ISMIP6 Antarctica: A multi-model ensemble of the Antarctic ice sheet evolution over the 21st century

• Published in: The Cryosphere
• Main Authors: Seroussi, H, Nowicki, S, Payne, AJ, Goelzer, H, Lipscomb, WH, Abe-Ouchi, A, Agosta, C, Albrecht, T, Asay-Davis, X, Barthel, A, Calov, R, Cullather, R, Dumas, C, Galton-Fenzi, BK, Gladstone, R, Golledge, NR, Gregory, JM, Greve, R, Hattermann, T, Hoffman, MJ, Humbert, A, Huybrechts, P, Jourdain, NC, Kleiner, T, Larour, E, Leguy, GR, Lowry, DP, Little, CM, Morlighem, M, Pattyn, F, Pelle, T, Price, SF, Quiquet, A, Reese, R, Schlegel, NJ, Shepherd, A, Simon, E, Smith, RS, Straneo, F, Sun, S, Trusel, LD, Breedam, JV, Van De Wal, RSW, Winkelmann, R, Zhao, Chen, Zhang, T, Zwinger, T
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus GmbH 2020
• Subjects: Earth Sciences; Other earth sciences; Earth system sciences; Antarctic; The Antarctic; East Antarctica; West Antarctic Ice Sheet; Antarc*; Antarctica; Ice Sheet; Ice Shelf; Ice Shelves
• Online Access: https://doi.org/10.5194/tc-14-3033-2020; http://ecite.utas.edu.au/141923

Ice flow models of the Antarctic ice sheet are commonly used to simulate its future evolution in response to different climate scenarios and assess the mass loss that would contribute to future sea level rise. However, there is currently no consensus on estimates of the future mass balance of the ice sheet, primarily because of differences in the representation of physical processes, forcings employed and initial states of ice sheet models. This study presents results from ice flow model simulations from 13 international groups focusing on the evolution of the Antarctic ice sheet during the period 2015-2100 as part of the Ice Sheet Model Intercomparison for CMIP6 (ISMIP6). They are forced with outputs from a subset of models from the Coupled Model Intercomparison Project Phase 5 (CMIP5), representative of the spread in climate model results. Simulations of the Antarctic ice sheet contribution to sea level rise in response to increased warming during this period varies between 7:8 and 30.0 cm of sea level equivalent (SLE) under Representative Concentration Pathway (RCP) 8.5 scenario forcing. These numbers are relative to a control experiment with constant climate conditions and should therefore be added to the mass loss contribution under climate conditions similar to presentday conditions over the same period. The simulated evolution of the West Antarctic ice sheet varies widely among models, with an overall mass loss, up to 18.0 cm SLE, in response to changes in oceanic conditions. East Antarctica mass change varies between 6:1 and 8.3 cm SLE in the simulations, with a significant increase in surface mass balance outweighing the increased ice discharge under most RCP 8.5 scenario forcings. The inclusion of ice shelf collapse, here assumed to be caused by large amounts of liquid water ponding at the surface of ice shelves, yields an additional simulated mass loss of 28mm compared to simulations without ice shelf collapse. The largest sources of uncertainty come from the climate forcing, the ocean-induced melt ...