Alexander von Humboldt’s integrative view of nature, combining exploration and long-term observations with a cross-disciplinary view on the biogeography of mountains provides a powerful inspiration for understanding changes in the water cycle of High Mountain Asia. This lecture synthesizes recent advances in hydro‑climatic and cryospheric research to assess evolving meteorology, snow and glacier dynamics, and water resources across the region. First, using high-altitude in situ datasets, we systematically quantify fine‑scale spatial and temporal variability and uncertainty in key meteorological variables, with emphasis on precipitation, temperature, and evapotranspiration. We then apply high‑resolution atmospheric modeling to diagnose how major mountain ranges shape regional climate and weather patterns and to evaluate projected shifts under future forcing scenarios. Turning to the cryosphere, we document changes in snow cover and glacier mass balance and discuss drivers related to debris cover, glacier geometry, glacier lakes, and snow dynamics. Finally, we analyze the high‑altitude water cycle by resolving regional heterogeneity in the contributions of snowmelt and glacier melt to streamflow, examining vegetation change and associated land–atmosphere feedbacks, and highlighting the role of groundwater in the mountain water cycle. We identify elevation bands that are disproportionately critical for sustaining mountain water supplies and downstream water security. The synthesis highlights critical challenges for high altitude hydro-climatic research, including persistent observational gaps at high elevations, scaling and representativeness issues, and limitations in coupled model integration and attribution. It offers recommendations for exploratory, inclusive, and collaborative research to advance process understanding and actionable water-resource assessments in the world’s mountain regions.

How to cite: Immerzeel, W.: Climate driven changes in ice and water through Humboldt’s lens in High Mountain Asia, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1732, https://doi.org/10.5194/egusphere-egu26-1732, 2026.

As a PhD student encountering the “Bretherton Diagram” for the first time, I was struck by the complexity of the Earth system and simultaneously motivated to bridge a gap in the model hierarchy—between general circulation models and simple box models. In 1990, I was fortunate to meet the late Daniel Wright, and together we set out to develop a compact and affordable model that would allow us to conduct our own climate simulations. This reduced-complexity climate model paved the way for a new class of models that enabled (i) large ensembles for probabilistic climate simulations, (ii) million-year integrations to explore paleoclimate dynamics, and (iii) the coupling of physical and biogeochemical cycles for direct tracer simulations.

Such reduced-complexity models opened the door to new collaborations with the highly organized paleoscience community. Suddenly, a tool became available that helped illuminate emerging and intriguing paleoclimate records, including shifts in ocean tracer distributions and abrupt changes in isotope records from Greenland ice cores, along with their associated fingerprints in Antarctic ice cores. The Dansgaard–Oeschger events continue to challenge our understanding, but, to quote Alfred Wegener, “we are like a judge confronted by a defendant who declines to answer, and we must determine the truth from the circumstantial evidence.”

Over four decades of effort, climate modeling and paleoclimate analysis have drawn closer together and now routinely produce this much-needed circumstantial evidence. Coupled physical–biogeochemical simulations help to exclude or support hypotheses concerning the sequence of events during glacial inceptions and terminations, as well as global shifts in climate dynamics during the Mid-Pleistocene Transition. The combination of paleoclimate modeling and high-resolution analyses of paleoclimate records also provides a foundation for consensus-building on the highly debated issue of high-impact events and tipping points, which will be assessed in the forthcoming IPCC AR7. In this way, paleoclimate science is centrally relevant to inform us about possible surprises or global disruption of the climate system in response to the continuing use of fossil fuels.

In this lecture, I will recall some of these highlights, share anecdotes, and discuss several of the open “big questions” that we still need to tackle. It has been a great privilege to be part of the climate science community and to be guided and inspired by colleagues and friends around the world. I am immensely grateful to the students, postdocs and colleagues with whom I could work in our shared effort to understand the climate system.

How to cite: Stocker, T.: From the Past to the Future: 40 Years of Shared Effort to Understand Climate, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4247, https://doi.org/10.5194/egusphere-egu26-4247, 2026.

A new geological map (scale: 1:1.5 M) of the Greater Himalayan Ranges has been compiled and will be published in two sheets. The Western Sheet includes the Pamir, Hindu Kush, Karakoram, Kohistan, Ladakh ranges, including SW Tibet, with the Nanga Parbat syntaxis, and the Pakistan and Indian Himalaya. It extends from the Afghanistan-Pakistan border in the west to the India-Nepal border in the east. The Eastern Sheet includes the Nepal, Sikkim, Bhutan, Arunachal Pradesh ranges, southeast Tibet, Namche Barwa syntaxis, the Shillong Plateau and northwest Myanmar (Burma) ranges. The map includes four cross-sections, and a detailed Key. Together with magmatic, metamorphic, thermobarometric, strain measurements, and geochronological and geophysical data, several key geological processes can be deduced from all these geological strands:

The India-Asia collision is marked by the Indus – Yarlung Tsangpo suture zone containing Tethyan oceanic sedimentary and volcanic rocks, and Jurassic and Cretaceous ophiolites. The age of final collision is given by the youngest marine Nummulitic limestones (50.5 Ma), after which continental fluvial conglomerates and lacustrine Indus Group molasse sediments predominate. Structures along the ITSZ are steep and dominantly folded and backthrust to the north. The northern Himalaya (Tethyan Himalaya) consist of strongly folded and thrust shelf sediments of Neoproterozoic – Eocene age, showing south-vergent folds and thrusts in the south and steep north-vergent backthrusts and folds along the north (Great Counter Thrust).

The western (Nanga Parbat) and eastern (Namche Barwa) Himalayan syntaxis both exhume Pliocene-Pleistocene metamorphic-magmatic (U-Pb monazite ages 0.9-0.7 Ma) cordierite+sillimanite leucogranite melts and migmatites, that may represent deep, unexposed levels of the northern Himalaya. The Greater Himalayan Sequence comprises the metamorphic core of the Himalaya and corresponds to the major zone of high topography. Eocene – Miocene metamorphism reaches kyanite grade, and later sillimanite grade. The youngest (~13-11 Ma) and deepest (~1.2 GPa) granulite facies rocks in the Ama Drime range, north of Everest, contain lenses of garnet+omphacite+orthopyroxene granulitised eclogites representing the deepest levels of thickened crust. Himalayan migmatites and leucogranites containing K-feldspar+garnet+tourmaline+muscovite+biotite with late cordierite, occur along the highest structural levels of the Great Himalayan Sequence along the entire chain. U-Pb monazite ages span 35-11 Ma, with the majority around 23-19 Ma. Many of the highest peaks are comprised of these leucogranites (Shivling, Manaslu, Shisha Pangma, Langtang Lirung, Nuptse, base of Everest, Makalu, Kangchenjunga, Kula Kangri etc). Most leucogranites have intruded as sills that can mapped for >70 km across strike in the Rongbuk valley, Tibet.

The metamorphic core of the Himalaya is bounded by a north-dipping low-angle normal fault (South Tibetan Detachment) showing right way-up metamorphic isograds along the top, and a south-vergent ductile shear zone (Main Central Thrust) with inverted metamorphic isograds along the base. The geometry is consistent with the southward extrusion of a partially molten layer of middle crust during the Miocene (Channel Flow). The Lesser Himalaya structure is consistent with the Critical Taper model. The active Main Himalayan thrust is the youngest thrust along which the Indian plate is subducting and uplifting the Himalaya now.

How to cite: Searle, M.: A new Geological Map of the Greater Himalayan Ranges; mountain building processes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1900, https://doi.org/10.5194/egusphere-egu26-1900, 2026.

Planets form and acquire their compositions from the residual dust and gas in protoplanetary disks surrounding young stars. The chemical nature of this material governs nearly every aspect of planetary composition, from bulk chemistry and volatile inventories to atmospheric properties and the conditions required for life. In this talk, I will present recent advances from cosmochemical studies of meteorites, asteroids, and returned planetary samples that provide new constraints on the formation and early evolution of the Solar System. High-precision isotopic measurements reveal that planetary building blocks inherited nucleosynthetic heterogeneity from their natal environment, reflecting both stellar sources and thermal processing within the protoplanetary disk. In particular, emerging evidence shows that supernova-derived material was delivered to the disk in volatile interstellar ices and selectively removed in the inner disk, establishing large-scale chemical gradients that were subsequently recorded by asteroids and planets. These observations support a formation framework in which planetesimals formed rapidly by streaming instability and grew predominantly by pebble accretion, allowing efficient inward transport of volatile-rich material during the main growth phase of rocky planets. Together, these results link disk-scale transport processes, planetary accretion timescales, and the origin of volatile elements, and suggest that the acquisition of life-essential volatiles is a natural outcome of planet formation. As such, the chemical conditions required for habitable worlds may be common in planetary systems beyond our Solar System.

How to cite: Bizzarro, M.: From stars to planets: chemical pathways to habitable worlds, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4229, https://doi.org/10.5194/egusphere-egu26-4229, 2026.

Flood risk emerges from dynamic interactions among climate extremes, human systems, and cascading impact pathways that extend into economic, social, and health domains. Traditional risk assessments often inadequately represent these interdependencies. Responding to emerging evidence that flood risk is shaped by interdependencies, health impacts, and evolving vulnerability, my research develops a suite of methodological approaches to advance systemic flood risk modelling. These include system dynamics modelling to capture feedback between hazard, exposure, vulnerability, and human adaptation; hierarchical Bayesian regression and multivariate statistical models to quantify cascading impacts across sectors and scales; and scenario-based simulations that explore how changes in drivers and adaptive responses modulate risk pathways. We further leverage longitudinal survey datasets, probabilistic methods, and open datasets to bridge local empirical findings with broader flood risk dynamics. By integrating health risk metrics which are often missing from conventional frameworks alongside economic and social outcomes, our methods aim to quantify the full cascade of flood impacts and support evidence-based adaptation strategies and inclusive disaster risk management that reflect the complex Human–Flood system.

How to cite: Sairam, N.: Quantifying Cascading Economic, Social, and Health Impacts of Flooding, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13128, https://doi.org/10.5194/egusphere-egu26-13128, 2026.

To oversimplify things slightly, there are two types of story in journalism: the short ones and the long ones. I’ve spent much of my career so far focussed on the latter, known as features, which has meant an awful lot of head-scratching about how to keep readers engaged, excited, gripped by a story that goes on for several thousand words – no simple matter in the age of AI slop and TikTok.  

