulated over these sites and compared with field measurements to quantify residual errors and assess the sensitivity of the inversion algorithms to off-nadir acquisition effects. These activities ensure the robustness and scientific usability of the derived L2 products in both nadir and off-nadir observation modes.

As a demonstration, the L2 processor was applied to PRISMA-SG images acquired over snow-covered areas in the Italian Alps. The results were compared with the standard L2 products provided by the image supplier. The comparison shows close general agreement in reflectance spectra while correcting artifacts present in the standard products, including topographic effects, adjacency effects, and off-nadir-induced reflectance overestimation. Notably, the corrected reflectance values remain physically consistent and do not exceed unity, a problem often observed in the standard products.

This work consolidates the L2 processing capabilities for PRISMA-SG, providing validated, reliable, and application-ready hyperspectral products. The approach demonstrates the importance of accounting for off-nadir geometry and second-order atmospheric and topographic effects, enabling robust use of PRISMA-SG data for environmental monitoring, snow cover studies, and other Earth observation applications.

How to cite: Santini, F., Palombo, A., Mirzaei, S., Pignatti, S., and Pascucci, S.: Development of an Advanced L2 Processor for PRISMA Second-Generation within the COOL Project: Application to Snow-Covered Terrain, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12971, https://doi.org/10.5194/egusphere-egu26-12971, 2026.

Modelling streamflow in mountainous areas is challenging. The presence of snow is an additional factor to consider, as it is the primary driver of streamflow dynamics in mountain catchments. In addition, this complexity increases in the Mediterranean mountains, where snow dynamics are more variable, with specific characteristics, including shallow snowpack, high density, and evaposublimation rates that cannot be neglected when assessing water resource availability during the dry season. Many approaches, with varying levels of complexity, have been used to model streamflow in mountainous areas. In general, these models are calibrated and evaluated against streamflow without considering their performance with respect to snow dynamics. That is, river discharges are well represented, but not due to the correct reasons.

This study assesses the implications of selecting snow parameterizations for streamflow modelling in Mediterranean mountain catchments, considering not only streamflow but also snow performance. Five different hydrological models, with different conceptualizations – lumped, semi-distributed, and fully distributed – and with different levels of complexity regarding snow parameterization – degree-day, radiation-day, and mass and energy balance approach– have been used. These models are: (1) GR4J associated with CemaNeige (lumped with degree-day snow model), (2) SWAT (semidistributed with degree-day snow model), (3) HYPE (semidistributed with radiation-day snow model), (4) GEOFRAME (semidistributed with temperature-radiation-day snow model), and (5) WiMMed (distributed with mass and energy balance snow model). Models were calibrated against streamflow observations and evaluated for snow performance using remote-sensing-derived snow-cover area. A spectral mixture analysis carried out using Landsat imagery, considering the three main land cover types over the region: snow, shallow vegetation, and rocks, was performed to define the fraction of snow in each cell. The values of these pixels were aggregated at the catchment scale for comparison with the simulations. The Guadalfeo River basin in southern Spain has been selected as representative of a Mediterranean mountain-coastal catchment for this analysis.

Preliminary results indicate that the complexity of snow dynamics is better captured by the more complex approach, namely, the fully distributed mass and energy balance snow model. However, the assessment indicates that simpler approaches can be valid when analyzing changes and seasonality rather than actual values. This observation underscores the potential to use this model in an ensemble to compute hydrological uncertainty, as is common in hydrological seasonal prediction and climate studies.

Acknowledgments: This work is part of the project PCI2024-153496, funded by MCIU/AEI/10.13039/501100011033 and EU

How to cite: Gómez-Beas, R., Egüen, M., Formetta, G., Polo, M. J., and Pimentel, R.: Are snow patterns well modelled when simulating river discharge in Mediterranean mountain catchments? A multimodel approach assessment using remote sensing data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17516, https://doi.org/10.5194/egusphere-egu26-17516, 2026.

Seasonal snow in mountain catchments is highly heterogeneous, yet snow water equivalent (SWE) is rarely available at spatial and temporal scales useful for hydrology and ecosystem applications. We present a multi-source retrospective SWE reconstruction framework that produces daily 30-meter resolution SWE over mountains by integrating (i) SAR-based wet-snow information from Sentinel-1 Normalised Radar Backscatter (NRB) product; (ii) optical snow-cover dynamics given using Sentinel-2 and Sentinel-3 data and (iii) in-situ meteorological forcing. A key advantage is that the method does not rely on spatially distributed precipitation fields, which remain a dominant uncertainty in mountain snow modelling.

The approach is built around a pixel “state” concept (accumulation, equilibrium, ablation) that constrains physically plausible SWE evolution through the season. Snow presence is represented by a daily high-resolution snow-cover-area (SCA) time series obtained by gap-filling and downscaling coarse snow-cover fraction with high-resolution optical observations, followed by a state-aware regularization that removes implausible transitions. Snow melt is computed using an enhanced temperature-index (ETI) model driven by air temperature and incoming shortwave radiation. However, ETI formulations do not explicitly resolve cold content and internal energy storage; as a result, they can trigger melt earlier than expected, as they do not account for delays imposed by the snowpack thermal inertia. To constrain the onset of true meltwater conditions, we integrate Sentinel-1 wet-snow maps derived from the new NRB time series, using multi-temporal backscatter changes to detect wet-snow conditions.

The Sentinel-1 NRB product provides radiometrically terrain-corrected backscatter (γ⁰) using the local incidence angle and mapping the data onto a reference coordinate system [1]. This improves consistency over complex topography compared to conventional Level-1 GRD processing. In addition, a novel cloud-native Zarr format enables fast, chunked access to long time series, facilitating regional-scale analyses.

We demonstrate the method in the Maipo region (Andes), where shortwave radiation dominates snowmelt. Preliminary results show that combining daily optical snow-cover dynamics with NRB-informed wet-snow timing enables SWE reconstructions that are temporally consistent across full seasons and, critically, prevents ETI-driven melt before liquid water is detected. Additionally, in the presentation, the NRB products and their assessment for the analysis of timeseries over mountains will be provided.

References

[1]  G. H. X. Shiroma, M. Lavalle and S. M. Buckley, "An Area-Based Projection Algorithm for SAR Radiometric Terrain Correction and Geocoding," in IEEE Transactions on Geoscience and Remote Sensing, vol. 60, pp. 1-23, 2022.

How to cite: Marin, C., Premier, V., Mang, N., and Castelletti, D.: Evaluating the use of NRB Sentinel-1 product for reconstructing high resolution SWE in mountains, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18431, https://doi.org/10.5194/egusphere-egu26-18431, 2026.

Mountain snow is a critical component of the hydrological cycle and climate system, making reliable information on snow depth (SD) essential for water resource management and climate studies. Estimating SD in mountainous terrain remains challenging due to complex topography, heterogeneous land cover, and highly variable snow and weather conditions. Synthetic Aperture Radar (SAR) is suitable in such environments, as it provides frequent observations, high spatial resolution, and sensitivity to snow properties independent of cloud cover and illumination. In particular, Sentinel-1 C-band SAR backscatter-based method enables large-scale and continuous SD monitoring, but faces limitations in vegetated, shallow, or wet snow conditions. To overcome these limitations, this study proposes an improved machine learning (ML) framework that incorporates new input variables derived from Sentinel-1 and other optical data, improving upon existing Sentinel-1–based ML approaches for SD estimation. Additionally, the framework is designed for efficient implementation using preprocessed Sentinel-1 data available in Google Earth Engine, thereby minimising the computational burden of handling SAR data and facilitating scalable application across regions and time periods. The methodology is implemented across three climatically and physiographically distinct mountainous regions: the Colorado Rocky Mountains, the European Alps, and the Indian Western Himalayas. Across all three regions, the proposed model substantially performs better than the existing methods, achieving MAE(r) values of 7.9 cm (0.96), 22.3 cm (0.91), and 68.4 cm (0.72), respectively. Since the physical scattering processes governing C-band SAR responses to snow are not yet fully characterized, explainable AI techniques are applied to interpret model predictions and quantify the influence of input variables under varying environmental conditions. The results show region-specific and seasonal dependencies linked to snow type, vegetation cover, and surface conditions, providing new physical insights into the sensitivity of Sentinel-1 C-band backscatter to snow depth.

How to cite: Rajendiran, C. P. and Ramsankaran, R.: Physical Insights into Sentinel-1 SAR-Based Snow Depth Estimation Using Machine Learning and Explainable AI Across Different Mountainous Regions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19246, https://doi.org/10.5194/egusphere-egu26-19246, 2026.

The presence or absence of snow in the landscape strongly modulates land surface energy exchanges and governs key ecosystem processes in high-mountain catchments. In mid-latitude mountain regions, such as the Pyrenees, which are dominated by intermittent and ephemeral seasonal snowpacks, pronounced intra-annual spatial variability in snow cover complicates the accurate characterisation of snow temporal dynamics.

Although a wide range of snow products and remote sensing platforms are currently available, many of them have significant limitations when applied to complex, mountainous environments such as the Pyrenees. These limitations include data gaps caused by cloud cover and confusion between snow and clouds; reduced accuracy in areas affected by topographic shadows; insufficient illumination due to low solar elevation at the time of satellite overpass; and the trade-off between spatial and temporal resolution. Furthermore, as most existing products are designed for large-scale applications, they can introduce significant errors when high spatial detail is required. This is particularly pertinent in catchment- and sub-catchment-scale hydrological, biogeochemical, and ecological studies.

In this context, we propose a methodological approach that combines the daily temporal resolution of snow gap-filled MODIS products with Sentinel-2-derived snow cover as the ground truth, using k-nearest neighbour (k-NN) classification. We generated daily binary snow presence/absence maps at a spatial resolution of 20 m over the study area using a logistic regression model incorporating general explanatory variables such as elevation, slope, aspect, monthly solar radiation and the spatial and temporal information of snow cover, such as distance-to-snow maps derived from MODIS.

Preliminary results show that the logistic regression framework generates daily snow cover maps that are spatially and temporally consistent, substantially reducing data gaps and improving the representation of intermittent and ephemeral snow zones, which are expected to become increasingly prevalent under future climate change. Model outputs were evaluated against independent ground-based observations, including snow pole measurements, telenivometer data, showing good agreement across elevation gradients and seasons. Together, these results demonstrate the potential of the proposed approach to capture fine-scale spatio-temporal variability in snow cover, providing a robust basis for catchment-scale analyses of snow–hydrology and snow–biogeochemistry interactions in high-mountain regions.

How to cite: Navarro Planes, M., Pons, X., and Gómez Gener, L.: Estimating daily high-resolution snow cover in the Central Pyrenees using logistic regression with Sentinel-2 and MODIS data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19704, https://doi.org/10.5194/egusphere-egu26-19704, 2026.

Snow albedo is a key control on surface energy balance in snow-covered environments, yet its estimation from multispectral satellite observations remains uncertain due to limited spectral resolution and spatial heterogeneity in snow reflectance. Thus, accurate surface albedo estimates over snow-covered landscapes are critical for the development of reliable satellite-based albedo products. However, validation data in snowy environments remains scarce, especially at high spatial resolution. This is problematic because within a single satellite scene, snow surfaces often exhibit substantial variability that challenges assumptions of spectral homogeneity of snowpack underlying many reflectance-to-albedo parameterizations.

We present a comparative framework that integrates hyperspectral Unmanned Aerial Vehicle (UAV) observations with multispectral satellite data to evaluate the limitations of derived snow albedo within the spectral configurations of Landsat 8, Landsat 9, and Sentinel 2. Our assessment extended across three distinct snowscapes: alpine, prairie, and taiga in Montana (USA), Montana, and Northern Finland; respectively. Our field-based approach employed two commercial hyperspectral sensors (Resonon Pika L and IR-L), to measure surface reflectance across the VIS–NIR–SWIR range (400-1700 nm; Landsat Bands 1-6; Sentinel 2 Bands 1-11) at high spectral (>250 bands) and spatial (0.3 m) resolution.

We isolated snow-only satellite scenes using a Convolutional Neural Network, enabling the identification of heterogeneous snow surfaces within each snowscape. Hyperspectral reflectance measurements were transformed into Landsat- and Sentinel-equivalent band reflectance using weighted sensor response functions, enabling direct band-wise comparison between hyperspectral and multispectral observations.

Our results highlight systematic discrepancies in Landsat reflectance: notably, strong overestimations in Bands 1, 2, and 5, and a consistent underestimation in Band 6 (SWIR1), with surface reflectance biases reaching up to 17%. The CNN-based classification highlighted the high spatial variability in snow reflectance, underscoring the limitations of assuming homogeneous conditions. These findings demonstrate the need to enhance validation strategies for snow-covered regions and provide a scalable protocol that integrates UAV-based acquisitions, high-resolution spectral measurements, and supervised scene analysis. This work contributes to improved characterization of snow albedo uncertainty and supports refinement of satellite-derived snow albedo products for cryospheric applications.

How to cite: Sproles, E. A., Fonseca-Gallardo, D., Hamp, S., Shaw, J. A., Wood, J., Hanula, H.-R., Pirazzini, R., and Logan, R. D.: Evaluating uncertainties in modeled snow reflectance using UAV-based hyperspectral imaging and multispectral remote sensing, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20414, https://doi.org/10.5194/egusphere-egu26-20414, 2026.

Snow Water Equivalent (SWE) is a critical parameter in the global and regional water cycle and climate system. However, accurately measuring SWE change using satellite remote sensing remains a challenge. While the Interferometric Synthetic Aperture Radar (InSAR) is a promising technique to retrieve SWE from space, its application has been constrained until recently by the lack of spaceborne observations combining optimal low-frequency (e.g., L-band) radar frequencies with short temporal baselines. Furthermore, interferometric coherence is a key factor that affects the accuracy of the unwrapped phase and the subsequent SWE retrieval. However, the repeat-pass InSAR coherence modelling over snow has not been sufficiently investigated.

Our study presents the first demonstration of SWE change retrieval using spaceborne repeat-pass L-band InSAR observations from the Chinese Lutan-1 mission. The study area focused on the Altay region in Xinjiang, China, during the winter of 2023–2024. Continuous interferometric pairs with 4/8-day temporal baselines are processed for phase changes and then estimate SWE variations. The retrieved SWE change shows a good agreement with in-situ SWE observations during the dry snow period (January 12 to February 9, 2024), with a Root Mean Square Error (RMSE) of 9 mm and a correlation coefficient (R) of 0.48 for the 4-day temporal baselines. However, a heavy snowfall event observed from February 9 to 17, 2024, induced severe decorrelation, leading to phase unwrapping errors that pose a challenge to SWE retrieval. To address the decorrelation mechanism of snow, the InSAR coherence model for snow is established based on the assumption of a bivariate Gaussian distribution for the ground and snow surface. The time-series modeled coherence shows a consistent trend with the observed Lutan-1 coherence, capturing effectively the decorrelation process caused by snowfall events and snow compaction processes. Furthermore, validation of the modeled coherence against Lutan-1 observations shows a strong agreement (R=0.87) over the entire study period from January 12 to March 28, 2024.

Overall, this study demonstrates the capability of spaceborne L-band InSAR with short revisit intervals to effectively retrieve SWE change under appropriate snow conditions. However, the retrieval accuracy is significantly constrained by severe decorrelation during heavy snowfall events. These results highlight both the potential and challenges of operational SWE monitoring from existing and upcoming L-band SAR missions such as Chinese Lutan-1, NASA’s NISAR, JAXA’s ALOS-4, and ESA’s ROSE-L, which are characterized by short repeat cycles, wide swath coverage, and high spatial resolution.

How to cite: Zhou, J., Lei, Y., Pan, J., Li, W., and Shi, J.: Snow Water Equivalent retrieval and InSAR Coherence modeling using L-band Lutan-1 data, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20729, https://doi.org/10.5194/egusphere-egu26-20729, 2026.

The seasonal dynamics of snow in Morocco's High Atlas Mountains play a crucial role in the region's water supply, particularly through snowmelt runoff and groundwater recharge in a semi-arid context. Snowmelt provides a significant amount of water to surface and groundwater reservoirs, especially during the summer when precipitation is very rare. However, monitoring snow cover and melt processes in this region remains difficult due to complex topography, high spatial variability, frequent cloud cover in winter, and limited in situ observations. To this end, in this study, we examine the synergistic use of optical and microwave satellite data to improve the monitoring of snow dynamics in the High Atlas.

Optical observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) provide high temporal resolution estimates of snow cover extent, but they are limited by cloud contamination and variable illumination conditions in mountainous terrain. To overcome these limitations, microwave observations from the Sentinel-1 and the Global Microwave Imager (GMI)/Tropical Microwave Imager (TMI) are integrated. The combined optical-microwave framework enables us to improve the temporal continuity and robustness of dynamic snow retrievals, allowing for better characterization of snow accumulation and melt phases across elevation gradients in the High Atlas Mountains, under both clear and cloudy conditions.

The results show that the multi-sensor approach significantly improved the temporal continuity and reliability of snow dynamics monitoring compared to single-sensor approaches. The integration of microwave data allowed for consistent identification of accumulation and melt events, particularly during cloudy periods when MODIS data are not available. In particular, it allowed for better detection of rapid snow events that are often missed by optical data alone and also reduced uncertainty in estimates of snow cover duration, which is essential for assessments of water availability in the High Atlas Mountains. Overall, the approach developed here offers significant potential for improving hydrological modeling and quantifying the contribution of snowmelt to water reservoir storage in semi-arid mountainous regions where data are scarce.

How to cite: Ouatiki, H., Miorqi, C., Lhimer, A., and Chehbouni, A.: Enhancing Snow Dynamics Monitoring in the Moroccan High Atlas Using Combined Optical and Microwave Satellite Observations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21369, https://doi.org/10.5194/egusphere-egu26-21369, 2026.

High-resolution 3D mapping of subterranean environments remains challenging due to their complex geometry, low-light conditions, and restricted accessibility. Among these environments, caves represent particularly demanding settings where detailed spatial documentation is essential for monitoring processes, supporting exploration and conservation efforts. Laser scanning has become a key technique for capturing accurate and detailed 3D representations of caves that form the basis for this heritage documentation and multidisciplinary research. Despite these advances, the creation of cave maps still commonly relies on traverse-line measurements and field sketches, later digitized using specialized cave-surveying software. In recent years, LiDAR data have been used for deriving the cave extent. While this method effectively captures the general geometry of cave passages, the delineation of cave-floor units, sediments, speleothems, rock blocks, and other features remains largely manual and relies heavily on the surveyor’s interpretation. As a result, feature boundaries vary between authors, and detailed cave-surface representation lacks reproducibility that is problematic for long-term documentation. In this study, we explore the use of deep-learning semantic segmentation for classifying selected cave-floor surface types based on geometric features derived from LiDAR data. Building on previous work focused on semi-automatic cave-map generation from LiDAR point clouds, we extend the workflow from deriving cave extent and floor morphology toward the automated interpretation of surface materials and forms. The method was tested on several common cave-floor surface types, including clastic sediments, flowstone, and bedrock, as well as artificial surfaces and objects typical in showcaves. The resulting classifications show that deep-learning models can distinguish surfaces with subtle geometric differences and produce consistent, reproducible delineations of units that are traditionally mapped by hand. Compared with manual digitization, the approach reduces subjectivity and provides a scalable way to generate polygonal layers used in speleocartographic workflows.

How to cite: Nováková, M., Šupinský, J., and Širotník, J.: Deep-learning classification of cave-floor surface types from LiDAR data for detailed cave mapping, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-807, https://doi.org/10.5194/egusphere-egu26-807, 2026.

Digital Elevation Models (DEMs) are fundamental to hydrological modelling, watershed delineation, flood hazard assessment, and resource management. However, the reliability of these applications depends heavily on the vertical accuracy of the DEMs. Although several global DEM products with 30-m spatial resolution are widely available, variations in sensor technology, data acquisition methods, and surface characteristics can significantly influence their accuracy and suitability for hydrological studies. This research provides a comparative evaluation of five commonly used global DEMs—TanDEM-X, ASTER GDEM, SRTM, Copernicus DEM, and ALOS World 3D—by assessing their vertical accuracy against high-resolution airborne LiDAR data and ICESat-2 ATL06 measurements. The findings aim to inform best practices for selecting DEMs in hydrological modelling and catchment-scale applications, particularly in data-scarce regions.

The Flinders River catchment in northern Queensland was selected as the critical test area for evaluating how DEM errors propagate into hydrological calculations. This region is characterised by low rainfall and pronounced topographic variability, encompassing flat lowland plains, dissected upland terrain, and localised areas of steep slopes. All DEMs were standardised to a common horizontal and vertical reference framework and co-registered with the test datasets to eliminate systematic discrepancies. ICESat-2 ATL06 data were rigorously filtered to retain only the highest-quality measurements, based on a combination of quality flags, topographic slope thresholds, and signal strength criteria in vegetated areas.

Elevation differences were computed at matched locations, and DEM performance was evaluated using key statistical metrics, including bias, root mean square error (RMSE), mean absolute error (MAE), median error, and standard deviation. To provide a more comprehensive assessment, error behaviour was analysed in relation to terrain slope and catchment characteristics, highlighting zones most vulnerable to error propagation in flow routing and watershed delineation. Systematic patterns in DEM error were further examined with respect to sensor characteristics under varying landscape conditions.

Results indicate that TanDEM-X and Copernicus DEM exhibit the highest vertical accuracy, closely aligning with ICESat-2 and LiDAR observations, whereas ASTER GDEM and SRTM show larger mean errors, particularly in dissected or mountainous terrain. These findings suggest that TanDEM-X and Copernicus DEM are preferable for hydrology-focused applications in semi-arid basins, while ASTER and SRTM should be used cautiously where precise modelling is required. The study underscores the importance of DEM accuracy evaluation in relation to basin characteristics, as errors can significantly influence hydrological modelling outcomes.

How to cite: Jafari, L., Jarihani, B., Koci, J., Sanislav, I., and Duce, S.: Comparative Analysis of 30-m DEM Products for Hydrological Applications: A Case Study in the Flinders Catchment Australia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1968, https://doi.org/10.5194/egusphere-egu26-1968, 2026.

Historical film-based images, acquired during aerial campaigns since the 1930s and from satellite platforms since the 1960s, provide a unique opportunity to document changes in the Earth’s surface over the 20th century. Yet, these data present significant and specific challenges, including complex distortions in the scanned image and poorly known exterior and/or interior camera orientation. In recent years, semi- or fully-automated approaches based on photogrammetric and computer vision methods have emerged (e.g., Knuth et al., 2023; Dehecq et al., 2020; Ghuffar et al., 2022), but their performance and limitations have not yet been evaluated in a consistent way.

