The last two deglaciations mark transitions from glacial to interglacial climates, dramatically reshaping Northern Hemisphere ice sheets. Numerical modelling of these transitions provides critical insight into the processes controlling ice-sheet retreat and collapse. Comparing the last two deglaciations allows us to evaluate how different forcings and initial conditions influence ice-sheet dynamics and understand the interplay between orbital forcing, greenhouse gases, abrupt climate changes and ice sheet instabilities in driving ice sheet evolution.
We use the fast yet comprehensive coupled General Circulation Atmosphere–ice-sheet model FAMOUS–BISICLES to simulate the Northern Hemisphere ice-sheet evolution during the penultimate deglaciation (140–128 thousand years ago; ka) and the last deglaciation (21-7 ka), with particular interest in the abrupt Bølling warming (14.5 ka). Our simulations follow the PMIP4 (Palaeoclimate Model Intercomparison Project 4) protocols and are forced with prescribed sea surface temperatures and sea ice from transient climate model outputs to reduce biases and force millennial abrupt climate changes.
First, we compare the penultimate and last deglaciations to assess how orbital forcing, greenhouse gas concentrations, and uncertain model parameters and SST inputs shape both the pace and spatial patterns of ice retreat. Results indicate a faster ice retreat during the penultimate deglaciation. Sensitivity experiments show that the rate of deglaciation is particularly sensitive to processes that impact the surface mass balance, but ice dynamics also play an important role. Sub-shelf melt rate is less significant; however, it can be important where confined ice shelves are able to form. Although insolation drives the deglaciations, rising greenhouse gases and warming SSTs significantly amplify the ice-sheet response to orbital forcing.
Second, we focus on the abrupt Bølling warming (~14.5 ka). Our simulations show accelerated deglaciation during this event, though the magnitude of response depends on the ice-sheet topography during the warming and on the pattern of abrupt SST increase prescribed. Marine-based sections, particularly the Barents–Kara ice sheet, exhibit the greatest sensitivity to prescribed ocean changes.
How to cite: Gregoire, L., Patterson, V., Snoll, B., Ivanovic, R., Gandy, N., Rome, Y., Arthur, F., and Sherriff-Tadano, S.: Northern Hemisphere ice-sheet dynamics during the last two deglaciations: responses to gradual and abrupt climate changes, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8317, https://doi.org/10.5194/egusphere-egu26-8317, 2026.
The Mid-Pleistocene Transition (MPT) marks one of the most profound reorganizations of the Earth’s climate system over the Quaternary. During this interval, the dominant glacial-interglacial cyclicity shifted from 40 kyr to 100 kyr without a corresponding change in orbital forcing, implying fundamental internal feedbacks within the climate system. Post-MPT glaciations became longer (up to ~60 kyr), more severe, and characterized by larger and more stable Northern Hemisphere ice sheets. Despite intensive research into the mechanisms driving the MPT, the response of ocean trace metal cycling to Northern Hemisphere ice-sheet dynamics remains poorly constrained, limiting our ability to fully integrate ice-sheet evolution with changes in ocean circulation, elemental cycling, and the carbon cycle.
Here we present a new authigenic neodymium isotope (εNd) record from ODP Site 982 (1134 m water depth), spanning 1.4–0.6 Ma and capturing the MPT. Our record reveals clear and systematic glacial-interglacial εNd variability linked to the evolving Icelandic Ice Sheet (IIS) and its modulation of volcanic erosion and weathering fluxes into the NE Atlantic, coupled with southward shifts in deep-water formation during glacials. Before the MPT, interglacial εNd values of -13.5 to -12.5 indicate persistent influence of Labrador Sea-derived waters, whereas glacial intervals are marked by more radiogenic εNd from -11 around 1.4 Ma to -9 by 1.1 Ma, reflecting increasing Icelandic volcanic input influence associated with IIS expansion. From ~1.1 Ma onward, the εNd contrast between climate states intensifies and reaches its strongest amplitude, with interglacials becoming slightly more unradiogenic (to -14) and glacials reaching radiogenic values up to -8. This persistent pattern of radiogenic in glacials and unradiogenic in interglacials continues into later cycles, indicating that Icelandic volcanic weathering and IIS extent reached their maximum expression since the MPT. Our results demonstrate that the IIS exerted first-order control on NE Atlantic seawater Nd isotope cycling during glacial periods, and that this modulation strengthened across and after the MPT. Importantly, the gradual amplification of Icelandic erosion signals suggests that Northern Hemisphere ice-sheet expansion (at least in Iceland) was a response to, rather than the initial trigger of, the MPT, consistent with coupled ice-sheet–carbon cycle feedback frameworks.
How to cite: Xu, A. and Frank, N.: Strengthened Icelandic Ice Sheet control on Northeast Atlantic neodymium isotope variability across the Mid-Pleistocene Transition, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10172, https://doi.org/10.5194/egusphere-egu26-10172, 2026.
Glaciers are key hydro-climatic indicators and markers of atmospheric changes in the past, making them essential tools for reconstructing glacial paleoenvironments and paleoclimates. As a climatically stable period that is drastically different from today, the Last Glacial Maximum (LGM, 26–19 ka BP) is widely used as a benchmark for evaluating climate sensitivity (i.e., a key parameter linking atmospheric CO₂ to temperature) and for comparing climate model simulations with continental reconstructions from multiple proxy archives.
Pollen assemblages are a commonly used proxy for reconstructing past temperature changes, as they offer broad spatial coverage across Europe. However, particularly in Europe, simulated LGM annual temperatures often show substantial disagreement with reconstructions and appear highly heterogeneous across models. Dated glacier extents provide an independent archive, helping to assess data–model comparisons.
Temperature is a critical variable to estimate the surface mass balance of glaciers (i.e., the difference between accumulation and ablation). Surface mass balance models (e.g., the positive degree day, PDD, model; [1]) provide the climatic conditions required to reproduce the extent of paleo-ice sheets (inverse approach), as constrained by geomorphological evidence.
PDD-based ice sheet models in central Europe ([2]; [3]) indicate stronger LGM cooling than pollen reconstructions (e.g., [4]), a mismatch likely linked to seasonal biases given the high sensitivity of glaciers to seasonal temperatures ([5]; [6]). Yet, seasonal LGM reconstructions remain scarce, and recent syntheses highlight marked inconsistencies in seasonality anomalies across European glaciated regions, including the Vosges ([7]) - which are too small to be captured by climate models (Global Circulation Models, GCMs).
Using a new compilation of 10Be cosmogenic exposure ages ([8]; [9]) in the Vosges Mountains (NE France) and the GRISLI ice sheet model ([10]), this study investigates the impact of LGM seasonal and precipitation anomalies on simulated glacier extents and on LGM data-model cooling agreement.
As results, we deduce a high variability of LGM climate conditions sufficient to reproduce the paleo-ice sheet extent in the Vosges, yet none of them match the pollen-based paleoclimatic reconstructions ([11]). However, some LGM climate models produce temperature conditions (annual and seasonal) similar to the GRISLI results, while producing lower precipitation in the Vosges (60% to 120% lower than GRISLI results). While the calibration of the GRISLI model has a minor effect on these results, one of the more feasible ways to minimize data–model discrepancies in climate spaces - considering paleoclimatic reconstructions - would be to substantially increase precipitation (+380%, i.e., ~5 times modern precipitation) in the restricted Vosges massif during the LGM.
[1] Reeh, 11-128 (erschienen, 1991)
[2] Allen +, https://cp.copernicus.org/articles/4/249/2008/
[3] Heyman, https://doi.org/10.1016/j.yqres.2012.09.005
[4] Davis +, https://cp.copernicus.org/articles/20/1939/2024/
[5] Oerlemans and Riechert, https://doi.org/10.3189/172756500781833269
[6] Huss and Hock, https://www.nature.com/articles/s41558-017-0049-x
[7 & 11] Fénisse +, in prep
[8] Harmand, https://doi.org/10.4000/rge.9703
[9] Blard +, in prep
[10] Quiquet +, https://doi.org/10.5194/gmd-11-5003-2018
How to cite: Fénisse, G., Quiquet, A., Brenner, J.-B., Blard, P.-H., and Bekaert, D. V.: Seasonal climate impacts on LGM glaciers in the Vosges(France): Insights from GRISLI modeling and paleo-extent, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12182, https://doi.org/10.5194/egusphere-egu26-12182, 2026.
Ice-sheet and glaciers constitute an essential component of the climate system and the main storage of freshwater on Earth. Regions particularly sensitive to climate change, the nature and magnitude of their responses to anthropogenic disturbances remain largely uncertain despite the associated challenges (melting ice and reduction of Earth's albedo, contribution to sea level rise, modifications of the oceanic circulation, etc.). In this context, studying the response of the cryosphere to past climate change can give valuable insights about its future evolution. The rapid temperature variations that occurred during the last glacial period are of specific interest for this purpose.
The Late Pleistocene (129-12 ky BP) is indeed marked by abrupt climate oscillations between relatively cold (stadial) and warm (interstadial) conditions in the Northern Hemisphere occurring at millennial time scale. These Dansgaard-Oeschger cycles (D-O) are responsible for strong sub-orbital climate variability, typically about 50% of glacial-interglacial amplitude in Greenland temperature (1). Although the driving mechanisms of D-O remain unclear, changes in the Atlantic Meridional Overturning Circulation are usually invoked for explaining these events, with oscillations between strong and weak transport modes (occurring either spontaneously or in response to external forcing (2)).