In this lecture, I’ll spill the beans on how we do things at New Scientist magazine, where I have worked for just over 10 years, with special reference to an idea known as “sleepy cat” from the mind of my brilliant former colleague Graham Lawton. I’ll also show how I used some of the tricks of creating compelling narratives in one of the stories in my book, The Meteorite Hunters – namely the tale of Jon Larsen, the Norwegian jazz guitarist who hunts cosmic dust on urban rooftops. 

Whether you want to better understand how journalists think, yearn to improve your own writing, or just enjoy thinking about how stories work, there should be something of interest here for you.

How to cite: Howgego, J.: Sleepy cat and the cosmic dust: Lessons for non-fiction writing from 10 years as a magazine editor , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3534, https://doi.org/10.5194/egusphere-egu26-3534, 2026.

In October of 2025, the first female Prime Minister of Japan was appointed, marking a historic milestone for the gender equality movement. This event signifies the first female leader in over 140 years of Japanese political history.

This phenomenon seems to be breaking the glass ceiling in Japan's older, male-dominated political society. Japanese female leaders are now facing a new vision beyond the glass ceiling.

Among Japanese geoscience societies, the female president of the Japan Geoscience Union (JpGU) and the Geological Society of Japan (JGS) has not yet been raised. The JGS was established in 1893 and celebrated its 130th anniversary in 2023, having a similar longevity to the Japanese parliament. The first EDI committee of JGS was established in 1995 to promote women in geoscience. Since that time, such EDI committees/WG of JGS and JpGU have continued their efforts to encourage women's involvement by implementing measures such as conducting surveys, setting up a childcare room during the conference for participants with children, and arranging research exchange meetings among female scientists; however, no remarkable progress has been achieved.

The turning/breaking point came in 2018, when we began collaborating with colleagues from the EGU and the AGU to organize sessions promoting EDI. International collaboration on EDI, whether formal or informal (e.g., several online meetings led by Dr. Claudia JESUS-RYDIN), has provided us with diverse perspectives and strongly fostered the development of initiatives, thereby advancing EDI in the Earth sciences. For example, the EDI logo was introduced at the EGU 2021 General Assembly, the JpGU Meeting 2021, and the 2023 JGS annual meeting. Later, the ECS logo was introduced in Japan as well.

In this challenging age of accelerating global warming and frequent disasters, the role of geoscience research and researchers is crucial. Although our cultures, customs, values, and languages differ, recognizing these differences while transcending them to respect one another and work together is undoubtedly a critical key to overcoming these difficulties. This requires steady and consolidated international collaboration among Earth scientists, working hand in hand beyond various barriers and ceilings.

In Japan, the glass ceiling has first broken down at the top of the political field, long considered the most lagging in women's participation (one of the reasons cited for Japan being ranked worst (118th) among G7 nations in the Gender Gap Index 2025), and society is moving slowly forward with perspectives different from the old ways and through unexpected procedures.

Beyond the glass ceiling lie new challenges; however, if we continue to strive forward while upholding the spirit of Equity/Equality, Diversity, and Inclusion (EDI) with our colleagues, we will see a new horizon.

How to cite: Rie, H. S.:  Beyond the glass ceiling, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9389, https://doi.org/10.5194/egusphere-egu26-9389, 2026.

Scientific thinking requires the critical analysis of information, while science itself thrives on the diversity of ideas. Yet, science, technology, engineering, and math (STEM) subjects have historically struggled to be inclusive and accessible to students from underrepresented communities - meaning we often miss a diversity of voices. Furthermore, STEM subjects have often been rigid in their teaching structure, creating barriers to education for students with more specific (or unrecognised) learning needs.

To address this, our science outreach course Think Like A Scientist was designed to improve critical thinking and encourage independent thought by applying adaptive education practices to create inclusive and accessible classroom environments. The program started in 2017 and has been applied in several different settings (e.g., schools and adult learning centres), but has mainly featured in prisons around the world (including England, Canada, Australia, and Spain).

Our students in prison often have a complex relationship with learning – such as low confidence in themselves or the education system (which is also a common trait amongst STEM university students from diverse communities). In addition, a classroom can present numerous other barriers for prison students (e.g., sensory, communication, information processing, and regulation) which particularly impacts neurodivergent learners (e.g., autism, ADHD, OCD, dyslexia, etc.). In our teaching in prison, we have been conscious of creating different educational access points that are not solely reliant on rigid teaching structures.

In this Katia and Maurice Krafft Award talk, I will outline the choices we have made in prison education to increase educational engagement - and how these choices can map onto other avenues of science communication to widen STEM participation. I’ll also share the impact of such practices on our students and how placing learners at the centre of education can be transformative.  

Fundamentally, as a society we need an informed population of any background who can think critically, especially in today’s world of fake news. In our sessions, we replicate this through learning from each other to Think Like A Scientist.

How to cite: Heron, P. and the Think Like A Scientist team: What we’ve learned from teaching people in prison to Think Like a Scientist , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8373, https://doi.org/10.5194/egusphere-egu26-8373, 2026.

We are living in a world of wicked issues, climate crisis, geopolitical instability, mis- and disinformation, to name a few. Interconnected and complex issues require system-level analysis across disciplinary boundaries. Yet conventional models of science advice often fall short: When subscribing to a linear logic of science-policy communication, the advice is often not timely, lacks phenomenal/systemic perspective and thus impact remains low.

Sustaining societal resilience amid uncertainty requires that science-policy collaboration is strategically and systematically embedded in decision-making. Knowledge brokering offers an accessible but potentially transformative means of driving this systemic change.

Drawing on our experience as knowledge brokers in Finland, we demonstrate practical approaches that reimagine how researchers engage with policymakers, stakeholders, and society at large. We share concrete methods and tools from national policymaking that can be adapted to diverse policy contexts internationally.

How to cite: Lammensalo, L. and Koivulehto, I.: Knowledge Brokers: Turning Research into Policy Impact, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21069, https://doi.org/10.5194/egusphere-egu26-21069, 2026.

Cryptogamic communities (CC) are assemblages of photoautotrophic non-vascular organisms, such as cyanobacteria, algae, lichens, and bryophytes, being accompanied by heterotrophic bacteria, microfungi, and archaea. They colonize almost all substrates on Earth, including soil, rocks, and vegetation. CC are particularly relevant in drylands, where they cover vast regions as biological soil crusts (biocrusts) colonizing the uppermost centimeters of the soil. Biocrusts perform highly relevant ecosystem processes, as they fertilize the soil by fixing carbon and nitrogen, balance water cycling, influence plant germination and growth, and effectively stabilize dryland soils.

Knowledge of the composition and distribution patterns of CC across spatial scales serves as a prerequisite to investigate their functional roles in regional and global Earth system processes. Thus, together with my research team, I investigated the microbial composition of biocrust types, defined by the visible photoautotrophic component (cyanobacteria, lichens, bryophytes), and discovered that these were characterized by distinct microbial communities that in turn impacted physiological biocrust functioning. For biocrust mapping, we established a deep learning-based classification technique, which, besides identification, also allows neighborhood and growth analyses. For biocrust identification at the regional scale, I developed one of the first high-resolution remote sensing algorithms utilizing hyperspectral imagery.

During my research, I investigated several functional roles of CC. In an international research team, we identified biocrusts as key nitrogen (N) fixers with an annual fixation of ~11.5 Tg, corresponding to ~18% of the overall N fixation in natural biomes. During N cycling in CC after fixation, we were the first to show major releases of reactive gases NO and HONO. These emissions were linked to precipitation, but heterogeneous microscale mechanisms limited process understanding. To address this, we now developed a controlled in-situ setup and applied a mechanistic model to clarify the underlying processes.

Applying a modeling approach, we developed a first global biocrust map, revealing that biocrusts cover ~18 * 10⁶ km², corresponding to about 1/3 of the global dryland area. Combining this map with data on the soil-stabilizing role of biocrusts, we assessed biocrust relevance in global dust cycling. Our results revealed that biocrusts reduce dryland dust emission and cycling by 60%, thus preventing the release of ~0.7 Pg of dust per year. This study was the first assessing global biocrust relevance and including this in Earth system models.

Although biocrusts thrive under extreme environmental conditions, our studies univocally demonstrate their high sensitivity towards global change. Utilizing our deep learning-method on a 16-year biocrust monitoring project on the Colorado Plateau, we observed a decrease in biocrust coverage by ~40%, with lichens and bryophytes reacting particularly sensitive to extended drought events. Similarly, biocrust coverage on the global scale will decrease by 16-39% until the year 2070 according to our mapping and modeling approach.

In summary, my research reveals that CC play key roles in biogeochemical processes but are also vulnerable by global change, which need to be considered both in ecosystem management and Earth system models to fully reflect their role and effectively meet future challenges of the Anthropocene.

How to cite: Weber, B.: Relevance of cryptogamic communities in Earth system processes under the impact of global change, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12853, https://doi.org/10.5194/egusphere-egu26-12853, 2026.

Subduction zones play a key role in the tectonic and chemical evolution of the Earth and are the site of the largest earthquakes and most explosive volcanic eruptions. Subduction zones are diverse, varying in rates, shape of the trench and slab, relative contribution and direction of trench motion versus plate motion, coupling between the two plates, and state of stress of the upper plate.

To understand what controls such diversity, my group and several others have been building a systematic understanding of subduction dynamics, starting from the simplest system of a single subducting plate, free subduction.  Free subduction models illustrate how sensitive the subduction system is to the balance between slab density which drives it, the resistance of the plate to bending at the trench (and base of the transition zone) and drag by the mantle below the unsubducted plate and around the slab. Tectonic reconstructions and seismic tomography show that in response to the extra resistance to sinking encountered at the transition to the lower mantle most slabs retreat and flatten. Such observations constrain the magnitude of slab strength relative to the other forces. Any dynamic models of subduction, even for investigating more complex dynamic settings, need to ensure plate properties yield such an earth-like sinking mode of subduction.

Varying trench shapes can be understood from variations in plate width, which lead to simple C-shaped trenches for small subduction zones or W-shapes for trenches that are long relative to slab bending lengths. Although slab pull is the dominant driver of mantle convection, local (plate-age) dependent slab buoyancy does not have a strong expression in trends of plate and trench velocities, indicating the importance of considering spatially varying plate buoyancy. Models show that buoyant features such as aseismic volcanic ridges can lead to either slab steepening or flattening depending on the background plate buoyancy and strength and position relative to the free-subduction shape of the trench. Together, these factors explain quite a bit of the complexity seen in natural subduction zones. Further influences come from global plate interactions, which limit the motions of upper and lower plates, and mantle flow including upwellings and flow driven by previously subducted slab remnants.