The ongoing “Historical Images for Surface Topography Reconstruction Intercomparison eXperiment (Historix)” project aims at comparing existing methods for processing stereoscopic historical images and harmonizing processing tools.

Within this experiment, participants are provided with a set of historical images and available metadata and invited to return a point cloud and estimated camera parameters. We selected two study sites near Casa Grande, Arizona, and south Iceland, chosen for their  good availability of historical images and variety of terrain types. For each site, we selected 3 sets of film-based images acquired in the 1970s or 80s, overlapping in space and time: aerial images with fiducial marks from publicly available archives and 2 image sets from the American Hexagon (KH-9) reconnaissance satellite missions acquired by the mapping camera (KH-9 MC) and panoramic camera (KH-9 PC). The submitted elevation data will be cross-validated across different image sets and participant submissions, as well as against reference elevation data over stable terrain. The spread in the retrieved elevations will be analysed with respect to image type, terrain type and processing methods to highlight the strengths and limitations of the different approaches.

In this presentation, we will introduce the experiment design, the selected benchmark dataset, the current methodologies and the preliminary results of the intercomparison. Finally, we will present some of the open-source code that exist or are being developed to process historical images.

How to cite: Dehecq, A., Knuth, F., Belart, J., Piermattei, L., Ressl, C., McNabb, R., and Godin, L.: Historical Images for Surface Topography Reconstruction Intercomparison eXperiment (Historix), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3936, https://doi.org/10.5194/egusphere-egu26-3936, 2026.

The Antarctic Peninsula (AP) is a hotspot of global warming, with pronounced atmospheric warming reported during the 20th century. Although it is critical in terms of climate change studies, the mass balance of glaciers prior to 2000 remains poorly constrained. Existing mass balance estimates are further characterized by high uncertainties due to a lack of observations. In contrast, more than 30000 historical images in archives are the sole direct observations to quantify past glacial changes and their contribution to sea-level rise. 

In this study, we present a unique, timestamped, high-resolution Digital Elevation Model (DEM) and orthomosaic dataset, derived from aerial imagery that covers about 12000 km2 area on the western Antarctic Peninsula and surrounding islands between 66–68° S. We used a film-based aerial image archive from 1989 acquired by the Institut für Angewandte Geodäsie (IfAG), and is kept in the Archive for German Polar Research at the Alfred Wegener Institute, Germany, to generate the historical DEMs and orthoimages. The historical DEMs were co-registered to the Reference Elevation Model of Antarctica (REMA) mosaic on stable terrain. Our historical DEMs have vertical accuracies better than 6 m and 8 m with respect to modern elevation data, REMA, and ICESat-2, respectively. We have made this dataset publicly available at  https://doi.org/10.5281/zenodo.16836526.

Initial mass balance estimates from DEM differencing of our 1989 DEM with recent surfaces from REMA strip DEMs show a near-constant ice mass despite widespread glacier frontal retreat and thinning. We hypothesize that low-elevation ice thickness loss in this period is largely compensated by higher surface mass balance in higher areas. However, this regime appears to be changing, with glaciers transitioning toward increased dynamic activity with enhanced mass loss, and higher ice fluxes.

How to cite: Thota, V. K., Seehaus, T., Knuth, F., Dehecq, A., Salewski, C., Farías-Barahona, D., and H.Braun, M.: Historical aerial imagery–derived Digital Elevation Models and orthomosaics for glacier change assessment in the western Antarctic Peninsula since 1989, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4849, https://doi.org/10.5194/egusphere-egu26-4849, 2026.

Quantifying pebble size, shape, and roundness is fundamental to
understanding sediment transport and abrasion in fluvial systems, yet
remains challenging in natural, densely packed settings.  Most existing
approaches rely on 2D imagery and therefore fail to capture true
three-dimensional morphology. Here, we present a curvature-based instance
segmentation framework for reconstructed surface meshes and demonstrate its
role as a key step enabling 3D roundness and orientation analysis.

In our approach, individual pebbles are detected directly from 3D surface
reconstructions using curvature features, without prior shape assumptions.
Validation against high-resolution reference models yields a high detection
precision of 0.98, with remaining errors mainly due to under-segmentation
in overly smooth reconstructions.  Estimates of 3D pebble orientation are
strongly controlled by the represented surface area, highlighting both the
potential and current limitations of orientation retrieval from incomplete
surface segments.

We illustrate how reliable segmentation allow downstream 3D shape and
roundness analyses that are not accessible in 2D, including curvature-based
surface metrics and volumetric descriptors. Example fluvial scenes
demonstrate that segmentation quality directly controls the stability of
roundness estimates and their geomorphic interpretation. Our results
establish curvature-based 3D pebble segmentation as a methodological
foundation for reproducible analyses of pebble shape, roundness, and
orientation in natural river systems.

How to cite: Rheinwalt, A. and Bookhagen, B.: Curvature-based pebble segmentation as a foundation for 3D roundness and orientation analysis, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5922, https://doi.org/10.5194/egusphere-egu26-5922, 2026.

Currently available global Digital Elevation Model (DEM) surfaces are either derived from the stereoscopic exploitation of multispectral satellite imagery, point-wise laser altimetry measurements or the interferometric processing of bistatic synthetic aperture radar data, but only radar data allows the acquisition of a global product in a reasonable timeframe. The public private partnership of DLR and Airbus in the TanDEM-X mission paved the ground for the WorldDEM product line and its derivatives such as the Copernicus DEM. Both datasets are based on data acquisitions from December 2010 to January 2015, manual and semi-automated DEM editing procedures and represent a very accurate, very consistent and only pole-to-pole DEM data set. The Copernicus DEM is available with a free-and-open licence.

Various ecosystems such as the geosphere, biosphere, cryosphere and anthroposphere are subject to continuous changes which demand the monitoring of Earth’s topography in regular updates of global Digital Elevation Model data. The WorldDEM Neo product represents the successor of the aforementioned WorldDEM but is based on a fully-automated editing & production process and newer data: the on-going TanDEM-X mission is expected to operate until 2028 and has created an archive of up-to-date DEM scenes ready for integration into a new global DEM coverage (>90% of global landmass acquired between 2017 and 2021; ~60% of global landmass acquired again between 2021 and 2025). In conjunction with continuous improvements of the fully-automated production processes, a new global DEM coverage of WorldDEM Neo is produced early 2026. DEM applications such as the orthorectification of raw satellite imagery will benefit from the availability of an accurate and up-to-date global DEM dataset. Other applications such as multi-temporal 3D change analysis based on a single satellite mission (TanDEM-X) are possible and support the understanding of environmental changes thanks to the 3rd dimension. The rapid availability of the error-compensated WorldDEM Neo Digital Surface Model (DSM) and bare-ground Digital Terrain Model (DTM) after raw data acquisition serve various applications of global DEMs. Future acquisitions of the on-going TanDEM-X mission (until 2028) allow the processing of final and up-to-date DSM and DTM coverages at the end of the mission lifetime.

The presentation comprises a short look into the history with its manual & semi-automated DEM editing procedures. The main focus will be on the fully-automated production processes for truly global DSM & DTM coverages. Accuracy metrics, 3D change statistics between the different global coverages but also visual impressions of the various global DEM coverages will be addressed, too. On-going challenges with interferometry-based elevation data are part of an outlook and different error compensation strategies (e.g. height reconstruction from radar amplitude data based on machine-learning techniques) are highlighted.

How to cite: Fahrland, E. and Schrader, H.: Updating and upgrading a global Digital Elevation Model - the fully automated production of WorldDEM Neo with acquisitions until 2025, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6660, https://doi.org/10.5194/egusphere-egu26-6660, 2026.

Avalanches are critical contributors to the mass balance and spatial accumulation patterns of mountain glaciers. While gravitational snow redistribution models predict high localized accumulation, these predictions lack field validation due to the difficulty of monitoring highly dynamic avalanche cones. Here, we present two years of high-resolution monitoring of a large avalanche cone in the accumulation area of Argentière Glacier (French Alps). To capture these dynamics, we employed a multi-sensor approach: Uncrewed Aerial Vehicle (UAV) surveys and a time-lapse photogrammetry array consisting of 7 low-cost cameras deployed ~1 km away from the cone. The distance of the sensors from the surveyed area, its geometry (>30°), its surface characteristics (smooth snow surface) and the absence of fixed stable terrain due to the surrounding headwalls being episodically covered in snow made this environment particularly challenging for the photogrammetry methods applied. Point clouds and Digital Elevations Models were produced at a two-week resolution using Structure-from-Motion photogrammetry in Agisoft Metashape v1.8.3. with the alignment being constrained with Pseudo Ground Control Points. We could further co-register all point clouds to a September UAV acquisition with the Iterative Closest Point algorithm from the open-source project Py4dgeo, using automatically-derived stable ground from the RGB information of the images.

Methodological validation shows that while side-looking time-lapse photogrammetry captures the overall trend, it tends to underestimate elevation changes compared to UAV data, with biases up to 1.8 m and standard deviations of 2–6 m. Winter-time acquisitions with low light conditions over smooth snow surfaces also lead to reduced correlation over the cone. Despite these uncertainties, our results reveal extreme spatial variability in accumulation. The top of the cone is the most active zone, exhibiting elevation changes of ~30 m annually and a strong accumulation of 60 m w.e. between March 2023 and 2025 when accounting for the ice flow—roughly 15 times the annual mass balance recorded by the GLACIOCLIM program in the nearby accumulation area not affected by avalanche deposits. We identify a topographical threshold for snow storage: the upper cone fills early in the season until reaching a critical slope of ~35°, after which subsequent avalanches bypass the apex to deposit mass at the cone’s base. From May onwards, mass redistribution is further modulated by the development of surface channels. Our findings demonstrate that time-lapse photogrammetry is a viable tool for monitoring dynamic glacier surfaces and provide rare empirical evidence of the dominant role avalanches play in glacier mass budgets.

How to cite: Kneib, M., Wagnon, P., Arnaud, L., Balmas, L., Laarman, O., Jourdain, B., Dehecq, A., Le Meur, E., Brun, F., Kneib-Walter, A., Santin, I., Charrier, L., Faug, T., Mazzotti, G., Rabatel, A., Six, D., and Farinotti, D.: Use of time-lapse photogrammetry to capture substantial accumulation rates on an on-glacier avalanche deposit , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9007, https://doi.org/10.5194/egusphere-egu26-9007, 2026.

River bank erosion represents a dynamic geomorphic hazard, particularly in meandering channels where migration rates threaten critical infrastructure and agricultural land. While our previous work on the Sajó River (Hungary) established a novel, low-cost monitoring framework utilizing Raspberry Pi (RPi) cameras for near-continuous observation, the reliability of photogrammetric reconstruction under uncontrolled outdoor conditions remains a critical challenge. This study presents a systematic evaluation of the accuracy constraints inherent in automated Structure-from-Motion (SfM) processing pipelines, with a specific focus on optimizing image alignment across a wide range of scene conditions.

To determine the robustness of RPi imagery, we conducted a comprehensive sensitivity analysis of the SfM-based image alignment phase. We systematically tested over 120 variations of processing parameters, manipulating keypoint and tie-point limits, upscaling factors, and masking strategies. The implementation of rigorous masking was critical, as the imagery is geometrically challenging: the moving river surface in the foreground and the sky in the background occupy the majority of the field of view, leaving only a narrow, static fraction of the image relevant for reliable 3D reconstruction. These combinations were evaluated against a dataset representing the full range of environmental variability, including clear, cloudy, dark, foggy, overexposed, and rainy conditions, as well as distinct hydrological states such as low flows, flood events, and snow cover.

Preliminary results indicate that a specific balance of 30,000 keypoints and 5,000 tie points (ratio 6.0) optimizes reconstruction fidelity, achieving an RMS error of 0.75 pixels under clear weather conditions. Notably, the system demonstrated unexpected robustness in low-light scenarios, maintaining consistent error margins of 1.17–1.18 pixels across various configurations. Conversely, scaling up these limits beyond the optimum yielded diminishing returns, confirming that higher computational loads do not necessarily equate to improved geometric accuracy. Furthermore, we applied gradual selection algorithms to filter sparse point clouds, removing unreliable points based on reconstruction uncertainty to isolate the most geometrically valid features.

The crucial final phase of this research bridges the gap between digital reconstruction and physical reality. We validate the optimized SfM-based point clouds by comparing them directly against high-precision Terrestrial Laser Scanning (TLS) data acquired during two previous campaigns and upcoming field surveys. This multi-temporal comparison allows us to quantify specific error margins for volumetric and horizontal material displacement calculations. By defining these accuracy constraints, we establish a validated protocol for calculating erosion volumes during high-flow events, ensuring that automated, low-cost monitoring systems can provide actionable, high-precision data for river management even under adverse environmental conditions.

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The research was funded by the DAAD-2024-2025-000006 project-based research exchange program (DAAD, Tempus Public Foundation).

How to cite: Bertalan, L., Kovács, L., Duran Vergara, L. C., Abriha, D., Krüger, R., Blanch Gorriz, X., and Eltner, A.: Optimizing SfM workflows for continuous river bank monitoring: evaluating image alignment accuracies across diverse environmental conditions, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9167, https://doi.org/10.5194/egusphere-egu26-9167, 2026.

Long-term observations of glacier mass change provide a key indicator of atmospheric warming and are essential for understanding glacier behaviour and responses to climate forcing. Archived aerial photographs represent an underutilised source of historical information from which three-dimensional surface geometry can be reconstructed to quantify past glacier change. This approach is particularly valuable in Antarctica, where surface-elevation change prior to the 1990s remains poorly constrained due to limited pre-satellite altimetry and a scarcity of reliable Ground Control Points (GCPs). As a result, historic mass-balance estimates have largely relied on climate reanalysis and modelling.

Advances in photogrammetric techniques have substantially improved the efficiency and accuracy of Digital Elevation Models (DEMs) derived from historical aerial imagery. Here, we present a newly compiled inventory of Antarctic aerial surveys conducted throughout the twentieth century, documenting their spatial and temporal coverage to identify regions suitable for DEM reconstruction. Then, building on established workflows, we show newly constructed DEMs for three glaciers that formerly fed the Larsen A Ice Shelf on the Antarctic Peninsula, capturing surface geometry both before and after its collapse in 1995. These reconstructions reveal heterogenous glacier responses to reduced buttressing, controlled by local morphology and consistent with previous regional observations.

How to cite: Rowe, E., Willis, I., and Fenney, N.: Compiling an Inventory of Historic Antarctic Aerial Photographs to Measure Long-Term Glacial Mass Balance Change from Digital Elevation Models, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13015, https://doi.org/10.5194/egusphere-egu26-13015, 2026.

As part of the DFG research group “Sensitivity of high alpine geosystems to climate change since 1850” (SEHAG), high-resolution multibeam sonar data was collected from the proglacial Grastallake in the Ötztal valley during a boat survey in the summer of 2025. The Grastallake has an area of approximately 63,000 m², a maximum depth of approximately 16 m, and lies at an altitude of 2,584 m. The lake is situated in a former cirque, and its shores and the surrounding are partly composed of loose material and partly of solid rock. In the western part, there is a large whaleback with already known Egesen-moraines on top. On the southern and eastern shores, larger active debris flow cones are coupled to the lake, with meltwater runoff from the higher Grastalferner glacier flowing into the lake as a perennial stream via the eastern debris flow cone. Due to the permanent inflow from the glacier and the topographic conditions of the catchment area, the eastern debris flow cone is very active and has intensively been reshaped by several extreme debris flow events during the last years.

The bathymetric data was collected using a Norbit multibeam sonar (WBMS), which was supplemented by an SBG INS system (dual GNSS patch antenna system, SBG Eclipse D) by Kalmar Systems. Since the underwater topography of the lake was unknown and its high turbidity due to the glacier inflow, the first step was to conduct a rough survey of the lake. This step made it possible to create a coarse depth map on site in order to identify spots with shallow water, determine the system settings, and draw up a navigation plan along strips. After field work the recorded data was processed using Quinertia for trajectory calculation and Opals for strip adjustment. This resulted in a final 3D point cloud with an average point density of 400 points per square meter, which was converted to raster data in order to perform spatial analyses.

Using the data, geomorphological forms were mapped in a first step. In addition to a previously unknown late glacial moraine section, the underwater deposits of recent debris flows became visible. In addition to mapping, geomorphological structures were used for spatial analysis, such as comparing the depositions of debris flows above and below the water. Since the data is very well suited for mapping underwater structures, this case study demonstrates the enormous potential of bathymetric data acquired by multibeam sonar measurements, that has rarely been used for geomorphological studies to date. Multitemporal analysis in the sense of a 4D analysis could only be carried out to a limited extent in this case study. However, with the data now available, multitemporal analysis, i.e., quantification of sediment input into lakes, will also be possible in the future. This would then enable assessments to be made of the hazard potential of newly formed lakes in the proglacial area and of their lifespan. 

How to cite: Haas, F., Stark, M., Rom, J., Dammert, L., Kohlhage, T., Himmelstoss, T., Kara-Timmermann, D.-E., Altmann, M., Surrer, C., Baumgartner, K., Fischer, P., Betz-Nutz, S., Heckmann, T., Pfeifer, N., Mandlburger, G., and Becht, M.: Using high-resolution bathymetric data from a multibeam sonar acquisition to map and analyse geomorphical underwater structures in the proglacial Grastallake in the Horlachtal valley/ Ötztal Alps, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13875, https://doi.org/10.5194/egusphere-egu26-13875, 2026.

In recent years, forest management and inventory have increasingly relied on handheld personal laser scanners (H-PLS) for capturing flexible three-dimensional data. These systems have become essential for extracting critical tree attributes, such as diameter at breast height (DBH) and tree height. Most traditional H-PLS systems utilize Simultaneous Localization and Mapping (SLAM), which fuses LiDAR and Inertial Measurement Unit (IMU) data to reconstruct environments. However, SLAM is based on relative sensor measurements, which inherently causes accumulated errors and trajectory drift. In complex forest environments, similar-looking stems and moving vegetation can further confuse the mapping process, resulting in distorted point clouds or duplicated stems that reduce the accuracy of extracted tree attributes.

While Global Navigation Satellite System (GNSS)-based Real-Time Kinematic (RTK) positioning provides centimetre-level absolute accuracy and usually drift-free trajectories, its application in forestry is critically hindered by signal obstruction in dense canopies. The integration of GNSS-RTK and SLAM offers a robust and synergetic solution to these challenges, allowing one method to compensate for the failures of the other. A promising development in this field is an H-PLS system that integrates GNSS-RTK, IMU, LiDAR, and camera measurements to generate georeferenced point clouds directly in the field. This hybrid approach utilizes LiDAR and camera data to maintain positioning during GNSS outages and utilizes RTK information to re-initialize and correct the trajectory once the signal is restored.

Our study evaluates whether this integrated GNSS-RTK SLAM approach improves point cloud geometry and tree attribute extraction compared to traditional SLAM methods without GNSS integration. We conducted a field campaign in a mixed forest stand during the leaf-off period to simulate realistic operating conditions with alternating GNSS visibility. The performances of a SLAM-only and a SLAM + GNSS-RTK H-PLS were validated against highly accurate terrestrial laser scanning (TLS) reference data. The analysis involved tree segmentation to assess individual tree identification and the derivation of DBH, stem positions, and tree heights. Furthermore, we investigated internal geometric quality by analysing local noise levels using cross-sectional residuals relative to fitted circles and assessed spatial homogeneity to identify artifacts like duplicated stems or gaps.

Initial results indicate that the SLAM + GNSS-RTK H-PLS system provides DBH estimates comparable to TLS, with observed differences of 6.3 mm and 1.17 cm for major and minor axes, respectively. Despite slight overestimations due to scattering, the significantly reduced acquisition time makes this integrated system an efficient alternative for forestry applications. These findings contribute to a better understanding of how integrated positioning systems can enhance mobile laser scanning workflows and support the development of autonomous, high-precision forest mapping solutions.

How to cite: Rünger, C., Binapfl, S., Maiwald, F., Krüger, R., and Eltner, A.: High-precision point cloud generation for forest inventory: Integrating GNSS-RTK and SLAM for handheld laser scanning, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17031, https://doi.org/10.5194/egusphere-egu26-17031, 2026.

Many topographic scenes demonstrate complex dynamic behavior that is difficult to map and understand. A terrestrial laser scanner fixed on a permanent position can be used to monitor such scenes in an automated way with centimeter to decimeter quality at ranges of up to several kilometers. Laser scanners are active sensors, and can continue operation during night. Their independence from surface texture properties ensures in principle that they provide stable range measurements for varying surface conditions.

Recent years have seen an increase in the employment of such systems for different applications in environmental geosciences, including forestry, glaciology and geomorphology. This employment resulted in a new type of 4D topographic data sets (3D point clouds + time) with a significant temporal dimension, as such systems can acquire thousands of consecutive epochs.

However, extracting information from these 4D data sets turns out to be challenging, first, because of insufficient knowledge on error budget and correlations, and second, because of lack of algorithms, benchmarks, and best-practice workflows.

The presentation will showcase recently active systems that monitored a forest, a glacier, an active rockfall site and a sandy beach respectively. Data from these systems will be used to illustrate different systematic challenges that include instabilities of the sensor system, meteorological and atmospheric influence on the data product and the maybe surprising need for alignment of point clouds from different epochs.

In addition, different ways to extract information from these 4D data sets will be discussed, in connection with particular applications. While bi-temporal change detection is often a starting point for exploring 4D data, several methods are being developed that truly exploit the extensive time dimension, including tracking, trend analysis, time series clustering and spatio-temporal region growing.

Lessons learned from experiences with these systems in different domains lead to several recommendations for future employment considering field of view design, auxiliary sensors (e.g. IMU, camera, weather station) and the possible deployment of low-cost alternatives, thereby providing a view on the near future of permanent laser scanning.

Reference

Lindenbergh, R., Anders, K., Campos, M., Czerwonka-Schröder, D., Höfle, B., Kuschnerus, M., Puttonen, E., Prinz, R., Rutzinger, M., Voordendag, A & Vos, S. (2025). Permanent terrestrial laser scanning for near-continuous environmental observations: Systems, methods, challenges and applications. ISPRS Open Journal of Photogrammetry and Remote Sensing, 17, 100094. DOI: 10.1016/j.ophoto.2025.100094

How to cite: Lindenbergh, R., Vos, S., and Hulskemper, D.: Permanent terrestrial laser scanning for environmental monitoring, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17484, https://doi.org/10.5194/egusphere-egu26-17484, 2026.

