Evidence of Antarctic Ice Sheet Loss Despite Sub-freezing Surface Temperatures

Geology, 11 February 2022

New research resolves a long-standing discrepancy between marine records from the Ross Sea, which indicate complete ice sheet loss in that region during interglacials (warmer periods, with CO2 around 280ppm); versus land records that show persistent cold, sub-freezing conditions which should have maintained the ice sheet. This study resolved this discrepancy by using high-resolution climate models to show that below-freezing surface temperatures can persist on Antarctic land surfaces, even when elevated air and water temperatures melt all the ice in the neighboring Ross Sea, causing some degree of ice sheet collapse and related multi-meter sea-level rise. These findings provide strong evidence of the large influence of ocean warming on Antarctic ice sheets dynamics. This emphasizes the need to avoid Paris Agreement temperature overshoot scenarios that cause global oceans to absorb more heat, which may cause continued ice sheet loss even as air temperatures decline in response to later emissions reductions or carbon drawdown. Carbon dioxide levels today already are much higher than the 280ppm interglacial norm.