The resulting imbalance between the bending a free slab tries to achieve and the bending it undergoes to adjust to the net forces acting on the system affects how much of the deformation is viscous versus elastic. An initial study showed that a measure of this elasticity (the Deborah number) may correlate with the proportion of larger relative to smaller intraplate earthquakes.  In my talk, I will present a summary of some of these key previous insights into subduction dynamics and natural examples.

How to cite: Goes, S.: Towards understanding the dynamics of subduction zone diversity, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10356, https://doi.org/10.5194/egusphere-egu26-10356, 2026.

Earth's mantle drives fundamental processes that shape our planet and directly impact us. Convective flow induces both lateral and vertical motion of the surface, with consequences across timescales. Over geological time, dynamic topography modulates continental flooding, sedimentary basin development, and global sea level. On shorter timescales, glacial isostatic adjustment governs the ongoing response to ice sheet fluctuations, reshaping coastlines and redistributing ocean mass. These vertical motions, coupled with lateral plate displacements, also control the burial and exhumation of rocks, processes central to the genesis of mineral and critical resource deposits. Quantitative models of mantle dynamics are therefore essential not only for understanding Earth's past but for anticipating its future trajectory.

Traditional forward modelling approaches, while physically rigorous, fail to fully exploit the wealth of observational constraints now available, including seismic tomography, geodetic measurements, tectonic reconstructions, and geological indicators of past topography. These data encode invaluable information about mantle structure and rheology that forward models cannot systematically assimilate.

Here I present a framework for constructing Digital Twins of Earth's Mantle, physics-based models systematically optimised against observations using formal inverse methods. Central to this approach is the adjoint method, which enables efficient computation of gradients through complex time-dependent simulations, making large-scale inversions tractable.

I demonstrate this framework across three complementary problems spanning temporal scales. For long-term mantle evolution, I show how seismic tomography and plate reconstructions can be inverted to recover Earth's mantle history in the Cenozoic. Turning to the present day, I illustrate how observations of dynamic topography constrain three-dimensional variations in mantle rheology. Finally, addressing shorter timescales, I consider glacial isostatic adjustment, where the joint reconstruction of ice loading history and mantle viscosity structure emerges from geodetic and geological sea-level data.

Together, these applications establish adjoint-based Digital Twins as powerful tools for synthesis across Earth science disciplines, enabling both retrodiction of past states and predictions that inform sea level projections, coastal vulnerability assessment, and mineral exploration.

How to cite: Ghelichkhan, S.: Digital Twins of Earth's Mantle: Adjoint Inverse Approaches for Reconstructing Mantle Dynamics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19971, https://doi.org/10.5194/egusphere-egu26-19971, 2026.

In Gutenberg’s era, earthquakes were understood primarily as phenomena involving the release and propagation of seismic wave energy. Since the 1960s, seismic wave radiation has been explained by fault slip, and various characteristics of earthquakes have been successfully described by slip processes governed by friction laws on fault surfaces. As a result, the view that “earthquakes are fault slip” became widely accepted, and earthquake size is now usually represented not by radiated seismic energy but by seismic moment, a measure of fault slip. However, while earthquakes certainly involve fault slip, it is incorrect to assume that all fault slip represents an earthquake.

The discovery and increasing understanding of slow earthquakes in recent decades have made it necessary to reconsider a fundamental question: What exactly is an earthquake? What distinguishes slow earthquakes from regular earthquakes? Under what conditions does this distinction arise? Do regular earthquakes begin in a universal manner? Addressing such questions leads to a view of earthquakes as a coupled process of rock fracture and wave radiation that cascades through hierarchical heterogeneities spanning a wide range of spatial and temporal scales. I aim to discuss approaches for understanding—and ultimately forecasting—such complex, multiscale phenomena.

How to cite: Ide, S.: Rethinking Earthquakes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4764, https://doi.org/10.5194/egusphere-egu26-4764, 2026.

Earthquake source processes are described based on friction laws on faults, bulk constitutive behavior of the surrounding medium, and the stress state of an intricate fault network, including off-fault damage. The combination of these components forms a dynamic earthquake rupture model that accounts for the seismological, geodetic, and geological observations, as well as enables estimation of the earthquake energy budget. While such models help clarify key factors characterizing earthquake source processes, trade-offs among these factors often prevent identifying the dominant physical mechanism. For example, enhanced near-field high-frequency radiation can be attributed to fault roughness, structural heterogeneity, or coseismic off-fault damage (Okubo et al., 2019), each of which can produce similar observational signatures.

To mitigate the modeling uncertainties, information available from laboratory experiments can be utilized, such as fault geometry, bulk elastic properties, stress state, and frictional conditions. Here, I demonstrate this concept through a laboratory study aimed at controlling the size and location of earthquake source patches on a laboratory fault (Okubo et al., in revision). This approach provides a predetermined source configuration that can be incorporated into a dynamic rupture model. Circular gouge patches as earthquake sources were placed on a 4-meter-long laboratory fault in a large-scale biaxial apparatus, generating microearthquakes during the evolution of preslip or afterslip on the entire fault in stick-slip experiments. Acoustic emission waveforms carefully corrected for instrumental response and attenuation suggest that these earthquake clusters exhibit non-self-similar scaling. Using the controlled source geometry and the observed source parameters, we developed a dynamic rupture model that is quantitatively consistent with laboratory observations. Although this model is not a unique solution for explaining the observed non-self-similar scaling, given the limited information available to fully resolve the rupture process even under laboratory conditions, it complements previously proposed models for non-self-similar earthquakes and provides a useful basis for interpreting natural earthquakes.

Close integration of experiments and modeling is key to updating previous findings by addressing limitations in existing modeling frameworks. Large-scale experiments allow for spatially dense measurement arrays relative to the characteristic length scales of dynamic ruptures. Models quantitatively constrained by these high-quality measurements help clarify the details in source processes and play an important role in determining which observables, and at what resolution, are required to effectively monitor faulting activity.

How to cite: Okubo, K.: Advancing Knowledge of Earthquake Source Processes Through Dynamic Rupture Modeling with Natural and Laboratory Observables, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14630, https://doi.org/10.5194/egusphere-egu26-14630, 2026.

Sources of geophysical anomalies, such as density, susceptibility, conductivity, reflectivity, etc., are not always random as we often assume, but follow a scaling/fractal distribution. This has been demonstrated by analyzing borehole data from the German Continental Deep Drilling Programme (KTB) and other boreholes used for oil exploration. The new scaling spectral method (SSM) was developed to interpret gravity, magnetic, resistivity, and other geophysical measurements, which are better than the conventional spectral method. The application of fractal and scaling approaches in Earth science is widespread across all aspects of geophysics, including the acquisition, processing, and interpretation of geophysical data. The selection criteria for spacing for measurement stations in a 1D survey or grid size for a 2D survey have been suggested. Similarly, processing of non-stationary data is subdivided into stationary data for which the SSM can be applied. Potential field theory has also been studied in the context of fractals or scaling laws and has been found to be worthwhile in inferring the physical properties of the subsurface. The Voronoi tessellation approach using fractional dimension has been applied to model the subsurface from field geophysical data. Here, an attempt is made to discuss the in-depth review of the application of the fractal/scaling approach for qualitative and quantitative interpretation of complex sources of interest. The implications of this study will be beneficial for readers, enabling them to understand the gaps in subsurface source characterization, with practical applications demonstrated through field geophysical examples. 

How to cite: Dimri, V. P.: The Fractal Nature of the Earth: Redefining Geophysical Interpretation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2491, https://doi.org/10.5194/egusphere-egu26-2491, 2026.

Ground deformation fields are widely recognized as key tools for the study of geological phenomena such as volcanic eruptions, which cause displacements in the Earth’s surface and interior. When ground deformation data are available, modeling approaches enable the characterization of deformation sources, such as overpressurized and migrating volcanic or hydrothermal fluids within the crust. Geodetic data modeling is therefore a powerful approach for monitoring volcanic systems, managing alerts, and mitigating possible disasters.

For the characterization of ground deformation, the satellite-based Interferometric Synthetic Aperture Radar (InSAR) technique now plays a significant role, as it provides high-quality spaceborne data with extensive coverage and varying resolution. Moreover, several technological efforts are currently ongoing within the Earth Observation framework to advance SAR sensors and related satellite missions, as well as to refine data systems in order to automatically provide measurements of the Earth’s surface deformation in near real time. However, these advancements have not yet been matched by comparable progress in geodetic data modeling strategies. Indeed, the most commonly used modeling approaches, based on parametric optimization and tomographic inversion algorithms, are often unable to address the inherent issues of inverse problem solutions. In addition, they rarely guarantee a reliable characterization of the volcanic context, as they rely on several assumptions underlying analytical models. Finite Element (FE) approaches can potentially ensure greater reliability, although the number of variables to be managed and the computational cost increase considerably. As a result, modeling strategies may fail to determine a unique solution for source parameters when adequate model constraints are not available.

This research topic aims to address ambiguities in the modeling of volcanic deformation sources in order to ensure the full exploitation of the large amount of available InSAR data. This task requires methods capable of providing unambiguous constraints on source parameters while being fast, computationally efficient, and easy to implement in automatic modeling tools, making them suitable for monitoring systems. Our proposal is based on imaging and multiscale methods of potential fields, which satisfy these requirements, even though the deformation field itself is not formally defined as a potential field.

Here, we demonstrate that, under certain conditions, potential field theory can be applied to analyze deformation fields, which can be expressed through harmonic and homogeneous functions. During the lecture, we present several tests validating the proposed arguments and discuss the usefulness of potential field theory in addressing different real-world cases (e.g., Campi Flegrei caldera, Yellowstone caldera, Okmok volcano, Uturuncu volcano, and Fernandina and Sierra Negra volcanoes), using Multiridge and ScalFun methods to constrain the geometric parameters of magmatic reservoirs, boundary analysis techniques to image medium heterogeneity, and potential function evaluation to reconstruct the three-dimensional displacement field.

The results highlight that the proposed methodological suite meets all the necessary requirements to improve the geodetic modeling of volcanic systems and can be integrated into monitoring facilities as an automatic and efficient tool.

