EGU General Assembly 2024  

The Indian Summer Monsoon Rainfall (ISMR) holds pivotal importance in the predominantly agrarian landscape of India, occurring from June to September. While the influence of large-scale atmospheric circulation on the monsoon has been extensively studied, the role of land surface processes remained largely unexplored until the early 2000s. In order to assess the impact of land surface evapotranspiration on monsoon rainfall in terms of recycled precipitation from June to September, we employed a dynamic recycling model. Our investigation revealed that land evapotranspiration contributes 20-25% of moisture to the late monsoon rainfall in September, specifically in Central and Northeast India. It is important to note that, as the recycling model relied on a reanalysis dataset, it does not account for contributions from land water management practices, such as irrigation.

To comprehensively address the human water management component within the human-natural water cycle in South Asia, we implemented a coupled land-atmosphere regional framework using the Weather Research Forecasting – Community Land Model (WRF-CLM). The primary drawbacks of the state-of-the-art irrigation schemes in land surface models, applied to Indian case studies, included the absence of provisions for considering paddy fields, which typically maintain a submerged cropland. Additionally, they did not consider India-specific irrigation practices, driven not by soil moisture measurements or agricultural necessity but by electricity and water availability, often uncontrolled and characterized by randomness. Moreover, existing irrigation datasets developed and used in the literature for South Asian regions considered the wrong crop season, focusing on pre-monsoon summer rather than the monsoon crop season, leading to misleading findings. By incorporating India-specific scenarios, our study demonstrated that alterations in land irrigation practices induce changes in atmospheric circulation, consequently influencing monsoon rainfall patterns, primarily in September. To substantiate these observations, we constructed a causal network among land-atmosphere variables across different river basins in India. Causal discovery methods revealed connections from land to atmosphere within a basin, atmosphere to atmosphere across basins, and atmosphere to land within a basin. This highlights that two neighboring river basins, traditionally assumed to be hydrologically independent when designing water management practices, are, in fact, interconnected through intricate land-atmosphere-land connections. These findings underscore the necessity for a systematic evaluation of India’s proposed large-scale river interlinking project, emphasizing the importance of addressing land-atmospheric feedback to ensure the project's success and sustainability.

How to cite: Ghosh, S.: Land-Atmosphere Interactions in Human-Natural Indian Summer Monsoon System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1614, https://doi.org/10.5194/egusphere-egu24-1614, 2024.

Is the Atlantic Overturning Circulation approaching a tipping point?

The Atlantic Meridional Overturning Circulation (AMOC) has a major impact on climate, not just around the northern Atlantic but globally. Paleoclimatic data show that it has been rather unstable in the past, leading to some of the most dramatic and abrupt climate shifts known [1].

These instabilities are due to two different types of tipping points, linked to amplifying feedbacks in the large-scale salt transport and in the convective mixing which drives the flow [2,3]. Of particular concern is the evidence for an ongoing weakening of the AMOC [4,5]: it likely is already at its weakest in a millennium [6].

These tipping points present a major risk of abrupt ocean circulation and climate shifts as we push our planet further out of the stable Holocene climate into uncharted waters. The lecture will discuss the paleoclimatic data, the instability mechanisms, the evidence for an AMOC slowdown and how close we may be to a dangerous tipping point.

References

[1] Rahmstorf, S., 2002: Ocean circulation and climate during the past 120,000 years. Nature 419, 207-214. doi:10.1038/nature01090

[2] Rahmstorf, S., 1995: Bifurcations of the Atlantic thermohaline circulation in response to changes in the hydrological cycle. Nature 378, 145-149. doi:10.1038/378145a0

[3] Rahmstorf, S., 1994: Rapid climate transitions in a coupled ocean-atmosphere model. Nature 372, 82-85. doi:10.1038/372082a0

[4] Rahmstorf, S., J.E. Box, G. Feulner, M.E. Mann, A. Robinson, S. Rutherford, and E.J. Schaffernicht, 2015: Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation. Nature Climate Change 5, 475–480. doi:10.1038/nclimate2554

[5] Caesar, L., S. Rahmstorf, A. Robinson, G. Feulner and V. Saba (2018). Observed fingerprint of a weakening Atlantic Ocean overturning circulation. Nature 556, 191–196. doi:10.1038/s41586-018-0006-5

[6] Caesar, L., McCarthy, G. D., Thornalley, D. J. R., Cahill, N. & Rahmstorf, S. Current Atlantic Meridional Overturning Circulation weakest in last millennium. Nature Geoscience (2021). doi:10.1038/s41561-021-00699-z

How to cite: Rahmstorf, S.: Is the Atlantic Overturning Circulation approaching a tipping point?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22395, https://doi.org/10.5194/egusphere-egu24-22395, 2024.

Orogeny, i.e. the formation of mountains, represents perhaps the most spectacular surface expression of plate tectonics. Orogenic belts are regions in the continental lithosphere where horizontal shortening results in crustal thickening, accompanied by magmatism, metamorphism, and the formation of Earth's highest topographic reliefs. The search for the dynamic mechanisms underlying orogeny has been ongoing since the early days of geology.

Building upon the influential work of Holmes (1931), we delve into the relationship between orogeny style and mantle dynamics. Here, I propose to distinguish between two types of orogeny: "subduction orogeny," associated with one-sided upper mantle subduction, and "mantle orogeny," linked to larger mantle convection cells. Extreme crustal thickening is a hallmark of the latter. Our proposition suggests that mantle orogeny is triggered by the penetration of slabs into the lower mantle, altering convection length scales. Numerical dynamic models support this idea, demonstrating that upper plate compression is linked to slab penetration into the lower mantle. Slabs can further induce buoyant plume upwelling intensifying whole mantle convection and upper plate compression.

To validate this model, we examine the geological and topography evolution record. Present-day compressional backarc regions often coincide with slabs subducting into the deep lower mantle. The temporal evolution of Nazca and Tethyan slabs, along with associated Andean Cordillera and Tibetan-Himalayan orogenies, suggests that extreme crustal thickening beneath Bolivia and the Tibetan plateau occurred during slab penetration into the lower mantle. This thickening in the Tertiary period bears similarities to Pangea assembly events. We propose that Late Paleozoic large-scale compression is related to a shift from transient slab ponding in the transition zone to lower mantle subduction. If our model holds true, the geological record of orogeny in continental lithosphere can be a valuable tool for understanding time-dependent mantle convection. Episodic lower mantle subduction may, in turn, be causally linked to the supercontinental cycle.

How to cite: Faccenna, C.: Orogeny and mantle dynamics : Holmes (1931) revisited, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16761, https://doi.org/10.5194/egusphere-egu24-16761, 2024.

The core is the deepest part of the planets. It is partially or totally liquid in all the terrestrial planets of the Solar System and sometimes generates a magnetic field (it is the case for the Earth and Mercury). Rapidly rotating planets like Earth and Mars, which are in addition inclined in space, undergo gravitational effects from the Sun and their moons (as well as from the other planets to a minor extend). Consequently, Mars and the Earth wobble in space: their rotation axis is doing a precession around the perpendicular to the ecliptic and additional periodic motions called nutations. Nutations provide information about the core and about the coupling mechanisms between the core and the mantle. Additionally, these two planets exhibit variations in their rotation called length-of-day (LOD) variations. The most recent data from using the VLBI (Very Long Baseline Interferometry) technique for the Earth and from the NASA InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) mission on Mars provide insights on the processes modifying their rotation and orientation in space. While nutations are very well understood, LOD are difficult to predict. Seasonal changes are mostly related to external geophysical fluids: atmosphere, ocean, and hydrosphere for the Earth, atmosphere and icecaps for Mars. While we have no precise series long enough for Mars, it is not the case for the Earth for which long timescale (decadal) LOD variations are mostly linked to the core. Even polar motion of the Earth can provide information about the core.

How to cite: Dehant, V.: Rotation of Mars and the Earth revealing their core properties., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1234, https://doi.org/10.5194/egusphere-egu24-1234, 2024.

Terrestrial environments and their ecosystems demand healthy, sustainable, and resilient soils. Over the past couple of decades, significant efforts have been made to safeguard global soils, yet the materials and resources responsible for soil formation have been widely overlooked.  The transition from bedrock to soil – a zone often described as ‘soil parent material’ – holds an exciting yet untapped potential for helping us address some of the largest environmental challenges, including climate change and the biodiversity crisis. In this award lecture, I will present a strand of my research programme ‘Building Tomorrow’s Soils’ which seeks to establish how soil parent materials enhance the sustainability, health, and resilience of soil systems. First, with a focus on carbon sequestration, I will highlight how the bedrock–soil transition zone has the potential to be a long-term store of organic carbon. I will then present research which shows that some soil parent materials release petrogenic (i.e. rock-derived) organic carbon into soils. These understudied inputs of organic carbon to soils are currently absent from most, if not all, soil carbon models, which threatens our ability to optimize soil carbon management in the long-term. Finally, I will argue that developing a mechanistic understanding about this transition zone – this underexplored material which is neither rock nor soil in structure and function, but a blend of both – requires a similarly cross-disciplinary approach.

How to cite: Evans, D.: Digging into the Future: The transition between bedrock and soil as an underexplored frontier zone in geoscience, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11742, https://doi.org/10.5194/egusphere-egu24-11742, 2024.

Today, our world of 8 billion people and countless other species faces planetary crises that are interconnected, complex, and existential in scale and comprehension, including climate change, biodiversity loss, pollution, nitrogen, and poverty. Scientists are at the heart of designing the studies to understand these threats, producing the data that calibrates them, and interpreting the those data. They are among the first members of society to recognise these threats and often the most committed to preventing their worst outcomes. For action on these crises, the general public, and policymakers representing them, need to understand the risks and also care about the outcomes: a job for the media, authors, artists and filmmakers. However, science and the media have very different communication styles and approaches, something that scientists often find uncomfortable. How can scientists best manage their public outreach, and work with the media to ensure their expertise and knowledge helps society navigate a better future?

How to cite: Vince, G.: Existential Threat: How Scientists Can Work With The Media To Communicate Complex Systemic Crises, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21986, https://doi.org/10.5194/egusphere-egu24-21986, 2024.

South Africa has an exceptionally rich geological heritage, including tourist attractions such as Table Mountain and the Cradle of Humankind, as well as important economic deposits, such as gold, diamonds, coal, and Platinum-Group-metals. South Africa also has a rich cultural and linguistic heritage. Our people are known for their resilience, born from our uncomfortable and ugly past – apartheid. Although apartheid came to an end in 1994, its impact remains visible today, with widespread poverty, inequality, poor education, violence and corruption. English, despite only being a first language for 8% of the population, dominates scientific discourse in South Africa. This is partly a result of apartheid, whose aim was to exclude the majority of non-white South Africans from the scientific community. Given the poor education system, many South Africans, despite holding a grade 12 qualification, still struggle with the language, particularly at varsity level. IsiXhosa is the mother tongue of over 8 million people, and is mutually intelligible with Zulu, Northern Ndebele and Southern Ndebele, meaning it is potentially accessible to 23 million people. Classroom studies have demonstrated that people engage more and understand better when the conversation is in their native tongue^1-3

Despite the fact that South Africa is an exporter of many geological resources, and the intertwined history of mining with the black community, geology remains inaccessible to most people. South Africans, and Africans in general, are big storytellers - stories about the constellations, the moon, and the universe as a whole. This project, Reclaiming the rocks: ukuthetha ngezifundo zomhlaba ngesiXhosa, is an open invitation to invite all South Africans to share in their rich geological history through storytelling. It is a statement that science, like music, knows no language. We have summarized the most compelling stories about South Africa’s geological history, translated them into isiXhosa, and host them on an open access website (chosindabazomhlaba.com), and on YouTube. Recently, we started a school drive, reading these stories to school children. This project has had an impact on the lives of many people, whether they spoke isiXhosa or not, geologists or not. Next, we plan to write a children’s book and expand the school drive. Our ultimate goal is to develop a Geological encyclopedia written in isiXhosa and the other South African languages.