Beachrocks are cemented coastal deposits formed within the intertidal zone by the precipitation of magnesium-rich calcium carbonate. They constitute important paleogeographic and paleoclimatic markers, as they allow the reconstruction of past shoreline evolution. In addition, beachrocks influence current coastal dynamics and represent valuable geological heritage and ecological reservoirs that require preservation.

This study focuses on a sequence of multiple beachrock levels located along the Catalan Coast (NE Iberian Peninsula). The system consists of a complex sequence of submerged beachrocks with a wide formation range, situated at water depths between −0.25 m and −48 m below the current sea level. These deposits exhibit lateral continuity of up to 4.5 km and are characterized by reduced thicknesses and low geomorphic expression. The underlying substrate is composed of unconsolidated marine sediments. In certain sectors, a spatial overlap with Posidonia oceanica meadows occurs.

The aforementioned characteristics hinder their cartographic representation using traditional methods, such as aerial image interpretation and hillshade maps derived from bathymetric data, particularly for thin structures located at greater depths and in areas where Posidonia oceanica meadows are present.

The aim of this study is to evaluate the usefulness of the Red Relief Image Map (RRIM) method as an alternative quantitative terrain visualization tool for the cartography of submerged beachrocks. This method is based on the quantitative attribute openness, which expresses the degree of dominance or enclosure of a location on an irregular surface and enhances concave (negative openness) and convex (positive openness) features. Using this attribute, the RRIM method combines three main elements: topographic slope, positive openness and negative openness, allowing the visualization of subtle, low-relief topographic structures on apparently flat surfaces.

Using this approach, this study aims to improve the identification and cartographic delineation of submerged beachrock levels and to define optimal visualization parameters that contribute to a better understanding of the beachrock sequence.

How to cite: Vicente, M.-A., Mencos, J., and Roqué, C.: Testing the Red Relief Image Maps methodology to enhance the beachrock cartography in Torredembarra coast (Catalan coast, West  Mediterranean Sea), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17571, https://doi.org/10.5194/egusphere-egu26-17571, 2026.

How to cite: Kugler, L., Rada, C., Webster, C., Wegner, J. D., Berthier, E., and Piermattei, L.: Long-term glacier elevation change at Gran Campo Nevado since 1945 , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17927, https://doi.org/10.5194/egusphere-egu26-17927, 2026.

Badlands are among the most rapidly developing landscapes and exhibit a significant degree of geomorphological activity. In semi-arid/ sub-humid landscapes, specific precipitation dynamics result in particularly rapid geomorphological development. This applies in particular to land cover and geomorphology. This study employs quantitative, multi-temporal analysis to examine the spatio-temporal changes in a sub-humid calanchi badland in the upper Val d'Orcia (Italy) over a period of ten years (2014-2024). Particular emphasis lies on the dynamics of geomorphological processes and topographical changes, while considering the variables of vegetation and precipitation. The analysis encompasses both extreme events and prolonged rainfall lasting several days, which are the primary factors for surface changes in subhumid badlands. The utilisation of UAS SfM-MVS in conjunction with precise dGNSS measurements facilitates high-resolution change detection and landform analysis across five distinct observation periods, each spanning two years (= five DoD). The interactions between vegetation and geomorphological processes are investigated using a semi-automatic mapping approach based on the Triangular Greenness Index (TGI) and the interpretation of topographical changes (DoD). The vegetation analysis are based on high-resolution orthomosaics with a resolution of 0.05 m, while the geomorphic change detection analysis is carried out on 2.5D rasterised digital surface models with a resolution of 0.25 m. The major results are as follows: The mean slope gradient of the entire study site remained largely stable despite certain areas showing enhanced geomorphic activity. The DoD analysis revealed four 'geomorphic hot spots', areas of enhanced geomorphic activity and sediment contribution from the tributaries to the main valley (the major deposition area). The annual erosion rates vary between -0.4 cm (2018-2022) and -4 cm (2022-2024). The observed topographic changes can be attributed primarily to high-magnitude events (complex landslides and debris-like flows) that occur irregularly. The multi-temporal mapping of landforms has revealed a significant reduction in water erosion, with a 50% decrease observed from 35% in 2014 to 17% in 2024. Furthermore, the combination of 2D-mappings and 2.5D DoD-analysis enabled the documentation of a geomorphological process previously unknown in badland areas, namely gravitational bulging. This describes the deformation of sediments in lower-lying clay layers as a response to water infiltration, high swelling capacities of clays and the pressure exerted by the sediment packages lying above them. A significant increase in vegetation cover has been observed, particularly in areas designated as potentially moist and gentle terrain, often the deposition areas from the previous period. In general, vegetation underwent a gradual transition, evolving from a fragmented to a continuous structure, primarily due to the widespread colonisation of the main valley and the landslide pathways.  Although the area affected by erosion processes decreased over the course of the study period, erosion rates remained relatively constant. This indicates a shift from high-frequency to high-magnitude processes in the most recent observation period. Overall, the phase under consideration in this study (2014-2024) can be characterised as a phase of badland stabilisation.

How to cite: Stark, M., Sannino, A., Trappe, M., Rom, J., Forster, J., Kahlenberg, G., Haas, F., and Vergari, F.: From badland to bushland? Analysis of geomorphic process dynamics and vegetation development in a sub-humid calanchi area based on high-resolution UAS data (2014-2024)., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18399, https://doi.org/10.5194/egusphere-egu26-18399, 2026.

The recovery of historical topography from analogue aerial archives has has become a well-established workflow in geosciences, unlocking high-resolution records of topographic change that were previously inaccessible. However, the standard practice for sharing these results relies on static FTP servers or raw file downloads. Consequently, these datasets often remain difficult to discover, particularly for researchers from other disciplines who cannot easily assess the spatial coverage or relevance of the archive through static file lists. Furthermore, existing web-based visualization solutions often require complex database configurations and advanced full-stack development skills, rendering them inaccessible for many geoscience research groups lacking dedicated software engineers.

In this work, we present a lightweight, open-source web application designed to support the publication of historical photogrammetric data. The design prioritizes portability and ease of deployment for non-developers. Unlike complex Content Management Systems (CMS) that rely on heavy database backends, our tool utilizes a streamlined file-based ingestion pipeline. Researchers can deploy a fully interactive instance by populating a directory structure with standard geospatial vector formats (e.g., Shapefiles, GeoJSON) and point cloud data. The Node.js-based backend automatically parses these inputs to configure the visualization interface, thereby eliminating the need for manual database administration.

We demonstrate the capabilities of the website using a dataset from the Antarctic TMA archive with ~ 250.000 images. The resulting interface facilitates spatio-temporal discovery through an interactive map that visualizes survey footprints, including the residuals between metadata-derived and SfM-estimated positions. This allows users to rapidly assess geometric quality and survey coverage. To extend the platform beyond simple 2D mapping, we present the architectural integration of Potree for browser-based 3D visualization. We discuss the workflow for streaming massive point clouds to the client, a feature designed to transform the website from a passive gallery into an active analytical tool for measurement and validation. Finally, we address the challenge of data distribution by outlining the implementation of a bulk-download utility, structured to allow users to filter and request specific subsets of raw imagery, associated metadata and processed data based on their visual selection.

By providing a self-contained, low-dependency solution, we aim to shift the community standard from static archiving to dynamic, interactive exploration. This tool allows geoscientists to easily share their historical images and reconstructions and make their data truly accessible to the broader scientific community without the overhead of custom software development.

How to cite: Dahle, F., Lindenbergh, R., and Wouters, B.: From Static to Dynamic: Modernizing the Sharing of HistoricalPhotogrammetry Datasets, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19445, https://doi.org/10.5194/egusphere-egu26-19445, 2026.

Desert kites are large prehistoric hunting traps typically composed of two long, low stone walls that converge toward an enclosure.  These structures are widely distributed across the arid and semi-arid margins of the Middle East and Central Asia, exhibiting substantial variability in size, geometry, construction techniques, and topographic setting. To better understand their functionality from the Neolithic to sub-contemporaneous times, terrestrial laser scanning has increasingly been used to capture high-resolution three-dimensional representations of desert kites, enabling detailed characterization of their construction and local terrain setting. However, the kites’ subtle expression, their large spatial extent, and their progressive blending into the natural surface complicate their detection. These difficulties are further exacerbated by variable point density resulting from the alignment of multiple terrestrial scans, unavoidable occlusions caused by topography or vegetation, and the sheer volume of data produced by high-resolution ground-based surveys.  Together, these factors make the reliable identification and analysis of desert kite features within raw terrestrial point clouds a challenge, which requires extensive manual intervention and expert interpretation.

In this study, I present an automated, machine-learning-based approach for highlighting desert kite features directly within 3D point clouds derived from terrestrial laser scanning, without the need for manual annotation or labelled training data. The proposed method is based on the premise that the kites' structures introduce geometric irregularities (anomalies) relative to the surrounding natural surface. Rather than explicitly modelling the kite's form  or imposing predefined shape descriptors, the method learns a representation of the underlying terrain surface directly from the point cloud. This learned representation is then used to reconstruct the surface, which is subsequently compared to the original terrestrial measurements. Local deviations between the reconstructed surface and the original point cloud are quantified, with larger reconstruction errors interpreted as potential surface anomalies indicative of the kite's features. 

The proposed workflow is fully data-driven and unsupervised. It does not rely on prior knowledge of kite geometry, site-specific heuristics, or expert-defined thresholds. Instead, the learning process adapts to the local surface characteristics captured in the input dataset, making it robust to variations in resolution, occlusions, and terrain complexity commonly encountered in terrestrial laser scanning surveys. 

The findings demonstrate that surface-reconstruction-based anomaly detection offers a promising pathway for the automated identification of desert kite features in terrestrial 3D point clouds. More broadly, the approach is applicable to archaeological structures that exhibit weak or subtle geometric signatures. By reducing dependence on manual interpretation and labelled datasets, the method supports more objective, scalable, and reproducible analyses of archaeological landscapes, particularly in complex terrain where anthropogenic features are embedded within natural surfaces.

How to cite: Arav, R.: Detecting desert kites in 3D point clouds by learning anomalies, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20499, https://doi.org/10.5194/egusphere-egu26-20499, 2026.

Despite significant advancements in landslide monitoring, landslides occurring on densely forested slopes remain largely unexplored. While conventional subsurface characterization methods (e.g., DPH, CPT, percussion drilling) are often impractical due to limited accessibility and steep rugged terrain, surficial analyses using remote sensing techniques frequently face challenges in capturing high-resolution ground surface data due to occlusion caused by dense vegetation cover as well as technical limitations.
Although trees and forests are generally acknowledged to reduce the probability of landslide occurrence, they are unlikely to prevent or substantially mitigate deep-seated landslides or failures on very steep slopes. Instead, trees may serve as proxies of landslide activity, potentially improving the understanding and monitoring of densely forested slopes. Affected by slope movements, trees experience external growth disturbances and develop characteristic growth anomalies that can be partly attributed to underlying landslide processes.

Multiple studies have demonstrated the feasibility of extracting such external growth disturbances, primarily stem tilting, by assessing the inclination and curvature of tree stems in LiDAR point clouds, greatly building upon previous forestry-related studies exploring the mapping, classification, and derivation of stem parameters such as height and diameter from digital twins. However, the potential to extract externally visible eccentric growth patterns in stem cross-sections at heights of maximum bending, analogous to dendrogeomorphologic tree-ring analyses, as a proxy for landslide activity has not yet been explored. Additionally, the classification of overall tree shape may provide valuable insights into the characteristics of underlying slope movements, but, to the best of the author’s knowledge, this has not been addressed in previous research.

To investigate the potential of automatically extracting tree shape and stem eccentricity from LiDAR data, and to evaluate their suitability as proxies of landslide activity, we introduce an improved two-stage processing pipeline for tree identification and extraction, along with a dedicated framework for digital dendrogeomorphology. Building upon previous work, we compute normal vectors of locally fitted planes and projected point densities to separate trees from the point cloud. To enhance the extraction of complex shaped trees (e.g., S-shaped or pistol-butted) characteristic of landslide-prone slopes, we introduce dynamically adjusted normal vector thresholds derived from estimated stem inclination. After segmenting tree stems from the point cloud, ellipses are fitted at configurable height intervals to determine cross-section centroids. These centroids are then connected as vertices of a 3D polyline, which is subsequently smoothed using a natural spline to represent the generalized stem geometry. Based on the curvature of the resulting polyline, the height of maximum bending is identified, and the corresponding cross-section eccentricity is extracted. In addition, the curvature of the polyline is used to categorically classify overall tree shape.

Our digital dendrogeomorphology approach applied to 3D point clouds enables accurate extraction of stem eccentricity, even for complex tree shapes typical of landslide-prone slopes. When paired with automated tree-shape classification, these data offer insights into slope movement and improve understanding of landslide processes in densely forested environments.

How to cite: Kamaryt, T.-H. and Müller, B.: Tree Geometry as a Potential Proxy for Landslide Activity in Densely Forested Slopes: A LiDAR-Based Digital Dendrogeomorphology Approach, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21238, https://doi.org/10.5194/egusphere-egu26-21238, 2026.

Large-scale infrastructure development in mountain regions produces significant changes in slope morphology and surface processes. However, stability assessments conducted after construction often rely on static or short-duration evaluations. These approaches tend to assume an immediate geomorphic adjustment to human disturbance, which can overlook delayed and nonlinear responses of hillslopes. This study examines terrain adjustments that occur with a time delay following major construction activities in complex mountainous settings. The analysis is based on a series of high-resolution topographic datasets obtained through repeated LiDAR surveys along the Sibiu - Pitești motorway corridor in the Southern Carpathians of Romania. Changes in terrain configuration caused by excavation, filling, drainage alteration, and the unloading of slopes are identified by comparing elevation models and terrain metrics. Instead of focusing solely on deformation located at the site of intervention, the study investigates terrain responses that appear later and in areas situated upslope or laterally from the engineered zones. Findings show that slope instability and surface reorganization often emerge after a measurable time delay, typically reactivating existing geomorphic features such as drainage pathways, slope breaks, and erosional forms. These responses are not random but show a strong dependence on prior landscape conditions and the type of construction-related disturbance. The results emphasize the limitations of early assessments performed shortly after construction, which may fail to capture landscape dynamics relevant for landslide initiation. The study demonstrates the usefulness of repeated LiDAR mapping for detecting evolving terrain responses in engineered mountain landscapes and supports the integration of time-sensitive processes into hazard assessment strategies.

How to cite: Al-Taha, W., Andra-Topârceanu, A., and Mustățea, S.: Delayed slope response to infrastructure-induced landscape modifications in mountainous terrain revealed by high-resolution LiDAR analysis, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21758, https://doi.org/10.5194/egusphere-egu26-21758, 2026.

As glaciers retreat, permafrost degrades, and mountains destabilize, modern landscape evolution is increasing the potential for catastrophic events, such as the Birch Glacier collapse on May 28, 2025. To improve our understanding of mass movements in mountainous regions and support future hazard assessment and risk mitigation efforts, we are generating time series of glacier surface elevation change from historical aerial photography provided by the Swiss Federal Office of Topography (Swisstopo). 

In this case study, we leveraged multi-temporal photogrammetric reconstruction and Digital Elevation Model (DEM) coregistration techniques, implemented in the Historical Structure from Motion (HSfM) pipeline, to generate an ~80-year record of self-consistent DEMs and orthoimage mosaics from analog film imagery collected over the Birch Glacier between 1946 and 2010. From 1985 until 2010 we generated nearly annual surface measurements, making this a unique and remarkably dense historical time series. The time series is augmented with modern surface measurements generated from linescan and UAV imagery collected during the period of 2010 to 2025. To quantify the uncertainty of elevation change measurements we compute residuals with respect to the swissSURFACE3D elevation over stable ground, defined by the swissTLM3D land surface classification. The reconstructed time series provides geometric constraints to precisely model the preconditioning phase leading up to the May 2025 Nesthorn-Birchglacier hazard cascade, which may help mitigate future risks in mountainous terrain (see Jacquemart et al. 2026 in GM3.1)

How to cite: Knuth, F., Hodel, E., Heisig, H., Marty, M., Jacquemart, M., Bauder, A., Simmen, J.-L., and Farinotti, D.: Automated photogrammetric reconstruction of Birch Glacier, Switzerland (1946–2025): A high-density time series of topographic change preceding catastrophic glacier collapse, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22072, https://doi.org/10.5194/egusphere-egu26-22072, 2026.

The Southern Alps of New Zealand are regarded as an important key site for studying Holocene glacier chronologies in the mid-latitudinal southern hemisphere. Consequently, most global reviews of the topic include respective records and utilise them for (intra-)hemispheric correlations and palaeoclimatic analyses. These particular approaches are, however, closely connected to three common paradigms: (i) There is a representative and reliable compilation of glacier records for the entire Southern Alps, (ii) the European Alps are a well-suited and appropriate northern hemispheric glacier region for any comparative purpose, and (iii) air temperatures are the sole relevant driver of glacier variability in New Zealand.

In a recent study ¹⁰Be cosmogenic radionuclide dating (CRN) and Schmidt-hammer exposure-age dating (SHD) were applied to extent the regional database and obtain surface-exposure ages from moraines on Holocene glacier forelands in eastern Aoraki/Mt.Cook National Park, Arrowsmith Range, and Liebig Range. Re-calculated published ¹⁰Be CRN age data were, alongside previously obtained results from both central Aoraki/Mt.Cook and Westland/Tai Poutini National Parks, utilised for a comparative chronological analysis. Unlike previous approaches glacier records were differentiated by sub-regions of the Southern Alps and interpreted accordingly. Neither amalgamation of individual glacier records nor non-differentiated compilation took place. This multi-proxy approach was combined with detailed geomorphological mapping and assessment to tackle the regionally specific 'geomorphological uncertainty' potentially interfering with all subsequent interpretation of chronological data.

Chronological analysis and subsequent palaeoclimatic interpretation worked well if they were restricted to sub-regional levels. In the Arrowsmith Range strong glacial activity and multiple advances during the Early Holocene could be confirmed, with a similar pattern likely for the Liebig Range. A correspondence to frequent Early Holocene cold periods indicated by rock glacier activity in the Ben Ohau Range is obvious. But in contrast to these drier eastern sub-regions no evidence for Early Holocene advances exists for central and western sub-regions. At Classen Glacier in eastern Aoraki/Mt.Cook National Park, geomorphologically reliable morainic evidence shows a significant Mid-Holocene advance at c. 5.4 ka. It is possibly corresponding to evidence from Mueller and Tasman Glaciers. This advance coincides with an intensification of westerly airflow established around that time. Together with a 'Little Ice Age'-maximum during the mid-/late 18th century CE in Aoraki/Mt.Cook National Park and recent advances at the end of the 20th century it also indicates that (seasonal) atmospheric circulation patterns, in particular the intensity of westerly airflow, and precipitation should not be ignored as climatic factors influencing glacier variability. Finally, with its pronounced West-East precipitation gradient potentially responsible for different sub-regional glacier records, the Southern Alps share several glaciologically relevant climatic conditions with the maritime Scandinavian Mountains, but hardly with the generally drier European Alps.

Further refinement of the Holocene glacier history for the Southern Alps constitutes a significant challenge. It requires a more detailed understanding of both the variability of individual glacier records and the need for spatial differentiation before attempting to compile a representative Holocene glacier chronology for the entire Southern Alps. Furthermore, certain common paradigms need to be critically reviewed and re-considered. 

How to cite: Winkler, S.: Re-visiting New Zealand's Holocene glacier chronology - Time to overcome certain paradigms and consider spatial differentiation?, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1403, https://doi.org/10.5194/egusphere-egu26-1403, 2026.

During the last Pleistocene glacial cycle, Taiwan's high mountain ranges were glaciated in the uppermost altitudinal zone with a calculated lowering of the equilibrium line altitude (ELA) of ca. 1500 m down to 2800 m (Hebenstreit et al. 2025). Glacial erosion of the upper valley reaches formed trough-valleys. Lateral and terminal moraines as well as outwash deposits were deposited at or near the ice margins, respectively, at different stages of the glaciation. Subsequently, slope processes and fluvial activity have been reworking those sediments and reshaping those landforms during and after the glaciation to adjust the relief gradually to its present shape. These processes are called paraglacial processes (Ballantyne 2002).

In the Hsueh Shan range, we mapped a sequence of terraces composed of cobbles and boulders at the confluence of the Taoshan river and the Chijiawan river at an altitude of ca. 1900 m, which corresponds with the assumed lowest altitude of the last-glacial glacier termini. Surface exposure dating with paired in-situ produced terrestrial cosmogenic nuclides (TCN) of meter-sized boulders on the terrace surfaces gives evidence of enhanced glacio-fluvial activity, presumably reworking glacial deposits during the last phase of the glaciation at the Pleistocene-Holocene transition. 

Lowering of the altitudinal zones and consequently of surface processes during glacial times entails periglacial processes on slopes not affected by glacial or fluvial processes (Böse 2006). This includes frost weathering and solifluction. The periglacial zone is presently restricted to altitudes above 3500 m in Taiwan.

A sediment profile at ca. 2050 m on the slope above the glacio-fluvial terraces shows a stratification typical for cover beds in mountainous periglacial environments (Kleber & Terhorst 2024): Above debris of local underlying bedrock follow layers enriched by aeolian dust. The sediment has been partly reworked and mixed by solifluction. Optically stimulated luminescence (OSL) ages of the silty matrix confirm its formation during the last glacial cycle; and a lowering of the periglacial altitudinal zone of 1500 m can be inferred.

References

Ballantyne, C. K., 2002: Paraglacial geomorphology. Quaternary Science Reviews

21 (18–19), 1935-2017.

Böse, M., 2006: Geomorphic altitudinal zonation of the high mountains of Taiwan. Quaternary International 147 (1), 55-61.

Hebenstreit, R., Hardt, J., Böse, M., 2025: The lowermost last‐glacial equilibrium line altitude in the Taiwanese Central Mountain Range and its implications for the palaeoclimate and the tropospheric moisture transport in East Asia. Journal of Quaternary Science 40 (5), 831-846.

Kleber, A., Terhorst, B. (eds.) 2024: Mid-Latitude Slope Deposits (Cover Beds)

2nd Edition. Elsevier Science

How to cite: Böse, M. and Hebenstreit, R.: Late Quaternary paraglacial and periglacial deposits in the high mountains of Taiwan, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2778, https://doi.org/10.5194/egusphere-egu26-2778, 2026.