Our work analyse the European Alps ice field dynamics in response to rapid climate perturbations during the last glacial cycle. Most modelling experiments on this region focus on the reconstruction of the ice-sheet extent during the Last Glacial Maximum, but studies on the impact of D-O like events are less common. Following an approach tested over the Northern Hemisphere (3), we force the ice-sheet model GRISLI over the Alps during Marine Isotope Stage 3 (60-27 ky BP) with downscaled Paleoclimate Modelling Intercomparison Project climate data. Using two indexes, associated with orbital and millennial-scale variability and respectively applied to i) an Interglacial-LGM anomaly field ii) an AMOC with and without freshwater flux anomaly field, the method allows to take into account the different spatial patterns resulting from orbital and millennial climate fluctuations. The gap between the spatial resolutions of the Global Climate Models simulations and GRISLI is bridged using the downscaling model GeoDS, based on topographical and large scale circulation information.
(1) Wolff et al. (2010) https://doi.org/10.1016/j.quascirev.2009.10.013
(2) Li and Born (2019) https://doi.org/10.1016/j.quascirev.2018.10.031
(3) Banderas et al. (2015) https://doi.org/10.5194/gmd-11-2299-2018
(4) Brenner et al. (preprint) https://doi.org/10.5194/egusphere-2025-3617
How to cite: Brenner, J.-B., Quiquet, A., Roche, D., and Paillard, D.: European Alpine ice-field dynamics in context of past rapid climate change, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20275, https://doi.org/10.5194/egusphere-egu26-20275, 2026.
The Northern Hemisphere ice sheets have undergone significant periodic changes during the Quaternary. These changes not only influence global sea-level fluctuations but also drive global climate evolution. Consequently, reconstructing the evolution of these ice sheets has been a key objective in Earth science. Over recent decades, tracking the sources of ice-rafted debris (IRD) in the Arctic Ocean's deep-sea sediments has enabled researchers to systematically reconstruct the histories of the North American and Eurasian ice sheets. However, due to the lack of diagnostic provenance tracers specific to the East Siberian Ice Sheet, its evolution remains highly controversial. To address this gap, we conducted a provenance analysis based on a comprehensive detrital zircon U-Pb age dataset. This dataset comprises 10,111 new ages from both surface sediments on the circum-Arctic shelves and IRD in deep-sea cores from the central Arctic Ocean. Our results reveal distinct zircon age distributions across different circum-Arctic shelf regions. Notably, a prominent age peak at ~90–110 Ma serves as a diagnostic fingerprint for sediments derived from the East Siberian continent and shelf. Central Arctic Ocean sediments from at least four glacial intervals contain coarse zircon grains bearing this diagnostic ~90–110 Ma peak, strongly indicating iceberg transport from East Siberia. This implies that the East Siberian continent and shelf experienced multiple glaciations, likely within the past three glacial-interglacial cycles. The repeated glaciation of East Siberia likely exerted significant, though still poorly quantified, influences on both polar and global climates during the late Quaternary. Our findings provide new insights into the history of Northern Hemisphere glaciation and propose a valuable approach for reconstructing ice sheet evolution.
How to cite: Feng, H., Yao, Z., Shi, X., Zhang, Z., Lu, H., Zhang, H., Liu, Y., Shan, X., Dong, J., Dong, L., Yang, G., Hu, L., Vasilenko, Y., Astakhov, A., and Bosin, A.: Multiphase glaciations in East Siberia during the late Quaternary revealed by Arctic zircon U-Pb ages, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15767, https://doi.org/10.5194/egusphere-egu26-15767, 2026.
This study presents a modelled reconstruction of the past ice dynamics of the Fennoscandian Ice Sheet, paying particular attention to the interactions between the ice sheet margin in Poland and the Baltic and Norwegian Channel Ice Streams. The focus is on the Late Vistulian time period, 24 – 12 ka BP, a key stage of the Last Glacial Period, characterized by significant climatic fluctuations and a dynamic evolution of the ice sheets over Northern Europe. In our reconstruction we use a numerical model constrained by empirical data, such as glacial landforms, glacial and postglacial deposits, and geochronology, to test the relationship between the modelled extent of the Fennoscandian Ice Sheet and its climatic and basal boundary conditions. A series of simulations were carried out for the Fennoscandian and British–Irish ice sheets with a spatial resolution of 10 km. These simulations applied and modified climates from the Paleoclimate Modelling Intercomparison Project – Phase 4 (PMIP4), and in tandem explored the importance of basal friction conditions on ice behaviour in this region. The modelling results reveal the existence of ice streams with diverse spatiotemporal characteristics. Their widths range from several tens to several hundreds of kilometres, while velocities vary from a few hundred to more than 1000 meters per year. The dynamic behaviour of these ice streams strongly controls the southern extent of the Fennoscandian Ice Sheet during deglaciation, forming pronounced lobate outlets reaching several hundred kilometres in length and several hundred meters in thickness at the Southern margin. Significantly, adjustments impacting friction beneath one ice stream alters its behaviour in such a way that it then influences the dynamics of other ice streams. In particular, there is a significant interplay such that when we reduce activity of Norwegian Channel Ice Stream, the ice divide between the Baltic Ice Stream and the Norwegian Channel Ice Stream migrates. As a consequence, this changes the behavior of Baltic Ice Stream and the extent of the ice at the ice sheet margin in Poland. This is the first time the two major outlets of the Fennoscandian Ice Sheet have been shown to be so strongly linked in controlling the wider southern margin of the ice sheet.
How to cite: Kalita, J. Z., Jamieson, S., Clason, C., Szuman, I., Hjelstuen, B., Aschwanden, A., and Prill, M.: Reconstruction of the late Vistulian Fennoscandian Ice Sheet - based on numerical modelling and sensitivity analyses , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18694, https://doi.org/10.5194/egusphere-egu26-18694, 2026.
Coupled climate-ice-sheet modeling is still in its developing stage, and feedback processes between ice sheets and climate are still not yet fully understood. Here, we use simulations with a coupled climate-ice-sheet model to investigate teleconnections between Northern Hemispheric ice sheets and the Antarctic ice sheet (AIS) without direct freshwater forcing. We show that ice mass removal in the Northern Hemisphere can alter AIS evolution through a series of feedbacks. Changes in surface properties and orographic effects warm the newly deglaciated areas and the North Atlantic Ocean at mid-depth. The warmer water masses propagate to the Southern Ocean, where internal oscillations periodically deliver them to the Antarctic coast. These repeated warm water intrusions destabilize the Ross ice shelf, ultimately triggering a runaway retreat of the West Antarctic ice sheet. Our results underscore the importance of coupled bi-hemispheric climate-ice-sheet modeling to capture global teleconnections between ice sheets and climate.
How to cite: Testorf, P., Schannwell, C., Kapsch, M.-L., and Mikolajewicz, U.: Coupled Climate-Ice-Sheet Simulations Reveal Novel Teleconnection Between Northern Hemisphere Ice Sheets and the Antarctic Ice Sheet, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7109, https://doi.org/10.5194/egusphere-egu26-7109, 2026.
The accelerated melting of the Greenland Ice Sheet is one of the consequences of current global warming. In addition to being affected by Arctic amplification, Greenland could contribute dramatically to future sea-level rise. However, our current knowledge of the evolution of the Greenland Ice Sheet (GrIS) during the warmest periods of the Quaternary, as well as of subglacial geology and geochemistry, remains limited, notably due to the scarcity of available basal ice and subglacial sediment samples. Within the framework of the ERC Green2Ice project, we present preliminary results from the analysis of basal ice and subglacial sediments from the Camp Century ice core (1966, northwestern Greenland, 1388 m depth beneath the ice sheet, frozen bed). For comparison, we also studied samples collected from different glacio-geological settings in the Kangerlussuaq region (western margin of Greenland): (i) a subglacial drilling sample (H1-1, 1250 m depth, temperate bed) and (ii) a sediment sample from the Kangerlussuaq River. Morphological, mineralogical, and isotopic analyses were conducted to characterize the geological and geochemical nature of the debris, their provenance, and the sequence of processes recorded, such as deglaciation phases and subglacial weathering. Six samples (four from the Camp Century basal sediment section, one from the Kangerlussuaq River, and one from the H1-1 drill) with grain sizes ranging from 125 µm to 2 mm were analysed using Scanning Electron Microscopy (SEM) coupled with Energy-Dispersive Spectroscopy (EDS). Grain morphologies observed under SEM reflect different transport modes (glacial, fluvial, aeolian), allowing the identification of local phases of ice-sheet retreat and advance. EDS provides information on grain mineralogy, notably the presence of clay coatings, which are indicative of stable, ice-free environmental conditions. The clay fraction of the basal and subglacial ice from Camp Century, as well as that of H1-1 and the Kangerlussuaq River, was analysed by X-ray Diffraction, providing information on the different clay mineral species present, some of which indicate deglaciation conditions. Finally, the isotopic ratio 87Sr/86Sr and ɛNd of Camp Century samples and those from the Kangerlussuaq region constrain the provenance of the debris. The morphological and mineralogical analyses reveal (i) distinct geological source areas depending on location and (ii) a complex grain history combining sedimentary transport and weathering phases during ice free conditions. 87Sr/86Sr and ɛNd isotopic analyses from the silicates of the basal and subglacial ice samples will provide further constrains on the source materials, this constraint being notably key to assess the origin of the clay fraction in the silty ice of Camp Century, and in the intermediate ice rich unit with the basal sedimentary section.
How to cite: Crinella Morici, L., Blard, P.-H., Prud'Homme, C., Marrocchi, Y., Stibal, M., Klímová, P., Skonieczny, C., Leblanc, M., Mahaney, W. C., Perdrial, N., Zimmermann, C., Ardoin, L., Tison, J.-L., Steffensen, J. P., Fripiat, F., Svensson, A., and Dahl-Jensen, D.: Glacial processes and sediment provenance in basal ice, subglacial and fluvial sediments from Greenland: insights from mineralogy, grain morphology, and isotopic analyses, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14169, https://doi.org/10.5194/egusphere-egu26-14169, 2026.