How to cite: Hashibi, S. and Tostevin, R.: Reclaiming the rocks: ukuthetha ngezifundo zomhlaba ngesiXhosa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2760, https://doi.org/10.5194/egusphere-egu24-2760, 2024.

Measurements in the remote unpolluted atmosphere have tremendous power to reveal processes that are happening on a global scale.   In the marine atmosphere where nitrogen oxide (NOx) levels are very low,  the photochemical loss rate of tropospheric ozone dominates over production, allowing loss processes to be sensitively explored.   We showed that bromine and iodine emitted from open-ocean marine sources initiate important global-scale catalytic ozone-destroying cycles and found that the deposition of ozone and subsequent reactions at the sea surface are a substantial pathway for production of volatile iodine.   Production of ozone in the remote atmosphere is predominantly regulated by the abundance of NOx, which also exerts substantial control over the hydroxyl radical (OH), the most important oxidant in the atmosphere.  It is now emerging that NOx regeneration pathways, namely the photolysis of particulate nitrate, could provide the dominant source of NOx to the marine atmosphere.  This has significant implications for our understanding of the chemistry of the remote troposphere.  This presentation discusses advances made in understanding these important, predominantly natural, cycles and their impacts on the atmosphere.

How to cite: Carpenter, L., Callaghan, A., Chance, R., Evans, M., Lee, J., Read, K., Rowlinson, M., Shaw, M., Sherwen, T., Andersen, S., Tinel, L., and Plane, J.: Discovering global-scale processes in the marine atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11717, https://doi.org/10.5194/egusphere-egu24-11717, 2024.

Tropical cyclones (TCs), also referred to as hurricanes or typhoons, are amongst the deadliest and costliest natural hazards, affecting people, economies, and the environment in coastal areas around the globe when they make landfall. TCs are projected to become more intense in a warming climate, enhancing the risks associated with their wind speeds, precipitation and storm surges. It is therefore crucial to minimize future loss of life and by performing accurate TC risk assessments for coastal areas. Calculating TC risk at a global scale, however, has proven to be difficult, given the limited temporal and spatial information on landfalling TCs around much of the global coastline, and how this is going to change under climate change.

To overcome these limitations, we developed a novel approach to calculate TC risk under present and future climate conditions using the Synthetic Tropical cyclOne geneRation Model (STORM). STORM is a fully statistical model that can take any input dataset and statistically resamples this to an equivalent of 10,000 years of TC activity under the same climate condition. The resulting publicly available STORM dataset contains of enough TC activity in any coastal region of interest to adequately calculate TC probabilities and risk from. Furthermore, the STORM algorithm has been expanded with a future-climate module, enabling globally consistent local-scale assessments of (changes in) TC risk. This presentation will discuss the challenges and opportunities in using such synthetic datasets, particularly in the light of improving our understanding of TC risk. 

How to cite: Bloemendaal, N.: Weathering the STORM: Challenges and opportunities in tropical cyclone risk research , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21254, https://doi.org/10.5194/egusphere-egu24-21254, 2024.

Volatile organic compounds (VOCs) are important mediators of forest-atmosphere interactions, regulating plant performance and atmospheric processes. Amazonian forests comprise the dominant source of VOCs to the global atmosphere. Yet, there is a poor understanding of how VOC emissions vary in response to ecophysiological and environmental controls in Amazonian ecosystems and even less understanding of how ecosystem emissions respond to climate extremes and land use change. I will summarize my work on VOC emissions from different ecosystems and scales in the Amazon and point out that VOCs can be indicators of forest stress and, therefore, a possible metric of forest vulnerability. First, I will present the state-of-the-art of VOC emissions and their interactions with the climate system in the Amazon. Next, I will demonstrate how these interactions can differ when considering different forest types and environmental stresses, including extremes of heat and drought. Finally, I will highlight the recent progress of VOC emissions investigated in the so-called "Amazon arc of deforestation" and indicate the potential of VOCs as a metric of forest vulnerability in climate modeling.

How to cite: Gomes Alves, E.: Volatile Organic Compounds: mediators of forest-atmosphere interactions and indicators of forest vulnerability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1832, https://doi.org/10.5194/egusphere-egu24-1832, 2024.

My fascination with the biogeosciences started with the investigation of nitrogen (N) and phosphorus (P) enrichment of lakes stimulating the growth of diatoms leading to increased sedimentation and eventual depletion of dissolved silicate from the water column. At that time most research on the global Si cycle was focused on weathering and had not explored the complexity of the terrestrial biogeochemical cycle. Our research demonstrated that diatoms and phytoliths, e.g. biogenic silica that accumulates in the living tissues of growing plants, are transported from lakes and rivers on the continents into the oceans. The emerging understanding is that the flux and isotopic composition of dissolved silicate delivered to the ocean has likely varied over time mediated by a fluctuating continental pool.

An important question we addressed was if reductions of P and N could reduce eutrophication and degradation of freshwater and marine ecosystems. Our analysis explored the rationale for only P or only N reductions and concluded that dual–nutrient reduction strategies were needed for aquatic ecosystems. A focus on only P or only N reduction should not be considered unless there is clear evidence or strong reasoning that reducing the inputs of only one nutrient is justified in that ecosystem and will not harm downstream ecosystems.

The depletion of dissolved oxygen in bottom waters is one of the common responses of aquatic ecosystems to eutrophication. A classic example is the semi-enclosed brackish Baltic Sea. Our research has shown that the Baltic Sea is the largest anthropogenically induced hypoxic area in the world, which has increased 10-fold during the last century due to increased nutrient inputs. Concurrently, the coastal zone has experienced increasing hypoxia during the same period with the Baltic Sea coastal zone containing over 20% of all known sites suffering from hypoxia worldwide. Our research has highlighted the continuously growing problems of hypoxia and anoxia with eutrophication.

Altered global biogeochemical cycles is not only a feature of the Anthropocene but ongoing geological processes. Our recent research has focused on the use of silicon isotope signatures of unaltered sponges and radiolarians to estimate dissolved silicate drawdown as a proxy for the changes in the productivity of diatom communities in the Mesozoic oceans and how the ocean chemistry changed with the evolution of diatoms. Our major results to date suggest that dissolved silicate has been low in the oceans for at least the last 100 million years because of the extreme efficiency of dissolved silicate uptake by diatoms reducing ocean concentrations.

My continued enchantment with biogeochemical processes and collaboration with other creative scientists has lead to uncovering new biogeochemical pathways which stimulates the drive to learn more about how ecosystems operate.

How to cite: Conley, D.: Reflections regarding our biogeochemical studies in lakes and marine environments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12020, https://doi.org/10.5194/egusphere-egu24-12020, 2024.

Major efforts have been made in recent decades to decipher the climate of the past and its drivers with the help of proxy archives. Reconstructions of past climate variations are of immediate societal relevance because they serve as a baseline for anthropogenic climate change, and help us understand how past societies coped (or failed to cope) with extreme climate events. Good paleoclimatology, however, relies on ever more precise and accurate dates. While many proxy archives provide continuous year-by-year sequences going back many thousands of years, ambiguities in their interpretation introduce time uncertainty which increases over time. As a consequence, natural climate variability is underestimated when time-uncertain climate reconstructions are combined.

Through the use of "Miyake events" — novel time markers that are accurate to the year, globally distributed and detectable in different climate archives — it has recently become possible to better date and synchronize some of these climate archives, notably the polar ice-core records. The revised dating of ice cores from both Greenland and Antarctica combined with technological advances based on real-time continuous flow analysis techniques has shed new light on a prominent impact of volcanic eruptions on past climate and human societies. In this talk, I will highlight how we can date ancient eruptions, (sometimes to the season), geochemically identify their provenance and quantify their climate impact potential through emissions of sulfuric gases using large networks of ice cores. Case studies include prominent eruptions from Vesuvius or Santorini as well as eruptions largely unknown to the general public, for example from Alaska. I will discuss linkages to precisely dated proxies (e.g. tree-rings) and documentary records to demonstrate the accuracy of the new ice-core chronologies and to delineate climatic and societal responses to external shocks caused by major volcanic eruptions. In my concluding remarks, I will show how such lessons from the past can help to improve our understanding of past natural climate variability and to quantify global risks arising from volcanic activity in the future.

How to cite: Sigl, M.: A slice through time — securing timelines of past climate, global volcanism and human societies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8168, https://doi.org/10.5194/egusphere-egu24-8168, 2024.

The Mid-Pleistocene Transition (MPT) is commonly characterized as a change in both temperature and ice volume from smaller amplitude, 41-kyr variability to higher amplitude, ~100-kyr variability in the absence of any significant change in orbital forcing. Here we reassess these characteristics based on our new reconstructions of changes in global mean surface temperature (DGMST) and global mean sea level over the last 2.5 Myr. Our reconstruction of DGMST includes an initial phase of long-term cooling through the early Pleistocene followed by a second phase of accelerated cooling during the MPT (1.5-0.9 Ma) that was accompanied by a transition from dominant 41-kyr low-amplitude periodicity to dominant ~100-kyr high-amplitude periodicity. Changes in rates of long-term cooling and variability are consistent with changes in the carbon cycle driven initially by geologic processes followed by additional changes during the MPT in the Southern Ocean carbon cycle. The spectrum of our sea-level reconstruction is dominated by 41-kyr variance until ~1.2 Ma with subsequent emergence of a ~100-kyr signal that, unlike global temperature, has nearly the same concentration of variance as the 41-kyr signal during this time. Moreover, our sea-level reconstruction is significantly different than all other reconstructions in showing fluctuations of large ice sheets throughout the Pleistocene as compared to a change from fluctuations in smaller to larger ice sheets during the MPT. We attribute their longer period variations after the MPT to modulation of obliquity forcing by the newly established low-frequency CO₂ variability. Specifically, prior to reaching their maximum size at the end of each ~100-kyr interval, ice-sheet response to periods of lower CO₂ was modulated by higher obliquity, and vice versa, with the times of maximum ice-sheet growth only occurring when low CO₂ combined with the next obliquity low. Ice sheets then began to melt in response to the next increase in obliquity, with the subsequent sequence of events and feedbacks leading to a termination. High-resolution ice-core CO₂ records that extend beyond 0.8 Ma are needed to test this hypothesis. Otherwise, large ice sheets shared a common size threshold throughout the Pleistocene equivalent to sea level below -80 m that, when exceeded, resulted in a termination that was paced by the next increase in obliquity.

How to cite: Clark, P. U., Shakun, J., Rosenthal, Y., Pollard, D., Köhler, P., Hostetler, S., Bartlein, P., Liu, Z., Zhu, C., Schrag, D., and Pisias, N.: A Revisionist View of the Mid-Pleistocene Transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3722, https://doi.org/10.5194/egusphere-egu24-3722, 2024.