How to cite: Barone, A.: Potential field theory for ground deformation: a new tool for the space-borne monitoring of volcanoes and fluid reservoirs., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12462, https://doi.org/10.5194/egusphere-egu26-12462, 2026.

To extract, or 'retrieve' atmospheric properties from the observed radiance spectra from a planetary atmosphere requires software that can generate the expected radiances from a guessed atmospheric model, compare the radiances with those measured, determine how the model should be updated to reduce any discrepancy between the modelled and observed radiances, and then iterate these steps until these differences are minimised. One such retrieval model is NEMESIS (Nonlinear optimal Estimator for MultivariatE Spectral analySIS), which was initially developed by myself and my colleagues in the 1990s, and which has since been continually updated and enhanced. NEMESIS has now been used in more than 300 papers retrieving atmospheric properties from observed thermal and solar-reflected radiance spectra from all the planetary atmospheres in our solar system and also some beyond. NEMESIS uses the Optimal Estimation framework for atmospheric retrievals and is written in FORTRAN. Recently, more Bayesian frameworks have become computationally possible and favoured, especially for exoplanetary retrievals where prior constraints are almost entirely absent. Hence, NEMESIS has recently been updated to Python (ArchNEMESIS), and combined with PyMultiNest to allow nested sampling retrievals that can better explore the degeneracy between different atmospheric properties. I will review how NEMESIS retrievals have improved our understanding of planetary atmospheres over the last 30 years and how the development of ArchNEMESIS has breathed new life into the NEMESIS/ArchNEMESIS project. 

How to cite: Irwin, P.: A voyage of discovery: Exploring the atmospheres of solar system planets and exoplanets with NEMESIS, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2813, https://doi.org/10.5194/egusphere-egu26-2813, 2026.

How to cite: Hay, H.: Neighbouring moons, partial melt, and oceans: Tides of rocky and icy outer solar system satellites , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7478, https://doi.org/10.5194/egusphere-egu26-7478, 2026.

Solar corona fills the whole solar system with the stream of ionized particles – solar wind. Its basic parameters and their evolution with the distance from the Sun were predicted by the Eugene Parker’s hydrodynamic theory in the middle of the last century but the latest observations covering the range from 0.09 to 100 AU give us the possibility to check and modify this crude simplification.

Two essential features distinguish the solar wind from a classical hydrodynamic flow - its weakly collisional nature and the presence of a magnetic field. The absence of frequent collisions allows a motion of different ion populations with various velocities and thus one should ask what a “real” solar wind velocity is. The magnetic field is not just passively frozen in the solar wind plasma as is often assumed, but its force action plays an important role in the release of the solar wind from the corona. Moreover, the magnetic field facilitates excitation and propagation of a variety of waves. The wave interactions lead to turbulence and form interplanetary shocks but their role in the solar-wind acceleration and heating is still not fully understood.

The lecture synthesizes multi-decade observations from numerous spacecraft to address these issues and to discuss their implications for solar-wind formation and evolution through heliosphere. Recent studies have revealed significant changes in the radial trends of plasma and magnetic-field parameters, including ion velocity (Nemecek et al. 2020), plasma beta (Safrankova et al. 2023), interplanetary shock properties and occurrence rates (Kruparova et al. 2025; Park et al. 2023), velocity-temperature relations (Durovcova et al. 2026), and the cross helicity of fluctuations (Park et al. 2025) in the region near Mercury’s orbit. We focus on the physical processes shaping this region and discuss possible interpretations of the observed phenomena. While solar-wind formation and evolution are currently the subject of intense investigation enabled by new observational capabilities, this lecture emphasizes our group's contributions to present knowledge.

How to cite: Nemecek, Z. and Safrankova, J.: Solar wind on the path from the Sun to Earth, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7940, https://doi.org/10.5194/egusphere-egu26-7940, 2026.

Event attribution studies, which assess whether and to what extent human-induced climate change has made extreme weather events more likely or severe, have become routine in recent years. For many regions, multiple studies now exist for the same type of extreme event, with research on heatwaves dominating in Europe and globally, while studies on heavy rainfall are the most represented ones in Asia and North America. However, significant gaps remain, particularly for small island states, which have been largely neglected by attribution research. The growing abundance of studies in certain regions and for certain hazards raises questions about the added value of additional attribution analyses, for example, extreme heat in Europe or India, or heavy rainfall in Ireland or China, where sufficient evidence already exists. While the precise definition of an extreme event can influence quantitative attribution results, recent findings indicate that the effect of different datasets often explains more variance than event definition, particularly for temperature extremes. This lecture will present these new insights, drawing on a decade of experience from World Weather Attribution, and discuss their implications for the broader field of event attribution and for proposed operational services, including when new studies are necessary and how methodological choices affect the interpretation of results.

How to cite: Otto, F., Barnes, C., Keeping, T., Philip, S., Pinto, I., Clarke, B., Zachariah, M., and Bergin, C.: The added value of yet another attribution study , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3780, https://doi.org/10.5194/egusphere-egu26-3780, 2026.

The south west corner of Australia holds a level of plant diversity unmatched outside tropical rainforests; fostered through millions of years of isolation and relative tectonic and climatic stability.  Across deep time, pressures of pollinator scarcity, severe nutrient limitation in an ancient, highly weathered Critical Zone, and fire disturbance have produced what might be the most specialised flora in the world.  Southwest Western Australia (SWWA) is also on the bleeding edge of climatic heating and drying, in a trend that has been apparent since the 1960s.  Water resources management in response to these trends has made the cities of SWWA global leaders in conservation and water technologies – but as the drying continues, groundwater recharge is dropping, phreatophytic plants are dying, and more severe summer heatwaves and droughts are impacting key ecosystems over huge areas.  In this Darcy Oration, I hope to introduce you to the often forgotten, but exceptional set of ecosystems, catchments and Critical Zones of SWWA, and ask how can ecohydrology as a discipline support meaningful adaptation to such climatic changes in this megabiodiverse, hyper-endemic area?  I will present a potential hierarchy of actions and research gaps to consider, and suggest that research in support of making decisions about where and how to adapt is a key challenge for our community.  Finally, I will spend a little time reflecting on my personal experiences as a caregiver to special needs children, and how those caregiving responsibilities impact a career in hydrological science.

How to cite: Thompson, S.: Ecohydrological Adaptation to Climate Change - from Gondwana to the Globe, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15399, https://doi.org/10.5194/egusphere-egu26-15399, 2026.

Today, Antarctica appears as a continent locked in eternal ice and snow, but its sedimentary record preserves rich fossil archives of past life. Because present-day Antarctic landmasses have already been circling in polar latitudes for more than 300 million years, many Antarctic fossil occurrences derive from past high-latitude palaeoecosystems without modern analogue. Of special importance are exceptional plant-fossil assemblages—some classic, some only recently discovered—from the early Mesozoic of the Transantarctic Mountains. These yield exquisitely preserved plant compressions and anatomically preserved biotas in silicified peat and wood, allowing detailed insights into the biology and ecology of past polar forests during times of global warmth. The Late Triassic vegetation of Gondwana is particularly well-known. It was dominated by Dicroidium seed-ferns, conifers, ginkgoes, cycads, and diverse fern communities, and documents sophisticated adaptations to extreme seasonal light regimes, including widespread deciduousness, growth dormancy, and specialized understorey life strategies. There is now increasing evidence that such high-latitude ecosystems acted as evolutionary refugia during major biotic crises. The iconic Triassic Dicroidium plants, for example, survived the end-Triassic mass extinction in Gondwanan high-latitude populations and persisted there long into the Jurassic, far beyond their time of disappearance at lower latitudes. Recent discoveries from previously unexplored regions of northern Victoria Land substantially expand this perspective, revealing unexpected growth strategies, complex ecological interactions, and evidence for extreme evolutionary stasis. Taken together, the fascinating fossil record of the Transantarctic Mountains highlights the varied roles of high-latitude palaeoecosystems in plant evolution during times of global change.

How to cite: Bomfleur, B.:  The green poles of a warmer past: how Antarctic polar forests shaped plant evolution , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23290, https://doi.org/10.5194/egusphere-egu26-23290, 2026.

How rapidly advancing climate change will impact the water cycle and its extremes remains poorly understood and is the origin of much uncertainty. This uncertainty limits our ability to build societal and ecosystem resilience – contributing to policy challenges for adaptation to water scarcity and other hydro-climatic risks. In this context, we rely on hydrologic simulation models to provide robust short-term predictions as well as long-term projections of water cycle dynamics across scales. Even though advancements in observational systems and increasingly detailed simulation models enable us to observe and simulate the water cycle at unprecedent resolutions over large domains, intercomparison studies still reveal inconsistent emergent model behavior. These large domain models are difficult to constrain using current observational datasets given that these are often highly imbalanced, while available theory provides only limited guidance regarding which hydrologic processes we can expect to dominate in diverse climates and landscapes. At the same time, the performance of machine learning models improves rapidly, bypassing process knowledge and therefore questioning the basic need for scientific understanding.

In this talk, I argue that process-based evaluation is an important bridge between hydrologic theory, observations and simulation models – even in the presence of high model complexity and significant data imbalances. I will discuss examples of how process-based evaluation can elicit controlling factors on hydrologic processes by utilizing hydrologically relevant gradients in both simulated and observed data. Thus, demonstrating how this approach can provide a pathway towards assessing and ultimately improving the consistency between perceived and simulated hydrologic process controls over large domains.

How to cite: Wagener, T.: Advancing hydrologic science through process-based evaluation of models, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14330, https://doi.org/10.5194/egusphere-egu26-14330, 2026.

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.

This presentation discusses the definition of randomness, the sources of randomness in the physical system (the Universe) as well as in the formal mathematical system. I discuss how randomness, through nonlinearity and chaos, the second law of thermodynamics, the quantum mechanical character of small scales, and stochasticity, is an intrinsic property of nature. I then move to our mathematical system and show that even in this formal system we cannot do away with randomness, and that the randomness in the physical world is consistent with the origins of randomness suggested from the study of mathematical systems. Many examples are presented ranging from pure mathematical processes, to natural processes, to social processes, and to life in general, which clearly demonstrate how the combination of rules and randomness produces and explains the world we live in. Finally, a possible explanation is provided as to why rules and randomness cannot exist by themselves but instead, they have to coexist.

How to cite: Tsonis, A.: On the Origins of Randomness, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1503, https://doi.org/10.5194/egusphere-egu26-1503, 2026.