Despite several studies (Coutterand, 2010 and references theirin) over the past decades, the chronology of glaciers advance and expansion at the Last Glacial Maximum (LGM) and subsequent retreat during the Lateglacial period in the northern French Alps remains poorly constraint, as data are still too scarce and sometimes contradictory. In this area, the interactions between major glaciers, such as the Rhône and Arve glaciers in the north and Isère glacier in the south, represent major challenges for reconstructing post-LGM glacial dynamics. Here, we present a new framework for understanding Lateglacial glacial dynamics in the Arve Valley, integrating 18 new ¹⁰Be exposure ages from glacially-transported boulders, with revised geomorphological mapping based on LiDAR-derived DEMs.

Our results indicate that the deglaciation of the Arve Valley initiated with a phase of glacial thinning around 17.6 ka BP. The Arve glacier subsequently thinned progressively but persisted in the downstream sector of the valley until the end of a readvance phase at 15.9 ka BP. Then, the glacier retreated by over 30 km within 300 years, before withdrawing toward the Mont-Blanc massif ahead of the Younger Dryas readvance.

These findings are integrated with previous studies (Wirsig et al., 2016; Roattino et al., 2022; Serra et al., 2022) conducted in the Northwestern Alps, including the Lyon piedmont lobe and the Mont-Blanc massif area, to propose a regionally consistent deglaciation scenario. To further refine our understanding, we confront ¹⁰Be exposure ages with numerical simulations using the Instructed Glacier Model (IGM, Leger et al., 2025). A dual approach enables a critically assessment of both methods: calibration of exposure ages corrections (e.g., erosion rates, snow shielding) using a model run, and inversely, using calculated exposure ages to constrain the resulting model. This will enable us to analyse possible deglaciation rates and spatial patterns in the Northwestern Alps, as well as the influence of key parameters such as geography, topography, and climate.

Coutterand, S. 2010: Etude géomorphologique des flux glaciaires dans les Alpes nord-occidentales au Pléistocène récent : du maximum de la dernière glaciation aux premières étapes de la déglaciation. PhD thesis. Université Savoie Mont-Blanc.

Leger, T. P. M., Jouvet, G., Kamleitner, S., Mey, J., Herman, F., Finley, B. D., Ivy-Ochs, S., Vieli, A., Henz, A. & Nussbaumer, S. U. 2025: A data-consistent model of the last glaciation in the Alps achieved with physics-driven AI. Nature Communications 16, 848. https://doi.org/10.1038/s41467-025-56168-3.

Roattino, T., Crouzet, C., Vassallo, R., Buoncristiani, J.-F., Carcaillet, J., Gribenski, N. & Valla, P. G. 2022: Paleogeographical reconstruction of the western French Alps foreland during the last glacial maximum using cosmogenic exposure dating. Quaternary Research 111, 68–83. https://doi.org/10.1017/qua.2022.25.

Serra, E., Valla, P. G., Gribenski, N., Carcaillet, J. & Deline, P. 2022: Post-LGM glacial and geomorphic evolution of the Dora Baltea valley (western Italian Alps). Quaternary Science Reviews 282, 107446. https://doi.org/10.1016/j.quascirev.2022.107446.

Wirsig, C., Zasadni, J., Christl, M., Akçar, N. & Ivy-Ochs, S. 2016: Dating the onset of LGM ice surface lowering in the High Alps. Quaternary Science Reviews 143, 37–50. https://doi.org/10.1016/j.quascirev.2016.05.001.

How to cite: Portal, Q., Crouzet, C., Buoncristiani, J.-F., Leger, T., Jouvet, G., and Carcaillet, J.: Lateglacial glaciers dynamics in the Mont Blanc foreland (Northern French Alps): new chronological and geomorphological constraints, with model-data coupling in the Arve Valley, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5367, https://doi.org/10.5194/egusphere-egu26-5367, 2026.

During the Last Glacial Maximum (LGM), many glaciers in the Eastern Alps terminated in narrow inneralpine valleys resulting in a limited amount of datable landforms. At the former Enns and Mur Glaciers, boulders, at or close to laterofrontal moraine ridges were dated with cosmogenic ¹⁰Be. Boulders at the Mur Glacier are composed of weathering-resistant pegmatite gneiss, whereas quartzbreccia/greywacke was the only suitable boulder lithology in the Enns Glacier region. This lithology consists of large quartz components within a fine matrix and is more easily affected by weathering. Ages inferred from ¹⁰Be concentrations in pegmatite gneisses (Mur Glacier) are around 20 ka, in accordance with other ages around the Alps. In contrast, Enns Glacier boulders yielded surprisingly young ages between 14-17 ka. In order to obtain plausible LGM ages via erosion corrections from the ¹⁰Be concentrations, a 30 cm thick surface layer would need to be removed (if the boulder was at the surface since deposition). In order to understand, if such a large amount of material can be removed from the quartzbreccia, we applied freeze-thaw cycle experiments to both lithologies. For the experiment, we produced four cubes, roughly 2x2x4 cm in size, three of quartzbreccia and one of pegmatite gneiss. Each of the quartzbreccia cubes has a different thickness of weathering crust (0-4 cm) with abundant holes and cracks. Their mineralogical composition is quartz, carbonate, and phyllosilicates with a preferential orientation. All cubes were dried, weighted and their volume determined and afterwards they were subjected to over 100 freeze-thaw cycles. To simulate moisture and rain, the cubes were thawed in a water bath at a constant temperature of 20 °C.  All cubes were photodocumented before the test, roughly every three weeks over a 4 months period, and after the test. CT scans were made of one quartzbreccia cube before and after the test to better visualise structural changes within the cube. The freeze-thaw cycles show that the quartzbreccia cubes weather much more intense than the pegmatite gneiss. No visual changes were detected in the latter, whereas quartzbreccia cubes constantly changed. Water seems to enter the cubes following pathways along the aligned sheet silicates. These delicate minerals are then destroyed and once enough matrix is removed, larger quartz crystals fall out, which is nicely seen on the photos. Overall, this process seems to result in a rather continuous loss of material, but varies in different cubes and even on different planes of the cubes. As a result, cosmogenic ¹⁰Be is removed constantly. Additionally, the nature of discontinuous weathering results in an inhomogeneous ¹⁰Be production due to edge effects resulting in loss of ¹⁰Be at the rim of a raised quartz pebble. In summary, the freeze-thaw cycles show that the quartzbreccia weathers much faster than the pegmatite gneiss and therefore the age difference could at least partly be explained. Therefore, caution is required when dating conglomerates, breccias or similar lithologies with cosmogenic ¹⁰Be.

How to cite: Griesmeier, G. E. U., Hausenberger, A., Nacu, C., Reitner, J. M., Braumann, S., Neuhuber, S., and Le Heron, D. P.: Freeze-thaw cycles investigate weathering properties of different lithologies used in 10Be exposure age dating in the Eastern Alps, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5511, https://doi.org/10.5194/egusphere-egu26-5511, 2026.

A detailed morphometric and modelling-based analysis was conducted on 197 palaeocirques across the western Putorana Plateau, Central Siberia, to refine reconstructions of mountain glacier extent and associated palaeoclimatic conditions during the last major phase of glaciation. Previous work in the region quantified cirque geometry and inferred palaeo-equilibrium line altitudes from cirque floor elevations. Here, these geomorphological constraints are integrated with physically based glacier reconstructions using the PalaeoIce 2.0 model to simulate ice thickness, surface geometry, and glacier extent for individual cirques.

The cirques display mean widths of approximately 1000 m and mean lengths of 936 m, forming near-circular, amphitheatre-like landforms indicative of sustained glacial erosion. Cirque heights range from 111 to 591 m, reflecting both variability in erosional intensity and topographic controls. Strong positive correlations between length, width, and height (L×W: 0.758; L×H: 0.610) indicate proportional scaling of cirque dimensions. Mean cirque slopes are 23.5°, with steep headwalls reaching up to 80°, while more than half of cirque areas are characterised by gentler slopes associated with overdeepened floors, where tarns are frequently present.

Cirque floor altitudes range from 447 to 1568 m, providing first-order constraints on former glacier geometry. PalaeoIce 2.0 reconstructions indicate a mean palaeo-equilibrium line altitude of approximately 658 m, corresponding to a depression of ~1042 m relative to present conditions. Modelled glacier geometries are consistent with extensive, topographically confined mountain glaciers developed within individual cirques during the Last Glacial Maximum. Associated palaeoclimate estimates suggest mean summer air temperatures of approximately −1.5 °C and annual precipitation of ~634 mm to sustain such glaciation.

These results demonstrate the value of combining cirque morphometrics with numerical ice-flow modelling to refine palaeoglacier reconstructions in high-latitude mountain regions. The PalaeoIce 2.0 simulations provide an independent, physically based framework for evaluating cirque-derived palaeoclimate inferences and for improving understanding of mountain glacier behaviour along the margins of larger ice-sheet systems.

How to cite: Oien, R. and Lee, E.: Integrating cirque morphometrics and numerical modelling reconstructions in Putorana, Central Siberia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10021, https://doi.org/10.5194/egusphere-egu26-10021, 2026.

During the Pleistocene ice ages, Central Europe formed a mostly unglaciated corridor between the Fennoscandian Ice Sheet and the Alpine ice complex. The mountains of this region hosted small ice masses at the time. However, the extent, timing and climate conditions under which glaciers existed, as well as their erosional imprint on the landscape remain poorly understood. Solving these challenges is important for understanding the impact glaciation may have had on the distribution of biota and permafrost, which, in turn, can be used to reconstruct former human migration routes in Central Europe. This project aims to reconstruct the past glaciation of the Central European uplands and its palaeoclimate implications, focusing on the mid-elevation mountains in the region, such as the Bohemian/Bavarian Forest, the Fichtel Mountains, the Ore Mountains, and the Sudetes.

Firstly, we aim to identify and date former ice extents and determine the style of glaciation through geomorphological mapping of glacial depositional and erosional landforms and their radiometric dating with terrestrial cosmogenic nuclides and optically stimulated luminescence. Secondly, we will conduct morphometric analyses and geophysical surveys to determine the degree of glacial erosion of cirques and valleys and assess the influence of plateau surfaces as potential snow or ice accumulation areas. Finally, we will apply a numerical glacier model (Parallel Ice Sheet Model) to identify the degree of temperature cooling and precipitation increase or decrease from present-day to grow glaciers that match the mapped and dated extents. Thus, an understanding of past glaciation and climate over Central Europe during the Pleistocene will be produced, with a wide relevance for the palaeoclimatology, ecology, and archaeology research communities. This poster will introduce the project and present initial results.

How to cite: Balaban, C. I., Nieslony, M., Krause, D., Engel, Z., Křížek, M., Seguinot, J., Zekollari, H., and Margold, M.: Reconstructing the Quaternary glaciation of the central European uplands and its palaeoclimate implications, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11933, https://doi.org/10.5194/egusphere-egu26-11933, 2026.

Reconstructions of glacier Equilibrium Line Altitudes (ELAs) from geomorphological evidence are often the only source of quantitative palaeoclimatic information in mountainous regions. The ELA is the average altitude of zero net mass balance and divides a glacier into an accumulation and an ablation area. While primarily controlled by summer temperature and winter precipitation, the position of the ELA is also frequently modulated by local topoclimatic factors, such as shading, supraglacial debris cover, avalanching or wind-driven snow redistribution. As a result, there can be substantial differences of several 100 meters between ELAs of neighbouring glaciers within the same climatic region. If such topoclimatic controls are not accounted for, this can introduce notable biases into ELA-based palaeoclimate reconstructions.

To better constrain the effect of topoclimatic control on glacier ELAs at the regional to global scale, we present the results of a comprehensive data analysis based on the Randolph Glacier Inventory (RGI), version 7.0. We compare glacier-specific ELAs calculated through the Accumulation Area Ratio and Area-Altitude Balance Ratio methods to a variety of topographic parameters, such as the amount of received solar radiation, the curvature of the ice surface and the topographic openness of the terrain. We show that there is a strong correlation between local ELA differences and some of these parameters and use a machine-learning tool to predict this ELA offset using only a digital elevation model and a glacier outline as input. This tool can be used to assess the topographic bias related to any calculated ELA and has the potential to lead to more reliable palaeoclimate reconstructions in a variety of settings.

How to cite: Rettig, L., Huss, M., and Kneib, M.: Quantifying topoclimatic control on glacier Equilibrium Line Altitudes at the regional and global scale, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12599, https://doi.org/10.5194/egusphere-egu26-12599, 2026.

Cosmogenic nuclide surface-exposure dating has emerged as a key tool in glacial geomorphology. Accurate application of the technique relies first on establishing local nuclide production rates using independently dated calibration sites. Certain regions of the world, such as the low latitudes, host few existing calibration sites. Developing local production rate calibrations in the low-latitudes is therefore a crucial first step for robust application of surface-exposure dating in these regions, particularly as cosmogenic nuclide production is theoretically more sensitive to changes in Earth’s magnetic field in the low-latitudes. Here we present a new local cosmogenic beryllium-10 production rate from the equatorial Rwenzori Mountains of Uganda based on radiocarbon dating of basal sediments from the moraine-dammed Lake Mahoma (~21.3 kyr BP; ~2,900 m asl). We also present the results of a systematic investigation of the performance of different parameters used to scale production rates spatially and temporally (e.g., scaling frameworks, geomagnetic field reconstructions, atmospheric models) using two public online calculators and limiting radiocarbon age data from nearby Lake Kopello (~4,000 m asl) in the Rwenzori. Our results highlight the sensitivity of low-latitude, high-elevation cosmogenic nuclide production to discrete parameters and underline the need for additional low-latitude production rate calibration sites.

How to cite: Jackson, M., Anderson, N., Kelly, M., Russell, J., Mason, A., Garelick, S., Doughty, A., Nakileza, B., Hutchinson, L., Geier, G., and Hidy, A.: A new low-latitude, high-elevation cosmogenic beryllium-10 production rate from the Rwenzori Mountains, Uganda, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13373, https://doi.org/10.5194/egusphere-egu26-13373, 2026.

New ¹⁰Be exposure ages from the Arenig mountains, North Wales have been obtained to complement ³⁶Cl ages and help constrain the timing of deglaciation in NE Wales. The last phase of cirque glaciation is dated to the Younger Dryas and this is consistent with previous assumptions of deglaciation in Wales. In South Wales, in the Brecon Beacons, the last cirque glaciers were higher than those in the north, which is consistent with increasing cirque altitude with lower latitude. Radiocarbon dating from bogs inside of moraines in these cirques also supports a Younger Dryas age for the last phase of glaciation. However, further south in the South Wales Valleys, the last former cirque glaciers were at some of the lowest altitudes in Wales. The glaciers occupied cirques that are lower than in the nearby Brecon Beacons and these cirques represent an anomalous population of low-lying cirques compared with the rest of Wales. Reasons for this are either because 1) wetter conditions existed the South Wales Valleys than the rest of Wales leading to lower cirque glaciation during the Younger or 2) the last cirque glaciers were present and formed moraines prior to the Younger Dryas, possibly when the Welsh Ice cap covered Wales north of the Brecon Beacon watershed divide. Ongoing work will apply ¹⁰Be exposure dating from moraine boulders and ¹⁴C dating from bogs inside of moraines in the cirques of the Brecon Beacons and South Wales Valleys to test these hypotheses further. 

How to cite: Hughes, P., Thomas, O., Darvill, C., Ryan, P., and Fink, D.: Examining the nature and timing of deglaciation in Britain: new evidence from the Arenigs, Brecon Beacons and South Wales Valleys, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13791, https://doi.org/10.5194/egusphere-egu26-13791, 2026.

The sensitivity of alpine glaciation to climatic warming is underscored by global reductions in ice mass over the last century and accelerated losses observed in recent decades. Given the dependence of local populations, infrastructure, and ecosystems on reliable snowpack and meltwater supply, the forecasted demise of many mountain glaciers critically motivates investigations into the dynamics underlying glacial retreat and advance under past boundary conditions. However, the timing and extent of glacial limits are progressively less well constrained through geologic time, particularly in mountain regions, due to the inevitable loss of geomorphic indicators through subsequent glacial advance and erosion. Secondary mineral deposits in some alpine caves offer a unique solution to glacial reconstructions, because warm-based ice cover allows the cave system to remain unfrozen with active speleothem growth. Importantly, the loss of soil cover and presence of glacial ice induces an abrupt switch from a carbonic-acid to a sulfuric-acid dominated system in caves hosted by impure carbonate rocks, which can be detected through geochemical analysis of radiometrically dated speleothems. While this category of ‘subglacial speleothems’ has long been described, only recently has a thorough multiproxy approach been developed and tested, which can robustly identify the timing and dynamics of glaciation over alpine cave sites. In addition to key changes in the stable-isotope composition of carbon (δ¹³C) and oxygen (δ¹⁸O), the dominance of sulfuric-acid dissolution leads to an increase in speleothem sulfate, often by more than an order of magnitude, which may be accompanied by a decrease in the δ³⁴S of sulfate due to enhanced sulfide oxidation. Glacial weathering processes are captured by certain trace elements in speleothem calcite, whereas the redox evolution of infiltrating waters (reflecting the hydrological balance of surface and subglacial meltwaters) is reflected in the oxygen-isotope composition of speleothem sulfate. Finally, U-series dating (U-Th and U-Pb) allows for accurate geochronological constraints, sometimes with per mil precision, throughout the Quaternary and beyond. Herein, we present case studies from the European Alps and Western Caucasus that successfully document the advance and retreat of warm-based glaciers without reference to surficial deposits and landforms. We further discuss uncertainties associated with the site-specific behavior of geochemical proxies that may limit their application to some glacial reconstructions.

How to cite: Baker, J., Honiat, A., Wynn, P., Moseley, G., Mertz, R., and Spötl, C.: A multiproxy speleothem-based approach to reconstructing alpine glaciation beyond the limits of geomorphological evidence, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14454, https://doi.org/10.5194/egusphere-egu26-14454, 2026.

Yukon Territory has been repeatedly affected by the northern Cordilleran Ice Sheet (NCIS). Although termed an ice sheet, it is better described as an ice complex, with quasi-independent lobes originating from mountainous areas around the border of the Yukon. This ice complex produced irregular, digitate glacial limits largely on the plateau area of central Yukon, at the eastern edge of unglaciated Beringia. These limits have broadly followed a pattern of progressively diminished extent. It is likely that variable precipitation across the source areas of these lobes affected their extent and timing during various glacial cycles. The growth model of the NCIS is contingent on ice from numerous cirques and ice fields in the source areas eventually amalgamating into these large, coalescent, ice lobes. What is unclear is the contribution of cirque and valley glaciers from the distal mountainous areas near the limits of glaciation. This research describes the contribution of cirque and valley glaciers in two areas at or near the limit of glaciation from MIS 6-2.

Ruby Range in southwest Yukon was affected by the Saint Elias lobe. It encompasses the limits of MIS 2, 4 and 6 glaciations. Stratigraphic analysis paired with ¹⁰Be surface exposure dating indicates extensive local ice production from cirques and plateau surfaces during MIS 2. During early MIS 2, local valley glaciers advance to the edge of the range but had retreated up valley during inundation by the St. Elias lobe, likely due to local precipitation reduction. These alpine ice centres were responsive to deglacial climatic fluctuations and hosted significant re-advances during the Older Dryas during rapid retreat of the St. Elias Lobe despite their location in the rain shadow of the St. Elias Mountains. The MIS 4 limit is slightly more extensive than the MIS 6 limit, likely because local ice growth contributed significantly to this portion of the St. Elias Lobe. The record and limit of the MIS 6 glaciation is poorly constrained here but 150 km to the NW, MIS 6 is 4 km more extensive than 4.

Granite Creek is in Gustavus Range in central Yukon at the MIS 2 limit of the Selwyn lobe. It was completely overrun during MIS 6, but cirque glaciers were extensive early enough that the Selwyn lobe did not inundate local cirque valleys. Stratigraphic studies indicate extensive MIS 4 cirque glaciation but provide no evidence of a proximal Selwyn lobe. During MIS 2, cirque glaciers near the margin were partially overrun by the Selwyn lobe. A tongue of the Selwyn lobe blocked Granite Creek forming a lake, and cirque glaciers terminating in the lake advanced due to floating ice margins. These limits are not reflected in the geomorphic record; well-defined MIS 2 moraines are recessional from this maximum.

This research indicates peripheral ice accumulation could contribute to the NCIS. However, stratigraphic studies indicate that peripheral ice sources in many cases were asynchronous with advances from primary source areas, likely due to variations in precipitation caused by the expansion of the CIS.

How to cite: Ward, B., Cronmiller, D., Steinke, J., Bond, J., and Lamothe, M.: Distal Cirque Contribution to the Northern Cordilleran Ice Sheet, Yukon Territory , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14826, https://doi.org/10.5194/egusphere-egu26-14826, 2026.

Andean landscapes contain key paleoclimate records of the Southern Hemisphere. However, many mountain regions in the Andes remain scarcely investigated in detail. In this study, we present an analysis of the Nevados de Chillán Volcanic Complex (NCVC), in Southern Chile (37ºS), aiming at unveiling the potential of this landscape to register past climatic conditions. This site is within a region of Temperate-Mediterranean climate transition (TMT; 35.5°–39.5°S), which comprises most of the Southern Volcanic zone (SVZ) of the Andes, that host the most active volcanoes of the cordillera, almost all of them are ice-capped. These volcanoes witnessed the multiple expansions and retreats of the Patagonian Ice Sheet (PIS) during Pleistocene glaciations and of smaller mountain glaciers during the Holocene, reflecting local climatic variations. Our findings show the NCVC preserves a recent and diverse glacial record, as identified with a detailed geomorphological mapping (1:20.000). The elevation and preservation of glacial deposits and scoured bedrock point to multiple glacial advances after the Last Glacial Maximum. Current analysis of ages obtained with ³⁶Cl dating of andesitic boulders atop moraines support field observations and geomorphological interpretations, with different episodes from Early-Middle Holocene until the last centuries. The oldest measurements in could represent late glacial advances, which also occurred in central Andes and Patagonia. Ages from frontal moraines are coeval with the Little Ice Age, consistent with results of recent studies in adjacent volcanic areas. From lateral moraines dispersed age results suggest persistent glacial activity since the last millennia until 200 years ago. The younger ages are supported by historical accounts from 19^th century that document glacial extent comparable with the location of sampled boulders.  Overall, these results should be interpreted in light of uncertainties related to geomorphological mapping and especially with chronological constraints.  Despite these limitations, the integrated approach adopted here provides a useful framework to identify regional-scale patterns of glacier fluctuations and to assess their sensitivity to climatic variability during the Late Pleistocene–Holocene.

