Evolution of the Antarctic Ice Sheet Over the Next Three Centuries From an ISMIP6 Model Ensemble

• Published in: Earth's Future
• Main Authors: Seroussi, Hélène, Pelle, Tyler, Lipscomb, William, Abe-Ouchi, Ayako, Albrecht, Torsten, Alvarez-Solas, Jorge, Asay-Davis, Xylar, Barre, Jean‐baptiste, Berends, Constantijn, Bernales, Jorge, Blasco, Javier, Caillet, Justine, Chandler, David, Coulon, Violaine, Cullather, Richard, Dumas, Christophe, Galton-Fenzi, Benjamin, Garbe, Julius, Gillet-Chaulet, Fabien, Gladstone, Rupert, Goelzer, Heiko, Golledge, Nicholas, Greve, Ralf, Gudmundsson, G. Hilmar, Han, Holly Kyeore, Hillebrand, Trevor, Hoffman, Matthew, Huybrechts, Philippe, Jourdain, Nicolas, Klose, Ann Kristin, Langebroek, Petra, Leguy, Gunter, Lowry, Daniel, Mathiot, Pierre, Montoya, Marisa, Morlighem, Mathieu, Nowicki, Sophie, Pattyn, Frank, Payne, Antony, Quiquet, Aurélien, Reese, Ronja, Robinson, Alexander, Saraste, Leopekka, Simon, Erika, Sun, Sainan, Twarog, Jake, Trusel, Luke, Urruty, Benoit, van Breedam, Jonas, van de Wal, Roderik, Wang, Yu, Zhao, Chen, Zwinger, Thomas
• Other Authors: Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Modélisation du climat (CLIM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Observatoire des Sciences de l'Univers de Grenoble (Fédération OSUG)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP), Université Grenoble Alpes (UGA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2024
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Antarctic; The Antarctic; West Antarctica; Antarc*; Ice Sheet; Ice Shelf
• Online Access: https://hal.science/hal-04692217; https://hal.science/hal-04692217v1/document; https://hal.science/hal-04692217v1/file/Earth%20s%20Future%20-%202024%20-%20Seroussi%20-%20Evolution%20of%20the%20Antarctic%20Ice%20Sheet%20Over%20the%20Next%20Three%20Centuries%20From%20an%20ISMIP6%20Model.pdf; https://doi.org/10.1029/2024EF004561

International audience Abstract The Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) is the primary effort of CMIP6 (Coupled Model Intercomparison Project–Phase 6) focusing on ice sheets, designed to provide an ensemble of process‐based projections of the ice‐sheet contribution to sea‐level rise over the twenty‐first century. However, the behavior of the Antarctic Ice Sheet beyond 2100 remains largely unknown: several instability mechanisms can develop on longer time scales, potentially destabilizing large parts of Antarctica. Projections of Antarctic Ice Sheet evolution until 2300 are presented here, using an ensemble of 16 ice‐flow models and forcing from global climate models. Under high‐emission scenarios, the Antarctic sea‐level contribution is limited to less than 30 cm sea‐level equivalent (SLE) by 2100, but increases rapidly thereafter to reach up to 4.4 m SLE by 2300. Simulations including ice‐shelf collapse lead to an additional 1.1 m SLE on average by 2300, and can reach 6.9 m SLE. Widespread retreat is observed on that timescale in most West Antarctic basins, leading to a collapse of large sectors of West Antarctica by 2300 in 30%–40% of the ensemble. While the onset date of retreat varies among ice models, the rate of upstream propagation is highly consistent once retreat begins. Calculations of sea‐level contribution including water density corrections lead to an additional ∼10% sea level and up to 50% for contributions accounting for bedrock uplift in response to ice loading. Overall, these results highlight large sea‐level contributions from Antarctica and suggest that the choice of ice sheet model remains the leading source of uncertainty in multi‐century projections.