Projection of the Antarctic surface mass balance by 2100 using MAR

The surface mass balance of the Antarctic ice sheet is often considered as a negative contributor to the sea level rise as snowfall accumulation largely overestimates ablation through wind erosion, sublimation and runoff. Contrary to the Greenland ice sheet, current surface melting is limited to relatively scarce events over the Antarctic peninsula, ice shelves and more generally peripheral areas. However, surface melting can significantly affect the stability of ice shelves through hydrofracturing, potentially leading to their disintegration, acceleration of grounded ice and increased sea level rise. Although a large increase in snowfall is expected in a warmer climate, more numerous and stronger melting events could conversely lead to a larger risk of ice shelf collapse. In this study, we provide an estimation of the surface mass balance of the Antarctic ice sheet for the end of the 21st century by forcing the state-of-the-art regional climate model MAR with three different global climate models. We chose the models (from both the Coupled Model Intercomparison Project Phase 5 and 6 - CMIP5 and CMIP6) providing the best metrics for representing the present Antarctic climate. Our results show that the increase in snowfall compensates snow ablation though sublimation and runoff over the margins except over the Larsen and Amery ice shelves. However, melt rates over the other ice shelves are higher than those that led to the collapse of Larsen A and B ice shelves, suggesting a high probability of ice shelf collapses by 2100.