How to cite: Navas, S., Fernández, A., Jaque, E., Owen, L., Figueiredo, P., and Stansell, N.: Glacial record and 36Cl cosmogenic dating in the Nevados de Chillán Volcanic Complex, Northern Patagonia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16061, https://doi.org/10.5194/egusphere-egu26-16061, 2026.

How to cite: Van Cappellen, M. and Zekollari, H.: Towards Reconstructing Ice-Dynamical Holocene Glacier Fluctuations , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18100, https://doi.org/10.5194/egusphere-egu26-18100, 2026.

Numerical models simulating potential future climate schemes are tested against different proxy-based reconstruction of paleoclimate and must be finely tuned. In the north Atlantic region, records indicate that the Last Glacial Termination was interrupted by rapid, high-amplitude reversals (Heinrich Stadial 1, Younger Dryas) during which temperatures got back to nearly ice-age cold conditions.
These events are thought to be year-round cooling periods and could be close analogues for future climate change in the north Atlantic region. Terrestrial glacial deposits give a high resolution vantage on abrupt shifts but remain poorly investigated. Previous studies based on surface exposure dating on glacial landforms show that glaciers retreats occurred within HS1 and YD, contradicting the prevailing models. Thus mapping palaeo-mountain glaciers former extend, dating their retreat and reconstructing their successive palaeo-equilibrium lines altitude allow to determine whether this pattern is a consensus for the northern hemisphere palaeo-glaciers. This approach also provides information on the timing and magnitude of past climate change. This study is based on the west coast of Ireland directly impacted by westerlies, located downwind of the North Atlantic Ocean and which contains key sites where palaeo-mountain glaciers let the footprints of their passage. Here, we present the first results  from the Geologic Perspectives on Abrupt Climate Change (GeoPAC²) project: Strengthening Ireland’s capacity for projecting future change. The new beryllium-10-dated glacier records reveals phase of ice retreat occurring within HS1. It questions the rising seasonality hypothesis which suggests an increase of summer temperatures during melting season. The results of this work will provide useful quantitative data for investigate North Atlantic climate variability and improve both climate and glaciological models.

How to cite: Roignot, A. and Bromley, G.: Palaeo-glaciers archives in western Ireland as a vantage on abrupt shifts of the Last Glacial Termination , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18404, https://doi.org/10.5194/egusphere-egu26-18404, 2026.

How to cite: von Römer, L., Zandler, H., Hartl, L., Lauria, M. V., Schöner, W., and Abermann, J.: Refining the history of changes in glacier geometry since the LIA at selected sites across the Austrian Alps , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18543, https://doi.org/10.5194/egusphere-egu26-18543, 2026.

Numerical palaeoglacier modelling is being applied to mountain glacier systems worldwide to investigate past ice dynamics, climatic controls, and glacier–climate interactions.  At present, there is no overview or consensus framework for evaluating the performance of these models, nor agreed standards for determining whether simulated glacier distribution and geometry are plausibly reconstructed through time.

To assess how palaeoglacier models in mountains are being validated and evaluated, we conducted a systematic review of 94 coupled mass-balance–ice-dynamics palaeoglacier models worldwide. For each study, we recorded validation approaches (visual, quantitative, and/or statistical), the glaciological attributes evaluated (extent, area, ice thickness, mass balance, ice flow, glacier distribution), the validation datasets used (direct geomorphological evidence versus previous model outputs), and the spatial structure of validation (point-, line-, polygon-, or grid-based). We also synthesised validation workflows to document the datasets, metrics, and decision criteria employed.

Our results show that the methodological design used to validate model outputs vary considerably between studies. We found that 80% of reviewed studies incorporate visual evaluation of model outputs to some extent, and 43% rely exclusively on subjective visual interpretation. A further 4% of studies do not perform any form of model validation or evaluation. Most studies validate glacier length (89%), whereas 48% of cases validate only one individual model output. Geomorphic reconstructions are used as validation datasets in only 27% of studies, indicating that most validation workflows rely on mapped glacial landforms. Because glacier length and glacial landforms dominate validation strategies, point- and line-based features constitute the majority of spatial validation data, with polygon- or grid-based approaches remaining comparatively rare.

We observe that the interpretation of model performance often remains subjective and reliant on the judgement of a limited number of research authors, which hinders reproducibility and intercomparison across studies. This reliance on subjective visual interpretation reflects persistent challenges in palaeoglacier model validation that are not being solved by existing tools and workflows designed to measure model-data fit. Our review indicates that uneven geomorphic evidence coverage, positional uncertainty between mapped landforms and simulated ice margins, resolution mismatches between geomorphic data and model outputs, chronological dating uncertainties, parameter uncertainty, and ‘equifinality’ (i.e., where multiple parameter combinations can yield similarly plausible glacier geometries) within glacier models collectively hinder robust quantitative validation.

Therefore, we propose a probabilistic, equifinality-aware validation framework that integrates geomorphically based reconstructions, multiple model outputs (e.g., ice extent, ice thickness), temporal steps (e.g., LGM and present-day), and performance metrics (e.g., overestimation, underestimation). Our approach evaluates ice cover as a probability field derived from an ensemble of acceptable simulations, explicitly acknowledging parameter non-uniqueness of equifinal modelling outputs. This approach identifies spatial patterns of robust agreement and persistent uncertainty, avoids subjective selection of a best-fit simulation, and enables domain-wide validation that captures spatial and temporal heterogeneity in glacier behaviour, thereby providing a more transparent and reproducible basis for evaluating palaeoglacier model–data fit.

How to cite: Lima, A. C., Barndon, S., Chandler, D. M., Yingkui, L., and Flantua, S. G. A.: Validation Practices in Mountain Palaeoglacier Modelling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19769, https://doi.org/10.5194/egusphere-egu26-19769, 2026.

During the Last Glacial Maximum (LGM), the European Alps were occupied by an extensive glacial network in which major trunk glaciers interacted with smaller tributary glaciers. In several areas, local glaciers flowed in directions opposite to those of trunk glaciers, particularly in distal sectors characterized by complex topography and high precipitation. Despite their likely widespread occurrence, the dynamics, the peculiar morphologies and specific related depositional facies of these glacier–glacier interactions remain poorly constrained.

In the southeastern Alps (Italy), the glacial system was dominated by the Adige trunk glacier. Regional-scale reconstructions have defined glacier geometry, flow paths, and Equilibrium-Line Altitudes across the Adige and Astico valleys, including an ELA of ~1580 m for the Fiorentini glacier (Monegato et al., 2024). However, these reconstructions primarily address trunk glacier behavior, leaving the interactions with local valley glaciers largely unexplored.

This study focuses on valleys where the Adige trunk glacier interacted with local glaciers descending from adjacent massifs, with the two ice bodies flowing in opposite directionsunder conditions of high orographic precipitation. The Terragnolo Valley represents a key example, where the presence of the distal Adige glacier, is documented by moraines at elevations of ~1400 m a.s.l., and were it interacted with local glaciers descending from the Monte Pasubio massif (~2200 m a.s.l.). Similar geomorphological configurations are found also in the Vallarsa and Ossaria valleys, enabling a comparative, valley-scale analysis within the same glacial system.

In the Terragnolo Valley, the interaction zone is marked by a thick glacigenic succession extending for ~10 km upstream, dominated by locally derived carbonate clasts, with only minor contributions from lithologies typical of the trunk glacier. This sedimentary pattern indicates a complex interaction between the two ice bodies and raises key questions regarding ice-flow coupling, relative timing of glacier advances, and the degree of dynamic independence of local glaciers during the maximum extent of the trunk glacier.

Overall, the studied valleys highlight how interactions between trunk and local glaciers in distal sectors can generate complex dynamics and sedimentary architectures, providing new constraints for reconstructing Alpine glacier dynamics and the distribution of glacigenic deposits in the tributary valleys.

How to cite: Fontana, A., Vidi, C., Monegato, G., and Rossato, S.: Interactions between trunk and local glaciers in distal Alpine valleys (southeastern Alps, Italy), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19840, https://doi.org/10.5194/egusphere-egu26-19840, 2026.

Mountain glaciers represent sensitive recorders of climate variability across a wide range of temporal and spatial scales. While their Lateglacial and Holocene dynamics are comparatively well constrained, glacier extent and behaviour prior to the Last Glacial Maximum (LGM) remain poorly documented in many mountain regions. In the Eastern Alps, the timing and magnitude of glacier advances during Marine Isotope Stage (MIS) 4 and MIS 3 are still debated, despite numerical glacier models predicting repeated pre-LGM advances into the Alpine foreland. This knowledge gap largely reflects (i) the scarcity of suitable terrestrial archives capable of recording such advances, (ii) the fact that organic material for radiocarbon dating is generally rare or absent in glacial settings and (iii) geomorphological evidence such as moraines is commonly eroded, reworked, or overprinted by subsequent glacier advances.

This study examines successions of ice-dammed glaciolacustrine sediments preserved in Alpine tributary valleys as alternative terrestrial archives for reconstructing pre-LGM glacier dynamics in the Eastern Alps. Ice-dammed lakes form when advancing trunk glaciers block the outlet of smaller tributary glaciers, creating temporary sediment traps that enable glaciolacustrine deposition. These ice-contact sediments record glacier advances and can survive multiple glacial cycles.

We focus on glaciolacustrine successions as ice-margin indicators and present a research approach that combines detailed sedimentological investigations with luminescence geochronology. The sedimentary architecture and stratigraphic relationships of ice-dammed sediments and associated delta complexes provide spatial constraints on an interconnected system of valley glaciers, including minimum ice-surface elevations and relative glacier extent. Chronological control is obtained using optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) dating of fine-grained quartz and feldspar (4–11 μm), respectively. Methodological challenges related to partial signal resetting are addressed using adapted bleaching-plateau tests [1], increasing confidence in the luminescence-based age constraints.

Our initial results from inneralpine sites indicate glacier advances which potentially reached into the Eastern Alpine foreland during MIS 4 and eventually MIS 3c, implying that glacier extent prior to the LGM was potentially more dynamic and spatially extensive than previously assumed. These results are consistent with numerical glacier model predictions [2].

From a methodological point of view, we conclude that (i) precise dating of ice-dammed lacustrine sediments enables reconstruction of the spatiotemporal dynamics of the associated ice-stream network, and (ii) luminescence-based lacustrine dating might complement geomorphological and cosmogenic-nuclide methods focused on lateral and frontal moraines used to delineate former ice margins.

References

1. Reimann, Tony; Notenboom, Paul D.; De Schipper, Matthieu A.; Wallinga, Jakob (2015): Testing for sufficient signal resetting during sediment transport using a polymineral multiple-signal luminescence approach. In: Quaternary Geochronology 25, S. 26–36. DOI: 10.1016/j.quageo.2014.09.002.

2. Jouvet, Guillaume; Cohen, Denis; Russo, Emmanuele; Buzan, Jonathan; Raible, Christoph C.; Haeberli, Wilfried et al. (2023): Coupled climate-glacier modelling of the last glaciation in the Alps. In: J. Glaciol. 69 (278), S. 1956–1970. DOI: 10.1017/jog.2023.74.

How to cite: Spitaler, B., Gruber, A., Reitner, J. M., and Meyer, M. C.: Are ice-contact lacustrine sediments in the Eastern Alps capable of constraining pre-LGM ice-stream network dynamics? , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20278, https://doi.org/10.5194/egusphere-egu26-20278, 2026.

The Ural Mountains form a major physiographic boundary between the East European Plain and West Siberia, both repeatedly glaciated during the Pleistocene by the Barents–Kara ice sheet. Although the present-day topography reflects significant glacial modification, the extent, chronology, and interaction of mountain glaciers with the Barents–Kara ice sheet remain poorly constrained. Correlation of glacial and interglacial deposits across the range is hindered by incomplete sedimentary records, contrasting palaeoclimatic conditions, and limited chronological control, which collectively obscure regional glacial reconstructions.  This study presents an extensive mapping exercise of hundreds of moraines in the northern Urals. These landforms are then used to reconstruct palaeoglacier equilibrium line altitudes (ELAs) to assess glacier distribution and synchroneity of moraine formation. ELA trends along the Urals are analysed to evaluate whether, and where, montane ice caps developed during the last major glaciation. Furthermore, palaeo-ELA data are used to link former ice margins to dated moraines in the Polar Urals, providing new insights into the spatial and temporal dynamics of montane glaciations south of the Arctic Circle. The findings indicate that  the E-W asymmetry in the hypsometry of the Urals exerted  the primary control on the development of the piedmont glaciers on the lowlands. Furthermore, Glacier reconstructions combined with geomorphological evidence favour the existence of extensive montane ice caps over the Urals with moisture sourced from extensive ice dammed lakes  locates on both sides of the mountain range.

How to cite: Kurjanski, B., Spagnolo, M., Bushueva, I., Barr, I., Rea, B., Solomina, O., and Kutuzov, S.: Palaeoglaciations in the Polar and Subpolar Ural Mountains., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21654, https://doi.org/10.5194/egusphere-egu26-21654, 2026.

This study advances our understanding of Quaternary glaciation in the southeastern Tibetan Plateau by integrating geomorphic evidence with numerical ice sheet modeling to constrain paleoclimate and ice dynamics. We focus on the Haizishan Plateau, a key region with well-preserved landforms (cirques, U-shaped valleys, moraines) and cosmogenic nuclide chronology indicating major glaciations during MIS 2 and MIS 6. Using these geomorphic and chronological constraints, we first reconstructed the Last Glacial Maximum (LGM) ice margin and then applied the PaleoIce flowline model to estimate paleo-ice thickness and surface elevation. These independent geomorphic reconstructions were then compared to the results of three-dimensional paleo-ice sheet simulations performed with the Parallel Ice Sheet Model (PISM), which were driven by inferred paleoclimate conditions.

The PISM simulations indicate an LGM characterized by a temperature depression of ~4°C and precipitation levels 60–70% of modern values. The model successfully replicates the regional ice cap evolution, showing limited glacial extent during MIS 3 and restricted advances in MIS 4. Critically, the simulated ice configuration aligns well with the geomorphically reconstructed evidence, including glacial lineation patterns, landform zonation, and overall extent, validating the model's performance. Our findings demonstrate the power of combining geomorphic reconstruction with dynamical modeling to refine the glacial and climatic history of high-mountain regions.

How to cite: Fu, P. and Li, Y.: Modelling Haizishan paleo ice caps in the SE Tibetan Plateau during the last glaciation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21690, https://doi.org/10.5194/egusphere-egu26-21690, 2026.

The temporal evolution of near-surface ice slabs (> 1m thick) on the Greenland Ice Sheet (GrIS) has significant implications for understanding both past variability and future changes in ice sheet mass balance. These ice slabs, formed through the refreezing of meltwater in the firn layer, modulate surface runoff dynamics and affect the ice sheet’s meltwater retention capacity, which is critical for understanding future surface mass balance (SMB) sensitivity to climate change. With ongoing climate warming, the mechanisms driving the formation and expansion of these ice slabs are likely to intensify. There is a need for coupled SMB and sub-surface firn models that can effectively simulate near-surface firn and ice slab evolution, allowing us to predict their long-term impact on Greenland's contribution to global sea-level rise.

In this study we present a 1-D physically based model with high vertical resolution (1 cm) to simulate surface melt, percolation, refreezing, ice slab evolution, runoff, and surface mass balance (SMB) across the GrIS. The high vertical grid resolution facilitates continuous simulation of the evolution of ice layers with thicknesses ranging from 1 cm to several metres. We applied a novel, laboratory defined, temperature-dependent ice layer permeability criterion whereby all ice layers are permeable above –0.15 °C but become impermeable beyond 1 m thickness. The model incorporates a novel parameterization of vertical snow and firn compaction, replacing frequently used theoretical relationships derived for dry snow compaction with a laboratory-derived, viscosity-based relationship for refrozen snow / firn more commonly found within percolation zones.

We applied the model to the GrIS from 1999 to the end of the 21st century at a spatial resolution of 0.11° and a temporal resolution of 15 minutes. The simulations reproduce the observed distribution of past ice slab occurrences across the GrIS and generate near-surface firn density profiles and proglacial discharge hydrographs that closely match available field measurements. The model also captures the observed interannual variability in the runoff limit, demonstrating strong consistency with satellite-derived estimates. We forced the model with future climate projections to investigate the projected evolution of near-surface ice slabs and their implications for future vertical firn densification, meltwater runoff and surface mass balance.

How to cite: Laha, S. and Mair, D. W. F.: Temporal Evolution of Near-Surface Ice Slabs on the Greenland Ice Sheet: From Past Variability to Future Change, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3362, https://doi.org/10.5194/egusphere-egu26-3362, 2026.

Freshwater fluxes from the Antarctic and Greenland ice sheets play a critical role in sea-level rise, ocean circulation, and the global climate system. These fluxes arise from both dynamical processes—such as ice discharge, iceberg calving, and basal melting of ice shelves—and from surface mass balance processes. In Greenland, surface meltwater runoff is already a major contributor to freshwater input, and it is projected to become increasingly important in Antarctica as climate warming progresses. 

While regional climate models (RCMs) are key to studying climate at regional and local scales, relatively few are equipped with advanced snow and firn models capable of producing accurate surface mass balance results. Here, we present a comprehensive, state-of-the-art collection of regional climate model simulations (RACMO2, MAR, and HIRHAM5) for both Greenland and Antarctica, forced by historical and SSP-scenario CMIP6 Earth System Models and extending to the year 2100. We briefly assess the modelled surface mass balance, accumulation, melt, and runoff, and highlight aspects of atmosphere–snow/ice interactions that remain an active area of model development. This dataset can be used to prescribe freshwater fluxes from surface mass balance to oceanic or climate modelling experiments, or as a comparison against in situ observational datasets.

How to cite: Verro, K., Hofsteenge, M., Amory, C., van de Berg, W. J., Boberg, F., van den Broeke, M., Carney, M., Case, E., van Dalum, C., Fettweis, X., Hansen, N., Mottram, R., Olesen, M., and van Tiggelen, M.: Historical and Future Surface Mass Balance Contributions to Antarctic and Greenland Ice Sheet Freshwater Fluxes , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3836, https://doi.org/10.5194/egusphere-egu26-3836, 2026.

Enhanced climate warming across Arctic glaciers, ice caps and the Greenland Ice Sheet has intensified melt and refreezing processes, producing more widespread regions of melt-affected, near-surface (< 12 m depth) firn within accumulation areas. Accurately simulating this near-surface region is important, as it governs the evolving capacity of ice sheets to retain meltwater through refreezing and thus strongly influences surface mass balance. Although over short timescales (days to months) refreezing of meltwater dominates changes in the density of melt-affected firn, over longer timescales (decades to centuries), densification through vertical compaction of refrozen firn remains significant. Whilst there is a substantial body of both field and theoretical work addressing the issue of dry firn densification by compaction of snow into firn and ice, i.e. in the absence of melting and refreezing, there is a need for better understanding of densification by compaction in melt-affected snow / firn increasingly found across accumulation areas of ice sheets and glaciers.

Firn densification can be defined via a constitutive equation, calculating the vertical compression rate due to stress from the overburden pressure dependent on firn viscosity. Laboratory studies have demonstrated the potential of controlled experiments to constrain the viscosity of dry snow of varying densities.  However, similar experimental constraints do not yet exist for refrozen, melt-affected firn. In this study we extend such laboratory approaches to refrozen snow/firn to quantify their effective viscosities. We undertook confined uniaxial compression tests on snow/firn samples with known grain sizes and densities (c. 400 – 600 kg m^-3), simulating expected ranges of overburden pressures to c. 12 m depth to establish the stress-strain rate relationships that define near-surface firn viscosities. Our experiments indicate an exponential increase in viscosity with density. The viscosity values calculated here for melt-affected snow/firn are broadly consistent with the lower envelope of viscosities reported in previous studies on cold dry firn, though they exceed those made in the field for temperate firn. The relationship of viscosity to snow/firn density allows our findings to be incorporated into large-scale firn densification and surface mass balance models, where resolving detailed microstructural processes and form is often impractical. By providing empirically constrained viscosity estimates tied directly to density, this work bridges a gap between field observations of melt-affected firn and the parameterizations required by regional and continental-scale models for more robust future projections of near-surface refreezing capacity of ice sheets and glaciers.

How to cite: Mair, D., Brown, G., and Laha, S.: Viscosity of melt-affected snow/firn derived from laboratory-based uniaxial compression experiments., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4980, https://doi.org/10.5194/egusphere-egu26-4980, 2026.

In the last decades, the Greenland ice sheet (GrIS) and its peripheral ice caps (GICs) have been rapidly losing mass through increased solid ice discharge and declining surface mass balance (SMB), i.e., the difference between precipitation accumulation and ablation from sublimation and surface runoff. Capturing SMB and its components at the local scale, notably across rapidly melting glaciers and ice caps, is therefore essential to accurately quantify Greenland’s contribution to global sea-level rise.

Here we compare long-term SMB reconstructions from two ERA5-forced regional climate models at ~5 km (MARv3.14 and RACMO2.3p2), further statistically downscaled to 500 m spatial resolution (1940-2024). These products are evaluated using in-situ measurements covering accumulation and ablation zones, as well as remotely sensed mass change records, showing good agreement. While the two models align Greenland-wide in terms of integrated SMB, individual components differ suggesting error compensation. MAR generally experiences both higher inland precipitation accumulation and larger surface runoff in marginal ablation zones than RACMO2, yielding approximately equivalent integrated SMB estimates. We examine these differences at the GrIS and GICs scale and further explore our products’ sensitivity to spatial resolution using corresponding downscaled SMB at 1 km.

How to cite: Noël, B., Fettweis, X., van de Berg, W. J., and van den Broeke, M.: Differing high-resolution Greenland ice sheet and peripheral ice caps surface mass balance since 1940, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6601, https://doi.org/10.5194/egusphere-egu26-6601, 2026.

Ice shelves currently stabilize the Antarctic ice sheet but are vulnerable to hydrofracturing in the future. A faster increase in surface melt compared to accumulation will cause a reduction in available firn pore space and will thus eventually lead to meltwater ponding at the surface.  However, current climate models disagree on the total volume of meltwater production and accumulation, and thus on the evolution of firn density over ice shelves. A lack of direct melt and refreezing observations on ice shelves, especially in areas of high melt, prevents a detailed benchmarking of climate and firn models.

