Warming Similar to Today Triggered Collapse of the West Antarctic Ice Sheet

Scientific Reports, August 19

During the Last Inter-Glacial (LIG, between ice ages) 125,000 years ago, ocean temperatures rose 1.5-2°C above pre-industrial levels. Ice loss accelerated across the West Antarctic Ice Sheet (WAIS), with ice melt and fracturing near the Amundsen Sea contributing 4 meters to sea-level rise. East Antarctica was less affected, and the Wilkes Basin – one of the largest meltwater drainage sites in East Antarctica – thinned, but did not retreat. Given projected warming even with very low emissions, these findings indicate that sections of the West Antarctic Ice Sheet may collapse even without any additional greenhouse emissions and related warming; but risks will increase as temperatures approach 2°C. A low emissions pathway must be followed to avoid crossing this apparent 2°C threshold, and irreversibly committing ourselves to more than 4 meters of additional sea-level rise from the WAIS.