Competing climate feedbacks of ice sheet freshwater discharge in a warming world

Freshwater discharge from ice sheets creates surface atmospheric cooling and subsurface ocean warming, representing negative and positive climate feedbacks, respectively. This study uses a coupled ice sheet-climate model to assess these competing feedbacks for the Antarctic Ice Sheet (AIS). The positive feedback dominates in moderate warming scenarios and early ice sheet retreat, but the negative feedback surpasses it in intense warming scenarios during the West Antarctic Ice Sheet's catastrophic collapse. The Atlantic Meridional Overturning Circulation (AMOC) is impacted by freshwater discharge from both the Greenland and Antarctic ice sheets, acting as an interhemispheric link that intensifies the other ice sheet's retreat via the Bipolar Seesaw. The findings highlight the crucial role of ice sheet-climate interactions through freshwater flux in future ice sheet retreat and sea-level rise.

Dawei Li, Robert M. DeConto, David Pollard, Yongyun Hu