Since 2022, a dedicated experiment takes place at two contrasting locations with existing long-term automatic weather observations on the Larsen C ice shelf, which is at risk of collapsing in the future. Here we present results from 3 years of data from an eddy covariance system, which measured the sensible and latent heat fluxes, a GNSS antenna that measured snow height change by interferometry (GNSSir), and a snow cosmic ray counter that measured the change in snow mass and thus bulk snow density.

We discuss the main challenges and recommendations in acquiring such data, the derived surface energy balance (SEB) fluxes, and the variation of bulk snow density due to accumulation and meltwater refreezing. We demonstrate that the turbulent fluxes can be correctly simulated with a bulk turbulence model, that the variation of surface roughness in time can also be extracted from GNSSir, and that the hourly melt fluxes and refreezing can be simulated within 10% accuracy using a skin energy balance model forced by standard single level observations.

How to cite: Van Tiggelen, M., Smeets, P., Reijmer, C., and van den Broeke, M.: Observations of turbulent heat exchange, surface melt and refreezing on the Larsen C ice shelf, Antarctica (2022-2025), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6842, https://doi.org/10.5194/egusphere-egu26-6842, 2026.

The firn layer regulates how an ice sheet responds to climate change, by modifying how changes in surface temperature, snow accumulation and ablation affects the ice sheet mass balance.  The firn layer can be simulated with a firn densification model. However, a variety of climate forcing time steps have been used to force such firn models in literature, ranging from 3-hourly to daily, monthly, or even annually. Reasons for selecting certain climate forcing time steps are most often practical: the data are not available at smaller time steps, the amount of forcing data becomes too large, or computational resources are insufficient. Evaluation of the impact of the selected forcing time step is often absent or based on different lines of reasoning.

In this study, we force the firn model IMAU-FDM with different surface climate forcing time steps for the Antarctic Peninsula and southern Greenland Ice Sheet. We show that the modelled firn layer contains more pore space for larger forcing time steps. Locations with limited firn pore space due to seasonal melt are most sensitive.

The largest differences in modelled firn pore space arise when there is no diurnal cycle in the climate forcing input data. This allows for coexisting snowmelt and sub-zero surface temperatures, leading to immediate shallow refreezing of meltwater. We also found that parameterizations for e.g. fresh snow density can become unsuitable when applied outside the physical conditions or climate forcing time step on which they are based. We argue that (1) firn models require input with at least a sub-daily forcing time step, (2) use of parameterizations should be critically assessed and only used consistently with the way they were originally developed, and (3) the forcing time step should be considered when interpreting firn model output.

How to cite: van den Aker, T., Kuipers Munneke, P., van de Berg, W. J., Immerzeel, W., and van den Broeke, M.: Climate forcing time step requirements for firn modeling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7541, https://doi.org/10.5194/egusphere-egu26-7541, 2026.

Accurate projections of ice sheet surface mass balance (SMB) are critical for sea-level rise estimates. Polar regional climate models (RCMs) coupled with firn models are the primary tools for simulating melt and projecting future SMB. However, the projections from different RCMs significantly deviate from each other. Additionally, the computational costs of polar RCMs and their firn models limit the creation of large ensembles needed to statistically assess the likely range in future melt and runoff.

Machine learning emulators offer a promising solution by enabling rapid predictions at a fraction of the computational cost. We therefore present machine learning emulators that predict daily surface melt and runoff from atmospheric variables from their associated polar RCM over Greenland. The emulators use a novel physics-informed, modular architecture that combines short-term weather patterns with long-term climate memory, capturing both immediate atmospheric forcing and accumulated firn characteristics.

Our work demonstrates that machine learning can successfully emulate firn model behavior from climate forcing alone. This represents a crucial first step toward computationally efficient emulation of polar RCMs, facilitating generation of large ensembles, sensitivity analysis, and potential integration as surrogate models within Earth system models.

How to cite: Schlager, E., Langen, P. L., Mottram, R. H., Scher, S., and Ahlstrøm, A. P.: Emulating Greenland Ice Sheet melt and runoff from polar RCMs with machine learning, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7895, https://doi.org/10.5194/egusphere-egu26-7895, 2026.

As one of the main contributors of global sea level rise, the Greenland Ice Sheet (GrIS) has been experiencing significant thinning and losing ice mass since the Earth observation era using satellites. ICESat-2, equipped with the photon-counting altimetric technology, provides an unprecedented elevation accuracy of 2-4 cm and extremely high spatio-temporal coverages for reducing uncertainties in mass balance estimation of the ice sheet. We have developed a multi-temporal elevation change estimation model (MECEM) that is especially tailored for processing the ICESat-2 data and estimating mass changes. Here, we present our assessment of surface elevation change across the GrIS and its peripheral glaciers, using ICESat-2 observations acquired between March 2019 and March 2024. A validation against GNSS-derived elevation change rates near the Summit Station during 2022–2024 demonstrates a close agreement. In addition, a comparison with independent elevation change products indicates a strong consistency, particularly over interior high-elevation regions. Our results reveal increased thinning in the southeast and southwest coastal regions and major outlet glacier systems, such as Jakobshavn Isbræ and Helheim Glacier. The ablation zone (< 1500 m) experiences a rapid thinning at an average rate of −0.48 ± 0.04 m yr⁻¹, while the interior region (≥ 1500 m) remains relatively stable with a slight thickening. The mean surface elevation change rate over the entire GrIS is −0.10 ± 0.02 m yr⁻¹. We further convert the surface elevation changes to ice mass changes by using corrections of firn air content and solid earth. A comparison with other studies and a discussion are also provided.

How to cite: Li, R., Liu, M., Chen, Q., He, Y., Wang, X., and Qiao, G.: Surface Elevation Changes and Mass Balance of the Greenland Ice Sheet from 2019 to 2024 from ICESat-2 Observations using a new MECEM model, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8541, https://doi.org/10.5194/egusphere-egu26-8541, 2026.

Surface mass balance (SMB) of polar ice sheets is a key component in quantifying their contribution to global sea-level rise. Accurate, high-resolution projections of SMB are therefore required to force ISMIP7 ice sheet models. In this study, we present preliminary results from SMBMIP, a comparison of several high-resolution SMB products over the Greenland Ice Sheet within the ISMIP7 framework. These products include, among others, SMB projections from the regional climate model MAR, statistical downscaling of MAR and the Earth System Model CESM2, and machine-learning outputs. For a meaningful comparison, participating projections are based on a same CESM2 historical climate and emission scenario. The aim is to explore uncertainties, performance and efficiency of various modelling approaches.

How to cite: Lambin, C., Dunmire, D., Senthil, N., Schlegel, N., Nowicki, S., and Noël, B.: ISMIP7 SMBMIP: a preliminary comparison of Greenland ice sheet surface mass balance products, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10038, https://doi.org/10.5194/egusphere-egu26-10038, 2026.

Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GFO) satellite missions, altogether referred to as GRACE hereafter, are a powerful tool to provide Greenland monthly mass anomaly estimates over a time span of more than two decades. Here we present a comparison between GRACE seasonal mass anomalies and surface mass balance (SMB) estimates from the Regional Atmospheric Climate Model RACMO2.3p2. The latter provides estimates of SMB and its individual components over Greenland with a daily temporal sampling and high spatial resolution, i.e. 5.5 km in the tundra area and 1 km over glaciated areas, using statistical downscaling. Our goals are to provide frameworks to independently evaluate the model and to estimate buffered water storage (BWS), i.e. temporal storage of meltwater in the deeper ice sheet system subject to discharge into the ocean during the melt season or soon thereafter.

The comparison spans the time interval between February 2003 and July 2022. Long-term (slow) trends are removed to exclude signals related to ice discharge variability and glacial isostatic adjustment (assuming the seasonal variability of these signals is negligible). The GRACE- and RACMO-based estimates are inverted into mean mass anomalies per calendar month to extract their typical seasonal patterns. The study area is limited to the coastal zone of Greenland, including the ice sheet ablation zone where signals related to BWS and under- or over-estimation of runoff are concentrated. The coastal zone is further divided into 12 areas for a detailed analysis. We compare the time series of seasonal patterns in terms of RMS differences, Pearson correlation coefficient, and Nash-Sutcliffe Efficiency (NSE). Over the entire coastal zone, the RMS difference is 13.7 Gt or 1.3 cm in terms of mean equivalent water height (about 14% of the total signal); the correlation coefficient and NSE are 0.992 and 0.980, respectively, indicating a sufficient match between the overall seasonal patterns of the two datasets. A few individual coastal zones also show a good agreement between GRACE- and RACMO-based estimates, with the RMS differences below 2 cm. In two northwestern coastal areas, however, GRACE- and RACMO-based mass anomalies show large discrepancies (e.g. NSE lower than 0.7), potentially due to an overestimation of modelled runoff. In two southwestern coastal areas, a mismatch is observed as well, with maximum differences occurring in July, in concert with the timing of BWS documented in earlier studies.

While previous studies already attempted to quantify BWS in Greenland, they did not account for the scaling of modelled runoff, introducing a biased estimation of BWS. In light of our study, a more comprehensive approach can be adopted for BWS quantification. Such an approach can also benefit from using other regional climate models for BWS estimation.

How to cite: Li, W., Ditmar, P., van den Broeke, M., Noël, B., and Wouters, B.: Comparison of GRACE/GFO- and RACMO-based seasonal mass anomalies over the coastal zone of Greenland, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10199, https://doi.org/10.5194/egusphere-egu26-10199, 2026.

The Getz Ice Shelf is a region of high surface melt potential, yet its annual melt days are typically fewer than 10. In contrast, the upstream region of the Amery Ice Shelf, which has similar latitude and altitude, is more prone to surface melting, with some areas recording over 50 melt days throughout the year. Ice surface temperature (IST) is a critical indicator of its surface energy budget and mass balance. To investigate the differences in IST between the Getz and Amery ice shelves, this study employed high-resolution thermal infrared data from the FY-3A MERSI-Ⅰ and FY-3D MERSI-Ⅱ satellites to retrieve summer IST over both ice shelves for 2008–2014 and 2019–2024, and conducted a comparative analysis of their spatiotemporal variation patterns. Time series analysis of the Getz Ice Shelf revealed no statistically significant IST trend in either period. However, an anomalous warming event exceeding 5 K was observed in March 2013, abruptly reversing the typical seasonal cooling and resulting in a higher monthly average IST for March than for February. Meteorological analysis linked this anomaly to an anticyclone in the Amundsen Sea, which drove strong poleward transport of moisture and heat. The consequent increase in mid- and low-level cloud cover enhanced downward longwave radiation, leading to rapid surface warming. Also for the Amery Ice Shelf, time series analysis revealed no statistically significant IST trend in either period. Comparative analysis of summer IST reveals similar average values for the Getz and Amery ice shelves, with Getz even warmer by nearly 2 K in some years. However, surface melting on Getz remains lower. Analysis incorporating precipitation data indicates that the Getz Ice Shelf receives significantly higher precipitation than the Amery Ice Shelf. The greater snowfall replenishes surface fresh snow, increases albedo, and thereby suppresses melting. This suggests that wet ice shelves surface with high accumulation have a higher temperature threshold for surface melting. Notably, surface precipitation over the Getz Ice Shelf during the summer warming period (October–December) showed a significant declining trend from 2012 to 2023. Given the absence of pronounced changes in IST, this reduction in precipitation may elevate the future risk of surface melting on the Getz Ice Shelf.

How to cite: Liu, T., Zhang, X., Pang, X., and Yang, Y.: A Study on Summer Surface Temperature of Antarctic Ice Shelves Based on FY-3 Satellite: A Case Study of the Getz and Amery Ice Shelves, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11304, https://doi.org/10.5194/egusphere-egu26-11304, 2026.

High-sensitivity borehole pressure sensors provide a novel means of monitoring the surface mass balance (SMB) of Earth’s great ice sheets. When properly coupled to the ice, these instruments are expected to detect millimeter-scale changes in ice thickness corresponding to variations in snow accumulation. The Boussinesq solution guarantees that a pressure sensor buried at a depth of 1000 m will represent a spatially weighted average of surface mass load variations with an approximate radius of 1000 m at the surface. The sensing system itself consists of a pressure sensor connected to a pressure coupling element such as a sack filled with antifreeze. Once freeze-in related transients have passed, the internal fluid pressure in the sack reflects the full overburden stress exerted by the overlying ice column. Long term drift of the sensors requires special engineering attention and may be corrected for using some combination of pre-deployment pressurization, in situ calibration, and/or the use of multiple in situ sensors. We discuss deployment considerations using the IceDiver thermal melt probe for a potential deployment at Greenland Summit Station. The borehole SMB observatory described here supports altimetry-based inference of glacier mass change, provides a critical dataset for validating firn densification models, and establishes a fundamentally new approach to measuring glacier mass balance.

How to cite: Lipovsky, B., Brand, B., Burnett, J., Michel-Hart, N., Smith, B., and Winebrenner, D.: A New View from Within: Borehole Pressure Sensors and the Measurement of Glacier Mass Balance, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11424, https://doi.org/10.5194/egusphere-egu26-11424, 2026.

Accurate simulation of the Greenland Ice Sheet (GrIS) surface mass balance (SMB) is essential for quantifying its contribution to sea-level rise. The regional atmospheric climate model MAR is widely used to study GrIS SMB changes and force ice-sheet models, highlighting the importance of assessing its performance and sensitivity to horizontal resolution. Here, we evaluate the latest MARv3.14 version at 5 km resolution and assess the impact of coarser resolutions (10–30 km) on simulated GrIS SMB and its components.

MAR outputs are evaluated against a range of independent observations, including in situ SMB measurements, automatic weather station records of near-surface meteorological variables, and satellite-derived melt extent and albedo products. At 5 km resolution, MAR reproduces observed SMB with a root-mean-square error of 0.53 m w.e. yr⁻¹. For near-surface meteorological variables and surface energy budget fluxes, model errors are smaller than the corresponding observed variability. The assimilation of bare-ice albedo, implemented in the latest MAR version, improves model performance in the ablation zone. Remaining biases in the accumulation zone suggest that improvements to the snow albedo scheme are further required. Simulated melt timing is consistent with satellite-based melt extent products.

Comparing simulations at different spatial resolutions, we find that SMB discrepancies mainly occur at the ice-sheet margins, characterized by strong topographic gradients. While integrated SMB differences generally remain within interannual variability, precipitation and runoff are highly sensitive to the model spatial resolution.

Corrections based on a vertical SMB gradient (as in Franco et al., 2012) or a sub-pixel methodology allowing the surface scheme (SISVAT) to be run at a higher resolution than the atmospheric model could deal in part with runoff discrepancies vs spatial resolution but precipitation anomalies remain a challenge. We conclude by discussing ongoing model developments, in particular the implementation of a sub-pixel methodology.

How to cite: Timmermans, G., Brice, N., Kittel, C., Thomas, D., Nicolas, G., Clara, L., and Xavier, F.: Evaluation of MARv3.14 over Greenland and the Impact of Model Resolution, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11626, https://doi.org/10.5194/egusphere-egu26-11626, 2026.

How to cite: van der Aa, K., Reijmer, C., Kuipers Munneke, P., van de Berg, W. J., and van Dalum, C.: Updated Climatology and Surface Mass Balance for the period 1979-2024 of the Antarctic Peninsula using RACMO2.4p1, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12210, https://doi.org/10.5194/egusphere-egu26-12210, 2026.

The Greenland ice sheet (GrIS) constitutes a major contributor to sea level rise, with significant mass losses dominated by surface melt and runoff over recent decades. The enhanced surface melt is concomitant with an observed decrease in albedo and a retreat of the snow line to higher elevations, amplified by melt-albedo feedbacks. A realistic representation of snow and ice albedo over the GrIS is therefore essential in climate models to correctly represent the surface energy balance, the meltwater production and the ice sheet surface mass balance.

In ORCHIDEE, the land surface component of the IPSL-CM Global Climate Model, snow albedo is currently represented with a decay parameterization based on snow age. Such simplified parametrizations are common in land surface schemes of CMIP earth system models. Our objective is to improve the representation of snow albedo over the GrIS using observations from PROMICE stations and MODIS retrievals. Our approach relies on the use of the History Matching calibration tool, based on Gaussian processes emulators, to identify the snow albedo parameters best adapted to Greenland conditions.

We first perform an offline calibration over Greenland to assess the ability of the ORCHIDEE model to reproduce the snow albedo decay  and the bare ice extent in summer. We show that a single year calibration allows for a good representation of snow albedo decay over the 2000–2019 period. We aim to revisit this approach by using the atmospheric component of IPSL-CM, LMDZ, coupled with ORCHIDEE, in a regional configuration. This will allow us to assess whether atmosphere-surface feedback needs to be taken into account during the calibration procedure. Finally, we assess if the improved representation of albedo decay enables the IPSL model to produce a more realistic decrease of the GrIS surface mass balance over recent decades.

How to cite: Conesa, P., Agosta, C., Charbit, S., and Beylat, S.: Control of snow albedo decay on Greenland surface melt using the land surface model ORCHIDEE, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12329, https://doi.org/10.5194/egusphere-egu26-12329, 2026.

Firn densification turns snow into glacial ice. At the surface of ice sheets, ice caps, and glaciers, firn modulates the interaction between atmosphere and ice, and is in turn affected by temperature, precipitation, wind, deposition, and ice dynamics. As climatic factors vary, the rate of firn densification changes even as the mass stays constant. These densification rates are used to correct satellite altimetry measurements of mass balance across the Greenland and Antarctic Ice Sheets. The IMAU Firn Densification Model (IMAU-FDM) is a 1D, semi-empirical model that simulates the evolution of snow grain size, firn density, firn air content, temperature, and liquid water content commonly used for continent-wide altimetry corrections. We will present the results of the FDM from an extended timeseries (1939-2023) and updated forcing (ERA5-forced RACMO2p3.2), along with a toolkit for post-processing and using the output. We show the impact of longer-term forcing changes the overall firn air content and densification rates, and the effects of a longer, earlier spinup period. 

How to cite: Case, E., Kuipers-Munneke, P., Brils, M., van de Berg, W.-J., Tijm-Reijmer, C., and van den Broeke, M.: Changes in Greenland firn densification from extended IMAU-FDM runs (1939-2023), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13516, https://doi.org/10.5194/egusphere-egu26-13516, 2026.

Understanding melt processes and their contribution to runoff in glacierized catchments requires accounting for the strong spatial variability of surface energy exchanges. In this study, we analyse the spatial distribution of surface energy and mass balance at Rutor Glacier, the sixth-largest glacier in the Italian Alps, using field observations and a spatially distributed, physically based modelling framework.

The model combines in situ meteorological measurements collected at different elevations with high-resolution topographic information derived from a 5 m digital elevation model. Surface energy and mass-balance components are solved across the glacier surface to investigate how elevation, slope, and aspect influence melt patterns. Simulations are conducted for two consecutive hydrological years (September 2023–August 2024 and September 2024–August 2025), allowing an assessment of interannual variability in surface energy exchanges and melt dynamics.

The analysis focuses on characterizing spatial patterns of surface energy balance and surface melting, exploring their implications for meltwater production at the cell and watershed scales. Modelled meltwater fluxes are compared with available discharge observations to evaluate the consistency between simulated melt dynamics and field-based hydrological signals. Results and their relevance for snow- and glacier-fed runoff generation in mountain catchments will be discussed.

How to cite: Bertagni, M., Marini, F., Tamea, S., and Camporeale, C.: Spatio-temporal variability of surface energy and mass balance at Rutor Glacier (Italian Alps), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13635, https://doi.org/10.5194/egusphere-egu26-13635, 2026.

When you want to know the future of the Greenland ice sheet, you are confronted with the question: What will be Greenland's surface mass balance (SMB) in the future? 

The Copenhagen Ice-Snow Surface Energy and Mass Balance Model (CISSEMBEL) is a unified surface mass balance model developed at the Danish Meteorological Institute (DMI) that serves dual purposes in climate modeling. First, it operates as a standalone model to compute surface mass balance (SMB) from a wide range of atmospheric forcing data, including reanalysis products, meteorological forecasts, and automatic weather station (AWS) observations. Second, it acts as an innovative coupling framework that integrates SMB modeling into an atmospheric model. Since CISSEMBEL corrects dynamically elevation differences between the coarsely resolved orography in global atmosphere models and the high-resolution target during runtime, CISSEMBEL delivers boundary conditions essential for accurate atmosphere-ice sheet interactions. Ultimately, it enables a seamless integration of Ice Sheet Models (ISMs) into Earth System Models (ESMs).

In this presentation, we show CISSEMBEL results following the protocol of the Greenland Ice Sheet (GrIS) SMB model intercomparison project (GrSMBMIP). We present results on the grid of the used EraInterim (EraI) forcing as well as higher-resolution simulations on an Ice Sheet Model Intercomparison (ISMIP) grid. Our model results show that initialization affects the final results. Also, the different downscaling approaches (directly to a higher-resolution target or via height classes) available in CISSEMBEL deliver similar results. Since various parameterizations are available, the user can analyze their impact on results and explore the consequences on the SMB that determines Greenland’s future.

How to cite: Rodehacke, C., Verro, K., Hansen, N., Krebs-Kanzow, U., and Mottram, R.: Surface Mass Balance Model CISSEMBEL linking ice sheets and ESMs: Results of standalone GrSMBMIP simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17009, https://doi.org/10.5194/egusphere-egu26-17009, 2026.

Regional climate models (RCM) with good snow schemes can provide high-resolution surface mass balance (SMB) estimates over Antarctica, but come with high computational costs limiting the number of realizations across Earth System Models (ESM) and shared socioeconomic pathways (SSP). SMB’s great local variability as observable in regions characterized by complex topography such as the Antarctic Peninsula, requires high resolution. Recent machine learning approaches have shown promising downscaling results as cost efficient alternative to RCMs. However, their limited transferability across forcings remains a drawback for practical application.

Here, we investigate transferability of a Convolutional Neural Network (CNN) based emulator predicting SMB over the Antarctic Peninsula utilizing multiple SSPs. Two training scenarios are compared: a) a perfect model setup where training and prediction are performed under the same SSP, and b) an imperfect model setup in which the emulator is trained on a higher emission scenario and applied to a lower emission scenario. The latter represents an interpolation along SSPs, therefore comparable performance to the perfect model setup is expected.

Preliminary analyses suggest consistency in large-scale statistics over the full domain with benchmarks set in earlier studies. However, pronounced local variability in model performance is observable, particularly in regions of high melt or precipitation. Ongoing work aims to quantify these differences, detect potential causes, and their implications for predictions in the imperfect model setup.