The geological units underlying the grounding line between the West Antarctic Ice Sheet and the Ross Ice Shelf are expected to contain a record of repeated ice advance and retreat in a key area for understanding interactions between the ice sheet, the ocean and the solid Earth through the warm and cold periods of the Quaternary. Direct sampling of the sedimentary units in the vicinity of the grounding line across the relatively slow-moving Kamb Ice Stream has been an ongoing focus for drilling efforts that involve first melting through roughly 600 m of ice. Geophysical methods suggest that the region is underlain by a sedimentary basin of yet-to-be-determined thickness. However, little is yet known about sediment lithology and stratigraphy in this region.
We present analysis of a grid of about 73 km of seismic reflection profiles collected in the Kamb Ice Stream grounding line region during three seasons since early 2015, integrated with the inversion of a grid of surface-collected gravity data. Seismic data were acquired with explosive charges frozen into shallow (mostly 25-m-deep) hot-water-drilled holes recorded by surface-deployed geophones buried in the firn. Seismic processing has been undertaken to maximise resolution of stratigraphic units at and below the sea floor. The inversion of coincident surface-based gravity data, integrated with airborne-gravity collected as part of the ROSETTA-Ice project, constrains basin thickness in the region of the seismic data.
The processed low-fold seismic data image the ice shelf, ocean cavity and underlying stratigraphy. The shallow stratigraphy appears to be mostly horizontally layered, typical of a sub-ice continental shelf environment. More than 300 m of sub-horizontally layered sedimentary strata can be identified above the first inter-ice multiple reflection in the data. Several distinct reflections interpreted as unconformities are identified in the seismic data, which combined with reflective characteristics, terminations and pinchouts enable a seismic stratigraphic interpretation to be undertaken. For example, unconformities between units could correspond to past glacial erosion episodes as the position of the grounding line in this region has migrated toward or away from the open ocean. The integration of surface and airborne gravity data here enables better constrained modelling of the thickness of the sedimentary basins in the region that cannot be imaged by the seismic reflection data.
How to cite: Gorman, A., Tankersley, M., Black, J., Horgan, H., Wilson, G., and Dunbar, G.: Shallow geology of the sub-ice-shelf Siple Coast, eastern Ross Sea, Antarctica constrained by reflection seismology and surface gravity surveying, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16180, https://doi.org/10.5194/egusphere-egu26-16180, 2026.
The Greenland Ice Sheet (GrIS) has experienced accelerated mass loss in recent decades and is expected to become a major contributor to global sea-level rise over the coming century. Understanding its response to climate forcing in a global warming context has become critical, particularly for the adaptation of coastal communities worldwide.
The last deglaciation of the GrIS offers valuable insights into ice-climate interactions, as extensive paleoclimatic records document its retreat through a period of major climate changes. During this interval, the GrIS retreated from its extensive Last Glacial Maximum (LGM) configuration to its present state, passing through the Holocene Thermal Maximum (HTM) when temperatures exceeded present-day values and may have overshot the GrIS tipping point. Despite the large amount of paleoclimatic data available, ice-sheet models struggle in reproducing key aspects of the observational record, and the magnitude of the GrIS contribution to sea level during the HTM remains highly uncertain.
In this study, we evaluate an ensemble of 3000 ice-sheet simulations performed with the ice-sheet model Yelmo against different observational constraints. These include: (1) LGM ice-sheet extent, (2) ice-core-derived surface elevations, (3) relative sea-level records, (4) retreat chronology based on the PaleoGrIS dataset, and (5) the present-day ice-sheet configuration (ice thickness, ice velocity, and bedrock uplift rates). By identifying the simulations that best match these constraints, we provide a geologically-constrained reconstruction of the GrIS during the last deglaciation.
How to cite: Gutiérrez-González, L., Tabone, I., Alvarez-Solas, J., Montoya, M., Swierczek-Jereczek, J., Pérez-Montero, S., Tesouro, S., Blasco, J., and Robinson, A.: Simulation of the Greenland ice-sheet deglaciation constrained by past and present observables, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-4033, https://doi.org/10.5194/egusphere-egu26-4033, 2026.
Ice loss from the Antarctic Ice Sheet could threaten coastal communities and the global economy if ice volume decreases by just a few percent. Observed changes in ice volume are limited to a few decades, and hard to interpret in the context of an ice sheet with response timescales reaching centuries to millennia. To gain a much longer-term perspective, we combine transient and equilibrium simulations of the Antarctic Ice Sheet response to glacial-interglacial warming and cooling cycles over the last 800,000 years. We find hysteresis between ice volume and climate forcing, caused by the crossing of tipping points as well as the long response time. Notably, West Antarctic Ice Sheet collapse contributes over 4 m sea level rise in equilibrium ice sheet states with little (0.25°C) or even no ocean warming above present. Given that climate projections indicate continued Southern Ocean warming, we will likely cross the threshold for West Antarctic Ice Sheet tipping in the coming decades (if not already). This supports other recent studies warning of substantial irreversible ice loss with little or no further climate warming.
How to cite: Chandler, D., Langebroek, P., Reese, R., Albrecht, T., Garbe, J., and Winkelmann, R.: Antarctic Ice Sheet tipping in the last 800,000 years warns of future ice loss, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21588, https://doi.org/10.5194/egusphere-egu26-21588, 2026.
Understanding the response of the Greenland Ice Sheet to past climate variability is essential for improving projections of its future evolution and contributions to sea-level rise. As part of the ChronIce project (Chronicling Greenland Ice Sheet evolution through past warm climates), this study investigates the response of the northern Greenland Ice Sheet to past climate forcing by reconstructing changes in physical weathering, erosion, and ice–ocean dynamics. We focus on North-West Greenland using a unique marine sedimentary archive recovered during International Ocean Discovery Program Expedition 400.
Temporal variations in glacial outlet provenance, weathering intensity, and erosion are examined using detrital mineralogical and geochemical approaches applied to sediment records from sites U1604, U1606, U1607 and U1608. Heavy mineral fractions are analyzed using Automated Quantitative Mineralogy–Scanning Electron Microscopy (AQM-SEM) and Laser Ablation–Inductively Coupled Plasma–Mass Spectrometry (LA-ICP-MS) that enables single-grain U–Pb geochronology and provenance fingerprints of ice-rafted debris (IRD). Here we will show results from zircon, apatite, titanite, and other datable minerals which, in combination with IRD grain-size and textural analyses, can provide new insights on sediment transport pathways, weathering processes and source regions linked to glacial erosion during the late Pliocene and Pleistocene.
How to cite: Störling, T., Keulen, N., Malkki, S. N., Thrane, K., Heredia, B., Monedero-Contreras, R. D., Perez, L. F., Zimmermann, H. H., and Knutz, P. C.: Tracing Greenland Ice Sheet dynamics during past warm climates, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12379, https://doi.org/10.5194/egusphere-egu26-12379, 2026.
The Greenland ice sheet (GrIS) is recognised as highly sensitive to climate change, with palaeoclimate evidence and modellingstudies suggesting that sustained global warming only marginally above present-day levels could trigger its complete deglaciation over multi-millennial timescales. Despite growing understanding of threshold behaviour in the GrIS, the implications of a temporal crossing of this temperature threshold, particularly the duration and magnitude of temperature overshoots, for the future GrIS mass loss trajectory remain poorly constrained. Here we present simulations of the next 10,000 years under a range of future anthropogenic emissions scenarios, performed using a fully coupled Earth system model with a dynamic GrIS and interactive atmospheric CO2 and CH4. Our model experiments span scenarios from strong mitigation to high emissions SSP pathways, allowing systematic exploration of the relationship between warming trajectories and ice sheet response.
We find that the long-term ice loss on Greenland is predominantly determined by the peak global temperature increase relative to pre-industrial levels, which generally occurs within the next few centuries depending on the emissions pathway. The GrIS contribution to global mean sea-level rise after 10,000 years increases by approximately 2 metres for each degree of warming above a critical peak global warming threshold of approximately 2°C above pre-industrial temperatures, which is close to the GrIS equilibrium tipping point. This finding is robust for different equilibrium climate sensitivities and across different scenarios. Furthermore, when accounting for variations in the Earth's orbital parameters over the next 10,000 years, the sensitivity of the GrIS mass loss to anthropogenic warming substantially increases, as future orbital configurations lead to higher summer insolation over Greenland.
Overall, our results demonstrate how 21st century climate policy will largely determine the fate of the GrIS for millennia to come.
How to cite: Willeit, M., Robinson, A., Kaufhold, C., and Ganopolski, A.: Long-term future Greenland ice loss determined by peak global warming, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14288, https://doi.org/10.5194/egusphere-egu26-14288, 2026.
We present here a multi-century simulation of future Greenland ice sheet evolution under 4xCO2 forcing with the Community Earth System Model version 2 bi-directionally coupled to the Community Earth Sheet Model version 2 (CESM2-CISM2). We examine the evolution of global climate, ice sheet topography and flow, as well as the individual components of the surface mass and energy balance. We compare results with a simulation with uni-directional coupling, where the atmosphere and land components see a prescribed pre-industrial ice sheet topography, and the ocean sees prescribed pre-industrial freshwater fluxes corresponding to the initial CESM2-CISM2 state in the two-way coupled baseline simulation. We find that albedo feedback causes the solar flux to be the primary energy contributor to total melt of the ice sheet. Changes in ice sheet elevation reduce the input of snowfall to the ice sheet due to enhanced rain over snow partition of precipitation. Changes in elevation cause more than doubling of melt rates after the ice sheet area has decreased by more than 50%.