Detection, attribution and projection of glacier and ice-sheet change characterize much of our community’s work, motivated in part by the associated impacts ranging from local hazards to regional water supply to global sea-level rise. Toward improved attribution of glacier change on local to regional scales, I profile work aimed at discerning the internal versus external drivers of glacier behaviour through process-oriented studies. Using examples from northern Canada, combining observational and numerical approaches improves our understanding of fundamental processes that define the boundary conditions at the ice interface with bedrock, water and atmosphere. These studies have allowed us to revisit questions related to glacier surging, hydrology and ice-dammed lakes and the co-evolution of glacier geometry and thermal structure, with occasionally surprising and counter-intuitive results.

While the internal dynamics of glacier systems have the potential to confound the climate signal on societally relevant timescales, the direct effects of climate via surface mass balance remain as important as ever. Improved observational platforms, advances in modelling and the growing abundance and availability of remotely sensed data have amplified our capacity to study these systems, and more generously than ever reveal information archived by glacier processes. Using these tools, we are now beginning to disentangle the contributions of the geologic substrate, environmental setting, internal ice dynamics and climate forcing to observed glacier change in globally significant ice-rich parts of the world.

How to cite: Flowers, G.: Understanding glacier processes to decode the drivers of glacier change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6597, https://doi.org/10.5194/egusphere-egu24-6597, 2024.

Supraglacial lake drainages are isolated events that deliver the largest observable fluxes of surface melt to the ice-sheet bed. This talk will present advances in the study of these lake drainages, through which we piece together an empirical understanding of glacier hydrology. We examine the ways in which lakes both respond to, and determine, the hydrologic and glaciologic conditions under which they exist. We begin with the process puzzle of what mechanisms drive the opening of fractures within the compressive regions where lakes form, allowing hydro-fracture-driven drainages to occur. Next, we follow drained lake water in time and space, using the natural experiments provided by the drainages to infer subglacial-drainage-system transmissivity and structure beneath kilometer-thick ice flowing at rates of tens to thousands of meters per year in Greenland. In widening our view to previous subglacial-flood events observed at other ice-sheet locations—as well as at alpine, valley, and tidewater glaciers—we observe surprising similarities across a wide range of ice thicknesses, flow speeds, and types of flood events. The similarities we observe are encouraging because they suggest that information on drainage-system structure and evolution gleaned from these episodic events can be used to understand the wider picture. Finally, we examine current challenges: how do we move from the observed mechanisms of individual lake drainages to an integrated understanding of the importance of hundreds of drainages for long-term ice-sheet response and ice-shelf collapse? Progress will require the combination of geodetic observations, hydrologic simulations, and geophysical models to deconvolve the differing mechanisms that result in clusters of drainages in the multiple settings in which lakes form.

How to cite: Stevens, L. A., Banwell, A. F., Behn, M. D., Chase, D. L., Das, S. B., Dell, R. L., Falconer, E., Joughin, I. R., Lai, C.-Y., Larochelle, S., Lu, G. J., McGuire, J. J., Nettles, M., Okal, M., Rines, J., and Willis, I. C.: Supraglacial Lake Drainage: from process puzzle to subglacial diagnostic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11275, https://doi.org/10.5194/egusphere-egu24-11275, 2024.

The analysis of deformation and failure in many sedimentary settings hinges upon a fundamental understanding of inelastic behaviour, failure mode of porous carbonate rocks and their implications on fluid flow at various scales. The mechanical compaction behaviour of carbonate rock of a broad range of porosity has been investigated in the laboratory over a wide range of stress conditions in the last decades. The phenomenology of brittle failure and inelastic compaction in this rock type with often bimodal pore size distribution was found similar to that of sandstone. Inelastic compaction in limestone involved primarily cataclastic pore collapse and micromechanical analysis showed the strong influence of the micropore size on the yield stress. Compaction experiments on porous limestones also revealed a broad spectrum of complex failure modes. In situ X-ray Computed Tomography imaging combined with Digital Volume Correlation provided the first observations of discrete compaction bands in a high porosity limestone. Permeability variations in carbonates associated with shear-enhanced compaction and these failure modes were found significantly smaller than variations previously reported in porous sandstones of comparable porosities.

In geophysical applications such 4D reservoir monitoring and the production of geothermal reservoirs, an understanding of the mechanical and chemical effects of pore fluid is fundamental. The mechanical influence of pore fluid on different properties is characterized by effective pressure coefficients. For limestone with dual porosity, both effective stress coefficients for permeability and pore volume change were observed to be consistently greater than unity. This implies that microscopic homogeneity is not a valid approximation for a limestone with dual porosity, and a realistic model must explicitly differentiate between the macropores and micropores, as well as account for their interplay in controlling the hydromechanical behaviour. Recent data showed that a significant weakening effect of water could also be expected in most carbonates. 

How to cite: Baud, P.: Inelastic compaction in porous carbonates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6574, https://doi.org/10.5194/egusphere-egu24-6574, 2024.

Due to contrasting results between laboratory tests, geophysical data, and field observations, the strength of the plagioclase-rich lower continental crust remains a topic of debate. It has been shown that its strength highly depends on the presence of fluids as they trigger metamorphic reactions that can result in permanent weakening. An important metamorphic reaction in the lower continental crust is the breakdown or hydration of plagioclase and the associated growth of epidote-group minerals, kyanite, quartz, and jadeite/albite. To investigate the impact of this particular reaction on the strength of the lower continental crust, we combined experimental work, i.e., Griggs-deformation tests, with extensive microstructural observations of the recovered experimental samples. Experimental conditions were 1 to 1.5 GPa confining pressure, 550 to 950 °C, and for the deformation tests, we used strain rates ranging from 10^-6 to 10^-5 s^-1. Our results reveal two main findings. First, deformed plagioclase aggregates as well as deformed granulite drill cores show that deformation-induced features in plagioclase grains, e.g., cleavage cracks and twin boundaries, act as nucleation sites for metamorphic reactions and melting. Consequently, reaction can progress faster in deformed samples as the effective reactive surface area is increased relative to undeformed counterparts. Second, when deformed under identical experimental conditions, pure epidote aggregates are consistently stronger or show equal strengths than pure plagioclase aggregates. Hence, a partial plagioclase breakdown, i.e., the exclusive growth of epidote-group minerals at low reaction progress, is not expected to result in permanent weakening. This result further strengthens the idea that a process akin to Zener pinning is a viable mechanism to cause long-term weakening in rocks.

How to cite: Incel, S., Renner, J., Schubnel, A., Labrousse, L., Baisset, M., and Mohrbach, L. K.: Deformation and reaction of plagioclase-rich rocks at conditions of the lower continental crust, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10806, https://doi.org/10.5194/egusphere-egu24-10806, 2024.

Data Science and Informatics methods have been at the center of many recent scientific discoveries and have opened up new frontiers in many areas of scientific inquiry. In this talk, I will take you through some of the most recent and exciting discoveries we've made and how informatics methods planned a central role in these discoveries. 

First, we will look at our work on data-driven biosignature detection, specifically how we combine pyrolysis-gas chromatography-mass spectrometry and machine learning to build an agnostic molecular biosignature detection model. 

Next, we will talk about how we used association analysis to predict the locations of as-yet-unknown mineral deposits on Earth and potentially Mars. These advances hold the potential to unlock new avenues of economic growth and sustainable development.

Finally, we will set our sights on exoplanets—celestial bodies orbiting distant stars. The discovery of thousands of exoplanets in recent years has fueled the quest to understand their formation, composition, and potential habitability. We develop informatics approaches to better understand, classify and predict the occurrence of exoplanets by embracing the complexity and multidimensionality of exoplanets and their host stars.

How to cite: Prabhu, A., Morrison, S., Hazen, R., Wong, M. L., Hystad, G., Cleaves II, H. J., Eleish, A., Cody, G., Gatne, V., Chavez, J. P., Ma, X., and Fox, P. and the Mineral Informatics Team: X-informatics at the center of scientific discovery: Detecting biosignatures, predicting mineral occurrences, and characterizing planetary kinds. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2658, https://doi.org/10.5194/egusphere-egu24-2658, 2024.

The earth sciences are first and foremost observational sciences, based on data collected on the planet over generations. It is from this data that interpretations, concepts and models are produced. The description of data by those who produced it and its conservation has always been a concern for scientists, to enable it to be reused and reproduced. This has been achieved by adopting common rules and standards, for example for indicating the geographical coordinates of an observation or the units of measurement used.

Today's scientific challenges, first and foremost the climate challenge, require the mobilisation of different scientific disciplines, often with different languages and practices.

The establishment of data infrastructures on an international scale means that researchers can use computer protocols to access considerable sources of data from their own and other disciplines. Digital tools such as AI make it possible to make machines 'reason' about data to produce new knowledge.

All these factors make it critical for both humans and machines to be able to 'understand' the data used. This understanding necessarily requires the adoption of common reference systems on an international scale and across all disciplines. These standards are based on a common 'vision' produced by the scientific community (and updated as knowledge evolves), resulting in vocabularies and ontologies shared by the community.

This presentation will look at the ecosystem for producing and maintaining standards for the geosciences and some of the issues involved in the relationship between scientists and the production and use of standards.

How to cite: Robida, F.: The central role of geoscience data standards in generating new knowledge, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4562, https://doi.org/10.5194/egusphere-egu24-4562, 2024.

The precision and accuracy of GPS/GNSS positioning has improved by considerably more than an order of magnitude over the course of my career, and the amount of data readily available (GNSS sites) has increased by several orders of magnitude. Over the last 40 years, geodesists have exploited this dramatic (and still continuing) increase in measurement capability to discover and study an ever-increasing set of phenomena. In the 1980s and early 1990s, the GPS satellite constellation was incomplete and there was only a sparse global tracking network. As a result, measurement noise limited rate accuracy to a few to several mm/yr, whereas today we are approaching accuracies of a few tenths of 1 mm/yr for long-term rates, and likely approaching the limit at which variability in surface loading makes motions fundamentally non-linear.

In this talk I will take a historical perspective, highlighting the improvement in measurement capabilities and our understanding of tectonic and other earth processes. At the beginning of my career, we focused on estimating rates of steady processes like rigid plate motions, the distribution of strain across rapidly-deforming plate boundary zones, or the displacements due to large earthquakes. We thought that over most of the Earth, motion and deformation mostly occurred linearly with time. The noise level in position solutions at that time was very high, and most non-linear variations in observed time series were considered to be noise either due to positioning error or to unstable geodetic monuments. While the deformation due to changing surface loads was recognized as a physical signal, knowledge of the changing loads was rudimentary and the signal was below the noise level in most cases. Today we recognize a wide variety of signals that produce a mix of linear and non-linear motions of the Earth, and positioning geodesy has become the essential tool for studying most of them. I have had the good fortune to work on measuring and understanding many of these processes, and I will discuss some of the highlights of the evolutionary path of positioning geodesy along with future perspectives. We have reached, or nearly reached, the point at which the approximation of linear motion breaks down because the measurement precision is now comparable to or smaller than the non-linear surface loading deformation over most of the planet. The coming years should see more exciting discoveries, but we must think broadly about the full range of geophysical signals that are contained within our data.