Positive results could enable the generation of additional SSP-runs from existing RCM simulations, therefore substantially reducing total computational cost relative to the number of predictions.

How to cite: Zirkel, E., Mottram, R., Verro, K., and Lhermitte, S.: Emulating Surface Mass Balance in the Antarctic Peninsula Under Changing Forcings: A Transferability Assessment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18429, https://doi.org/10.5194/egusphere-egu26-18429, 2026.

Direct observations of the surface mass balance (SMB) over the Greenland Ice Sheet are currently limited to basin-scale estimates and sparse in situ measurements, making a comprehensive observational assessment challenging. Therefore, RCMs remain the best option for producing spatially and temporally continuous SMB estimates, but models show substantial regional differences, even under present-day conditions. While satellite observations provide extensive information about surface processes, a fully satellite-based SMB product remains to be seen.

In this study, we present SMBnet, a deep learning model that estimates SMB over central West Greenland by integrating satellite observations, reanalysis data, and simple physical constraints. SMBnet combines satellite-derived ice surface temperature and albedo with ERA5 reanalysis data, ice velocity, and GRACE/-FO mass anomalies to produce spatially and temporally continuous SMB estimates. The model employs a U-Net architecture and is trained using multiple loss terms that enforce consistency with observations and incorporate physical knowledge of accumulation and ablation processes. Although applied here to central West Greenland, the approach shows clear potential for extending it to the entire ice sheet, offering a computationally efficient, observation-driven complement to traditional RCMs for estimating present-day SMB.

How to cite: Puggaard, A., Solgaard, A., S. Sørensen, L., Mottram, R., and B. Simonsen, S.: A physics-guided Deep Learning Model for SMB of Central West Greenland, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21387, https://doi.org/10.5194/egusphere-egu26-21387, 2026.

The Antarctic Peninsula is warming rapidly, with more frequent extreme temperature and precipitation events, reduced sea ice, glacier retreat, ice shelf collapse, and ecological shifts. Here, we review its behaviour under present-day climate, and low (SSP 1-2.6), medium-high (SSP 3-7.0) and very high (SSP 5-8.5) future emissions scenarios, corresponding to global temperature increases of 1.8°C, 3.6°C and 4.4°C by 2100. Higher emissions will bring more days above 0°C, increased liquid precipitation, ocean warming, and more intense extreme weather events such as ocean heat waves and atmospheric rivers. Surface melt on ice shelves will increase, depleting firn air content and promoting meltwater ponding. Under the highest emission scenario, collapse of the Larsen C and Wilkins ice shelves is likely by 2100 CE, and loss of sea ice and ice shelves around the Peninsula will exacerbate the current trends of land-ice mass loss. Collapse of George VI Ice Shelf by 2300 under SSP 5-8.5 would substantially increase sea level contributions. Under this very high emissions scenario, sea level contributions from the Peninsula could reach 7.5 ± 14.1 mm by 2100 CE and 116.3 ± 66.9 mm by 2300 CE. Conversely, under the lower emissions scenarios, the Antarctic Peninsula’s sea ice remains similar to present, and land ice is predicted to undergo only minor grounding line recession and thinning. Changes in sea surface temperatures and the change from snow to rain will impact marine and terrestrial biota, altering species richness and enhancing colonisation by non-native species. Ranges of key species such as krill and salps are likely to contract to the south, impacting their marine vertebrate predators. These changing conditions will also influence Antarctic Peninsula research, fisheries, tourism, infrastructure and logistics. The future of the Peninsula depends on the choices made today. Limiting temperatures to below 2°C, and as close as possible to 1.5°C (by following the SSP 1-1.9 or 1-2.6 scenarios), combined with effective governance, will result in increased resilience and relatively modest changes. Any higher emissions scenarios will damage pristine systems, cause sustained, irreversible ice loss on human timescales, and spread to Antarctic regions beyond the Peninsula.

How to cite: Davies, B. and the Antarctic Peninsula under present day climate and future low, medium-high and very high emissions scenarios team: The Antarctic Peninsula under present day climate and future low, medium-high and very high emissions scenarios, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1720, https://doi.org/10.5194/egusphere-egu26-1720, 2026.

We present an ensemble of physically-based ice sheet model projections for the Greenland ice sheet (GrIS) that was produced as part of the European project PROTECT. Our ice sheet model (ISM) simulations are forced by high-resolution regional climate model (RCM) output and other climate model forcing, including a parameterisation for the retreat of marine-terminating outlet glaciers. The experimental design builds on the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) protocol and extends it to more fully account for uncertainties in sea-level projections. We include a wider range of CMIP6 climate model output, more climate change scenarios, several climate downscaling approaches, a wider range of sensitivity to ocean forcing and we extend projections beyond the year 2100 up to year 2300, including idealised overshoot scenarios. GrIS sea-level rise contributions range from 16–76 mm (SSP1-2.6/RCP2.6), 22–163 mm (SSP2-4.5) and 27–354 mm (SSP5-8.5/RCP8.5) in the year 2100 (relative to 2014). The projections are strongly dependent on the climate scenario, moderately sensitive to the choice of RCM, and relatively insensitive to the ice sheet model choice. In year 2300, contributions reach 49 to 3127 mm, indicative of large uncertainties and a potentially very large long-term response. Idealised overshoot experiments to 2300 produce sea-level contributions in a range from 49 to 201 mm, with the ice sheet seemingly stabilised in a third of the experiments. Repeating end of the 21st century forcing until 2300 results in contributions of 58–163 mm (repeated SSP1-2.6), 98–218 mm (repeated SSP2-4.5) and 282–1230 mm (repeated SSP5-8.5). The largest contributions of more than 3000 mm by year 2300 are found for extreme scenarios of extended SSP5-8.5 with unabated warming throughout the 22nd and 23rd century. We also extend the ISMIP6 forcing approach backwards over the historical period and successfully produce consistent simulations in both past and future for three of the four ISMs. The ensemble design of ISM experiments is geared towards the subsequent use of emulators to facilitate statistical interpretation of the results and produce probabilistic projections of the GrIS contribution to future sea-level rise.

How to cite: Goelzer, H., Berends, C. J., Boberg, F., Durand, G., Edwards, T. L., Fettweis, X., Gillet-Chaulet, F., Glaude, Q., Huybrechts, P., Le clec’h, S., Mottram, R., Noël, B., Olesen, M., Rahlves, C., Rohmer, J., van den Broeke, M., and van de Wal, R. S. W.: Extending the range and reach of physically-based Greenland ice sheet sea-level projections, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2576, https://doi.org/10.5194/egusphere-egu26-2576, 2026.

The Antarctic Ice Sheet has undergone significant climate variability throughout glacial-interglacial cycles. Because thermal diffusion and advection rates are low, surface temperature anomalies propagate slowly to the base, imparting a thermal memory to ice sheets that persists for thousands of years. Since ice temperature controls viscosity, deformation rates, and subglacial processes, this inherited thermal structure exerts a direct influence on contemporary ice dynamics. Recent work on the thermal state of the Antarctic Ice Sheet (Raspoet & Pattyn, 2025) has explored uncertainties in boundary conditions and model approximations, but considered a thermal steady state, thereby assuming equilibrium with present-day climatic conditions and neglecting the legacy of past glacial-interglacial changes. In this study, we employ the thermomechanical ice-sheet model Kori-ULB, driven by reconstructed transient climate forcings spanning the last interglacial to the present day, to quantify the effects of paleoclimatic evolution on the thermal state of the Antarctic Ice Sheet and assess the implications for ice-sheet dynamics and model initialization. Results show that englacial temperatures are sensitive to the past climate history, leading to uncertainties of the same order as those related to the geothermal heat flow. Incorporating variations in surface temperatures and accumulation rates over the last glacial-interglacial cycle results in colder temperature profiles and basal thermal conditions, suggesting that steady-state ice-sheet models may overestimate present-day thermal conditions.

References:

Raspoet O., Pattyn F. (2025), Estimates of basal and englacial thermal conditions of the Antarctic ice sheet. Journal of Glaciology 71, e104, 1–16. doi: 10.1017/jog.2025.10087

How to cite: Raspoet, O., Coulon, V., and Pattyn, F.: The thermal memory of the Antarctic Ice Sheet, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3349, https://doi.org/10.5194/egusphere-egu26-3349, 2026.

The Greenland Ice Sheet (GrIS) has experienced accelerated mass loss in recent decades and is expected to become a major contributor to global sea-level rise over the coming century. Understanding its response to climate forcing in a global warming context has become critical, particularly for the adaptation of coastal communities worldwide.

The last deglaciation of the GrIS offers valuable insights into ice-climate interactions, as extensive paleoclimatic records document its retreat through a period of major climate changes. During this interval, the GrIS retreated from its extensive Last Glacial Maximum (LGM) configuration to its present state, passing through the Holocene Thermal Maximum (HTM) when temperatures exceeded present-day values and may have overshot the GrIS tipping point. Despite the large amount of paleoclimatic data available, ice-sheet models struggle in reproducing key aspects of the observational record, and the magnitude of the GrIS contribution to sea level during the HTM remains highly uncertain.

In this study, we evaluate an ensemble of 3000 ice-sheet simulations performed with the  ice-sheet model Yelmo against different observational constraints. These include: (1) LGM ice-sheet extent, (2) ice-core-derived surface elevations, (3) relative sea-level records, (4) retreat chronology based on the PaleoGrIS dataset, and (5) the present-day ice-sheet configuration (ice thickness, ice velocity, and bedrock uplift rates). By identifying the simulations that best match these constraints, we provide a geologically-constrained reconstruction of the GrIS during the last deglaciation.

How to cite: Gutiérrez-González, L., Tabone, I., Alvarez-Solas, J., Montoya, M., Swierczek-Jereczek, J., Pérez-Montero, S., Tesouro, S., Blasco, J., and Robinson, A.: Simulation of the Greenland ice-sheet deglaciation constrained by past and present observables, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4033, https://doi.org/10.5194/egusphere-egu26-4033, 2026.

Climate change challenges all Earth subsystems. The Greenland and Antarctic ice sheets together with the Atlantic Meridional Overturning Circulation are subsystems of particular concern, as they are subject to tipping points, i.e., thresholds above which their current state changes to another that is qualitatively and quantitatively different. Their stability has been studied in depth through offline (stand-alone) modeling and “one-way” coupling with each other. However, we know that in the past, the Northern and Southern hemispheres have interacted through the bipolar seesaw. Thus, these subsystems have the potential to interact with each other, but this relationship is challenging to simulate. Here we investigate the behavior of a simplified approach coupling the state-of-the-art ice-sheet model Yelmo with an ocean box model and, importantly, vice versa. We will show the results of exposing the system to various climate change scenarios in order to see how different ice timescale responses alter the coupled stability. 

How to cite: Pérez-Montero, S., Alvarez-Solas, J., Robinson, A., and Montoya, M.: Stability of the Greenland and Antarctic ice sheets when dynamically coupled through the Atlantic meridional overturning circulation., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5356, https://doi.org/10.5194/egusphere-egu26-5356, 2026.

We present here a multi-century simulation of future Greenland ice sheet evolution under 4xCO2 forcing with the Community Earth System Model version 2 bi-directionally coupled to the Community Earth Sheet Model version 2 (CESM2-CISM2). We examine the evolution of global climate, ice sheet topography and flow, as well as the individual components of the surface mass and energy balance. We compare results with a simulation with uni-directional coupling, where the atmosphere and land components see a prescribed pre-industrial ice sheet topography, and the ocean sees prescribed pre-industrial freshwater fluxes corresponding to the initial CESM2-CISM2 state in the two-way coupled baseline simulation. We find that albedo feedback causes the solar flux to be the primary energy contributor to total melt of the ice sheet. Changes in ice sheet elevation reduce the input of snowfall to the ice sheet due to enhanced rain over snow partition of precipitation. Changes in elevation cause more than doubling of melt rates after the ice sheet area has decreased by more than 50%.

How to cite: Vizcaino, M., Petrini, M., Sellevold, R., Feenstra, T., Wouters, B., Thayer-Calder, K., Lipscomb, W., and Leguy, G.: Evaluation of albedo and elevation feedbacks on Greenland complete deglaciation in a CMIP model: comparison of coupled and uncoupled simulations , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5397, https://doi.org/10.5194/egusphere-egu26-5397, 2026.

Firn currently covers almost 90 % of the surface of the Greenland Ice Sheet. Most of Greenland’s firn plateau experienced only occasional melt in the past but ever rising temperatures increase melting and it is uncertain how a future melting firn plateau will impact ice sheet mass balance, hydrology and ice dynamics. Assessing these impacts requires coupling firn models to ice sheet hydrology and ice dynamics models.

The FirnMelt ERC Synergy project will assess the Greenland Ice Sheet’s reaction to increased melting across its vast firn plateau. The project starts in April 2026 and will last for six years. The project is led by four PIs and will involve about 20 scientific and technical staff. Here we detail planned methods, models and timeline of the five overarching project tasks, namely (i) large-scale in situ and remote sensing measurements of all types of firn and meltwater discharge, (ii) parameterizing melting firn based on these measurements, (iii) develop firn models able to simulate melting firn and firn meltwater discharge in three dimensions, (iv) embedding these models into a ice-sheet model suite where they are coupled to ice sheet hydrology and ice dynamics, and (v) calculating how Greenland’s melting firn plateau will impact the entire ice sheet and its sea level contribution, until the year 2300.

How to cite: Machguth, H. and the The FirnMelt Team: FirnMelt: Greenland’s Melting Firn and Ice Sheet Response, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5653, https://doi.org/10.5194/egusphere-egu26-5653, 2026.

The future contribution of the Antarctic Ice Sheet to global sea-level rise remains the largest source of uncertainty in climate projections. This uncertainty is primarily driven by the complex interaction between the ocean and the ice shelf cavities. Most ice sheet models still rely on simplified melt parameterizations that fail to capture the complex oceanographic processes within sub-ice-shelf cavities, while fully coupled ice-ocean models remain too computationally expensive for large-scale sensitivity studies. In this study, we present ADMIRE (Antarctic Deep MELT and Ice REpresentation), a new ongoing-work intermediate-complexity framework. ADMIRE couples the ice sheet model Kori-ULB with DeepMELT, a deep learning emulator trained on high-resolution NEMO-SI3 simulations. This coupling allows for a more physically consistent representation of the ice-ocean interface at a fraction of the computational cost of a coupled ice-sheet-ocean model. We compare the sensitivity of the Antarctic grounding line migration and overall mass balance when using the DeepMELT emulator versus traditional melt parameterizations. Furthermore, we investigate the impact of temporal coupling steps and interpolation methods on the projections. Our preliminary results highlight the potential of machine learning-based emulators to bridge the gap between simple parameterizations and complex coupled models, providing more robust projections of Antarctica’s future but at a low computational cost, allowing for comprehensive and multi-century studies.

How to cite: Kittel, C., Burgard, C., and Coulon, V.: ADMIRE: Improving Antarctic mass balance projections by coupling a Deep Learning basal melt emulator with the Kori-ULB ice sheet model, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7003, https://doi.org/10.5194/egusphere-egu26-7003, 2026.

Coupled climate-ice-sheet modeling is still in its developing stage, and feedback processes between ice sheets and climate are still not yet fully understood. Here, we use simulations with a coupled climate-ice-sheet model to investigate teleconnections between Northern Hemispheric ice sheets and the Antarctic ice sheet (AIS) without direct freshwater forcing. We show that ice mass removal in the Northern Hemisphere can alter AIS evolution through a series of feedbacks. Changes in surface properties and orographic effects warm the newly deglaciated areas and the North Atlantic Ocean at mid-depth. The warmer water masses propagate to the Southern Ocean, where internal oscillations periodically deliver them to the Antarctic coast. These repeated warm water intrusions destabilize the Ross ice shelf, ultimately triggering a runaway retreat of the West Antarctic ice sheet. Our results underscore the importance of coupled bi-hemispheric climate-ice-sheet modeling to capture global teleconnections between ice sheets and climate.

How to cite: Testorf, P., Schannwell, C., Kapsch, M.-L., and Mikolajewicz, U.: Coupled Climate-Ice-Sheet Simulations Reveal Novel Teleconnection Between Northern Hemisphere Ice Sheets and the Antarctic Ice Sheet, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7109, https://doi.org/10.5194/egusphere-egu26-7109, 2026.

How to cite: Coulon, V. and Kittel, C.: Exploring ice-atmosphere feedbacks in Antarctica using coupled simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7112, https://doi.org/10.5194/egusphere-egu26-7112, 2026.

The Antarctic Ice Sheet (AIS) is the largest potential contributor to future sea-level rise, with an ice volume equivalent to 58 m of global-mean sea level. However, high uncertainties arise from the representation of key physical processes in ice-sheet models, such as basal sliding, ice-ocean interactions, and feedback mechanisms associated with glacial isostatic adjustment (GIA). Previous studies have estimated the future Antarctic sea-level contribution (SLC) by forcing an ice sheet spun up to a present-day equilibrium state. However, observations of the last decades indicate that the AIS is not in equilibrium, as it is undergoing net mass loss as a result of both ongoing anthropogenic climate change and its long-term adjustment following the last deglaciation. Here, we study the future SLC of the AIS using simulations that span a complete Last Glacial Cycle. To this end, we use the ice-sheet model Yelmo coupled to the GIA model Fastisostasy, and construct an ensemble that accounts for uncertainties in process representation. The model is forced using the PMIP3 ensemble-mean reconstruction of the Last Glacial Maximum (LGM) and the present-day climate, weighted by an index derived from Antarctic ice-core records. The simulations are initiated in the Last Interglacial and evaluated based on their consistency with geological constraints from the LGM and the deglaciation, as well as present-day observations of the AIS. Using these paleo-constrained model configurations, we then investigate the response of the AIS to different future climate-change scenarios.

How to cite: Tesouro, S., Álvarez-Solas, J., Blasco, J., Robinson, A., Swierczek-Jereczek, J., and Montoya, M.: The contribution of the Antarctic Ice Sheet to global sea level from the Last Glacial Cycle to the future, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7333, https://doi.org/10.5194/egusphere-egu26-7333, 2026.

There is a strong concern about how fast and how much the global sea level will rise in the next few decades due to the current global warming. However, the projection range is large due to uncertainties about the future evolution of the Antarctic ice sheet, particularly the possibility of the ice shelves' collapse.  

With the base submerged in seawater, these ice shelves are strongly influenced by the surrounding oceanic conditions, which can be split into two regimes: cold or warm cavity. When ice shelves are exposed to warm water, basal melt increases sharply, leading to a loss of buttressing of the grounded ice upstream and potentially the collapse of the shelf. Results from TIPMIP (Tipping Points Modelling Intercomparison Project) idealised experiments carried out by the UK Earth System Model (UKESM) with an interactive Antarctic ice sheet component suggest that tipping points for several ice shelves will be reached in the future at relatively high global warming levels (GWLs). However, it is questionable whether the warming thresholds for tipping that we find are realistic due to the model biases and other uncertainties. 

This study focuses on exploring the uncertainty in the climate simulated by UKESM and assessing the consequences of ice shelf tipping on the wider Earth System. To do this, we induce the cavity regime shift at a lower GWL than the reported threshold by mimicking the key climate change forcing identified from the higher GWL experiments via an artificial freshwater around the Antarctic ice sheet margin. By doing so, we obtain a pair of low GWL experiments with and without ice shelf tipping, which allows us to isolate the impact of ice shelf tipping on the Earth System. In addition, the experiment setup also allows us to explore the consequences of different scenarios of various freshwater hosing values. The preliminary results indicate that the excessive freshwater induces an expansion of Southern Ocean sea ice, leading to a cooling trend in global mean temperature. 

How to cite: Hoang, T. K. D., Smith, R. S., Naughten, K. A., and Jones, C. G.: Impacts of freshwater fluxes on ice shelves tipping points in UKESM , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7719, https://doi.org/10.5194/egusphere-egu26-7719, 2026.

In order to predict future changes in the Antarctic Ice Sheet under anthropogenic climate change, it is essential that we understand how it
responded to past climatic changes. The Antarctic Peninsula is seen as a bellwether system for the wider Antarctic Ice Sheet and, as such, is an
ideal palaeo-glaciological study area. The timings of the retreat of the ice front in this area since the Last Glacial Maximum have been
extensively researched and the configuration of the major ice streams that drained the ice sheet on the Northern Peninsula is broadly known.
However, the ice-ocean interactions that occurred during this period remain poorly understood. The identification and analysis of iceberg
ploughmarks can provide information on the extent of past ice sheets and the morphology of their calving fronts; past calving regimes and
hence the dynamic behaviour of the ice sheet in the past and how this may have changed over time; and past ocean circulation. During a
Schmidt Ocean Institute scientific cruise to the Antarctic Peninsula, high resolution, multibeam acoustic data was acquired in a poorly mapped
area of the Bellingshausen Sea near the Ronne Entrance. Thousands of iceberg ploughmarks were identified on bathymetric maps produced
from this data. These scours were mapped and their morphological characteristics were recorded. Morphometric analyses were undertaken,
including quantitative investigations of length, depth, width and sinuosity, and the intensity and distribution of scours were also investigated.
The implications of these results for the morphology and dynamics of the ice sheet and ice-ocean interactions since the Last Glacial Maximum
are then discussed. The insights gained from this study will be used to help validate and constrain ice sheet models where these ice-ocean
interactions are not currently well represented.

How to cite: Timbs, R. and Montelli, A.: Insight into ice-ocean interactions during the Last Deglaciation revealed by iceberg ploughmarks identified on the continental shelf of the West Antarctic Peninsula, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7838, https://doi.org/10.5194/egusphere-egu26-7838, 2026.

The last two deglaciations mark transitions from glacial to interglacial climates, dramatically reshaping Northern Hemisphere ice sheets. Numerical modelling of these transitions provides critical insight into the processes controlling ice-sheet retreat and collapse. Comparing the last two deglaciations allows us to evaluate how different forcings and initial conditions influence ice-sheet dynamics and understand the interplay between orbital forcing, greenhouse gases, abrupt climate changes and ice sheet instabilities in driving ice sheet evolution.

We use the fast yet comprehensive coupled General Circulation Atmosphere–ice-sheet model FAMOUS–BISICLES to simulate the Northern Hemisphere ice-sheet evolution during the penultimate deglaciation (140–128 thousand years ago; ka) and the last deglaciation (21-7 ka), with particular interest in the abrupt Bølling warming (14.5 ka). Our simulations follow the PMIP4 (Palaeoclimate Model Intercomparison Project 4) protocols and are forced with prescribed sea surface temperatures and sea ice from transient climate model outputs to reduce biases and force millennial abrupt climate changes.