How to cite: Vizcaino, M., Petrini, M., Sellevold, R., Feenstra, T., Wouters, B., Thayer-Calder, K., Lipscomb, W., and Leguy, G.: Evaluation of albedo and elevation feedbacks on Greenland complete deglaciation in a CMIP model: comparison of coupled and uncoupled simulations , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5397, https://doi.org/10.5194/egusphere-egu26-5397, 2026.
The Greenland Ice Sheet (GrIS) holds an ice volume equivalent to ~7 m of global sea-level rise, making its future evolution a critical component of sea-level projections. The rate and magnitude of ice loss strongly depend on ice–climate feedbacks, yet most Earth System Models (ESMs) still treat ice sheets as static entities, limiting their ability to simulate these essential interactions. The UK Earth System Model (UKESM) is a state-of-the-art ESM which includes dynamic models of the Greenland and Antarctic ice sheets, as well as a sophisticated climate - ice sheet coupling based on the explicit exchanges of water and energy. However, the impacts of this interactivity on projected climate and ice sheet evolution remain insufficiently quantified.
To assess the role of ice–climate feedbacks within a sophisticated, coupled ESM framework, we performed two multi-century climate simulations under high-emissions forcing (SSP5–8.5) using UKESM: a control run with a fixed GrIS geometry, and an interactive run in which the ice sheet evolves freely in response to climate drivers. For computational efficiency, an ice sheet acceleration mode was applied from 2100 onward, whereby the ice sheet model integrates ten years for each year of atmospheric-oceanic simulation. This method effectively projects the ice sheet’s evolution over two millennia (2100–4100) within a 200-year atmosphere-ocean simulation (2100–2300), although it does not fully include feedbacks from meltwater-driven changes in ocean circulation.
By comparing these simulations, we quantify the impacts of simulating a dynamic GrIS in the Earth System, ranging from local alterations in Greenland’s mass balance and sea-level contribution to remote downstream effects on atmospheric circulation. We identify that positive feedbacks—primarily from reduced surface albedo and lowering ice sheet elevation—become dominant after 2100, driving accelerated mass loss and influencing North Atlantic atmospheric circulation patterns. This study highlights the importance of two-way ice–climate coupling in ESMs for improving predictions of future climate and sea level changes.
How to cite: Ma, Y., Smith, R., George, S., Lang, C., Otosaka, I., and Hodson, D.: The Role of a Dynamic Greenland Ice Sheet in Future Climate: Insights from Multi-Centennial Coupled UKESM Simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18304, https://doi.org/10.5194/egusphere-egu26-18304, 2026.
Mass loss from ice sheets under the ongoing anthropogenic warming is a major contributor to sea-level rise. Previous studies suggest that global warming exceeding 2 °C could push the marine-based West Antarctic Ice Sheet beyond a critical threshold, triggering irreversible retreat and multi-meter rise in the global-mean sea-level. Climate overshoot scenarios are a key focus of CMIP7, yet most existing work on the reversibility of ice sheets is based on quasi-equilibrium simulations, with much less attention paid to ice sheets' stability and reversibility under century-scale transient climate forcing. Here we use climate and ice sheet models to simulate the evolution of the Antarctic and Greenland ice sheets under multiple climate overshoot scenarios. Results show that net-negative emissions in overshoot pathways can substantially reduce ice loss from the Greenland Ice Sheet, but are less effective in mitigating retreat of the West Antarctic Ice Sheet. This indicates that the West Antarctic Ice Sheet may also exhibit a tipping behavior under overshoot scenarios, and that achieving carbon neutral early is crucial to avoiding a potential catastrophic sea-level rise.
How to cite: Li, D.: Stability and reversibility of ice sheets in climate overshoot scenarios, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8704, https://doi.org/10.5194/egusphere-egu26-8704, 2026.
The contribution of ice sheets to future sea level rise remains highly uncertain, and complex positive feedback mechanisms can lead to accelerating melt in a warming climate. Yet, few climate models explicitly represent ice flow of Greenland and Antarctica, or their interactions with the rest of the climate system.
Here we present the coupling of the Elmer/Ice ice sheet model with the IPSL-CM7 climate model. Two-way coupling with the atmospheric and oceanic components of IPSL-CM7 (LMDZ and NEMO, respectively) occurs every simulated year. On the atmospheric side, the surface mass balance from LMDZ is used to force the ice sheet model. In this coupling step, a positive degree day scheme is used to re-calculate surface melt and runoff for Greenland to yield more realistic results. The elevation of the LMDZ domain’s bottom surface is in turn updated to account for the new ice sheet geometry provided by Elmer/Ice. On the ocean side, sub-ice shelf melting is explicitly represented where NEMO's resolution allows it and is extrapolated near the grounding line and under small ice shelves, where the cavity geometry is not resolved by the ocean model. NEMO’s computational domain is updated yearly to account for new icy or wet cells.
We then present the results of two 100-year simulations, which were conducted to test the robustness of the coupling and the behaviour of the model in a warming climate. The first simulation has a constant pre-industrial atmospheric CO2 concentration, whereas in the second one the CO2 concentration increases by 1% every year. We describe some interesting features that emerge due to increasing CO2 concentrations, such as the transition from cold to warm water on the continental shelf of the Amundsen Sea, and a retreat of the grounding line in this region.
While still in its early stage of development, this work is an important milestone in the addition of interactive ice sheets within the IPSL-CM7 climate model. Future developments include interactive ice fronts, which are currently fixed in the model, and the possibility of uncovering solid ground as ice sheets retreat.
How to cite: Bastien, L., Mathiot, P., Jourdain, N. C., Agosta, C., Caillet, J., Caubel, A., Charbit, S., Chekki, M., Deshayes, J., Dumas, C., Durand, G., Gillet-Chaulet, F., Marti, O., Mosbeux, C., and Vignon, E.: IPSL-CM-Elmer/Ice: a new coupled ice sheet – climate model, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12617, https://doi.org/10.5194/egusphere-egu26-12617, 2026.
Climate change challenges all Earth subsystems. The Greenland and Antarctic ice sheets together with the Atlantic Meridional Overturning Circulation are subsystems of particular concern, as they are subject to tipping points, i.e., thresholds above which their current state changes to another that is qualitatively and quantitatively different. Their stability has been studied in depth through offline (stand-alone) modeling and “one-way” coupling with each other. However, we know that in the past, the Northern and Southern hemispheres have interacted through the bipolar seesaw. Thus, these subsystems have the potential to interact with each other, but this relationship is challenging to simulate. Here we investigate the behavior of a simplified approach coupling the state-of-the-art ice-sheet model Yelmo with an ocean box model and, importantly, vice versa. We will show the results of exposing the system to various climate change scenarios in order to see how different ice timescale responses alter the coupled stability.
How to cite: Pérez-Montero, S., Alvarez-Solas, J., Robinson, A., and Montoya, M.: Stability of the Greenland and Antarctic ice sheets when dynamically coupled through the Atlantic meridional overturning circulation., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5356, https://doi.org/10.5194/egusphere-egu26-5356, 2026.
The Antarctic Ice Sheet (AIS) is the largest potential contributor to future sea-level rise, with an ice volume equivalent to 58 m of global-mean sea level. However, high uncertainties arise from the representation of key physical processes in ice-sheet models, such as basal sliding, ice-ocean interactions, and feedback mechanisms associated with glacial isostatic adjustment (GIA). Previous studies have estimated the future Antarctic sea-level contribution (SLC) by forcing an ice sheet spun up to a present-day equilibrium state. However, observations of the last decades indicate that the AIS is not in equilibrium, as it is undergoing net mass loss as a result of both ongoing anthropogenic climate change and its long-term adjustment following the last deglaciation. Here, we study the future SLC of the AIS using simulations that span a complete Last Glacial Cycle. To this end, we use the ice-sheet model Yelmo coupled to the GIA model Fastisostasy, and construct an ensemble that accounts for uncertainties in process representation. The model is forced using the PMIP3 ensemble-mean reconstruction of the Last Glacial Maximum (LGM) and the present-day climate, weighted by an index derived from Antarctic ice-core records. The simulations are initiated in the Last Interglacial and evaluated based on their consistency with geological constraints from the LGM and the deglaciation, as well as present-day observations of the AIS. Using these paleo-constrained model configurations, we then investigate the response of the AIS to different future climate-change scenarios.
How to cite: Tesouro, S., Álvarez-Solas, J., Blasco, J., Robinson, A., Swierczek-Jereczek, J., and Montoya, M.: The contribution of the Antarctic Ice Sheet to global sea level from the Last Glacial Cycle to the future, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7333, https://doi.org/10.5194/egusphere-egu26-7333, 2026.
