The Hysteresis of the Antarctic Ice Sheet
Date:
Ignite talk and poster at the Wilhelm and Else Heraeus Seminar on “Addressing Key Uncertainties in Modelling Physical and Ecological Tipping Dynamics in the Earth System (towards TIPMIP) at Döllnsee, Germany.
Abstract
The Antarctic Ice Sheet stores enough freshwater to raise the mean elevation of the oceans by nearly 60 meters globally and is thus constituting by far the largest source of potential future sea-level rise. Its long-term stability determines 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, using the ice-sheet model PISM, 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, i.e., 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 of several up to dozens of metres.