Climate models, in the form of Earth System Models (ESMs), are central to both climate science and climate-informed decision-making. Technically, they are complex, nonautonomous, and chaotic mathematical and computational representations of the Earth’s interacting “spheres”, including the atmosphere, oceans, cryosphere and biosphere. In practice, they are widely used to produce conditional projections of future climate under prescribed forcing and emissions scenarios - and remain the only tools capable of doing so within a physically consistent framework. However, despite their indispensable role, the interpretation of ESM outputs is fundamentally constrained by multiple sources of uncertainty, normally grouped as internal climate variability, uncertainty in future forcing scenarios, and uncertainty arising from model formulation.

While internal variability and scenario uncertainty have traditionally received most attention, attempts to partition uncertainty (e.g. [1]) have shown that it is actually the latter, model uncertainty, which is responsible for most uncertainty in climate projections. But despite its relevance, model uncertainty is frequently treated only implicitly, commonly subsumed under the broad label of “structural uncertainty”, with limited clarity regarding its definition or impact. This raises several unresolved questions of direct relevance to both modelling and decision-making efforts: what constitutes structural uncertainty in contemporary ESMs, how does it propagate through ensembles and projections, and how does it affect downstream socio-economic impact assessments and climate risk analyses? 

In this presentation, I will discuss these questions by reviewing recent advances in the characterisation and interpretation of model uncertainty (including results from my collaborators and myself, e.g. [2-4]) and examining their implications for the use of climate projections in scientific inference and decision-making. I conclude by identifying key conceptual and methodological gaps that must be addressed to improve confidence in climate information under persistent structural uncertainty.

With many and wholehearted thanks to all my collaborators, mentors, friends, colleagues, students and funders who made the journey to this award possible.

References:

[1] Lehner, F., Deser, C., Maher, N., Marotzke, J., Fischer, E. M., Brunner, L., Knutti, R., and Hawkins, E. (2020): Partitioning climate projection uncertainty with multiple large ensembles and CMIP5/6. Earth System Dynamics, 11, 491–508. https://doi.org/10.5194/esd-11-491-2020

[2] de Melo Viríssimo, F., Stainforth, D. A., and Bröcker, J. (2024): The evolution of a non-autonomous chaotic system under non-periodic forcing: A climate change example. Chaos, 34, 013136. https://doi.org/10.1063/5.0180870

[3] Martin, A. P., Bahamondes Dominguez, A., Baker, C. A., Baumas, C. M. J., Bisson, K. M., Cavan, E., Freilich, M., Galbraith, E., Galí, M., Henson, S., Kvale, K. F., Lemmen, C., Luo, J. Y., McMonagle, H., de Melo Viríssimo, F., Möller, K. O., Richon, C., Suresh, I., Wilson, J. D., Woodstock, M. S., and Yool, A. (2024): When to add a new process to a model – and when not: A marine biogeochemical perspective. Ecological Modelling, 498, 110870. https://doi.org/10.1016/j.ecolmodel.2024.110870

[4] de Melo Viríssimo, F., and Stainforth, D. A. (2025): Micro- and Macroparametric Uncertainty in Climate Change Prediction: A Large Ensemble Perspective. Bulletin of the American Meteorological Society, 106, E1319–E1341. https://doi.org/10.1175/BAMS-D-24-0064.1

How to cite: de Melo Viríssimo, F.: Is it possible to have confidence in climate information with structurally uncertain models?, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21589, https://doi.org/10.5194/egusphere-egu26-21589, 2026.

The ability to establish rheological and fluid‑transport laws in the lithosphere for use in geomechanics and geodynamics models depends on laboratory experiments validated by field observations. In experiments, a key challenge is reproducing the pressure, temperature, and fluid‑chemistry conditions found at depth while acquiring sufficient information inside rock samples to understand and generalize the detailed mechanisms of rock deformation and chemical evolution. Over the past fifteen years, breakthroughs in rock physics have been enabled by experiments conducted at large user facilities such as synchrotron and neutron sources. From shallow subsurface fluid–rock interactions to slow and fast rupture and down to the brittle–ductile transition at the base of the seismogenic zone and deep earthquakes, it is now possible to image geological processes in 4D (3D + time) with unprecedented spatial and temporal resolution in samples large enough to be representative of lithospheric processes.

Recent experiments demonstrate how a porous rock can become clogged and store carbon dioxide, including direct imaging of fluid mixing and precipitate formation, how porosity can be generated at the brittle–ductile transition, altering our view of fluid transfer at the base of the seismogenic zone, and how damage nucleates before and during earthquakes. These findings highlight the importance of dynamic porosity — which controls fluid transport and deformation — and call for integrating more widely this property into large‑scale models of Earth’s crust dynamics.

How to cite: Renard, F.: A revolution in rock physics: 4D imaging, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3917, https://doi.org/10.5194/egusphere-egu26-3917, 2026.

Rocks can be described as heterogeneous random materials, in the sense that they are composed of multiple domains of different phases. At the scale of a representative elementary volume (REV) — defined as the smallest volume over which measurements yield values representative of the entire rock sample — such heterogeneous materials can be treated as homogeneous and characterized by macroscopic or effective properties. Determining these effective properties is essential for describing geological processes occurring in reservoirs, aquifers, fault zones, and volcanic environments, as well as the structural changes they induce. However, complex interactions among the constituent phases result in a strong dependence of effective properties on nontrivial aspects of the microstructure, in particular for rocks with more than two or three different phases.

Over the past decades, a fruitful approach to investigating the relationship between rock properties and microstructure has involved predicting effective properties directly from microstructural information. This framework enables quantitative links to be established between microstructural evolution and changes in macroscopic properties. Following this rationale, laboratory-prepared synthetic rocks with specifically designed microstructural attributes have proven particularly valuable. Such materials have provided key insights into the influence of microstructure on mechanical properties, using relatively simple single- or two-phase rock analogs first, and synthetic materials with progressively more numerous distinct phases.

Here, I will summarize results we have collected in the past years by systematically investigating how specific microstructural attributes influence the mechanical behaviour of rocks. Compression experiments conducted on monodisperse sintered glass beads samples show that the stress required to reach inelastic deformation decreases when porosity or grain size alone increase. Using bidisperse and polydisperse sintered glass beads samples, we observe that this stress decreases when the degree of polydispersivity increases. In addition, under high-pressure triaxial compression, an increase in the degree of polydispersity alone leads to a transition in damage evolution from localized to more spatially distributed deformation. These results echo observations from shear experiments performed on heterogeneous fault gouges, where the spatial arrangement of weak and strong mineral phases, in addition to their relative proportions, exerts control on frictional properties and damage evolution during shearing.

More recently, we have employed nanoindentation to resolve spatial variations in elastic properties directly at the grain and crystal scale in natural rocks, allowing for the mechanical characterization of individual phases and quantification of mechanical heterogeneity at the bulk sample scale. These measurements will hopefully provide input parameters for the development and calibration of increasingly realistic synthetic rocks.

How to cite: Carbillet, L.: Determining the mechanical properties of heterogeneous rocks from a knowledge of microstructure, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21775, https://doi.org/10.5194/egusphere-egu26-21775, 2026.

Nowhere is the continental crust evolving more rapidly than in the core of orogenic belts where the thickened crust typically undergoes partial melting and orogenic collapse, leading ultimately to crustal stabilization. While the processes of accretion and collision may take 10-100 Myr, the collapse instability, involving flow of deep crust and formation and emplacement of metamorphic core complexes and migmatite domes, is short lived (1-10 Myr). Material transfer during orogenic collapse is achieved by (1) lateral flow near the base of the evolving continental crust, where highly sheared partially molten rocks remain buried, and (2) upward flow within metamorphic core complexes (MCCs) below bounding extensional fault systems. These MCCs are commonly cored by migmatite domes that provide exceptional windows into the dynamics of the deep orogenic crust. Therefore, extensional detachment systems and migmatite domes are prime recorders of how the mechanical and thermal instability introduced by crustal thickening and melting, transitions to a gravitationally equilibrated crust. Some notable research results from these systems include the record of fluid-rock interaction across detachments and the provenance of partially molten crust as observed in migmatite domes.

MCCs are bounded by detachment shear zones that record large strain and metamorphic gradients as well as effective fluid-rock interaction enhanced by intense deformation and recrystallization processes at the grain scale. Stable isotope analyses across detachment systems have delineated the limit between a zone dominated by surface-derived (meteoric) fluids above and a zone of prevailing metamorphic fluids below. In some cases, the meteoric fluid is consistent with a surface fluid that precipitated at high elevation and was involved in convective flow from the surface down to the detachment shear zone, likely during the initial stages of orogenic collapse. The rocks within migmatite domes are varied and include refractory lithologies, typically mafic enclaves or pods, that inform the provenance of partially molten crust. In some domes, mafic pods are made of eclogite, and the age of eclogite metamorphism (pressures of 1.5-2.0 GPa) is close to the age of migmatite crystallization. In other cases, eclogite that was formed in subduction zones was incorporated as blocks or pods and transported laterally within the partially molten crust over long distances across the orogen before being exhumed in domes. The presence of eclogite within migmatite suggests that the partially molten crust is sourced at near-Moho depths and is extremely mobile, with the ability to travel laterally (order of >100 km) as well as vertically. Phanerozoic orogenic cores provide a template for understanding the extent of reworking of continental material and the flow of this material during the stabilization of continental crust over geologic time.

How to cite: Teyssier, C.: At the Core of Orogens, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7238, https://doi.org/10.5194/egusphere-egu26-7238, 2026.

Soils are central regulators of the Earth’s biogeochemical cycles, yet the mechanisms that influence the role of soil organic matter in soil functioning and its vulnerability to human interventions are still not sufficiently understood. In my research, I have explored the processes leading to organic matter stabilization at contrasting scales in temperate and tropical ecosystems. In this lecture, I will present my vision of how these scales need to be integrated in an interdisciplinary approach to investigate how contrasting pedoclimatic conditions, management practices, and climate change influence biogeochemical cycling. I will also present my research on the development of innovative soil amendments and sustainable management strategies to enhance fertility and increase soil carbon sequestration with the aim to strengthen resilience to global change.