How to cite: Freymueller, J.: The Evolution of Positioning Accuracy and Linear vs. Non-linear Motions of the Earth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4118, https://doi.org/10.5194/egusphere-egu24-4118, 2024.

The Gravity Recovery and Climate Experiment Satellite mission has provided estimates of spatiotemporal changes in the Earth’s gravity field, which represents mass transport near the surface of the Earth. This unique satellite mission has been used to study groundwater depletion, lake volume changes, sea level rise, and the viscoelastic response of solid Earth to glacial cycles; glacial isostatic adjustment. In this talk, I will share my experiences: published, unpublished, and even incomplete, in using GRACE data for Earth system science and emphasize the power and limitations of this unique satellite mission. 

How to cite: Vishwakarma, B. D.: GRACE for Earth system science: novel insights into hydrology, sea level rise, and solid Earth uplift, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11422, https://doi.org/10.5194/egusphere-egu24-11422, 2024.

The growing global demand for metal resources requires new high-grade ore deposit discoveries. Known large sediment-hosted clastic-dominated base metal deposits predominantly occur in failed continental rifts and the passive margins of successful rifts. Understanding the large-scale geodynamic controls on rift-related mineralizing processes occurring on much smaller spatial and temporal scales can thus help identify new areas for exploration.

We numerically model 2D rift systems from inception to break-up with the geodynamic code ASPECT (Kronbichler et al., 2012; Heister et al., 2017) coupled to the landscape evolution model FastScape (Braun and Willett, 2013; Neuharth et al., 2022). With ~300-m resolution simulations, we investigate how rift type and the efficiency of sedimentary processes affect the formation of potential metal source and host rock domains, identified by their lithology and temperature. We subsequently analyse the optimal alignment of these domains where metals are respectively leached and deposited  with faulting events providing potential fluid pathways between them (e.g., Rodríguez et al., 2021). For favourable co-occurrences of source, pathway and host, we identify the tectonic conditions that predict the largest clastic-dominated lead-zinc deposits.

We show that the largest potential for metal endowment is expected in narrow asymmetric rifts at a distance of several tens of kilometres to the shore (Glerum et al., 2023). Characterized by rift migration, these rifts generate a wide and a narrow conjugate margin. On the narrow margin, the long-lived border fault accommodates a thick submarine package of sediments, including deep permeable continental sediments and shallower layers of organic-rich sediments. Elevated temperatures from continued thinning could lead to fluids leaching metals from the permeable sediments. Both the border fault and later synthetic faults can provide fluid pathways from the source to the shallow host rock in potential short-lived mineralisation events. In wide rifts with rift migration, these favourable configurations occur less frequently and less potential source rock is produced, limiting potential metal endowment. In simulations of narrow symmetric rifts, the potential for ore formation is low. Based on these insights, exploration programs should prioritize identifying exhumed ancient narrow margins formed in asymmetric rift systems.

Braun and Willett 2013. Geomorphology 180–181. 10.1016/j.geomorph.2012.10.008.

Glerum et al. preprint. EGUsphere 1-40. 10.5194/egusphere-2023-2518.

Heister et al. 2017. Geophys. J. Int. 210 (2): 833–51. 10.1093/gji/ggx195.

Kronbichler et al. 2012. Geophys. J. Int. 191: 12–29. 10.1111/j.1365-246X.2012.05609.x.

Neuharth et al. 2022. Tectonics 41 (3): e2021TC007166. 10.1029/2021TC007166.

Rodríguez et al. 2021. Gcubed 22: 10.1029/2020GC009453.

How to cite: Glerum, A. C., Brune, S., Magnall, J. M., Weis, P., and Gleeson, S. A.: Geodynamic controls on sediment-hosted lead-zinc deposits in continental rifts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5404, https://doi.org/10.5194/egusphere-egu24-5404, 2024.

Geodynamics is an actively expanding young quantitative science, which defined its mission very generally as introducing of physical-mathematical methods into traditionally observations-focused Earth and planetary sciences in order to understand and quantify origin and evolution of Earth and other planets. As such, this young science is not limited by any specific object or subject and widens its scope through time. This is a very natural process (‘instinctive evolution’) since human scales of direct observation are extremely limited in both time and space and since rapid progress of quantitative physical-mathematical and computational methods offers every day new and exceptional possibilities to explore sophisticated physical-mathematical models for understanding intrinsically complex natural processes. As the result of this ‘instinctive evolution’, new frontiers in geodynamics are (and always were) defined by its expansion toward other fields. Initially, Geodynamics mainly expanded towards Structural Geology and Tectonics. Currently, new Geodynamics expansion tendencies are clearly visible toward: Seismology, Geomorphology, Geochemistry, Petrology, Climatology, Planetology/Astronomy and Biology/Astrobiology. In this lecture, I will give some recent examples of this impressive expansion and outline future expectations and challenges.

How to cite: Gerya, T.: New Frontiers in Geodynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8300, https://doi.org/10.5194/egusphere-egu24-8300, 2024.

The global impact of diseases and environmental pressures on trees and forests has resulted in the decay and loss of a significant portion of the Earth’s natural heritage. Responding to this challenge, Ground Penetrating Radar (GPR), a well-established and reliable non-destructive testing (NDT) method, emerges as a fundamental assessment technique with vast potential. Its efficacy spans various domains, from Earth sciences to engineering, making GPR uniquely suited for forestry applications and offering a sustainable and non-invasive alternative to destructive methods like coring.

Within forestry applications, GPR assumes a critical role in optimising economic expenditure for tree maintenance while simultaneously enhancing public safety. Swift and reliable detection of subsurface anomalies make GPR essential in safeguarding natural heritage and facilitating early identification of tree decay, ultimately supporting effective tree disease control.

The present work explores the extension of GPR's capabilities to evaluate critical parameters in tree health, focusing on the assessment of root systems and the identification of potential structural weaknesses within tree trunks.

The study introduces a series of recent experimental-based and theoretical models, each contributing to the understanding and enhancement of tree assessment. These models refine the interpretation of intricate reflection patterns, providing a refined understanding of tree trunk conditions. Additionally, models for the early detection of decays and cavities in tree trunks are presented, offering valuable insights into the internal structure of trees and enhancing the sensitivity and precision of GPR for proactive tree health management.

In terms of assessing and monitoring tree roots, the study introduces methodologies designed to enhance the understanding of below-ground ecosystems. Developed algorithms for root detection and tracking, along with methodologies for estimating root mass density, offer insights into growth patterns and contribute to sustainable tree management practices. Furthermore, recent methodologies focus on understanding interconnections within tree root systems and the surrounding environment, identifying buried structures within the root system, addressing unique challenges faced by street trees in urban environments, refining the analysis of tree root systems using frequency spectrum-based processing, and integrating artificial intelligence for automatic recognition to enhance the efficiency of root system assessment.

Finally, unique case studies are presented, showcasing the methodology, survey planning, and site procedures. These case studies add depth to the exploration, reflecting the practical application of the research in diverse and challenging scenarios.

How to cite: Lantini, L. and Tosti, F.: Towards Sustainable Futures in Tree Assessment using Ground Penetrating Radar: Insights, Developments and Novel Perspectives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8419, https://doi.org/10.5194/egusphere-egu24-8419, 2024.

Volcanoes emit significant amounts of gases into the atmosphere through visible and non-visual degassing manifestations regardless of whether volcanoes are active or quiescent. The latter, also known as diffuse or silent degassing, occurs across the entire volcanic building. Water vapour (H₂O), carbon dioxide (CO₂), and sulfur (S) are the three most abundant magmatic volatiles, with CO₂ being the least soluble in silicate melts. Diffuse volcanic degassing alters the chemical composition of volcanes' ground/soil gas atmosphere, resulting in enrichment of CO₂, He, and other gas species. Over the last 25 years, extensive research on diffuse CO₂ degassing has been conducted at volcanic and geothermal systems, indicating that silent CO₂ degassing is an important mechanism for dissipating energy at volcanoes and contributes significantly to global CO₂ emissions from subaerial volcanism. As a result, diffuse CO₂ degassing studies have been regarded as a powerful tool in geochemical monitoring programs for volcanic surveillance, particularly in volcanic areas lacking visible gas manifestations (plume, fumaroles, hot springs, etc.), a valuable tool for identifying productive geothermal reservoirs, and a potential source of large amounts of CO₂ to the atmosphere via gobal subaerial volcanism.

Diffuse degassing investigations on volcanoes involve primarily in-situ ground CO₂ efflux measurements and the collecting of gases at a certain depth for later chemical and isotopic analysis. CO₂ and He are the two most interesting gas species to investigate in diffuse degassing studies due to their similar low solubility in silicate melts at low pressures and suitability as geochemical tracers of magmatic activity. However, once exsolved from the silicate melts, their journey through the crust to the surface is considerably different. While CO₂, as a reactive gas, is influenced by interfering processes (gas scrubbing by groundwaters and interaction with rocks, decarbonatation processes, biogenic production, and so on), He is chemically inert, radioactively stable, non-biogenic, highly mobile, and relatively insoluble in water. These properties minimize the interaction of this noble gas with the surrounding rocks or fluids during its ascent towards the surface. Their geochemical differences yield higher relative He/CO₂ ratio in the fumarole gases than is actually present in the magma, but it decreases when the magma reservoir reaches enough pressure to generate incipient fracture systems approaching the eruption, thus releasing considerably more of the magma volatiles.

Quantifying global volcanic CO₂ emissions from subaerial volcanism is critical for gaining a better knowledge of the rates and mechanisms of carbon cycling, as well as their effects on the long-term development of Earth's climate across geological timescales. Recent studies show that diffuse degassing contributes 47 to 174 Tg·y^-1 to the atmosphere, although our understanding of the global diffuse CO₂ degassing from subaerial volcanism could be larger.

Several examples of diffuse degassing research on many different volcanic systems around the world performed by our research team and collaborators during the last 25 years will be presented during my award/medal lecture, strongly supporting that diffuse degassing is a useful tool for volcanic surveillance and a significant contributor to the global CO₂ emissions from subaerial volcanism.

How to cite: Pérez, N. M. and the INVOLCAN/ITER Research Team: The silent degassing of volcanoes: a useful tool for volcanic surveillance and a significant contributor to the global CO2 emission from subaerial volcanism , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14781, https://doi.org/10.5194/egusphere-egu24-14781, 2024.

Over the Tertiary, the uplift of the Himalaya combined to the development of the monsoon generated the largest erosion basins of the planet. More than 80% of the erosion is exported to the Bay of Bengal by the Ganga-Brahmaputra river system and generates turbidity currents which convey detrital sediment building the Bengal Fan. In the modern Himalaya, the monsoon rainfall and tectonic processes shape the erosion pattern. The monsoon seasonal precipitation ensures efficient transport of sand-rich sediments in the basin despite long distances through a very flat floodplain and delta. Rapid transport also acts as a limiting factor for weathering as it reduces residence time in the floodplain but favors efficient carbon burial.

