Atmospheric stabilization of the East Antarctic ice sheet under warming

Abstract Most coupled Earth system models do not include fully interactive ice sheets, introducing uncertainty in future projections of polar climate and global sea level. To this end, we conduct 100,000-year-long simulations for different CO 2 conditions using the community Earth system model coupled to the bihemispheric Penn State University ice sheet–ice shelf model. Whereas global warming exceeding 2 °C above pre-industrial conditions and related subsurface ocean warming lead to the millennial-scale disintegration of the West Antarctic ice sheet, the East Antarctic ice sheet shows a much greater resilience, even at 10 °C or more of warming. The simulations reveal that a moister and cloudier atmosphere over Antarctica, with southward-shifted westerlies, increases snow accumulation and reduces shortwave radiation. For Greenland, a 6 °C threshold above pre-industrial levels is identified. Capturing the balance of ocean- and atmosphere-driven ablation and accumulation processes in coupled climate–ice-sheet models will improve projections of long-term sea-level rise.