Antarctic loss could double expected sea level rise by 2100, scientists say

Post date: Mar 31, 2016 3:10:16 PM

REUTERS/FILE

The melting of ice on Antarctica alone could cause seas to rise more than 42 feet by 2500.

By Brady Dennis and Chris Mooney WASHINGTON POST MARCH 30, 2016

Coastal cities including New York, London, Shanghai and Hong Kong could be flooded before the end of the century. The dramatic new study, published Wednesday in the journal Nature, predicts global warming could melt the West Antarctic ice sheet within decades—far faster than previously predicted. The collapse of this sheet, combined with ice melting in other regions, could cause seas to rise up to six feet by 2100. The study’s authors, Robert DeConto of the University of Massachusetts Amherst and David Pollard of Pennsylvania State University, also found the melting of the West Antarctic ice sheet is not yet inevitable, but that the emission reduction plans outlined in the 2015 Paris climate deal are far too weak to stop the sheet from melting.

ABSTRACT from Nature:

Contribution of Antarctica to past and future sea-level rise

      • Nature 531, 591–597 (31 March 2016) doi:10.1038/nature17145
        • Received 27 May 2015 Accepted 12 January 2016 Published online 30 March 2016

Polar temperatures over the last several million years have, at times, been slightly warmer than today, yet global mean sea level has been 6–9 metres higher as recently as the Last Interglacial (130,000 to 115,000 years ago) and possibly higher during the Pliocene epoch (about three million years ago). In both cases the Antarctic ice sheet has been implicated as the primary contributor, hinting at its future vulnerability. Here we use a model coupling ice sheet and climate dynamics—including previously underappreciated processes linking atmospheric warming with hydrofracturing of buttressing ice shelves and structural collapse of marine-terminating ice cliffs—that is calibrated against Pliocene and Last Interglacial sea-level estimates and applied to future greenhouse gas emission scenarios. Antarctica has the potential to contribute more than a metre of sea-level rise by 2100 and more than 15 metres by 2500, if emissions continue unabated. In this case atmospheric warming will soon become the dominant driver of ice loss, but prolonged ocean warming will delay its recovery for thousands of years.