The IODP Expedition 354 drilled the Bengal Fan with seven sites over a 320 km E-W transect at 8°N. This construcs a composite sedimentary record of Himalayan erosion over the Neogene and Quaternary. Sediments are predominantly composed of turbidites generated from the Ganga-Brahmaputra delta. Turbiditic sediments show mineralogical, geochemical and isotopic characteristics which reveal a close analogy with those of the modern Ganga-Brahmaputra river. Sand deposition is dominant and is present in several meters thick sand lobe as well as in levee turbidite (Bergmann et al. 2020). Sand was used to determine average erosion rates of the Himalaya using quartz in situ concentrations of cosmogenic 10Be. Those show stable rate in spite of the onset of a more unstable climate from the Pliocene to the Pleistocene (Lenard et al. 2020).

Major element concentrations and Sr-Nd isotopic compositions of turbidite samples reflect combined effects of geological sources exposed to erosion, weathering and mineral sorting during transport. Deciphering these controls, based on the comparison between turbidite samples and modern river sediments of the Ganga and Brahmaputra basin reveals evolution from Miocene to present. Changes appear in the abundance of detrital carbonates likely reflecting decreasing exposition of the Tethys Himalaya to erosion since Miocene. Clear increase in the silicate Na and Ca concentrations from Miocene to Pleistocene indicates major change in the weathering conditions in the basin which can be related to longer residence time of the sediment in the floodplain and lower erosion ratesin the Miocene.

Bergmann et al. 2020, G. cube 10.1029/2019gc008702
Lenard et al. Nat Geosc. 2020, doi:10.1038/s41561-020-0585-2

How to cite: France-Lanord, C., Galy, A., Galy, V., Huyghe, P., Lavé, J., Lenard, S., Limonta, M., Rigaudier, T., Spiess, V., and Tachambalath, A.: The Neogene record of Himalayan erosion in the Bengal Fan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19206, https://doi.org/10.5194/egusphere-egu24-19206, 2024.

While the deep Earth is not directly accessible, it can be explored by laboratory experiments under high-pressure and -temperature (P-T) combined with geophysical observations and geodynamical modeling. We conduct experiments using a laser-heated diamond-anvil cell (DAC) which can generate static high P-T beyond conditions at the center of the Earth. Combining such DAC experiments with in-situ X-ray observations at synchrotron sources and thermal/electrical conductivity measurements and ex-situ textural and chemical characterizations of recovered samples, we have been trying to uncover the structures, chemical compositions, physical properties, dynamics, and evolution of the deep Earth and planetary interiors. The lowermost part of the Earth’s mantle, sometimes called the D” layer, have been the most enigmatic region inside our planet, but the discovery of its main constituent crystals of post-perovskite dramatically improved our understanding of this mysterious layer. Recent hot debates on the core include its thermal conductivity and the mechanism of its convection that have sustained the planetary magnetic field since early history of the Earth. In addition, the Earth’s core is known to include substantial amounts of light elements such as sulfur, silicon, oxygen, carbon, and hydrogen, but its exact chemical composition has been highly controversial since Birch (1952). Hydrogen could be one of the important core light elements when considering that a large amount of water may have been delivered to the growing Earth and hydrogen is strongly siderophile (iron-loving) under high pressure. Nevertheless, the phase diagram and properties of iron hydrides are little known since hydrogen is least soluble into iron at ambient conditions. I will introduce these high-pressure studies on the deep mantle and core materials including our recent work on iron hydrides and discuss the possible ranges of Earth’s core composition.

How to cite: Hirose, K.: Exploring the deep Earth and planetary interiors by high-pressure experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1663, https://doi.org/10.5194/egusphere-egu24-1663, 2024.

The Moon is thought to have been covered initially by a deep magma ocean, its gradual solidification leading to the formation of the aluminium-rich plagioclase-bearing highland crust. We performed the first high-pressure, high-temperature experimental study of the mineralogical and geochemical evolution accompanying the full solidification of a lunar magma ocean (LMO) and provide new constraints on the presence of water in the early lunar interior. In a dry Moon, plagioclase appears after 68 per cent solidification and yields a crust with a thickness of ~68km¹, well above the lunar crustal thickness suggested by recent GRAIL mission gravitational data (34–43 km). Water-bearing experiments show a delay in the start and lowering of the volume of plagioclase formed during LMO crystallization, as observed previously for terrestrial magma. Using crustal thickness as a hygrometer we conclude that at least ~800 ppm water was present in the Moon at the time of LMO crystallization, indicating the Earth-Moon system was water-rich from the start^2,3.

Water does not only have remarkable effects on early LMO evolution, but also on the properties of Earth’s mantle rocks, however, how and how much transporting water into the deep Earth is still debated due to high mantle temperatures. Subduction of oceanic lithosphere transports surface H₂O into the mantle. Recent studies proved that stishovite and post-stishovites as high-pressure phases of SiO₂ have the potential to carry weight percent levels of water into the Earth’s interior along the geotherm of the subducting oceanic crust⁴. Regression of our experimental data indicates an H₂O storage capacity in stishovite of ~3.5 wt% in the transition zone and shallow lower mantle, decreasing to about 0.8 wt% at the base of the mantle⁵. As slabs subducted to the deepmost mantle, dehydration of these dense hydrous silica phases (DHS) can potentially change physicochemical properties of the Earth’s mantle by reducing melting point, forming new high-pressure phases and enhancing the oxygen fugacity heterogeneity of lower mantle⁶.

References:

[1] Lin Y., Tronche E. J., Steenstra E. S., and van Westrenen W. Experimental constraints on the solidification of a nominally dry lunar magma ocean. Earth Planet. Sci. Lett. 471, 104–116 (2017).

[2] Lin Y., Tronche E. J., Steenstra E. S., and van Westrenen W. Evidence for an early wet Moon from experimental crystallization of the lunar magma ocean. Nat. Geosci. 10, 14–18 (2017).

[3] Lin Y., Hui H., Xia X., Shang S., and van Westrenen W. Experimental constraints on the solidification of a hydrous lunar magma ocean. Meteorit. Planet. Sci. 55, 207–230 (2020).

[4] Lin Y., Hu Q., Meng Y., Walter M. and Mao H.-K. Evidence for the stability of ultrahydrous stishovite in Earth’s lower mantle. Proc. Natl. Acad. Sci. U. S. A. 117, 184–189 (2020).

[5] Lin Y et al. Hydrous SiO₂ in subducted oceanic crust and H₂O transport to the core-mantle boundary. Earth Planet. Sci. Lett. 594, 117708 (2022).

[6] Lin Y. and Mao H. K. Dense hydrous silica carrying water to the deep Earth and promotion of oxygen fugacity heterogeneity. Matter Radiat. Extremes 7, 068101 (2022).

How to cite: Lin, Y.: Effects of water on the evolution of the Early Moon and deep Earth investigated by experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4803, https://doi.org/10.5194/egusphere-egu24-4803, 2024.

Flow and transport scenarios taking place in porous media are characterized by a staggering range of physical, chemical, and biological processes. The dynamics associated with these are distributed across an astonishingly wide range of (spatial and temporal) scales, thus contributing to the challenges related to their observation and description. Direct observation and attempts to a quantitative characterization of these processes indicate that they are prone to multiple interpretations, as rendered through various conceptual and mathematical formulations and their parameterization. Even the outcomes of apparently straightforward models of flow (or chemical transport) can surprise us! As complexity related to the formulation and parametrization of processes and their feedbacks increases, so does the need to establish approaches enabling us to quantify the effect of various types of uncertainty on target quantities of interest. For example, tackling the often strong (spatial) heterogeneity of parameters embedded in a model and coping with our limited ability to describe all of the relevant details of the porous medium hosting processes of interest poses significant challenges. In this broad context, I will initiate a discussion about uncertainties related to process formulation and parametrization and the way they can propagate to model outputs such as, e.g., water availability, solute concentrations, source protection regions, or reaction rates. The discussion is set in a framework encompassing experimental studies, characterization of porous media heterogeneity, sensitivity analysis for model diagnosis, and stochastic inverse modeling. Sensitivity analyses approaches are tackled with a focus on their ability to identify the relative importance of processes (and associated parameters) embedded in a model and driving system behavior. The ensuing results are then employed to inform model calibration under uncertainty. All of these aspects are exemplified through the analysis of settings related to three distinct scales. These comprise a regional scale complex aquifer system subject to diverse forcings, a laboratory scale scenario involving dynamics of pharmaceuticals in a porous medium, and direct observations of processes acting at nanoscales and governing material fluxes associated with chemical weathering related to rock dissolution. While these systems are associated with very different scales (and processes), their analysis is unified through the use of stochastic approaches sharing common traits and leading to similar workflows for uncertainty quantification.

How to cite: Guadagnini, A.: A view into the richness of processes in porous media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9079, https://doi.org/10.5194/egusphere-egu24-9079, 2024.

Over the last fifteen years, hydrodynamic modelling has, like so many branches of hydrology, made the leap from local to global scales.  Where once we may have applied our models to single river reaches a few 10s of kilometres in length, we can now build and execute models at ~30m spatial resolution over the entire terrestrial land surface.  In turn, this has allowed us to address scientific and practical questions that were hitherto impossible to answer.  For example, global inundation modelling can help us understand and quantify large scale hydrological and biogeochemical cycles and many questions in flood risk management, for example decisions about future government spending on flood defences, analysing the solvency of flood insurance portfolios under extreme conditions, or determining climate change impacts, require predictions of flood risk at national, continental, or even global scales.

This paper therefore discusses the scientific developments that were needed to make this local-to-global transition possible and outlines what the latest generation of global inundation models now can (and cannot) do.  Finally, the paper looks at current limits to inundation modelling in terms of boundary conditions, flood defence data and model validation and considers the prospects for further improvements in model skill using the data from recently launched and forthcoming satellite missions such as SWOT and NISAR.

How to cite: Bates, P.: How far can we go in global flood inundation modelling?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6307, https://doi.org/10.5194/egusphere-egu24-6307, 2024.

Hazard models aim at making explicit our forecasting capability about future potentially adverse natural events. Hazard events are typically rare and not deterministically predictable, forcing hazard models to speak the language of certainty and uncertainty, that is, of probability. This is valid for any forecasting time window, from years to days/hours in the future (long- to short-term hazard), to the evaluation of the potential impact of an ongoing event in the next seconds/minutes/hours (warning/now-casting to urgent computing). Even though the definition of the target time window is driven by the users of the forecast (e.g. civil protections) and is not a scientific matter, the quantification of existing uncertainty given the time frame is certainly a scientific matter. Probabilistic hazard is commonly discussed mainly for long-term hazards, where large uncertainty dominates. In shorter-term forecasts, uncertainty may deacrease and practitioners are often tempted by simplified approaches that neglect uncertainty, like for eruption forecasting during volcanic crises, or for tsunami warning models after seismic or volcanic events. Nevertheless, uncertainty may still exist, and a rational scientific approach should let the results to speak about existing uncertainty, rather than to neglect it by definition. Is it possible to define a unified approach to probabilistic hazard entailing all time scales? The long-term integral hazard integrating all potential sources and generation/propagation conditions can be adapted to the different forecasting time windows, generating a unified framework in which the different time scales may feed to each other, producing homogeneous and easy-to-interpret results. This unified vision of hazard models, embracing long- to short-term hazard as well as warning and urgent computing models, is here discussed based on the recent advancements in models for volcanic, seismic and tsunami hazard and warning.

How to cite: Selva, J.: Hazard forecasting: is it a matter of time?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4270, https://doi.org/10.5194/egusphere-egu24-4270, 2024.