The Antarctic Peninsula is warming rapidly, with more frequent extreme temperature and precipitation events, reduced sea ice, glacier retreat, ice shelf collapse, and ecological shifts. Here, we review its behaviour under present-day climate, and low (SSP 1-2.6), medium-high (SSP 3-7.0) and very high (SSP 5-8.5) future emissions scenarios, corresponding to global temperature increases of 1.8°C, 3.6°C and 4.4°C by 2100. Higher emissions will bring more days above 0°C, increased liquid precipitation, ocean warming, and more intense extreme weather events such as ocean heat waves and atmospheric rivers. Surface melt on ice shelves will increase, depleting firn air content and promoting meltwater ponding. Under the highest emission scenario, collapse of the Larsen C and Wilkins ice shelves is likely by 2100 CE, and loss of sea ice and ice shelves around the Peninsula will exacerbate the current trends of land-ice mass loss. Collapse of George VI Ice Shelf by 2300 under SSP 5-8.5 would substantially increase sea level contributions. Under this very high emissions scenario, sea level contributions from the Peninsula could reach 7.5 ± 14.1 mm by 2100 CE and 116.3 ± 66.9 mm by 2300 CE. Conversely, under the lower emissions scenarios, the Antarctic Peninsula’s sea ice remains similar to present, and land ice is predicted to undergo only minor grounding line recession and thinning. Changes in sea surface temperatures and the change from snow to rain will impact marine and terrestrial biota, altering species richness and enhancing colonisation by non-native species. Ranges of key species such as krill and salps are likely to contract to the south, impacting their marine vertebrate predators. These changing conditions will also influence Antarctic Peninsula research, fisheries, tourism, infrastructure and logistics. The future of the Peninsula depends on the choices made today. Limiting temperatures to below 2°C, and as close as possible to 1.5°C (by following the SSP 1-1.9 or 1-2.6 scenarios), combined with effective governance, will result in increased resilience and relatively modest changes. Any higher emissions scenarios will damage pristine systems, cause sustained, irreversible ice loss on human timescales, and spread to Antarctic regions beyond the Peninsula.
How to cite: Davies, B. and the Antarctic Peninsula under present day climate and future low, medium-high and very high emissions scenarios team: The Antarctic Peninsula under present day climate and future low, medium-high and very high emissions scenarios, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1720, https://doi.org/10.5194/egusphere-egu26-1720, 2026.
There is a strong concern about how fast and how much the global sea level will rise in the next few decades due to the current global warming. However, the projection range is large due to uncertainties about the future evolution of the Antarctic ice sheet, particularly the possibility of the ice shelves' collapse.
With the base submerged in seawater, these ice shelves are strongly influenced by the surrounding oceanic conditions, which can be split into two regimes: cold or warm cavity. When ice shelves are exposed to warm water, basal melt increases sharply, leading to a loss of buttressing of the grounded ice upstream and potentially the collapse of the shelf. Results from TIPMIP (Tipping Points Modelling Intercomparison Project) idealised experiments carried out by the UK Earth System Model (UKESM) with an interactive Antarctic ice sheet component suggest that tipping points for several ice shelves will be reached in the future at relatively high global warming levels (GWLs). However, it is questionable whether the warming thresholds for tipping that we find are realistic due to the model biases and other uncertainties.
This study focuses on exploring the uncertainty in the climate simulated by UKESM and assessing the consequences of ice shelf tipping on the wider Earth System. To do this, we induce the cavity regime shift at a lower GWL than the reported threshold by mimicking the key climate change forcing identified from the higher GWL experiments via an artificial freshwater around the Antarctic ice sheet margin. By doing so, we obtain a pair of low GWL experiments with and without ice shelf tipping, which allows us to isolate the impact of ice shelf tipping on the Earth System. In addition, the experiment setup also allows us to explore the consequences of different scenarios of various freshwater hosing values. The preliminary results indicate that the excessive freshwater induces an expansion of Southern Ocean sea ice, leading to a cooling trend in global mean temperature.
How to cite: Hoang, T. K. D., Smith, R. S., Naughten, K. A., and Jones, C. G.: Impacts of freshwater fluxes on ice shelves tipping points in UKESM , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7719, https://doi.org/10.5194/egusphere-egu26-7719, 2026.
Melting from oceanic heat and basal lubrication from subglacial freshwater are fundamental elements of West Antarctic Ice Sheet mass balance that are poorly constrained. The ice streams feeding the Ross Ice Shelf grounding line periodically start and stall over decadal to century timescales due to shifts in these forcings. Here, we present in situ hydrographic measurements, noble gas abundances, and helium isotope ratios from a l a r g e subglacial channel melted into the base of stagnant Kamb Ice Stream. These data identify an outflowing plume containing subglacial freshwater admixture from upstream volcanic activity and anomalously warm inflowing seawater containing Circumpolar Deep Water from the Ross Sea, with oceanic heat delivery outpacing that from volcanism. Our results directly quantify both variables that affect the mass balance of the Ross Ice Shelf’s sensitive interconnected ice streams and highlight the vulnerability of this region of West Antarctica to increased forcing from a warming climate.
How to cite: Washam, P., Schmidt, B., Loose, B., Horgan, H., Stewart, C., Stevens, C., Lawrence, J., Hulbe, C., and Hurwitz, B.: Sources of oceanic and volcanic heat melting a subglacial channel in Kamb Ice Stream,West Antarctica, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12014, https://doi.org/10.5194/egusphere-egu26-12014, 2026.
Over the last two decades, the contribution of the West Antarctic Ice Sheet (WAIS) to sea level rise (SLR) has doubled. Current observations show that grounding-line retreat is highly discontinuous and strongly modulated by ocean variability, with the strength and timing of decadal extremes exerting a greater influence than long-term mean changes. Here, we analyse the future behaviour of the WAIS by incorporating multiple random realizations of plausible climate scenarios in Kori-ULB ice-sheet model simulations. We further develop a statistically robust metric to assess grounding line stability in a spatial context, not only in the time domain as currently expressed in terms of SLR uncertainties. We thus define a “safety band" as the location where grounding line retreat is still reversible. Beyond this band, glaciers undergo a self-sustained retreat irrespective of ambient climate conditions. On the contrary, grounding lines that remain within this band still allow for glacier slowdown and even re-advance in the absence of ocean melt or if sub-shelf accretion occurs. The window for effective climate mitigation therefore remains open only while the grounding line stays within this safety band. Our results provide a robust metric for assessing glacier stability and highlight the need to account for climate variability in sea-level rise projections.
How to cite: Moreno-Parada, D., Coulon, V., and Pattyn, F.: Mass loss reversibility of the West Antarctic Ice Sheet, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14389, https://doi.org/10.5194/egusphere-egu26-14389, 2026.
Record-shattering climate extremes are becoming a seemingly everyday reality across the globe as anthropogenic climate change accelerates. Over polar regions, similar weather extremes receive less attention, but are responsible for a recent pause and slight reversal of Antarctic ice loss since 2020 and ultimately mitigating global sea-level rise. In March 2022, one particularly extreme weather event in the form of an atmospheric river (AR) caused enough snowfall in East Antarctica to help make 2022 a positive mass year for Antarctica. Yet, this same event caused a heatwave that led to the highest temperature anomaly ever recorded globally (39° C) and triggered the final collapse of the Conger ice shelf simultaneously demonstrating the opposing yet significant effects of extreme weather on the Antarctic mass balance.
While the gradual thinning and grounding line retreat of ice shelves through ocean basal melting pushes ice shelves towards non-viability and collapse in a bifurcation-induced tipping point, extreme weather may trigger that collapse sooner through noise-induced tipping. However, short-medium term (10-50 years) increases in extreme snowfall events may mitigate ice loss more strongly than currently observed. Thus, to constrain future sea-level rise projections, the potential impacts from extreme weather in the short-medium term must be considered.
The uncertainty in predicting the influence of extreme weather on ice shelf stability is partly due to our limited ability to simulate many of the smaller scale processes and impacts that are essential to fully explain polar extreme weather in the present day combined with a limited understanding of how future changes in extreme weather patterns will influence ice sheet dynamics. Global climate models generally lack the spatial resolution to capture small-scale extreme weather processes, and evaluating their impact on ice sheet dynamics requires coupling to ice sheet models that is currently undeveloped.
In this talk, I will present the role of extreme weather in influencing the Antarctic mass balance and how extreme weather represents a potential climate tipping point for ice shelf stability. This will involve discussing the current state of Antarctic extreme weather research along with the uncertainties and research gaps in determining the extreme weather risk to ice shelf stability.
How to cite: Wille, J.: Understanding extreme weather risks to ice-sheet stability as a potential climate tipping point, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19541, https://doi.org/10.5194/egusphere-egu26-19541, 2026.
Earth’s climate is fast approaching a warming of 1.5°C above pre-industrial levels. While the global mean temperature change may be limited on the long term following an overshoot (or peak-and-decline) climate trajectory, the regional climate impacts in Antarctica that might result are highly uncertain: Given the complex interplay of several amplifying and dampening feedbacks in the Antarctic ice-sheet system and associated tipping dynamics, a rich set of changes – ranging from (fully) reversible to potentially irreversible to irreversible – are possible.
Here, we quantify the response of the Antarctic Ice Sheet and associated uncertainties across multi-centennial to millennial timescales to a wide range of projected climate overshoot trajectories using the Parallel Ice Sheet Model (PISM).
Overall, our results suggest that the impacts of overshooting 1.5°C on the Antarctic Ice Sheet worsen with increasing magnitude and duration, and are strongly dependent on the landing climate. Even temporary overshoots can have long-lasting, if not irreversible impacts, stressing the need for limiting global warming to ensure the stability of the Antarctic Ice Sheet across timescales.
How to cite: Klose, A. K. and Winkelmann, R.: Future Antarctic ice loss under climate overshoot trajectories, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11453, https://doi.org/10.5194/egusphere-egu26-11453, 2026.
Ice sheets play a central role in the Earth system: they regulate global sea level, influence ocean circulation through freshwater fluxes, and interact with the atmosphere via albedo and elevation feedbacks. Over recent decades, both the Greenland and Antarctic ice sheets have been losing mass at an accelerating rate, making them an increasing contributor to observed sea-level rise. This mass loss will continue throughout the 21st century and beyond. Yet, despite major advances in observations and modelling, projections of future ice-sheet mass loss remain affected by deep uncertainties, arising from complex ice dynamics, poorly constrained boundary conditions, and nonlinear interactions with the climate system.