I will highlight the benefits of international collaboration across continents in bringing together different viewpoints, enriching the research environment, and contributing to development. At the same time, the changing conditions we encounter when engaging with scientific knowledge, coupled with widespread misinformation, make it increasingly important to uphold scientific integrity. To nurture curiosity and inspire the next generation of scientists to seek truth with rigor and dedication, we should not entirely abandon the “old-fashioned” way of doing research. In this lecture, I will share my perspective on how soil scientists can continue to generate reliable knowledge, inform responsible management, and contribute to a sustainable future.

How to cite: Rumpel, C.: Soil organic matter research in a changing world, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6371, https://doi.org/10.5194/egusphere-egu26-6371, 2026.

Soil organic matter (SOM) is a cornerstone of ecosystem stability, yet its response to anthropogenic pressure is governed by molecular-scale processes that bulk analyses often fail to capture. This award lecture will illustrate how the application of stable isotopes at the compound-specific level provides a high-resolution lens to elucidate SOM complexity and dynamics across diverse environmental frontiers. By transitioning from established carbon-cycle isotope research to the pioneering frontier of organic phosphorus (OP) research, this work explores the molecular "fingerprints" of SOM dynamics.

In this award lecture, I will summarize my research on the molecular mechanisms of SOM transformation and the development of isotopic tools to decipher the turnover and fate of organic pools under varying environmental factors. First, I will provide an overview of how compound-specific stable isotope analysis (CSIA) revelas molecular shifts that precede detectable losses in diverse soil organic carbon forms, providing a diagnostic for soil vulnerability under diverse land uses and climate factors. This will comprise both a conventional biomarker extraction approach and a novel direct pyrolysis analytic technique.

Next, I will demonstrate how these isotopic approaches can be applied to disturbance ecology, specifically focusing on the resilience and transformation of organic matter in fire-affected soils. Finally, I will review the transition to the OP cycle, presenting innovative methodologies implemented to advance our understanding of C and P biogeochemical cycles, and providing unprecedented insights into the biogeochemical persistence of this major OP pool.

I will conclude by discussing how these molecular insights are vital for developing site-specific management strategies and interdisciplinary models that account for the simultaneous impacts of global change on multiple soil functions.

How to cite: San-Emeterio, L. M.: From carbon to phosphorus: Advancing compound-specific stable isotope analysis to decode soil organic matter dynamics across diverse environmental contexts, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20649, https://doi.org/10.5194/egusphere-egu26-20649, 2026.

Growth in satellite observations and modeling capabilities has transformed drought monitoring by enabling near real-time situational awareness. Yet many operational efforts still emphasize hazards rather than impacts, and they often miss the compound and cascading risks that frequently accompany drought, including heatwaves, wildfires, floods, and debris flows. In this presentation, we first introduce a real-time drought monitoring and seasonal prediction system that integrates diverse data streams with AI-based algorithms for drought forecasting (https://drought.eng.uci.edu/). We then describe how drought information can be expanded beyond hazard metrics by incorporating impact and vulnerability data to support impact-based assessment of extremes and decision-relevant risk insights (https://water.eng.uci.edu/).  Using several examples, we argue for an impact-centered drought monitoring paradigm that links hydroclimate conditions to physical and societal outcomes, such as crop yield losses, food insecurity, energy production disruptions, and labor impacts. We also highlight key challenges that must be addressed to make this approach operational, including inconsistent and incomplete drought impact records, limited Information about local water management and human interventions (e.g., demand, intra- and inter-basin transfers, pumping, and withdrawals), and persistent gaps between impact models and existing drought monitoring workflows. Finally, we discuss anthropogenic drought as a framing concept and show how impact-based drought analysis can be strengthened by representing drought as a coupled climate–human phenomenon rather than a purely climatic hazard. 

How to cite: AghaKouchak, A., Nguyen, P., Ung, T., de Oliveira, D., Hjelmstad, A., Massing, J., Aljohani, A., Love, C., Mirchi, A., Feldman, D. L., Placht, D., and Najib, D.: From Hazard to Consequence: Impact-Based Drought Monitoring and Prediction, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13488, https://doi.org/10.5194/egusphere-egu26-13488, 2026.

Rivers, deltas and coasts have dynamic patterns of sand, mud and vegetation. These patterns are colourful, energetic, alive, important to, and affected by, societies on Earth. In contrast, the remains of rivers and deltas on planet Mars tell a story of a dry, frozen and probably lifeless planet. For meaningful research, not only novel scientific methods are needed, but also the concepts enabling ourselves and our students to enhance our learning and societal application. We must and can do better in closing the circle between science, diversifying impact activities and educating the students. Our alumni could accomplish so much more if only they knew how.

Replicating and studying the dynamic patterns of river meandering and shallow estuaries in scale experiments (in my tidal flume www.uu.nl/metronome) has been challenging, not only because of the usual scaling problems. Representing such systems in scale experiments requires that we include a minimum set of processes and dynamic boundary conditions that allow a (quasi-)steady state to develop with the target patterns and behaviours. I will show how a complex biogeomorphic systems approach led to beautiful dynamic meandering rivers and estuaries in our lab. Our scale experiments play an unexpectedly large role in education and impact in showing tangibly how the rivers, estuaries and coastal plains developed and what this may mean for their management.

I will then take a step back and critically question what and how we are learning as experimenters and modellers. I learned about how we learn and how we can improve our learning and teaching by using concepts from philosophy of science on causality in complex systems, material modelling and representation of the world. I will focus on some academic thinking skills and societal literacy skills that are often underemphasized in education but fundamental to 21st century geomorphology with societal impact.

Third, societal use of, and interactions with, biogeomorphic systems pose challenges: the combination of accelerating climate crisis, historic land use change and intensifying economic activities deteriorate ecosystems and increase droughts, flooding and land loss. Ideally, societal responses to the climate and biodiversity crises are based on systems understanding on a timescale of years to centuries. Many scientists are hampered by taking either an activist position or an ‘objective’ or at least ‘neutral’ academic position, while there are 50 shades of green in between them. Merely ‘neutrally’ informing public and policymakers, as a sender, is ineffective because they, the receivers, have interests, perspectives and usually a lack of academic knowledge. Being an activist is also not often effective and may raise questions about the legitimacy of our science. How do we navigate these roles? I will show how I, in transdisciplinary teamwork, am learning to navigate the positionality of ‘neutral scientist’, educator, agent of change and political lobbyist, boldly stumbling where others have stumbled before.

How to cite: Kleinhans, M.: Concepts to close the circle between 21st century biogeomorphology, higher education and societal impact, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3116, https://doi.org/10.5194/egusphere-egu26-3116, 2026.

In recent years, many studies have been devoted to quantifying and mapping terrestrial CO₂ degassing. Besides climate effects, another reason to study the natural degassing of endogenous CO₂ concerns its role in tectonics, and here I will focus primarily on this aspect, referring to the results obtained in central and southern Italy. In central and southern Italy, non-volcanic CO₂ of deep origin is released from numerous vents and diffuse emission zones, and from groundwater with high CO₂ content. Groundwater degassing was estimated coupling hydrogeochemical and hydrogeological data and using the mass balance of the carbon dissolved in the springs of high flow rate (hundreds to thousands kg/s). This approach allowed us both to quantify the emission (2.1 × 10¹¹ mol yr⁻¹) and to create a detailed map of the process. The map shows two large degassing structures: TRDS (Tuscan Roman degassing structure) and CDS (Campanian degassing structure). The same CO₂-rich groundwater are “slightly thermal” having a temperature of few degree C higher than that expected for normal groundwater. These anomalous temperatures are due to high geothermal heat fluxes (up to 350 mW/m²). This coincidence, combined with the presence at depths > 10 km of a large zone of low-velocity of the seismic waves, suggested that the hot CO₂-rich fluids are probably emitted from a large magmatic intrusion located in the root of the central Apennines. The Apennine belt is characterized by seismicity that recently peaked with strong earthquakes in 2009 (L'Aquila earthquake, M = 6.3) and 2016 (Amatrice-Norcia earthquakes, M = 6.0 and 6.5). We observed that CO₂ emissions correlate with seismicity both geographically and over time: Apennine seismicity affects in fact the eastern edges of the TRDS and the CDS, and CO₂ emissions increased during, and likely before, the 2009 and 2016 events.

How to cite: Chiodini, G.: Carbon dioxide earth degassing, heat flux and earthquakes in central and southern Italy, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5052, https://doi.org/10.5194/egusphere-egu26-5052, 2026.

The Santorini volcano, Greece, attracts global scientific interest and constitutes a top tourist destination. The 17th century BCE eruption (“Minoan event") was likely the largest ever experienced by humanity. It was associated with significant tephra falls, earthquakes, and tsunamis inundating the eastern Mediterranean basin. Global climate changes were attributed to the Minoan event. Geological and archaeological evidence supports that the Minoan event drastically influenced eastern Mediterranean civilizations. Minoan tephra layers formed key horizon markers driving revisions of the Mediterranean civilization chronology. Comparative studies indicate great similarity between Santorini and Krakatoa, but the Minoan eruption exceeded in size the 1883 CE Krakatoa eruption. During historical times the volcanic cycle in Santorini restarted with eruptions of smaller size and magma emplacement in the caldera, thus shaping the Kamenae (Burned) islands, exactly as happened with the post-1883 generation of the Anak (Child) island in the Krakatoa caldera. In 1650 CE, a violent eruption occurred at the submarine Kolumbo volcano, which is situated a few kilometers outside the Santorini caldera but very likely is fed by the same magmatic chamber. Further research is needed to understand if magma generation at depth is possibly controlled by the occurrence of large-magnitude intermediate-depth earthquakes. The 1650 CE eruption and associated strong earthquakes and tsunamis caused loss of life and significant destruction. After several small-to-medium eruptive episodes during the 18th-20th centuries, Santorini has remained dormant since 1950. However, on 9 July 1956, the area to the east of Santorini was ruptured by a magnitude 7.7 tectonic earthquake, which, along with its large tsunami, caused extensive loss of life and destruction in the entire southern Aegean Sea. Submarine surveys indicate that the 1956 rupture zone possibly belongs to the same NE-SW-trending fracture zone passing from the Kolumbo and Santorini volcanoes. There is no historical evidence for similar tectonic earthquakes occurring in the past. Data-driven probabilistic seismic hazard assessment utilizing incomplete and uncertain earthquake catalogues indicates that the 1956-type earthquakes may have very long repeat times. During 2025, an unusual cluster comprising thousands of earthquakes but with a maximum magnitude of only 5.3 and sources at distances of 20-40 km to the east of Santorini caused extensive social anxiety. This was magnified because of two reasons. First, preventive measures taken by civil protection authorities were unprecedented. Second, uncontrolled public statements were expressed by specialists and non-specialists about imminent eruptions and forthcoming large earthquakes, which raised important geoethical challenges. The seismic crisis received international attention because Santorini is a spot of worldwide tourist interest. More than 13,000 people evacuated voluntarily. For the interpretation of the cluster, the “seismic swarm” hypothesis appears more as a “deus ex machina” explanation than a convincing scientific result. The competing “foreshocks-mainshock-aftershocks” model fits the data better. Santorini is a key volcano offering results valuable for better understanding the behavior of many volcanoes around the globe, revealing global climate impacts of volcanic origin, deciphering unknown aspects regarding prehistoric civilizations in the Mediterranean, and providing important lessons learned for volcanic and other geohazard management.  