First, we compare the penultimate and last deglaciations to assess how orbital forcing, greenhouse gas concentrations, and uncertain model parameters and SST inputs shape both the pace and spatial patterns of ice retreat. Results indicate a faster ice retreat during the penultimate deglaciation. Sensitivity experiments show that the rate of deglaciation is particularly sensitive to processes that impact the surface mass balance, but ice dynamics also play an important role. Sub-shelf melt rate is less significant; however, it can be important where confined ice shelves are able to form. Although insolation drives the deglaciations, rising greenhouse gases and warming SSTs significantly amplify the ice-sheet response to orbital forcing.

Second, we focus on the abrupt Bølling warming (~14.5 ka). Our simulations show accelerated deglaciation during this event, though the magnitude of response depends on the ice-sheet topography during the warming and on the pattern of abrupt SST increase prescribed. Marine-based sections, particularly the Barents–Kara ice sheet, exhibit the greatest sensitivity to prescribed ocean changes.

How to cite: Gregoire, L., Patterson, V., Snoll, B., Ivanovic, R., Gandy, N., Rome, Y., Arthur, F., and Sherriff-Tadano, S.: Northern Hemisphere ice-sheet dynamics during the last two deglaciations: responses to gradual and abrupt climate changes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8317, https://doi.org/10.5194/egusphere-egu26-8317, 2026.

Mass loss from ice sheets under the ongoing anthropogenic warming is a major contributor to sea-level rise. Previous studies suggest that global warming exceeding 2 °C could push the marine-based West Antarctic Ice Sheet beyond a critical threshold, triggering irreversible retreat and multi-meter rise in the global-mean sea-level. Climate overshoot scenarios are a key focus of CMIP7, yet most existing work on the reversibility of ice sheets is based on quasi-equilibrium simulations, with much less attention paid to ice sheets' stability and reversibility under century-scale transient climate forcing. Here we use climate and ice sheet models to simulate the evolution of the Antarctic and Greenland ice sheets under multiple climate overshoot scenarios. Results show that net-negative emissions in overshoot pathways can substantially reduce ice loss from the Greenland Ice Sheet, but are less effective in mitigating retreat of the West Antarctic Ice Sheet. This indicates that the West Antarctic Ice Sheet may also exhibit a tipping behavior under overshoot scenarios, and that achieving carbon neutral early is crucial to avoiding a potential catastrophic sea-level rise.

How to cite: Li, D.: Stability and reversibility of ice sheets in climate overshoot scenarios, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8704, https://doi.org/10.5194/egusphere-egu26-8704, 2026.

We present our development of the Ice sheet model for Integrated Earth-system Studies (IcIES2) for the Antarctic ice sheet configuration as a model development for CMIP7-ISMIP7. The flow of the ice is calculated with the shallow ice approximation (SIA) and shallow shelf approximation (SSA). To represent the migration of grounding lines, we use the grounding line flux boundary condition of Schoof (2007), following previous implementations (Pollard and DeConto 2012; 2020). The ice velocity fields are calculated using a hybrid approach that combines the SIA and SSA approximations, based on the ratio of basal sliding velocity to the depth-averaged velocity from the SIA solution. We perform sensitivity experiments on ice-sheet model parameters using the present-day bedrock topography and surface mass balance to obtain a reasonable present-day Antarctic ice-sheet configuration. We also perform experiments with an abrupt increase in sub-shelf melting to evaluate the model response to reduced ice shelf buttressing and marine ice sheet instability.

How to cite: Obase, T., Saito, F., and Abe-Ouchi, A.: Developments and evaluation of ice sheet model IcIES2 for Antarctic configuration, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8750, https://doi.org/10.5194/egusphere-egu26-8750, 2026.

When studying the future evolution and sea level contribution of the Greenland ice sheet, a realistic representation of ice sheet–atmosphere interactions in simulations is crucial. Therefore, to analyse the ice sheet evolution over the coming three centuries, we have performed several fully coupled ice sheet–regional climate model simulations. Our two-way coupled MAR–GISM simulations were driven by IPSL-CM6A-LR output under the SSP5-8.5 scenario, available up to 2300, and outlet glacier retreat was included through an empirical retreat parametrization.

To disentangle the long-term importance of ice mass loss through surface mass balance (SMB) versus marine discharge, we compare simulations with only atmospheric or oceanic forcing to simulations with both forcings applied simultaneously. They indicate that both atmospheric and oceanic forcing individually still lead to a similar sea level contribution by 2100. But, by 2300 the SMB-driven ice mass loss is about five times larger than the discharge-driven ice mass loss in our simulations, as the ice sheet retreats on land and gradually loses contact with the ocean. Besides, an analysis of the SMB components and freshwater fluxes between simulations demonstrates that surface melting and ice discharge through the ice–ocean boundary are mutually competitive processes.

Lastly, in terms of total ice mass loss, the importance of the chosen sensitivity parameter in the retreat parametrization increases over time. Whereas the difference in ice mass loss contribution from SMB versus discharge attenuates between simulations of differing sensitivity, because surface melting becomes increasingly dominant relative to marine discharge. Nevertheless, our simulations indicate that the applicability of the empirical retreat parametrization, which was developed for recent observations, becomes questionable over time. 

How to cite: Paice, C. M., Fettweis, X., and Huybrechts, P.: Surface melt outweighs ice discharge over the next three centuries in fully coupled MAR-GISM simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9160, https://doi.org/10.5194/egusphere-egu26-9160, 2026.

The magnitude of the Antarctic Ice Sheet's response to future climate scenarios in ice sheet models depends on the choice of initial and basal sliding conditions. Basal sliding cannot be directly measured but is instead commonly inferred from observed surface velocity or ice thickness assuming the ice sheet is in equilibrium with the modern climate. The inferred basal sliding field is also affected by assumptions of different model parameters and the ice rheology, which all impact the modelled ice sheet behaviour. Ice rheology is often treated as idealised, prescribed as uniform, or also inferred from velocity observations. Such approaches lead to either a non-unique problem or to compensating errors in the inferred fields due to intrinsic uncertainties in the observations.

To reduce compensating errors and not assume equilibrium with the modern climate, we force our ice sheet initial geometry with long-term temperature variations (i.e., a thermal spinup), thus generating a thermal structure (and therefore ice rheology) that is consistent with the ice sheet's long-term climate history. We assess different approaches to combine the thermal spinup with initialisation procedures for the Antarctic Ice Sheet, analysing their match to observed borehole temperatures at ice core sites. By initialising Antarctic Ice Sheet simulations with a thermal spinup, we improve our model’s initial conditions reducing the mismatch between modelled and observed ice sheet geometries and the uncertainty around the ice sheet's basal conditions and ice rheology with respect to basal and englacial temperatures. Finally, we use the different obtained initial states to show the impact of the ice sheet’s thermal history compared with idealised temperatures or equilibrium conditions on its sensitivity to future warming.

How to cite: Mas e Braga, M., Berends, T., Lambert, E., and Bernales, J.: The impact of ice sheet thermal memory in Antarctica’s response to climate warming, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9804, https://doi.org/10.5194/egusphere-egu26-9804, 2026.

The Mid-Pleistocene Transition (MPT) marks one of the most profound reorganizations of the Earth’s climate system over the Quaternary. During this interval, the dominant glacial-interglacial cyclicity shifted from 40 kyr to 100 kyr without a corresponding change in orbital forcing, implying fundamental internal feedbacks within the climate system. Post-MPT glaciations became longer (up to ~60 kyr), more severe, and characterized by larger and more stable Northern Hemisphere ice sheets. Despite intensive research into the mechanisms driving the MPT, the response of ocean trace metal cycling to Northern Hemisphere ice-sheet dynamics remains poorly constrained, limiting our ability to fully integrate ice-sheet evolution with changes in ocean circulation, elemental cycling, and the carbon cycle.

Here we present a new authigenic neodymium isotope (ε_Nd) record from ODP Site 982 (1134 m water depth), spanning 1.4–0.6 Ma and capturing the MPT. Our record reveals clear and systematic glacial-interglacial ε_Nd variability linked to the evolving Icelandic Ice Sheet (IIS) and its modulation of volcanic erosion and weathering fluxes into the NE Atlantic, coupled with southward shifts in deep-water formation during glacials. Before the MPT, interglacial ε_Nd values of -13.5 to -12.5 indicate persistent influence of Labrador Sea-derived waters, whereas glacial intervals are marked by more radiogenic ε_Nd from -11 around 1.4 Ma to -9 by 1.1 Ma, reflecting increasing Icelandic volcanic input influence associated with IIS expansion. From ~1.1 Ma onward, the ε_Nd contrast between climate states intensifies and reaches its strongest amplitude, with interglacials becoming slightly more unradiogenic (to -14) and glacials reaching radiogenic values up to -8. This persistent pattern of radiogenic in glacials and unradiogenic in interglacials continues into later cycles, indicating that Icelandic volcanic weathering and IIS extent reached their maximum expression since the MPT. Our results demonstrate that the IIS exerted first-order control on NE Atlantic seawater Nd isotope cycling during glacial periods, and that this modulation strengthened across and after the MPT. Importantly, the gradual amplification of Icelandic erosion signals suggests that Northern Hemisphere ice-sheet expansion (at least in Iceland) was a response to, rather than the initial trigger of, the MPT, consistent with coupled ice-sheet–carbon cycle feedback frameworks.

How to cite: Xu, A. and Frank, N.: Strengthened Icelandic Ice Sheet control on Northeast Atlantic neodymium isotope variability across the Mid-Pleistocene Transition, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10172, https://doi.org/10.5194/egusphere-egu26-10172, 2026.

The ice sheets of the Antarctic continent are supported and stabilised by floating ice shelves. Any future decrease in ice shelf mass and stability is expected to increase ice sheet drainage thus potentially contributing to a rise in the global sea level. Basal melting is a critical factor concerning ice shelf stability. Its rates are strongly dependent on the bathymetry underneath the ice shelves, as this directly influences sub-ice water circulation and its interactions with the open ocean. Therefore, accurate knowledge of sub-ice bathymetry is crucial to estimate the exchange of water masses and heat with the open ocean. We have created a model of the seafloor topography beneath the Evans Ice Stream - draining into the Ronne Ice Shelf, one of the world’s largest ice shelves - by the inversion of legacy airborne gravity data constrained by seismic and ice-penetrating radar depth references. The new bathymetric model is a distinct improvement over existing topographic compilations based on interpolated depths, providing a range of new information on topographic characteristics beneath the ice shelf with increased resolution and detail. The model shows a deep, asymmetric and U-shaped trough beneath the Evans Ice Stream that follows the ice stream’s flow direction. The bathymetry shows that the retrograde slope of the seafloor on the continental shelf and beneath the outer Ronne Ice Shelf continues as far as the ice stream’s grounding line. Should warm water masses from the open ocean cross the continental shelf edge, this slope would permit intrusion of these water masses all the way up to the grounding line. The new bathymetric model thus enables a step towards being able to more confidentially estimate basal melt rates beneath the Evans Ice Stream and their effect on ice shelf and ice sheet stability. The depth and shape of the seabed beneath numerous other ice shelves and areas of permanent sea ice coverage around the Antarctic margins remains poorly constrained or completely unknown. As well as the Evans cavity model, new data and plans for upcoming bathymetric modelling of some of these other areas are highlighted.

How to cite: Höppner, L. K., Eagles, G., Eisermann, H., Dorschel, B., Pail, R., Geissler, W. H., and Brisbourne, A. M.: Sub-Ice Shelf Topography in Antarctica: Aerogeophysical Modelling and Implications for Ice Shelf Stability – A Case Study at the Evans Ice Stream, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10519, https://doi.org/10.5194/egusphere-egu26-10519, 2026.

The mid-Piacenzian Warm Period (mPWP; 3.264 to 3.025 Ma) is a ~240 kyr long period with CO₂ concentrations between 350 and 530 ppmv, in the same range as in the middle of the road emission scenario SSP2-4.5 by 2100. Temperatures were between 2 and 5˚C above the pre-industrial state for a sustained period and as a result, sea-level high stands up to +17.2 m have been inferred. Taking into account a maximum contribution from thermal expansion of 1.6 m, the remainder should have been caused by (partial) melting of either the Greenland ice sheet (GrIS) or the Antarctic ice sheet (AIS), or both, as other ice sheets on the continents of the northern hemisphere were very likely absent.

Previous work has illustrated that the simulated GrIS and AIS size is strongly dependent on the applied climate -and ice sheet models. One way to constrain the ice sheet volume of the GrIS and AIS is by making use of the partition of the benthic oxygen isotope records in a terrestrial ice sheet component and a deep-sea temperature change component. Here we simulate various GrIS and AIS geometries based on available climate model output from the Pliocene Model Intercomparison Phase 2 (PlioMIP2) and compute the isotopic composition of the ice sheets. By selecting the ice sheet geometries that correspond best to the reconstructions for the terrestrial ice sheet component from the benthic oxygen isotope record, we further constrain the minimum GrIS and AIS extent during the mPWP.

How to cite: Van Breedam, J. and Huybrechts, P.: Modeling the Greenland ice sheet and Antarctic ice sheet during the mid-Piacenzian Warm Period, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10967, https://doi.org/10.5194/egusphere-egu26-10967, 2026.

During the Last Glacial Maximum, the Patagonian Ice Sheet (PIS) was the second-largest ice mass in the Southern Hemisphere after Antarctica, extending across the southern Andes from ~38°S to 55°S. Today, only 5% of this ice mass remains. Here, we present a continuous reconstruction of the extent and dynamics of the western PIS between 16 and 42 kyr cal BP, derived from marine sediment core MD07-3119. The core was analysed using a multiproxy inorganic approach, including grain size, ice-rafted debris (IRD), inorganic geochemistry, and bulk mineralogy, to reconstruct sediment provenance and transport processes. These results are compared with moraine-based chronologies from the eastern PIS. Variations in bulk mineralogy, IRD content, and inorganic geochemistry indicate that the western PIS, which was land-terminating until 37 kyr cal BP, experienced five distinct Ice Expansion Intervals between 16 and 37 kyr cal BP. Data indicate that each Ice Expansion Interval is associated with enhanced sediment input from the coastal metamorphic unit. Our record indicates periods of high sediment discharge of predominantly Patagonian batholith origin corresponding to melting phases between these advances. The longest advance, at 37–31 kyr cal BP, lasted nearly 6 kyr. Variations in provenance proxies imply that PIS outlet glaciers retreated at least 65 km inland between successive advances. Our reconstruction indicates a complex temporal relationship between the western and eastern PIS margins. Overall, most ice retreat intervals in MD07-3119 match terrestrial exposure ages from the eastern side of the PIS, but the eastern PIS often appears to start shrinking earlier than its western side.

How to cite: Lebeaupin, K., Bertrand, S., Siani, G., Michel, E., Andrzejewski, L., and Leonetti, J.: Extent and Dynamics of the Western Patagonian Ice Sheet Between 16 and 42 kyr cal BP, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11397, https://doi.org/10.5194/egusphere-egu26-11397, 2026.

Earth’s climate is fast approaching a warming of 1.5°C above pre-industrial levels. While the global mean temperature change may be limited on the long term following an overshoot (or peak-and-decline) climate trajectory, the regional climate impacts in Antarctica that might result are highly uncertain: Given the complex interplay of several amplifying and dampening feedbacks in the Antarctic ice-sheet system and associated tipping dynamics, a rich set of changes – ranging from (fully) reversible to potentially irreversible to irreversible – are possible. 

Here, we quantify the response of the Antarctic Ice Sheet and associated uncertainties across multi-centennial to millennial timescales to a wide range of projected climate overshoot trajectories using the Parallel Ice Sheet Model (PISM). 

Overall, our results suggest that the impacts of overshooting 1.5°C on the Antarctic Ice Sheet worsen with increasing magnitude and duration, and are strongly dependent on the landing climate. Even temporary overshoots can have long-lasting, if not irreversible impacts, stressing the need for limiting global warming to ensure the stability of the Antarctic Ice Sheet across timescales.

How to cite: Klose, A. K. and Winkelmann, R.: Future Antarctic ice loss under climate overshoot trajectories, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11453, https://doi.org/10.5194/egusphere-egu26-11453, 2026.

Melting from oceanic heat and basal lubrication from subglacial freshwater are fundamental elements of West Antarctic Ice Sheet mass balance that are poorly constrained. The ice streams feeding the Ross Ice Shelf grounding line periodically start and stall over decadal to century timescales due to shifts in these forcings. Here, we present in situ hydrographic measurements, noble gas abundances, and helium isotope ratios from a l a r g e subglacial channel melted into the base of stagnant Kamb Ice Stream. These data identify an outflowing plume containing subglacial freshwater admixture from upstream volcanic activity and anomalously warm inflowing seawater containing Circumpolar Deep Water from the Ross Sea, with oceanic heat delivery outpacing that from volcanism. Our results directly quantify both variables that affect the mass balance of the Ross Ice Shelf’s sensitive interconnected ice streams and highlight the vulnerability of this region of West Antarctica to increased forcing from a warming climate.

How to cite: Washam, P., Schmidt, B., Loose, B., Horgan, H., Stewart, C., Stevens, C., Lawrence, J., Hulbe, C., and Hurwitz, B.: Sources of oceanic and volcanic heat melting a subglacial channel in Kamb Ice Stream,West Antarctica, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12014, https://doi.org/10.5194/egusphere-egu26-12014, 2026.

Glaciers are key hydro-climatic indicators and markers of atmospheric changes in the past, making them essential tools for reconstructing glacial paleoenvironments and paleoclimates. As a climatically stable period that is drastically different from today, the Last Glacial Maximum (LGM, 26–19 ka BP) is widely used as a benchmark for evaluating climate sensitivity (i.e., a key parameter linking atmospheric CO₂ to temperature) and for comparing climate model simulations with continental reconstructions from multiple proxy archives.

Pollen assemblages are a commonly used proxy for reconstructing past temperature changes, as they offer broad spatial coverage across Europe. However, particularly in Europe, simulated LGM annual temperatures often show substantial disagreement with reconstructions and appear highly heterogeneous across models. Dated glacier extents provide an independent archive, helping to assess data–model comparisons.

Temperature is a critical variable to estimate the surface mass balance of glaciers (i.e., the difference between accumulation and ablation). Surface mass balance models (e.g., the positive degree day, PDD, model; [1]) provide the climatic conditions required to reproduce the extent of paleo-ice sheets (inverse approach), as constrained by geomorphological evidence.

PDD-based ice sheet models in central Europe ([2]; [3]) indicate stronger LGM cooling than pollen reconstructions (e.g., [4]), a mismatch likely linked to seasonal biases given the high sensitivity of glaciers to seasonal temperatures ([5]; [6]). Yet, seasonal LGM reconstructions remain scarce, and recent syntheses highlight marked inconsistencies in seasonality anomalies across European glaciated regions, including the Vosges ([7]) - which are too small to be captured by climate models (Global Circulation Models, GCMs).

Using a new compilation of 10Be cosmogenic exposure ages ([8]; [9]) in the Vosges Mountains (NE France) and the GRISLI ice sheet model ([10]), this study investigates the impact of LGM seasonal and precipitation anomalies on simulated glacier extents and on LGM data-model cooling agreement.

As results, we deduce a high variability of LGM climate conditions sufficient to reproduce the paleo-ice sheet extent in the Vosges, yet none of them match the pollen-based paleoclimatic reconstructions ([11]). However, some LGM climate models produce temperature conditions (annual and seasonal) similar to the GRISLI results, while producing lower precipitation in the Vosges (60% to 120% lower than GRISLI results). While the calibration of the GRISLI model has a minor effect on these results, one of the more feasible ways to minimize data–model discrepancies in climate spaces - considering paleoclimatic reconstructions - would be to substantially increase precipitation (+380%, i.e., ~5 times modern precipitation) in the restricted Vosges massif during the LGM.

[1] Reeh, 11-128 (erschienen, 1991)

[2] Allen +, https://cp.copernicus.org/articles/4/249/2008/

[3] Heyman, https://doi.org/10.1016/j.yqres.2012.09.005

[4] Davis +, https://cp.copernicus.org/articles/20/1939/2024/

[5] Oerlemans and Riechert, https://doi.org/10.3189/172756500781833269

[6] Huss and Hock, https://www.nature.com/articles/s41558-017-0049-x

[7 & 11] Fénisse +, in prep

[8] Harmand, https://doi.org/10.4000/rge.9703

[9] Blard +, in prep

[10] Quiquet +, https://doi.org/10.5194/gmd-11-5003-2018

How to cite: Fénisse, G., Quiquet, A., Brenner, J.-B., Blard, P.-H., and Bekaert, D. V.: Seasonal climate impacts on LGM glaciers in the Vosges(France): Insights from GRISLI modeling and paleo-extent, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12182, https://doi.org/10.5194/egusphere-egu26-12182, 2026.

Understanding the response of the Greenland Ice Sheet to past climate variability is essential for improving projections of its future evolution and contributions to sea-level rise. As part of the ChronIce project (Chronicling Greenland Ice Sheet evolution through past warm climates), this study investigates the response of the northern Greenland Ice Sheet to past climate forcing by reconstructing changes in physical weathering, erosion, and ice–ocean dynamics. We focus on North-West Greenland using a unique marine sedimentary archive recovered during International Ocean Discovery Program Expedition 400.

Temporal variations in glacial outlet provenance, weathering intensity, and erosion are examined using detrital mineralogical and geochemical approaches applied to sediment records from sites U1604, U1606, U1607 and U1608. Heavy mineral fractions are analyzed using Automated Quantitative Mineralogy–Scanning Electron Microscopy (AQM-SEM) and Laser Ablation–Inductively Coupled Plasma–Mass Spectrometry (LA-ICP-MS) that enables single-grain U–Pb geochronology and provenance fingerprints of ice-rafted debris (IRD). Here we will show results from zircon, apatite, titanite, and other datable minerals which, in combination with IRD grain-size and textural analyses, can provide new insights on sediment transport pathways, weathering processes and source regions linked to glacial erosion during the late Pliocene and Pleistocene.  

How to cite: Störling, T., Keulen, N., Malkki, S. N., Thrane, K., Heredia, B., Monedero-Contreras, R. D., Perez, L. F., Zimmermann, H. H., and Knutz, P. C.: Tracing Greenland Ice Sheet dynamics during past warm climates, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12379, https://doi.org/10.5194/egusphere-egu26-12379, 2026.