This talk provides a synthesis of recent progress in ice-sheet modelling, with a focus on developments that have reshaped our ability to simulate past and future ice-sheet evolution. We review advances in the representation of key physical processes, including grounding-line dynamics, basal friction, ice–ocean interactions beneath ice shelves, and damage and calving. We then discuss progress in coupling ice-sheet models with atmosphere and ocean models, ranging from improved offline forcings to emerging fully coupled Earth system frameworks, as well as the growing role of coordinated multi-model ensembles and their analysis in characterising uncertainty and identifying robust responses. We conclude by discussing ice-sheet predictability, showing how present-day observations can provide meaningful constraints on future evolution in specific regions, while informing where and why such constraints are not emerging elsewhere.
How to cite: Durand, G. and Mosbeux, C.: Modelling Ice-Sheet Contributions to Sea Level: Progress, Uncertainty, and Outlook, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16956, https://doi.org/10.5194/egusphere-egu26-16956, 2026.
This study presents European Ice Sheet reconstruction for the period of 0 to 800 ka BP. The model is based on linear regression of 65oN summer insolation, CO2 and the LR04 benthic δ¹⁸O stack fitted to relatively well reconstructed extents of European Ice Sheet during the Vistulian. We tested more than 30 million proxy combinations by scaling and time-shifting the predictors, and selected the best-performing variant using a least-squares criterion. The extrapolation for best combination, resulted in area time series over 800 ka period. The model shows strong relationship between European Ice Sheet area and 65oN summer insolation. Following the insolation signal, the potential for European Ice Sheet to expand and decay is higher than for global trend reflected by global ice volume proxies (i.e. LR04), leading to at least 16 fluctuations where ice sheet area reached area similar MIS2 values, including advances during global interglacial periods (e.g. during MIS7).The European Ice Sheet area during Early (MIS5d, MIS5b) and Middle Vistulian (MIS4) advances is on the same level as during Late Vistulian (MIS2). However, distribution of ice between Kara-Barents, Fennoscandian and British-Irish ice sheets differs and is asynchronous across the Vistulian. We examine this relationship and propose strategy to distribute the total European Ice Sheet area among these regions. Our study enables European Ice Sheet reconstruction trough computationally efficient model. We present a computationally efficient model for reconstructing the European Ice Sheet, enabling analysis of key climatic forcing drivers and better integration with the Earth’s climate system.
Funding sources: This research was funded by the National Science Centre (NCN) under grant no. 2024/08/X/ST10/00193 and 2015/17/D/ST10/01975.
How to cite: Szuman, I., Kalita, J. Z., Marks, L., Wieczorek, D., and Wachecka-Kotkowska, L.: Climatic proxy based statistical reconstruction of European Ice Sheet for period of 0 to 800 ka, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20859, https://doi.org/10.5194/egusphere-egu26-20859, 2026.
During the Last Glacial Maximum, the Patagonian Ice Sheet (PIS) was the second-largest ice mass in the Southern Hemisphere after Antarctica, extending across the southern Andes from ~38°S to 55°S. Today, only 5% of this ice mass remains. Here, we present a continuous reconstruction of the extent and dynamics of the western PIS between 16 and 42 kyr cal BP, derived from marine sediment core MD07-3119. The core was analysed using a multiproxy inorganic approach, including grain size, ice-rafted debris (IRD), inorganic geochemistry, and bulk mineralogy, to reconstruct sediment provenance and transport processes. These results are compared with moraine-based chronologies from the eastern PIS. Variations in bulk mineralogy, IRD content, and inorganic geochemistry indicate that the western PIS, which was land-terminating until 37 kyr cal BP, experienced five distinct Ice Expansion Intervals between 16 and 37 kyr cal BP. Data indicate that each Ice Expansion Interval is associated with enhanced sediment input from the coastal metamorphic unit. Our record indicates periods of high sediment discharge of predominantly Patagonian batholith origin corresponding to melting phases between these advances. The longest advance, at 37–31 kyr cal BP, lasted nearly 6 kyr. Variations in provenance proxies imply that PIS outlet glaciers retreated at least 65 km inland between successive advances. Our reconstruction indicates a complex temporal relationship between the western and eastern PIS margins. Overall, most ice retreat intervals in MD07-3119 match terrestrial exposure ages from the eastern side of the PIS, but the eastern PIS often appears to start shrinking earlier than its western side.
How to cite: Lebeaupin, K., Bertrand, S., Siani, G., Michel, E., Andrzejewski, L., and Leonetti, J.: Extent and Dynamics of the Western Patagonian Ice Sheet Between 16 and 42 kyr cal BP, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11397, https://doi.org/10.5194/egusphere-egu26-11397, 2026.
During the Last Glacial Maximum (23,000 to 19,000 years ago), the Patagonian Ice Sheet (PIS) covered much of the southern Andes between 38°S and 55°S, representing the largest ice mass in the Southern Hemisphere mid-latitudes. Geological evidence from Patagonia and New Zealand indicates that maximum ice extent was not synchronous with Northern Hemisphere ice-sheet evolution. Here we present transient numerical simulations of the Patagonian Ice Sheet spanning the entire Last Glacial Cycle.
Our results reveal two major phases of ice-sheet expansion, during Marine Isotope Stage 4 and late Marine Isotope Stage 3, superimposed by pronounced inter-millennial-scale variability. These high-frequency fluctuations are consistent with Southern Hemisphere climate variability and exerted a first-order control on the timing and magnitude of ice advances, particularly during intermediate glacial states. Long-term evolution of the PIS is closely linked to changes in integrated summer insolation. This metric combines summer duration and insolation intensity and exhibits an obliquity-like periodicity. This forcing provides a robust explanation for the timing and magnitude of major ice advances. We further suggest that integrated summer insolation played a broader role in modulating glacier behaviour across the Southern Hemisphere mid-latitudes, offering a unifying framework to interpret asynchronous glacial variability between hemispheres.
How to cite: Castillo-Llarena, A., Prange, M., and Rogozhina, I.: Timing and drivers of Patagonian Ice Sheet variability during the last glacial cycle, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17308, https://doi.org/10.5194/egusphere-egu26-17308, 2026.
In order to predict future changes in the Antarctic Ice Sheet under anthropogenic climate change, it is essential that we understand how it
responded to past climatic changes. The Antarctic Peninsula is seen as a bellwether system for the wider Antarctic Ice Sheet and, as such, is an
ideal palaeo-glaciological study area. The timings of the retreat of the ice front in this area since the Last Glacial Maximum have been
extensively researched and the configuration of the major ice streams that drained the ice sheet on the Northern Peninsula is broadly known.
However, the ice-ocean interactions that occurred during this period remain poorly understood. The identification and analysis of iceberg
ploughmarks can provide information on the extent of past ice sheets and the morphology of their calving fronts; past calving regimes and
hence the dynamic behaviour of the ice sheet in the past and how this may have changed over time; and past ocean circulation. During a
Schmidt Ocean Institute scientific cruise to the Antarctic Peninsula, high resolution, multibeam acoustic data was acquired in a poorly mapped
area of the Bellingshausen Sea near the Ronne Entrance. Thousands of iceberg ploughmarks were identified on bathymetric maps produced
from this data. These scours were mapped and their morphological characteristics were recorded. Morphometric analyses were undertaken,
including quantitative investigations of length, depth, width and sinuosity, and the intensity and distribution of scours were also investigated.
The implications of these results for the morphology and dynamics of the ice sheet and ice-ocean interactions since the Last Glacial Maximum
are then discussed. The insights gained from this study will be used to help validate and constrain ice sheet models where these ice-ocean
interactions are not currently well represented.
How to cite: Timbs, R. and Montelli, A.: Insight into ice-ocean interactions during the Last Deglaciation revealed by iceberg ploughmarks identified on the continental shelf of the West Antarctic Peninsula, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7838, https://doi.org/10.5194/egusphere-egu26-7838, 2026.
The mid-Piacenzian Warm Period (mPWP; 3.264 to 3.025 Ma) is a ~240 kyr long period with CO2 concentrations between 350 and 530 ppmv, in the same range as in the middle of the road emission scenario SSP2-4.5 by 2100. Temperatures were between 2 and 5˚C above the pre-industrial state for a sustained period and as a result, sea-level high stands up to +17.2 m have been inferred. Taking into account a maximum contribution from thermal expansion of 1.6 m, the remainder should have been caused by (partial) melting of either the Greenland ice sheet (GrIS) or the Antarctic ice sheet (AIS), or both, as other ice sheets on the continents of the northern hemisphere were very likely absent.
Previous work has illustrated that the simulated GrIS and AIS size is strongly dependent on the applied climate -and ice sheet models. One way to constrain the ice sheet volume of the GrIS and AIS is by making use of the partition of the benthic oxygen isotope records in a terrestrial ice sheet component and a deep-sea temperature change component. Here we simulate various GrIS and AIS geometries based on available climate model output from the Pliocene Model Intercomparison Phase 2 (PlioMIP2) and compute the isotopic composition of the ice sheets. By selecting the ice sheet geometries that correspond best to the reconstructions for the terrestrial ice sheet component from the benthic oxygen isotope record, we further constrain the minimum GrIS and AIS extent during the mPWP.
How to cite: Van Breedam, J. and Huybrechts, P.: Modeling the Greenland ice sheet and Antarctic ice sheet during the mid-Piacenzian Warm Period, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10967, https://doi.org/10.5194/egusphere-egu26-10967, 2026.