The intensification of extreme precipitation in a warming climate has been shown in observations and climate models to follow approximately theoretical Clausius-Clapeyron scaling. However, larger changes have been indicated in events of short-duration which frequently trigger flash floods or landslides, causing loss of life. Global analyses of continental-scale convection-permitting climate models (CPCMs) and new observational datasets will be presented that provide the state-of-the-art in understanding changes to extreme weather (rainfall, wind, hail, lightning) and their compounding effects with global warming. These analyses suggest that not only warming, but dynamical circulation changes, are important in the manifestation of change to some types of extreme weather, which must be addressed in the design of new CPCM ensembles. We use our projections to provide the first analyses of impacts on infrastructure systems using a new consequence forecasting framework and show the implications for adaptation. It will be argued that a shift in focus is needed towards examining extreme weather events in the context of their ‘ingredients’ through their evolution in time and space. Coupled with exploration of their causal pathways, sequencing, and compounding effects – ‘storylines’ –, this can be used to improve both early warning systems and projections of extreme weather events for climate adaptation.

How to cite: Fowler, H.: Rapidly intensifying extreme weather events in a warming world: how important are large-scale dynamics in generating extreme floods?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22472, https://doi.org/10.5194/egusphere-egu24-22472, 2024.

How to cite: Pouquet, A.: On a few characteristics of geophysical turbulent flows , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10769, https://doi.org/10.5194/egusphere-egu24-10769, 2024.

During the last decades, space missions provided in situ data of diverse space plasma environments with increasingly higher resolution. This enabled the possibility to investigate peculiar properties of fluctuations in the magnetic field and plasma parameters, transitioning from the magnetohydrodynamic (MHD) to the ion-kinetic regime. The ion-kinetic regime is characterized by a global self-similar scaling of fluctuations, in contrast to the local scale-invariance of the MHD ones. In a series of works, we developed a data-driven approach based on the Langevin equation in order to model statistical features of kinetic fluctuations. In practical terms, the stochastic process thus introduced represents the evolution of the magnetic field fluctuations as a function of the scale. As far as such fluctuations are of the Langevin type, their statistics evolve according to a Fokker-Planck equation. Studying the evolution of fluctuation statistics across the scales, e.g., structure functions, allows us to make predictions about global statistical properties, e.g., scaling exponents.

In this work, we review recent results obtained by using data from the ESA/Cluster mission in near-Earth space. We give evidence that the dynamics of magnetic field increments at kinetic scales can be modeled as a stochastic process of the Langevin type, and that the correct scaling law of the structure functions can be obtained through the stochastic equation in the non-diffusive limit, by linking the drift term of the Langevin equation to the Hölder exponent. Finally, this model allows us to derive the asymptotic limit of individual sets of fluctuations, giving thus predictions on the trend expected at kinetic scales.

How to cite: Benella, S.: Exploring space plasma fluctuations at kinetic scales through stochastic process theory, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11136, https://doi.org/10.5194/egusphere-egu24-11136, 2024.

The biological carbon pump is a series of processes that transfers organic carbon from the surface ocean into the deep ocean.  Without it, atmospheric CO2 levels would be ~ 50 % higher than pre-industrial levels.  Despite its importance, we currently struggle to understand how the strength and efficiency of the biological carbon pump varies temporally and spatially.  This makes it difficult to observe, and therefore model the pump, so our knowledge of how this important component of the global carbon cycle might respond to climate change is poor.  In this talk I’ll present recent progress on using autonomous vehicles to quantify variability in the biological carbon pump, discuss the current limitations in our understanding of the pump, and the implications of those knowledge gaps for robust modelling of the current and future pump. 

How to cite: Henson, S.: Future trends and climate feedbacks of the biological carbon pump, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2879, https://doi.org/10.5194/egusphere-egu24-2879, 2024.

My presentation will cover the present and recent configurations of Mars’ water cycle. The Martian water is only visible in two forms: gas and ice. The existence of a water cycle on Mars was deduced from the first seasonal monitoring of water vapor performed by the Viking mission in 1982. It revealed that the same seasonal and spatial pattern repeated itself for nearly two consecutive Martian years. After Viking, other missions have confirmed this initial conclusion: seasonal water vapor variations appear to be controlled by exchanges between various reservoirs, achieving an annual stationary state with some inter-annual differences. These variations are primarily influenced by the seasonal evolution of the climate in the north polar region, as the latter hosts the most massive reservoir of water, consisting of an ice cap of more than 2 million km³. When exposed to sunlight in spring and summer, this cap releases a massive amount of water vapor that then spreads across the Martian globe, only to return to the North Pole the following winter in the form of frost. Decades of theoretical and observational exploration have delivered a nearly comprehensive view of Mars’ water cycle. From the water molecules that leave the cap in summer to the hydrogen atoms that escape Martian gravity and get lost in space; I will show how the Mars missions and the 3D models used to simulate Mars’ climate have laid the foundations for our understanding of the main processes that govern the evolution of water on Mars.

How to cite: Franck, M.: Deciphering Mars’ water cycle with missions and models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2888, https://doi.org/10.5194/egusphere-egu24-2888, 2024.

How to cite: Mandon, L., Ehlmann, B. L., Greenberger, R. N., Ellison, E. T., Mayhew, L. E., and Templeton, A. S. and the Oman Drilling Project Science Team: Hyperspectral mapping of a kilometer of mantle rock core: insight into active serpentinization systems , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4012, https://doi.org/10.5194/egusphere-egu24-4012, 2024.

Seismic waves propagating through the Earth sample its structure, carry information about its fabrics and physical characteristics and record its present-day state and evolution. In the past, several velocity discontinuities within the radial Earth, which separate its fundamental regions, were retrieved. The lower mantle-core boundary was named as Gutenberg discontinuity in recognition of the Gutenberg’s discovery of the Earth’s core in 1913. This discontinuity relates to the abrupt decrease in P-velocity and diminishing of S-waves in the liquid core. In present-day terminology, the Gutenberg discontinuity is associated with the bottom of the D’’ layer. An area of low velocities in the Earth’s upper mantle denoted as G-discontinuity, has related to Gutenberg’s name until now. The low velocity zone exists just below the oceanic lithosphere, and its characteristics are often used globally in studies of lithosphere thickness in the view of modern plate tectonics. Gutenberg’s Seismicity of the Earth (1941) became a major influence in later scientists’ efforts to describe the theory of plate tectonics. The accuracy and validity of the Earth models depend on data quality and coverage, i.e., earthquake foci - seismic station ray distribution within the Earth volume studied. Small-sized to large-scale international passive seismic experiments, operated during several recent decades, recorded an unprecedented huge amount of high-quality data, which along with new techniques and computational facilities represent a big step forward in our knowledge of the Earth’s structure. However, many questions still remain unanswered and require further research. Current close international cooperation among seismologists involved in the experiments follow the spirit of Beno Gutenberg’s action as a driving force behind the acceptance of seismology as an international science of earthquake detection and the Earth studies.

We present models of the European lithosphere derived from the propagation of body waves, shear-wave splitting and radial and azimuthal anisotropy of surface waves, including ambient noise. Data for individual studies has been collected from international seismological databases (ISC, EIDA) and from several passive experiments we have organized or participated in. Initial isotropic models are upgraded into anisotropic ones, following the fundamental condition that seismic anisotropy is a 3D phenomenon and thus it has to be evaluated in 3D to get more realistic images of the Earth. We invert/interpret jointly anisotropic parameters of independent observables (directional variations of P-wave travel times, shear-wave splitting parameters) which leads to 3D self-consistent anisotropic models of the continental lithosphere with tilted symmetry axes and characteristic domain-like structure. The individual domains at size from several tenths to several hundreds of kilometers are often sharply bounded and of different thicknesses. We interpret the often sharply bounded domains with systematically oriented dipping fabrics in the continental mantle lithosphere by successive subductions of ancient oceanic plates and their accretions enlarging primordial continent cores. Consequent continental break-ups and assemblages of wandering micro-plates preserve fossil anisotropic fabrics and create patchwork structures of the present-day continents. Supporting arguments for such model exist in petrological and geochemical studies (Babuska and Plomerova, 2020).

How to cite: Plomerová, J.: Seismic images of the continental lithosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9250, https://doi.org/10.5194/egusphere-egu24-9250, 2024.

80% of earthquakes occur underwater, so ocean-bottom seismometers (OBS) are crucial for improving our understanding of earthquake source mechanics along unexplored offshore faults, and fillling key gaps in our images of the deeper solid Earth. Even for ocean islands and island arcs, land stations alone struggle to image underlying structures. Broadband OBSs have been through many design iterations, but many OBS deployments now yield high data recovery rates (>90%). 

Even though my first OBS deployment experience left me feeling seasick, I have since continued to seismically explore the oceans, taking part in several OBS projects. In this talk, I will focus on my recent results from experiments across the Atlantic Ocean. Compared to the faster-spreading and subducting Pacific lithosphere, the less well-studied Atlantic offers a key endmember for refining our knowledge of global tectonics and associated hazards.

In the Lesser Antilles subduction zone, subducting Atlantic lithosphere is heterogeneously hydrated. Local earthquakes recorded by OBSs (VoiLA experiment), allowed me to image seismic attenuation to map fluid and melt pathways through the slab and mantle wedge, showing how slab fluids precondition melt generation and volcanism in arc settings. In the mid-Atlantic, long transform faults can host large M~7 earthquakes in ultra-wide (20-30 km thick) fault zones, allowing a uniquely macro-scale view of how damage zones control seismogenesis. In 2017, OBSs (PI-LAB experiment) recorded a nearby Mw 7.1 earthquake on the Romanche transform fault, triggering detailed teleseismic analysis that show back-propagating rupture fronts, which have since been seen during the 2023 M7.8 Türkiye earthquake. More recently, I analysed a seismic swarm and dyke intrusion in the Azores, which lies on a diffuse transtensional plate boundary. Here, a temporary OBS network (UPFLOW project) installed around the uniquely narrow island of São Jorge yields high-resolution seismicity locations that shed light on magma inflow and drainage along pre-existing faults.

Overall, OBS experiments yield fascinating results, but these results come from vast team efforts, particularly from ship crews and OBS technicians, that often go uncredited. We need to work harder to ensure the long-term sustainability of data from these expensive, often publicly-funded projects, with OBS-specific data preprocessing complications a partial barrier to this.

How to cite: Hicks, S. P.: Uncovering the tectonic secrets of the Atlantic with broadband ocean-bottom seismology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14636, https://doi.org/10.5194/egusphere-egu24-14636, 2024.

Sedimentary calcium and magnesium carbonate minerals have recorded the evolution of life, climate, and CO₂ cycling for billions of years through their physical and chemical properties.  These largely depend on crystallization pathways related to fluid pH and supersaturation, biological processes, presence of additives and redox conditions.  As such, crystallization pathways define the properties of biominerals and abiotic carbonates that are used to reconstruct Earth’s history.