How to cite: Papadopoulos, G.: Large volcanic eruptions, earthquakes, and tsunamis in Santorini: a multi-hazard physical laboratory of global interest, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3519, https://doi.org/10.5194/egusphere-egu26-3519, 2026.

The central pillar of my research are the GRACE and GRACE-FO satellite missions. These missions provide a unique opportunity to observe spatial and temporal variations in the Earth’s gravity field. These variations reflect large-scale mass redistributions, which are dominated by water mass transport across continents, oceans, and ice sheets. Consequently, GRACE and its successor mission, GRACE-FO, enable global monitoring of changes in terrestrial water storage (TWS), integrating all water components from surface water over soil moisture, snow and ice, down to groundwater.

In this talk, I will take you on a journey from global observations of the Earth’s gravity field to physically interpretable data products over land and oceans, and demonstrate how these products can be applied in hydrological research.

Global gravity field solutions are typically delivered as spherical harmonic coefficients, a mathematical representation that is not directly accessible to most users. I will show how we transform this complex information into intuitive, user-friendly gridded datasets, including robust uncertainty estimates, an aspect crucial for many practical applications. I will also highlight the importance of such accessible data products for open science initiatives and public data platforms, including the Copernicus Climate Change Service.

Finally, I will present several case studies illustrating the use of TWS data in hydrology. These include the quantification of the ongoing Central European drought that began in 2018, as well as investigations into the interplay between climate change, natural variability, and human influence in the East African Rift region. I will also demonstrate the added value of combining TWS observations with complementary remote sensing datasets to assess global changes in groundwater storage.

How to cite: Boergens, E.: From Observations of the Earth’s Gravity Field to Insights into Hydrology, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3354, https://doi.org/10.5194/egusphere-egu26-3354, 2026.

Since the time of Kepler, Newton, and Huygens in the 17th century, geodesy has been concerned with determining the Earth’s figure, orientation, and gravitational field. The dawn of the space age in 1957 gave rise to a new branch of the discipline: satellite geodesy. It was only through the use of satellites that geodesy truly became a global science - oceans ceased to be barriers, and the Earth could be observed and measured as an integrated whole using consistent datasets. Particular attention was devoted to resolving the spatial structure of the Earth’s gravity field and, eventually, its temporal variations. Knowledge of the gravity field forms a natural link to the study of the Earth’s interior, the circulation of the oceans, and, more recently, the climate system. Today, changes in the gravity field provide key insights into climate change, including ice mass loss in Greenland and Antarctica, sea-level rise, and broader changes in the global water cycle. These advances have only been possible through the use of highly sophisticated gravity-field satellites, a field known as satellite gravimetry.

During the first four decades of space exploration, satellite gravimetry relied primarily on analyzing the orbital motion of satellites. Due to the uneven global distribution of tracking stations, initially limited measurement accuracy, and shortcomings in early analysis models, reconstructing global models of the Earth’s gravity field posed a major challenge. A decisive breakthrough came in the final decade of the 20th century with the transition from passive satellites to missions equipped with dedicated, high-precision instrumentation for gravity-field determination. The Vening Meinesz lecture will review the historical background of satellite gravimetry as well as mission objectives, measurement principles and implementation challenges of modern gravity missions like CHAMP, GRACE, GOCE, and GRACE-FO. It will further highlight selected scientific results and applications from these missions and outline opportunities for the next generation of geodesists arising from future gravity field missions currently under development.

Further reading: Frank Flechtner, Christoph Reigber, Reiner Rummel, and Georges Balmino (2021): Satellite Gravimetry: A Review of Its Realization, Surveys in Geophysics, 42:1029–1074, https://doi.org/10.1007/s10712-021-09658-0

How to cite: Flechtner, F.: Satellite Gravimetry: Realization and Further Prospects, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9119, https://doi.org/10.5194/egusphere-egu26-9119, 2026.

Thousands of volatile organic compounds are released into the atmosphere from both human activities and natural sources. These emissions fuel complex chemical reactions that influence air quality and climate. As societies transition to cleaner energy, as temperatures rise and ecosystems respond to climate stress, the composition and amount of these emissions are shifting. Understanding these changes is crucial to predict future air quality and climate, since emissions are the basic input of any atmospheric chemical transport model. However, measuring concentrations of volatile organic compounds is often not enough to understand emissions, as the rapid chemical transformations of these reactive compounds in the atmosphere make it hard to assess their source strength and source location.

Direct airborne emission observations are a powerful tool to address this. With such airborne flux observations, it is possible to map real-world emissions of volatile organic compounds at a landscape scale of few km².  This lecture will show how airborne flux observations helped us find that changes in urban emission composition were not reflected in current emission inventories and revealed links of anthropogenic emissions with temperature. It will also highlight our current research on how climate change-driven stress can change biogenic emissions and their impact on the atmosphere.

How to cite: Pfannerstill, E. Y.: Emissions in transition: Exploring air quality-climate links from cities to forests , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1680, https://doi.org/10.5194/egusphere-egu26-1680, 2026.

A multitude of Volatile Organic Compounds (VOC) are present in the air we breathe. These airborne chemicals make up the familiar scents of flowers, fuels, and firesmoke. On a global scale, however, the single largest VOC source is the Amazon rainforest.

Each day, as the giant Amazonian ecosystem takes up carbon dioxide through photosynthesis, it also releases a fascinating cocktail of reactive chemicals into the air. These trace compounds play several roles within the forest, including protecting leaves from oxidative damage and mediating chemical communication between plants and insects. Above the canopy, they shape global atmospheric chemistry by influencing the atmospheric oxidation capacity, particle formation and the radiative budget, as well as regional clouds and precipitation.

Since 2012 we have been using sensitive mass spectrometers to characterize VOC from the 325m ATTO measurement tower in the pristine Brazilian rainforest. Initial work focused on isoprene (C5H8) and monoterpenes (C10H16), whose emissions vary between wet and dry seasons in response to light and temperature. Parallel measurements of total OH reactivity showed that many additional reactive compounds must be present, and the search for these species revealed new VOC sources and sinks, from soil, mosses and lichen.

In 2022-2023, the CAFÉ-BRAZIL airborne campaign extended these VOC measurements up to 14 km altitude across the entire Amazon basin. Even at these heights, the forest imprint is clear. Nocturnal deep convection transports substantial amounts of VOC to the upper troposphere, where they can accumulate overnight and prime the atmosphere for complex organic photochemistry at dawn. These natural chemical processes will be disrupted by continued deforestation.

 Climate models predict that the Amazon rainforest will suffer more, severe drought periods in future. Our recent measurements over the Amazon and within the BIOSPHERE 2 rainforest facility show that chiral VOCs can serve as sensitive indicators of how the forest responds to drought stress, including the extreme 2023/2024 El Niño event. Measurements of VOC in air hold the key to unlocking the complex chemical processes operating within and above the Amazon rainforest ecosystem.

How to cite: Williams, J.: From Forest to Sky: Air Chemistry over the Amazon, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16771, https://doi.org/10.5194/egusphere-egu26-16771, 2026.

Understanding the exchange processes between terrestrial ecosystems and the atmosphere above is crucial for mitigating climate change and promoting ecosystem resilience. Over the past decade, I have investigated the land-atmosphere interactions with regard to energy, water vapor, and CO₂ fluxes in various ecosystems, including forests, croplands, and grasslands, at different spatial and temporal scales. In this lecture, I will present recent results of a near-natural mixed-beech forest in the National Park Hainich in central Germany. Based on a comprehensive long-term dataset of eddy covariance flux observations, we conducted statistical time series analysis to investigate the exchange processes of this diverse, near-natural ecosystem. Furthermore, in collaborations with various partner institutions additional observations are being obtained at this flux study site, such as drone imagery, terrestrial laser scans, vegetation optical depth, forest biomass inventory, phenological photos, and on tree-scale records of stem growth, sapflow and leaf water potential. Using this multi-scale dataset, we aim to improve our understanding of the link between forest exchange processes and tree response dynamics, as well as the impact of extreme weather events (e.g., droughts).

The Hainich forest represents a large carbon sink prevailing throughout the past 26 years. However, the ongoing warming trend is altering the start and duration of the growing season of trees and the herbal layer. Tree vitality is being impacted by diseases and recent drought events such as in 2018-2020 have changed the forest’s processes and dynamics. We observed an increase in the canopy gap fraction in 2021 indicating a significant increase in tree mortality. Surviving trees were affected differently by the droughts depending on their species, age, and competition. In particular, the growth of older and larger trees (mostly ash), was impaired during and after the drought period, resulting in a reduction of the overall CO₂ uptake strength of the forest ecosystem between 2018 and 2022. However, about half of the observed trees, mostly suppressed, vital beech trees, showed a positive growth trend during and after the drought period. The given structural diversity influences the responses and resilience of individual trees and the entire ecosystem. The comprehensive dataset further provides an opportunity to investigate the influence of climate and soil characteristics and of forest management on flux exchange processes within multi-site comparison studies.

How to cite: Klosterhalfen, A.: Flux exchange of a near-natural temperate deciduous forest under drought stress, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12627, https://doi.org/10.5194/egusphere-egu26-12627, 2026.

Roughly 90% of the organic carbon (OC) buried in the global ocean is stored in muddy sediments along continental margins. Estuarine "hotspots" are especially important, with deltas accounting for about 40% of this burial and fjords for around 12%. To understand the sources and fate of OC in aquatic systems, researchers have widely applied molecular biomarkers and bulk geochemical proxies. In my work, I will explore the application of both bulk analytical techniques and molecular biomarkers to investigate how environmental changes across the land–to-ocean aquatic continuum (LOAC) are influencing OC burial and long-term carbon sequestration.  These muds produced by rock weathering play a critical role in the global carbon cycle by binding and shielding OC from degradation. The quantity and characteristics of OC stored in these muds influence the extent, duration, and mechanisms of carbon sequestration.