The magnitude of the Antarctic Ice Sheet's response to future climate scenarios in ice sheet models depends on the choice of initial and basal sliding conditions. Basal sliding cannot be directly measured but is instead commonly inferred from observed surface velocity or ice thickness assuming the ice sheet is in equilibrium with the modern climate. The inferred basal sliding field is also affected by assumptions of different model parameters and the ice rheology, which all impact the modelled ice sheet behaviour. Ice rheology is often treated as idealised, prescribed as uniform, or also inferred from velocity observations. Such approaches lead to either a non-unique problem or to compensating errors in the inferred fields due to intrinsic uncertainties in the observations.
To reduce compensating errors and not assume equilibrium with the modern climate, we force our ice sheet initial geometry with long-term temperature variations (i.e., a thermal spinup), thus generating a thermal structure (and therefore ice rheology) that is consistent with the ice sheet's long-term climate history. We assess different approaches to combine the thermal spinup with initialisation procedures for the Antarctic Ice Sheet, analysing their match to observed borehole temperatures at ice core sites. By initialising Antarctic Ice Sheet simulations with a thermal spinup, we improve our model’s initial conditions reducing the mismatch between modelled and observed ice sheet geometries and the uncertainty around the ice sheet's basal conditions and ice rheology with respect to basal and englacial temperatures. Finally, we use the different obtained initial states to show the impact of the ice sheet’s thermal history compared with idealised temperatures or equilibrium conditions on its sensitivity to future warming.
How to cite: Mas e Braga, M., Berends, T., Lambert, E., and Bernales, J.: The impact of ice sheet thermal memory in Antarctica’s response to climate warming, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9804, https://doi.org/10.5194/egusphere-egu26-9804, 2026.
The Antarctic Ice Sheet has undergone significant climate variability throughout glacial-interglacial cycles. Because thermal diffusion and advection rates are low, surface temperature anomalies propagate slowly to the base, imparting a thermal memory to ice sheets that persists for thousands of years. Since ice temperature controls viscosity, deformation rates, and subglacial processes, this inherited thermal structure exerts a direct influence on contemporary ice dynamics. Recent work on the thermal state of the Antarctic Ice Sheet (Raspoet & Pattyn, 2025) has explored uncertainties in boundary conditions and model approximations, but considered a thermal steady state, thereby assuming equilibrium with present-day climatic conditions and neglecting the legacy of past glacial-interglacial changes. In this study, we employ the thermomechanical ice-sheet model Kori-ULB, driven by reconstructed transient climate forcings spanning the last interglacial to the present day, to quantify the effects of paleoclimatic evolution on the thermal state of the Antarctic Ice Sheet and assess the implications for ice-sheet dynamics and model initialization. Results show that englacial temperatures are sensitive to the past climate history, leading to uncertainties of the same order as those related to the geothermal heat flow. Incorporating variations in surface temperatures and accumulation rates over the last glacial-interglacial cycle results in colder temperature profiles and basal thermal conditions, suggesting that steady-state ice-sheet models may overestimate present-day thermal conditions.
References:
Raspoet O., Pattyn F. (2025), Estimates of basal and englacial thermal conditions of the Antarctic ice sheet. Journal of Glaciology 71, e104, 1–16. doi: 10.1017/jog.2025.10087
How to cite: Raspoet, O., Coulon, V., and Pattyn, F.: The thermal memory of the Antarctic Ice Sheet, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3349, https://doi.org/10.5194/egusphere-egu26-3349, 2026.
The future contribution of the Antarctic Ice Sheet to global sea-level rise remains the largest source of uncertainty in climate projections. This uncertainty is primarily driven by the complex interaction between the ocean and the ice shelf cavities. Most ice sheet models still rely on simplified melt parameterizations that fail to capture the complex oceanographic processes within sub-ice-shelf cavities, while fully coupled ice-ocean models remain too computationally expensive for large-scale sensitivity studies. In this study, we present ADMIRE (Antarctic Deep MELT and Ice REpresentation), a new ongoing-work intermediate-complexity framework. ADMIRE couples the ice sheet model Kori-ULB with DeepMELT, a deep learning emulator trained on high-resolution NEMO-SI3 simulations. This coupling allows for a more physically consistent representation of the ice-ocean interface at a fraction of the computational cost of a coupled ice-sheet-ocean model. We compare the sensitivity of the Antarctic grounding line migration and overall mass balance when using the DeepMELT emulator versus traditional melt parameterizations. Furthermore, we investigate the impact of temporal coupling steps and interpolation methods on the projections. Our preliminary results highlight the potential of machine learning-based emulators to bridge the gap between simple parameterizations and complex coupled models, providing more robust projections of Antarctica’s future but at a low computational cost, allowing for comprehensive and multi-century studies.
How to cite: Kittel, C., Burgard, C., and Coulon, V.: ADMIRE: Improving Antarctic mass balance projections by coupling a Deep Learning basal melt emulator with the Kori-ULB ice sheet model, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7003, https://doi.org/10.5194/egusphere-egu26-7003, 2026.
Antarctica has the largest potential contribution to sea-level change within the modern cryosphere. Therefore, reliable predictions of future sea-level change from the Antarctic Ice Sheet are crucial. Ice sheet interactions with other Earth system components are crucial for making accurate predictions of sea-level change, as relevant interactive feedbacks can amplify or dampen the anthropogenic induced effects and affect associated response time scales. In most ice sheet model projections so far, models generally assume constant bed topography and sea level. Neglecting the stabilizing sea-level feedback due to glacial isostatic adjustment (GIA), i.e., gravitationally, rotationally, and deformationally (GRD) consistent deformations of the solid Earth and sea level change, tends to overestimate the Antarctic Ice Sheet’s contribution to sea level rise on centennial timescales, particularly in regions with very low mantle viscosities and a thin lithosphere.
As part of the PalMod project, we present first results of multi-millennial future simulations with the interactively coupled Parallel Ice Sheet Model (PISM), which represents ice sheet dynamics, together with two glacial isostatic adjustment (GIA) models of different complexity: VILMA (VIscoelastic Lithosphere and MAntle model) and the Lingle–Clark (LC) model. For climatic forcing, we used surface temperature and surface mass balance from the regional climate model RACMO, forced by the climate model CESM2-WACCM, while long-term climate evolution was taken from CLIMBER-X. VILMA is applied as a global GIA model that captures all GRD components and accounts for the 3-dimensional Earth structure. The LC model, which is often used in ice sheet modelling, represents a regional viscoelastic GIA model with constant values for upper-mantle viscosity and lithosphere thickness and only accounts for vertical land motion. The simulations cover the period from the pre-industrial era up to the year 10,000. The projections assess the influence of different Earth structures on ice sheet mass changes, which we show result in particularly different trajectories on the longer time scales.
How to cite: Mojtabavi, S., Albrecht, T., Willeit, M., Wullenweber, N., Schachtschneider, R., and Klemann, V.: Antarctic Ice Sheet response over the next 10,000 years: ice sheet dynamics interacting with solid Earth deformations and sea-level change, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13478, https://doi.org/10.5194/egusphere-egu26-13478, 2026.
The ice sheets of the Antarctic continent are supported and stabilised by floating ice shelves. Any future decrease in ice shelf mass and stability is expected to increase ice sheet drainage thus potentially contributing to a rise in the global sea level. Basal melting is a critical factor concerning ice shelf stability. Its rates are strongly dependent on the bathymetry underneath the ice shelves, as this directly influences sub-ice water circulation and its interactions with the open ocean. Therefore, accurate knowledge of sub-ice bathymetry is crucial to estimate the exchange of water masses and heat with the open ocean. We have created a model of the seafloor topography beneath the Evans Ice Stream - draining into the Ronne Ice Shelf, one of the world’s largest ice shelves - by the inversion of legacy airborne gravity data constrained by seismic and ice-penetrating radar depth references. The new bathymetric model is a distinct improvement over existing topographic compilations based on interpolated depths, providing a range of new information on topographic characteristics beneath the ice shelf with increased resolution and detail. The model shows a deep, asymmetric and U-shaped trough beneath the Evans Ice Stream that follows the ice stream’s flow direction. The bathymetry shows that the retrograde slope of the seafloor on the continental shelf and beneath the outer Ronne Ice Shelf continues as far as the ice stream’s grounding line. Should warm water masses from the open ocean cross the continental shelf edge, this slope would permit intrusion of these water masses all the way up to the grounding line. The new bathymetric model thus enables a step towards being able to more confidentially estimate basal melt rates beneath the Evans Ice Stream and their effect on ice shelf and ice sheet stability. The depth and shape of the seabed beneath numerous other ice shelves and areas of permanent sea ice coverage around the Antarctic margins remains poorly constrained or completely unknown. As well as the Evans cavity model, new data and plans for upcoming bathymetric modelling of some of these other areas are highlighted.
How to cite: Höppner, L. K., Eagles, G., Eisermann, H., Dorschel, B., Pail, R., Geissler, W. H., and Brisbourne, A. M.: Sub-Ice Shelf Topography in Antarctica: Aerogeophysical Modelling and Implications for Ice Shelf Stability – A Case Study at the Evans Ice Stream, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10519, https://doi.org/10.5194/egusphere-egu26-10519, 2026.
We present our development of the Ice sheet model for Integrated Earth-system Studies (IcIES2) for the Antarctic ice sheet configuration as a model development for CMIP7-ISMIP7. The flow of the ice is calculated with the shallow ice approximation (SIA) and shallow shelf approximation (SSA). To represent the migration of grounding lines, we use the grounding line flux boundary condition of Schoof (2007), following previous implementations (Pollard and DeConto 2012; 2020). The ice velocity fields are calculated using a hybrid approach that combines the SIA and SSA approximations, based on the ratio of basal sliding velocity to the depth-averaged velocity from the SIA solution. We perform sensitivity experiments on ice-sheet model parameters using the present-day bedrock topography and surface mass balance to obtain a reasonable present-day Antarctic ice-sheet configuration. We also perform experiments with an abrupt increase in sub-shelf melting to evaluate the model response to reduced ice shelf buttressing and marine ice sheet instability.