Crystallization pathways, often preserved in carbonate ultrastructures have been widely investigated for biominerals and bio-mediated calcium and Ca-Mg carbonates by using High-resolution Transmission Electron Microscopy (HRTEM).  Synchrotron micro-X-ray fluorescence facilitates trace element mapping highlighted heterogeneities in their distribution as related to fabrics. Nano and micro-scale investigations of biominerals and bio-mediated carbonates have revealed that they consist of crystalline, nanocrystalline and amorphous phases, which may co-exist in the same sample and influence the distribution of trace, minor and major elements. Critically, the clustering of nanoparticles is considered a marker of biotic Ca-Mg-carbonates, whereas monomer- by-monomer crystal growth seems to characterize abiotic minerals. However, HRTEM investigation of abiotic sabkha dolomicrite formed primarily by aggregation of nanoparticles as a response to fluctuating aqueous chemistry. Abiotic cave CaCO₃ minerals (speleothems), when observed by HRTEM also revealed that nanoparticle attachment is one of several crystallization pathways, that result in inter-and intracrystalline micro to nano-porosity and the formation of intracrystalline defects.   Critically, both inter- and intra-crystalline porosity and defects accommodate both organic macromolecules and inorganic colloids. The exploration of non-classical crystallization pathways, exemplified by particle attachment, explains the frequently observed non-equilibrium integration of trace elements. This phenomenon extends to the heterogeneous lateral distribution of both trace elements and organic molecules, providing insights into the intricate processes shaping the crystalline matrix.

Nano-scale observations further revealed that porosity follows crystallographic orientations, which leads to a hypothesis that sector zoning is responsible for lateral heterogeneity of organic and inorganic “impurities”. However, sector zoning largely stems from a classical monomer-by-monomer growth under pH and supersaturation ranges that are commonly lower than what expected for particle attachment. It is then plausible that local pH and supersaturation conditions as well as the presence of impurities result in changes in crystallization pathways. Nanoparticles participating in non-classical particle attachment may consist of amorphous calcium carbonate (ACC), whose uptake of trace elements differs from that of calcite. Transformation of ACC into calcite may ultimately result in an observed non-equilibrium partitioning of trace elements in the final phase. This phenomenon, in addition to the possibility that pores and crystal defects host impurities, suggests that multiple crystallization pathways explain kinetic effects that hinder a direct and constant link from proxy data to environmental parameters in carbonate archives of Earth’s history.

It is proposed that fabrics of abiotic carbonates, their ultrastructure and geochemistry should be granted the same level of investigation given to biominerals when interrogating their capability to accurately record climate (or environmental) change. Examples of how this can be achieved will be presented for case-studies including Triassic dolomicrite, Pleistocene subglacial carbonates from Antarctica and Holocene tropical stalagmites.

How to cite: Frisia, S.: Sedimentary carbonates: fabrics, ultrastructures and geochemistry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2710, https://doi.org/10.5194/egusphere-egu24-2710, 2024.

Taphonomy is a discipline dedicated to the analysis of the different processes that influence the mechanisms of fossilization, affecting both fossils and their environment. In this sense, this research is focused on the premortem and postmortem processes affecting animal bones found in archaeological sites. Studies related to human evolution can be approached from different perspectives, being paleontological analyses the best procedure for identifying ancestors through fossils. Paleo-environmental studies explore the past environment and climate, conditioning human evolution and adaptation. On the other hand, archaeological studies (the area of this research), examine the material culture and behaviour of ancient populations.

Sites can be exclusively paleontological, with no human intervention, or archaeological, with evidence of human activity. In the latter, bones may have been altered by humans, carnivores, or natural processes. In this context, taphonomy allows to classify the origin of this alteration, being even possible to define the intervention of several agents on the same animal, such as humans, carnivores, and rodents, and the order of such intervention.

Evidence of human intervention on animals from the past is found in the marks left when processing meat or marrow. The analysis of cut and percussion marks is used to reveal the applied tools and methods. The research here presented is based on the implementation of technologies such as photogrammetry and geometric morphometry to document these marks in a three-dimensional way. Machine learning, deep learning, and advanced statistics are then applied to answer specific questions. In particular, three main key questions about human behaviour in past populations have been addressed:

What tools were used to process animal meat, and were there any preferences in raw materials? Three-dimensional reconstructions are applied to identify the morphology of cut marks and, through repeated experiments, determine which materials, such as flint, quartz, or volcanic rock, were used in the past.

Which carnivores occupied the sites after they were abandoned by humans, and how does this affect the paleoecology? Tooth marks on bones are analysed to differentiate with high reliability which carnivore handled a bone, providing relevant information on the paleoecological implications depending on the specific carnivore.

How does trampling affect bones exposed at sites, and what relevant information does it provide? Through trampling analysis, it is possible to determine when this occurred, providing important data on how long the bones were exposed before burial and the degree of site disturbance.

All the previous lines of research enable to assess site integrity, identify the carnivores involved, and understand human behavioural strategies in the processing of animal carcasses.

How to cite: Maté González, M. Á.: New technologies applied to modelling taphonomic alterations of human origins, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21896, https://doi.org/10.5194/egusphere-egu24-21896, 2024.

This is both an exciting and a challenging time to be a soil scientist. Societal interest in soil is thriving because of its pivotal role in food security, climate change, and biodiversity. But this interest comes with serious responsibilities, within the context of a scientific climate dominated by perverse incentives for funding and publishing. In this Philippe Duchaufour lecture I would like to reflect on some of the balances we should aim for, and the boundaries we should acknowledge, as soil scientists. I will do this for field of climate-related soil research; for the role of soil ecology in the transition towards sustainable agriculture; as well as for academic publishing.

The soil takes center stage in discussions regarding climate change mitigation. However, the focus is mostly on large-scale carbon sequestration (LSCS). There almost seems to be a dichotomy within the scientific community regarding the potential and desirability of LSCS, with exceedingly optimistic assessments finding their way to policy documents, and more critical publications on the limits or usefulness of LSCS apparently ignored. I will highlight some fundamental boundaries to large scale carbon sequestration, notably the amount of carbon available through photosynthesis. As a possible way forward, I will stress the importance of focusing on improving soil functioning rather than on increasing the carbon stock size.

The need for a transition towards more sustainable forms of agriculture while maintaining high productivity is broadly acknowledged within the scientific community. Such forms of agriculture should both include a high degree of circularity as well as a larger reliance on the benefits that soil biota provide. However, these two aspects are often not studied in relation to each other.  Earthworms provide an instructive case in this respect. It is clear that they are beneficial to crop growth – the literature even suggests an overall increase of 25% in crop yield in the presence of earthworms. Yet, this number is not realistic as many primary earthworm studies do not represent realistic systems. In particular, we should not claim that earthworms can compensate for the removal of nutrients through harvest. This can only be done through replenishment of nutrients from elsewhere – preferably in a circular manner. I will discuss how earthworms and other biota could positively affect nutrient recycling in future agricultural systems that will receive new, circular forms of soil amendments.  

Finally, scientific publishing is in crisis. Scientific articles are in many ways the basic building blocks of scientific careers, and yet the publishing process is overstretched and flawed. This is mostly related to imbalances: especially between those who pay and those who earn; and between those who write and those who review. I will highlight some of these imbalances, which are to some extend geographic, and will discuss to what extent switching to an open publishing model will resolve them. I will end with some thoughts on how to improve the publishing process, including a call for more cooperation between editors across journals to keep scientific publishing viable.

How to cite: Van Groenigen, J. W.: Beasts, Balances and Boundaries in Soil Science, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12483, https://doi.org/10.5194/egusphere-egu24-12483, 2024.

The sun, solar wind and magnetospheres exhibit non-linear processes that can couple across a broad range of space and time scales. These multiscale processes can be central to the dynamics of far from equilibrium plasmas, where collisionless processes dominate. This talk offers highlights from two interconnected approaches to advancing our understanding of multi-scale processes in solar system plasmas.

From the plasma physics: If sufficient simplifications can be made, we can study the plasma dynamics from first principles. The non-linear scattering and acceleration of energetic particles in current sheets, by wave particle interactions, and in shocks, can be approached from non self-consistent single particle dynamics allowing the full non-linear physics, including low-dimensional chaos, to be considered. The physics of shocks, reconnection, and its interplay with turbulence can be approached by fully kinetic self-consistent simulations, albeit with restrictions on physical dimension and the range of scales resolved. If bursty energy and momentum transport is an emergent process, then it can be captured by reduced models.

From the data: The full dynamics is revealed in all its richness in observations. A wealth of in-situ and remote observations are available from the fastest physical timescales of interest to across multiple solar cycles. In principle, these afford the study of specific physical process such as reconnection and turbulence, and system-scale processes such as the dynamics of magnetospheres, all of which are fully multiscale and non-linear. In practice, determining the physics from observations relies upon establishing robust, reproducible patterns and relationships from multipoint data in these inhomogeneously sampled, non time-stationary systems. As well as providing fundamental physical insights, these can deliver quantitative estimates of space weather risk.

How to cite: Chapman, S.: Multiscale matters: when coupling across multiple scales drives the dynamics of solar system plasmas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3620, https://doi.org/10.5194/egusphere-egu24-3620, 2024.

Large continental strike-slip earthquakes produce significant surface ruptures, tens to hundreds of kilometers long, with displacement that can reach several meters, depending on the magnitude of the earthquake. However, this information, and more specifically the detail of the surface ruptures has long been overlooked, as we missed efficient ways to document extensive ruptures. In the last decade, with the emergence of new remote sensing tools, our community came to realize that earthquake surface ruptures could bear significant information about fault structure and the way deformation is accommodated during earthquakes. Hence, through a systematic survey of surface ruptures, based on field observation and remote sensing data, we demonstrate that it is possible to define a fault segmentation that would not be arbitrary, but instead is related to some first-order characteristic of the brittle crust, the thickness of the brittle crust, also called the seismogenic thickness. This observation result has been tested and confirmed through a series of analogue and numerical experiments that allowed us to systematically study fault segmentation when varied the thickness of the brittle material. We also questioned the distribution of deformation along those fault segments during earthquakes, as the development of high-resolution image correlation technics gives us access to a more detailed picture of the ground deformation distribution around large strike-slip earthquake ruptures. More specifically, we have been able to show that in some places a significant part of the deformation is distributed off fault, up to 30%, accommodated by micro-cracks, or even in the bulk. This deformation is almost impossible to measure in the field and thus is not considered in classic models of earthquake source inversion. It might in fact be the reason why many models involve some shallow slip deficit, which is physically not understood, while it might only be an artefact of modeling. Eventually, the evolution through time of fault geometry and off-fault deformation is questioning the long-term evolution of fault geometry, a potential proxy for fault maturity. Here we show through analogue experiments that in fact, once a growing fault system has gone pass through a localization stage, where distributed deformation is drastically reduced, the fault system never simplifies further and keeps having some level of complexity associated with a steady amount of distributed deformation close to 20%, independently of the total amount of deformation accommodated by the fault system, suggesting that a fault system can probably be considered definitively mature almost immediately after its localization stage, for a small amount of total displacement.

How to cite: Klinger, Y.: Fault segmentation, off-fault deformation, and fault maturity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16741, https://doi.org/10.5194/egusphere-egu24-16741, 2024.

Recent research has highlighted that radiative feedbacks — and thus climate sensitivity — are not constant in time but depend sensitively on sea surface temperature patterns. I will discuss three implications of this realization.