Human activities, including dam construction, levee building, and climate change, have profoundly reshaped patterns of mud accumulation and organic carbon (OC) storage across diverse environments. I demonstrate that climate warming has generally increased mud–OC fluxes through processes such as glacier melt, enhanced erosion, and dam-driven sediment burial, although these effects vary regionally. From 1950 to 2010, dams reduced global riverine sediment delivery to the oceans by approximately 49%, despite rising upstream sediment loads, trapping an estimated ~60 TgC yr⁻¹ of organic carbon. At the same time, global coastal wetlands experienced a net loss of about 4,000 km² between 1999 and 2019, yet they continue to sequester substantial amounts of carbon (up to ~60 TgC yr⁻¹). In the Arctic, warming has accelerated permafrost erosion, mobilizing roughly 14 TgC yr⁻¹. Together, these examples highlight the complex and often competing influences of human activity and climate change on river systems and the global carbon cycle, with coastal zones emerging as both highly vulnerable and critically important for carbon sequestration. However, whether these changes ultimately enhance or diminish long-term OC storage remains uncertain, given the complexity and variability of the processes and timescales involved.

How to cite: Bianchi, T.: Carbon Processing in the Land-to-Ocean Aquatic Continuum (LOAC): Challenges in the 21st Century, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12722, https://doi.org/10.5194/egusphere-egu26-12722, 2026.

The global energy transition increasingly relies on the sustainable use of the subsurface, which commonly involves fluid injection. Such injection can induce earthquakes, posing significant challenges to the safety and operability of geo-energy applications. Addressing these challenges requires a geomechanical understanding of induced seismicity and the coupled subsurface processes that govern it. This Award Lecture introduces recent research on fluid injection-induced earthquakes, spanning the evaluation of causal mechanisms to an in-depth understanding of the fault-slip processes that control earthquake magnitude and frequency.

The first part of the presentation focuses on identifying and evaluating the causal mechanisms for injection-induced earthquakes. The problem is formulated as assessing the susceptibility of fracture and fault slip driven by coupled thermo-hydro-mechanical (THM) processes in fractured porous media. Through several geo-energy case studies, it is demonstrated that induced seismicity commonly results from fracture and fault reactivation through multiple, co-occurring mechanisms. The relative contribution of these mechanisms largely depends on regional geology, fracture and fault properties, ambient stress conditions, and operational parameters. Fluid overpressure typically develops rapidly following injection and may influence a large area, depending on hydraulic connectivity and fault permeability. Poroelastic stressing accompanies fluid pressurisation, with its contributions controlled by the distance to susceptible faults and fault orientation relative to the ambient stress field. Thermal stressing is generally more spatially localised around injection wells but can become dominant over longer timescales. In addition, fault slip-induced stress transfer can explain seismicity beyond the region affected by fluid pressure and poroelastic stress changes. Understanding these mechanisms enables the development of physics-based approaches for induced seismicity hazard assessment that explicitly account for both geological conditions and operational strategies.

The second part of the presentation addresses fault frictional slip processes that ultimately control the earthquake magnitude and frequency. Three key governing processes are identified for injection-induced fault slip: fluid pressurisation, hydraulic diffusion, and frictional nucleation, each characterised by a distinct timescale. Their interactions give rise to a wide range of induced earthquake behaviours. To disentangle their combined effects, a coupled hydro-mechanical-frictional modelling framework was developed that integrates frictional contact models for faults with poroelastic models for surrounding rocks. The results have shown that frictional properties exert first-order control on fault slip regimes and the maximum earthquake magnitude, whilst fluid pressurisation primarily governs earthquake frequency and also influences the maximum magnitude through poroelastic stressing. These effects are further modulated by hydraulic diffusion, highlighting the role of reservoir hydraulic conductivity in controlling how injected fluids interact with distant faults. Building upon this understanding, this contribution illustrates how fluid pressurisation rate influences induced earthquake magnitude and frequency, and discusses the implications for designing injection strategies that minimise seismic risk while maintaining operational efficiency.

Acknowledgement: I gratefully acknowledge the support and nomination by Prof. Sevket Durucan, Dr. Suzanne Hangx, Prof. Chris Spiers, Prof. Paul Glover, and Prof. Keita Yoshioka, and the many collaborators who contributed to the research presented.

How to cite: Cao, W.: Understanding fluid injection-induced earthquakes: From causal mechanisms to fault frictional slip, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13423, https://doi.org/10.5194/egusphere-egu26-13423, 2026.

Cryosphere-fed rivers drain glacier, snow, and permafrost landscapes and are characterized by glacial, nival, pluvial and mixed hydrological regimes. Such river systems originate from high-mountain areas and polar regions, and transport water, sediment, nutrients, and organic carbon downstream, underpinning the freshwater and coastal ecosystems and supporting the lives of more than one-third of the world's population. In response to the amplified climate change, accelerating glacier-snow melt and permafrost thaw, the cryosphere-fed rivers are overall becoming warmer, wider and muddier associated with markedly increasing river turbidity and suspended sediment concentrations. In this talk, I will present the observed and modelled changes in cryosphere-fed rivers and examine their implications for channel mobility and the carbon cycle across both High Mountain Asia and the pan-Arctic. To better assess the impacts of changing climate on the functions and services of river ecosystems in strategically important cold regions, I highlight the pressing need to integrate multiple-sourced river observations, to develop empirical, physics-based, and AI-based river flux models, and to promote interdisciplinary scientific collaboration. The innovative system approach would best come from the creation of an interdisciplinary collaborative initiative, where geomorphologists, climatologists, ecologists, glaciologists, permafrost scientists, hydrologists, and civil engineers work together to establish an integrated cryosphere-water-sediment-carbon-ecology observation platform that facilitates the mechanism understanding and development of novel and powerful models. Furthermore, dialogues and collaboration between international scientists, stakeholders, local communities, and policymakers would help to bridge the gaps between state-of-the-art scientific findings and practicable adaptation strategies.

How to cite: Li, D.: Cryosphere-fed rivers, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2198, https://doi.org/10.5194/egusphere-egu26-2198, 2026.

A wide variety of processes controls characteristics of water extremes: river floods, droughts, episodes of detrimental streamwater quality. Understanding generation processes of these events may assist in uncovering their emergence and support the interpretation of their changes. Here I show how objective event identification and transferable causative classification frameworks are able to overcome the limitations of locally tailored approaches and detect functional changes in extremes over large spatial domains and long temporal scales.

To pave the way towards more efficient adaptation measures for extremes we need to understand intricate links between their hazard and impact components better. Here I demonstrate how different generation processes of extremes are interlinked with the adaptation efficiency, previous societal experiences and awareness uncovering how they might shape socio-economic impacts. The examples show how bridging across domains can help to improve our preparedness and anticipate future impacts.

How to cite: Tarasova, L.: Water extremes under change: from processes to impacts, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13436, https://doi.org/10.5194/egusphere-egu26-13436, 2026.

The Atlantic Meridional Overturning Circulation (AMOC) plays a major role in shaping the Northern Hemisphere climate, and assessing the risk of a future slowdown has become a key challenge in ocean research. Over the past two decades, advances in observations and modeling have substantially refined our understanding of where and how deep waters are formed.

In this ‎Award Lecture of the OS‎ Division, I will review these developments to examine the drivers of North Atlantic dynamics and their representation in coupled climate models. First, I will focus on observation-based estimates of water mass transformation in the subpolar gyre, highlighting the dominant role of local buoyancy forcing in the Irminger and Iceland basins. Second, I will examine how deep water formation is simulated in coupled climate models, identifying key biases that lead to excessive formation in the Labrador Sea and assessing their implications for the AMOC at subpolar latitudes. Finally, I will discuss the southward propagation of deep waters and the coherence of AMOC variability across the North Atlantic, placing these results in the broader context of AMOC change at different timescale.

How to cite: Petit, T.: On the Role of Atmospheric Forcing on the North Atlantic Dynamic – Insights from Observations and Climate Models, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10992, https://doi.org/10.5194/egusphere-egu26-10992, 2026.

North Atlantic DeepWater (NADW), the return flow component of the Atlantic Meridional Overturning Circulation (AMOC), is a major inter-hemispheric ocean water mass with strong climate effects but the evolution of its source components on million-year timescales is poorly known. Today, two major NADW components that flow southward over volcanic ridges to the east and west of Iceland are associated with distinct contourite drift systems that are forming off the coast of Greenland and on the eastern flank of the Reykjanes (mid-Atlantic) Ridge. Here we provide direct records of the early history of this drift sedimentation based on cores collected during International Ocean Discovery Programme (IODP) Expeditions 395C and 395. We find rapid acceleration of drift deposition linked to the eastern component of NADW, known as Iceland–Scotland Overflow Water at 3.6 million years ago (Ma). In contrast, the Denmark Strait Overflow Water feeding the western Eirik Drift has been persistent since the Late Miocene. These observations constrain the long-term evolution of the two NADW components, revealing their contrasting independent histories and allowing their links with climatic events such as Northern Hemisphere cooling at 3.6Ma, to be assessed.

How to cite: Sinnesael, M. and Karatsolis, B. T. and the Expedition 395 Scientists: Onset of strong Iceland-Scotland overflow water 3.6 million years ago, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9577, https://doi.org/10.5194/egusphere-egu26-9577, 2026.

Since December 2024, Parker Solar Probe has reached the mission's closest perihelion distance of 9.8 solar radii six times.  Data from each orbit has shown the spacecraft has been diving deep below the Sun's Alfvén surface with each pass, and covering nearly half the Sun at the same time. These measurements may therefore be interpreted as some of the most unambiguous direct sampling of a star's corona to date in regions which could previously only be probed with remote sensing techniques. In this talk we will review some recent insights into the large scale structure of the solar maximum corona and the Alfvén surface revealed by these new data, as well as our recent work studying the properties of polar-like fast solar wind in its early life and its subsequent evolution. We will close with a brief discussion on what we stand to learn with Parker continuing these deep dives as the Sun retreats into its next solar minimum.

How to cite: Badman, S.: The outer reaches of the Solar Corona as measured by Parker Solar Probe, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12552, https://doi.org/10.5194/egusphere-egu26-12552, 2026.