How to cite: Obase, T., Saito, F., and Abe-Ouchi, A.: Developments and evaluation of ice sheet model IcIES2 for Antarctic configuration, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8750, https://doi.org/10.5194/egusphere-egu26-8750, 2026.
- 2Laboratory of climatology, SPHERES research unit, Department of Geography, University of Liège, Liège, Belgium
- 3Physical Geography Research Group, Department of Geography, Vrije Universiteit Brussel, Brussels, Belgium
Accurate projections of the Antarctic ice sheet contribution to future sea-level rise require a robust representation of ice–atmosphere interactions and associated surface mass balance (SMB) feedbacks. Although they remain computationally expensive, coupled ice–atmosphere simulations provide the ideal framework for capturing these processes.
In this work in progress, we present ongoing coupled simulations between the ice-sheet model Kori-ULB and the regional climate model MAR. The coupled Kori-MAR simulations are conducted over Antarctica for the period 1980–2100 and are forced by the IPSL-CM6A-LR climate model under the SSP5-8.5 scenario. We compare the coupled simulations with three simplified modelling approaches: (i) ice-sheet model experiments externally forced by MAR outputs assuming a fixed ice-sheet geometry, (ii) simulations using a positive degree-day (PDD) scheme forced directly by IPSL-CM6A-LR, and (iii) simulations using a PDD scheme forced by MAR(IPSL-CM6A-LR). This allows us to investigate the influence of ice geometry changes on Antarctic SMB and projected ice-sheet mass loss. In parallel, we assess the ability of simplified SMB methods to reproduce MAR-derived SMB fields and their temporal evolution. A key objective is to better constrain the melt–elevation feedback emerging in the coupled simulations and to use this information to calibrate and improve PDD-based approaches for long-term Antarctic ice-sheet projections.
How to cite: Coulon, V. and Kittel, C.: Exploring ice-atmosphere feedbacks in Antarctica using coupled simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7112, https://doi.org/10.5194/egusphere-egu26-7112, 2026.
The Tipping Points Modelling Intercomparison Project (TIPMIP) uses Earth System models (ESMs) and stand-alone models to assess tipping point risks. Within TIPMIP-ICE, stand-alone ice sheet models are forced with temporally extended atmospheric and oceanic output from multiple TIPMIP ESMs, making the choice of forcing a critical source of uncertainty.
We explore TIPMIP ESM results in Antarctica for the historical period as well as under positive and zero emission scenarios to (1) decide on suitable forcing data for ice sheet simulations and to (2) understand simulated ice sheet changes in relation to the ESM forcing. The analysis focuses on ocean potential temperature and salinity at the Antarctic continental shelf depth, near-surface air temperature, and precipitation as key fields for sub-shelf melt, surface mass balance, and ice sheet stability. It includes a comparison to observations and an assessment of multi-model differences under positive and zero emissions scenarios.
Comparing historical runs (1981-2010) to observations reveals oceanic temperature biases across the ESMs of up to +4°C/-2°C. Under an idealized positive emission experiment to +2°C of global mean warming, preliminary results show spatial variability across basins in Antarctica. Different models follow distinct atmosphere-ocean warming trajectories, resulting in different forcing patterns for ice sheet models.
These distinct warming trajectories could impact the risk of ice sheet tipping dynamics in TIPMIP-ICE, particularly the grounding-line stability of Antarctica. They underline the importance of having a diverse set of ESM forcings to enable future evaluation of feedbacks associated with tipping dynamics of the ice sheets such as melt-elevation feedback or marine ice sheet instability (MISI). Ongoing work extends this analysis to additional ESMs and to Greenland.
How to cite: Röntgen, L., Klose, A. K., Albrecht, T., Bernales, J., Guo, C., Wyser, K., Smith, R. S., Hvidberg, C., Yang, S., and Winkelmann, R.: Exploring Earth System Model Forcings for Ice Sheet Tipping Point Experiments in TIPMIP-ICE, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14253, https://doi.org/10.5194/egusphere-egu26-14253, 2026.
Firn currently covers almost 90 % of the surface of the Greenland Ice Sheet. Most of Greenland’s firn plateau experienced only occasional melt in the past but ever rising temperatures increase melting and it is uncertain how a future melting firn plateau will impact ice sheet mass balance, hydrology and ice dynamics. Assessing these impacts requires coupling firn models to ice sheet hydrology and ice dynamics models.
The FirnMelt ERC Synergy project will assess the Greenland Ice Sheet’s reaction to increased melting across its vast firn plateau. The project starts in April 2026 and will last for six years. The project is led by four PIs and will involve about 20 scientific and technical staff. Here we detail planned methods, models and timeline of the five overarching project tasks, namely (i) large-scale in situ and remote sensing measurements of all types of firn and meltwater discharge, (ii) parameterizing melting firn based on these measurements, (iii) develop firn models able to simulate melting firn and firn meltwater discharge in three dimensions, (iv) embedding these models into a ice-sheet model suite where they are coupled to ice sheet hydrology and ice dynamics, and (v) calculating how Greenland’s melting firn plateau will impact the entire ice sheet and its sea level contribution, until the year 2300.
How to cite: Machguth, H. and the The FirnMelt Team: FirnMelt: Greenland’s Melting Firn and Ice Sheet Response, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5653, https://doi.org/10.5194/egusphere-egu26-5653, 2026.
When studying the future evolution and sea level contribution of the Greenland ice sheet, a realistic representation of ice sheet–atmosphere interactions in simulations is crucial. Therefore, to analyse the ice sheet evolution over the coming three centuries, we have performed several fully coupled ice sheet–regional climate model simulations. Our two-way coupled MAR–GISM simulations were driven by IPSL-CM6A-LR output under the SSP5-8.5 scenario, available up to 2300, and outlet glacier retreat was included through an empirical retreat parametrization.
To disentangle the long-term importance of ice mass loss through surface mass balance (SMB) versus marine discharge, we compare simulations with only atmospheric or oceanic forcing to simulations with both forcings applied simultaneously. They indicate that both atmospheric and oceanic forcing individually still lead to a similar sea level contribution by 2100. But, by 2300 the SMB-driven ice mass loss is about five times larger than the discharge-driven ice mass loss in our simulations, as the ice sheet retreats on land and gradually loses contact with the ocean. Besides, an analysis of the SMB components and freshwater fluxes between simulations demonstrates that surface melting and ice discharge through the ice–ocean boundary are mutually competitive processes.
Lastly, in terms of total ice mass loss, the importance of the chosen sensitivity parameter in the retreat parametrization increases over time. Whereas the difference in ice mass loss contribution from SMB versus discharge attenuates between simulations of differing sensitivity, because surface melting becomes increasingly dominant relative to marine discharge. Nevertheless, our simulations indicate that the applicability of the empirical retreat parametrization, which was developed for recent observations, becomes questionable over time.
How to cite: Paice, C. M., Fettweis, X., and Huybrechts, P.: Surface melt outweighs ice discharge over the next three centuries in fully coupled MAR-GISM simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9160, https://doi.org/10.5194/egusphere-egu26-9160, 2026.
We present an ensemble of physically-based ice sheet model projections for the Greenland ice sheet (GrIS) that was produced as part of the European project PROTECT. Our ice sheet model (ISM) simulations are forced by high-resolution regional climate model (RCM) output and other climate model forcing, including a parameterisation for the retreat of marine-terminating outlet glaciers. The experimental design builds on the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) protocol and extends it to more fully account for uncertainties in sea-level projections. We include a wider range of CMIP6 climate model output, more climate change scenarios, several climate downscaling approaches, a wider range of sensitivity to ocean forcing and we extend projections beyond the year 2100 up to year 2300, including idealised overshoot scenarios. GrIS sea-level rise contributions range from 16–76 mm (SSP1-2.6/RCP2.6), 22–163 mm (SSP2-4.5) and 27–354 mm (SSP5-8.5/RCP8.5) in the year 2100 (relative to 2014). The projections are strongly dependent on the climate scenario, moderately sensitive to the choice of RCM, and relatively insensitive to the ice sheet model choice. In year 2300, contributions reach 49 to 3127 mm, indicative of large uncertainties and a potentially very large long-term response. Idealised overshoot experiments to 2300 produce sea-level contributions in a range from 49 to 201 mm, with the ice sheet seemingly stabilised in a third of the experiments. Repeating end of the 21st century forcing until 2300 results in contributions of 58–163 mm (repeated SSP1-2.6), 98–218 mm (repeated SSP2-4.5) and 282–1230 mm (repeated SSP5-8.5). The largest contributions of more than 3000 mm by year 2300 are found for extreme scenarios of extended SSP5-8.5 with unabated warming throughout the 22nd and 23rd century. We also extend the ISMIP6 forcing approach backwards over the historical period and successfully produce consistent simulations in both past and future for three of the four ISMs. The ensemble design of ISM experiments is geared towards the subsequent use of emulators to facilitate statistical interpretation of the results and produce probabilistic projections of the GrIS contribution to future sea-level rise.
How to cite: Goelzer, H., Berends, C. J., Boberg, F., Durand, G., Edwards, T. L., Fettweis, X., Gillet-Chaulet, F., Glaude, Q., Huybrechts, P., Le clec’h, S., Mottram, R., Noël, B., Olesen, M., Rahlves, C., Rohmer, J., van den Broeke, M., and van de Wal, R. S. W.: Extending the range and reach of physically-based Greenland ice sheet sea-level projections, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2576, https://doi.org/10.5194/egusphere-egu26-2576, 2026.
