The Hysteresis of the Antarctic Ice Sheet
Date:
Poster at the 28th International Polar Conference at Potsdam, Germany.
Abstract
The ice sheets of West and East Antarctica are among the most policy-relevant large-scale tipping elements in the Earth system. Combined, they store enough water to raise the mean elevation of the oceans by nearly 60 meters and are thus constituting by far the largest source of potential future sea-level rise. Their long-term stabilities determine the fate of our coastal cities and cultural heritage on centennial and millennial time scales. Feedbacks with the atmosphere and ocean give rise to potential nonlinearities with respect to temperature changes.
In a comprehensive modelling analysis, we show that the Antarctic Ice Sheet exhibits a multitude of temperature thresholds beyond which ice loss into the ocean is irreversible. Each of these thresholds gives rise to hysteresis behaviour: that is, the currently observed ice-sheet configuration is not regained even if temperatures are reversed to their present-day levels.
Our results imply that if the Paris Agreement is not met, one or more critical thresholds might be subsequently crossed in Antarctica, committing us to long-term, possibly irreversible, sea-level rise.