First, I will show how coupled climate models fail to reproduce observed surface warming patterns and global mean top of the atmosphere (TOA) radiation trends. I use large initial condition ensembles to compare observations to account for internal variability and model mean-state biases. For certain periods, not a single ensemble member can reproduce observed values of surface temperature trends and TOA radiation trends. Models which more greatly underestimate the observed local sensitivity of surface and TOA, and models with a weak variability in the Equatorial Pacific surface temperatures tend to have a higher equilibrium climate sensitivity. Despite these astonishing observation-model discrepancies their global-mean temperatures are simulated well which points to a common model problem in surface heat fluxes and ocean heat uptake.

Second, I will discuss the relevance of the pattern effect for climate change projections. Given that problems coupled models have in reproducing observed warming patterns, we should doubt their pattern evolution in projections. I will introduce “surface warming pattern storylines” starting from the observations and bridging to simulated future patterns in standard scenarios. I show that (CMIP) coupled climate models used ubiquitously for climate change projections underestimate the uncertainty of possible global-mean temperature evolutions due to their surface warming patterns throughout the 21st century.

Third, I will introduce how a feed-forward convolutional neural network (CNN) can be trained to learn the pattern effect and predict global-mean TOA radiation from surface warming patterns. I use explainable artificial intelligence methods to visualize and quantify that the CNN draws its predictive skill for physically meaningful reasons. Remarkably and different from traditional approaches, I can predict radiation under strong climate change from training the CNN on internal variability alone. This out-of-sample application works only when feedbacks are allowed to be non-linear or equivalent, changing in time, which is another, independent manifestation of the relevance of the pattern effect.

How to cite: Rugenstein, M.: The pattern effect: How radiative feedbacks depend on surface warming patterns and influence near-term projections , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12777, https://doi.org/10.5194/egusphere-egu24-12777, 2024.

The transition to sustainable energy systems introduces a complex landscape, wherein geothermal energy and carbon dioxide storage (CCS) play critical roles. These activities target geological formations that are always faulted and fractured. As the focus intensifies on alternative energy systems for decarbonisation, understanding these faulted rocks in the subsurface gains great importance. Fault and fracture systems can act not only as conduits for fluid flow but they can also be zones of mechanical weakness that may respond dynamically to fluid pressure changes due to natural geological processes or anthropogenic activities, such as CCS or geothermal extraction. This dual role of fault and fracture systems as pathways for fluid flow and as potential triggers for mechanical failure makes their study a cornerstone of sustainable subsurface resource management. The challenge lies in accurately characterising the permeability of these systems and estimating their mechanical behaviour under changing stress conditions. This is vital for ensuring the integrity and efficacy of operations like CCS and geothermal energy extraction, where even slight variations in fluid pressure can have significant implications. For instance, experiences from the fluid injection experiment for an enhanced geothermal system in Basel, Switzerland, and the In Salah CCS pilot site in Algeria highlight how minor changes in pore fluid pressures (as little as 10 MPa) can induce leakage and/or seismic activities. We highlight selected case studies from both active and prospective CCS and geothermal sites (in Svalbard and Mid-Ethiopian Ridge, respectively). These examples illustrate methodologies in fault stability analysis and geomechanical characterization, shedding light on the relationship between fluid flow, stress alterations, and rock mechanics in faulted and fractured formations. By coupling empirical data with modelling techniques, we present strategies to mitigate risks and enhance the efficiency of subsurface decarbonisation efforts.

How to cite: Rizzo, R. E., Keir, D. B., Busch, A., Forbes Inskip, N., Healy, D., Gudbrandsson, S., De Siena, L., and Vannucchi, P.: Fault Lines to Frontlines: Geomechanical Challenges of Sustainable Energy Transition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15525, https://doi.org/10.5194/egusphere-egu24-15525, 2024.

Quantifying landscape form can provide crucial insight into the interactions between tectonics and climate. River long profile morphology, quantified by metrics such as channel steepness, is the most commonly used tool to investigate topographic form, with many studies relating long profile morphology to uplift rate, precipitation, sediment properties, or lithology, for example. River long profiles record the signal of external forcing over large spatial scales (i.e. tens of kilometres). This has many advantages: for example, it is a convenient scale for analysing variations in large-scale processes, such gradients in tectonic uplift. It also means that high resolution digital elevation models (DEMs) are not required and therefore river long profiles can be extracted globally. However, analysis of river long profiles over tens of kilometres can also result in signal smoothing and subsequent loss of finer scale tectonic or climatic signatures encoded into the landscape.

Tectonic and climatic processes do not only leave their fingerprint in the long profiles of rivers. Hilltops, hillslopes, and valleys make up the majority of Earth’s landscapes by area, yet their morphology has received much less attention than that of rivers. This is in part due to the difficulty in accurately extracting hilltops and valley morphology from DEMs, especially on a global scale. Here, I show that we can now extract hilltop and valley metrics from high-resolution (< 15 m) DEMs over orogenic to continental scales using new topographic analysis techniques and high-performance computing facilities. I argue that by combining hilltop, hillslope, and valley metrics, we can obtain more information about tectonic and climatic processes than from river profiles alone.

How to cite: Clubb, F.: Going beyond the river long profile, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6103, https://doi.org/10.5194/egusphere-egu24-6103, 2024.

Human-water feedbacks have been increasingly studied in the last decades, motivating the foundation of new disciplines such as socio-hydrology and, in general, enhanced interest toward conceptualization and modelling of the spatial and temporal dynamics of human-water systems. With anthropogenic activities being widely recognized as a major driver of global change and the human population being increasingly exposed to hydroclimatic extreme events, human systems are now at the forefront of the water cycle. Yet, human preferences, behaviors, and decisions in relation to water systems - including water usage dynamics, adoption of precautionary measures against climate extremes, and adaptation of urban landscapes - are often modelled based on behavioral or economic theories, or derived from small-scale samples. This often leads to heterogeneous results, which are often case-specific, or lack validation against real-world observations.

The availability of increasingly fine-resolution data from distributed sensors and databases (e.g., water consumption data from intelligent meters, flood insurance adoption records at the household level, and socio-demographic data) and earth observations (e.g., aerial and satellite imagery) provides us with an empirical basis to model heterogeneous individual and societal behavioral patterns, along with their determinants.

In my research, I strive to develop multi-disciplinary data-driven behavioral modelling approaches that bridge hydrologic/hydraulic sciences, informatics, economics, and systems engineering and harness information from multi-scale human data and earth observations and the power of data analytics and machine learning to better understand, model, and characterize human behaviors in coupled human-water systems. In this talk, I will first provide an overview of recent advances in descriptive behavioral modelling in human-water systems, with a focus on household-to-continental scale modelling of residential water consumption patterns and adoption of household flood insurance. Second, I will elaborate on modelling challenges that are motivating ongoing research related to machine learning-based behavioral models, including model explainability, data and computational requirements, generalization and scalability, and the influence of data resolution in time and space. Finally, I will discuss how developing descriptive models that learn human behaviors retrospectively can be used to inform forecasting tasks and formulate policy-relevant recommendations to shape future societal adaptation to climate change. Implications span from informing the design of feedback-based digital user engagement in pursuit of water conservation, to fostering proactive climate adaptation, addressing societal inequalities and heterogeneous water access and affordability conditions, or evaluating incentive programs and policies for sustainable urban development.

How to cite: Cominola, A.: Learning from the past to shape the future. Harnessing multi-scale human data and earth observations to foster sustainable water usage and societal adaptation to climate change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19445, https://doi.org/10.5194/egusphere-egu24-19445, 2024.

Recent disasters have demonstrated the growing challenges faced by society as a result of multi-hazards and compound events. The impacts of such disasters differ significantly from those caused by single hazard disasters: often the impacts of a multi-hazard disaster exceed those of the sum of the impacts of the individual hazards. Recognizing this complexity, the scientific community and international organizations, such as the UNDRR, have been advocating for a more integrated approach in multi-(hazard)risk research. This requires bridging across individual hazard types, but also learning from methodological advances made in neighbouring research fields such as the compound events community.

This talk aims to highlight recent advances in assessing the complexities of multi-(hazard)risk and discusses opportunities for further enhancing our modeling capabilities through multidisciplinary collaboration. A crucial challenge of modelling compound and multi-hazard risk, is that of the spatiotemporal dynamics of risk. This includes for example, an improved understanding of post-disaster recovery after multi-hazard disasters and the role of (changing) local contexts within which disasters take place such as the dynamics of socioeconomic vulnerability and the likelihood of post-disaster disease outbreaks. Embracing these challenges and opportunities can support more comprehensive and effective disaster risk management strategies in the future.

How to cite: de Ruiter, M.: Advancing multi-(hazard)risk science: embracing complexity and cross-disciplinary collaborations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10624, https://doi.org/10.5194/egusphere-egu24-10624, 2024.

In this seminar, I will explore the oceanic processes that drive melting of the Antarctic Ice Sheet, and consequent global sea level rise. Different processes lead certain areas of the Antarctic Ice Sheet to be more susceptible to rapid ocean-driven melting, while other areas to be more resilient. I will also show the emergence of a feedback between the ice sheet and Southern Ocean: increased melting leads to warming of the oceanic waters surrounding Antarctica, with consequences for future sea level rise. I will conclude by describing how increased melting of the Antarctic Ice Sheet as well as changes in sea ice affect the global ocean abyss and its ability to store anthropogenic heat and carbon.

How to cite: Silvano, A.: The global influence of ice-ocean interactions in Antarctica, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10184, https://doi.org/10.5194/egusphere-egu24-10184, 2024.

Coronal mass ejections (CMEs) are humongous structures that permeate the heliosphere as they travel away from the Sun. Beginning their journey from a more-or-less localised region in the solar atmosphere, they expand to many times the size of the Sun through the corona, measure about 0.3 au in radial extent by the time they reach 1 au, and interact with the structured solar wind and other transients to form so-called merged interaction regions in the outer heliosphere. One of the most prominent challenges in heliophysics is the achievement of a complete understanding of the intrinsic structure and evolution of CMEs, in particular of their spatiotemporal variability, which in turn would allow more precise forecasts of their arrival time and space weather effects throughout the heliosphere. The most common methods to detect and analyse these behemoths of the solar system consist of remote-sensing observations, i.e. 2D images at various wavelengths, and in-situ measurements, i.e. 1D spacecraft trajectories through the structure. These data, however, are often insufficient to provide a comprehensive picture of a given event, due to the scarcity of available measurement points and the enormous scales involved. Some ways to circumvent these issues consist of taking advantage of multi-spacecraft observations of the same CME (usually at different heliolongitudes and/or radial distances) and to use simulations to complement the available measurements and/or to investigate the 3D structure of CMEs without constraints on the number of synthetic observers.

In this presentation, we will first provide a review of the advantages of multi-spacecraft observations of CMEs and how they have helped us build the overall picture of CME structure and evolution that forms our current understanding. We will then showcase examples of detailed CME studies, both in the observational and modelling regimes, that have been made possible due to the availability of multi-point measurements. These will include events observed remotely and/or in situ by the latest generation of heliophysics missions, i.e. Parker Solar Probe and Solar Orbiter. Finally, we will speculate on possible future avenues that are worthy of exploring to reach a deeper understanding of CMEs from their eruption throughout their heliospheric journey, especially in terms of novel space missions that may improve not only our knowledge from a fundamental physics standpoint, but also our prediction and forecasting capabilities.

How to cite: Palmerio, E.: Analysing CME observations and simulations with multi-spacecraft techniques, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13951, https://doi.org/10.5194/egusphere-egu24-13951, 2024.