West Antarctic Meltwater can Prevent an AMOC Collapse

TL;DR

This study demonstrates that meltwater from the West Antarctic Ice Sheet can stabilize the Atlantic Meridional Overturning Circulation, potentially preventing its collapse even under high greenhouse gas emission scenarios.

Contribution

It reveals a previously unknown stabilizing effect of West Antarctic meltwater on the AMOC, contrasting with the destabilizing influence of Greenland meltwater.

Findings

WAIS meltwater increases AMOC resilience

Under certain conditions, WAIS meltwater can prevent AMOC collapse

Stabilization occurs for high-emission scenario trajectories

Abstract

The Atlantic Meridional Overturning Circulation (AMOC) and polar ice sheets are coupled tipping elements, allowing for potential cascading tipping events in which tipping is facilitated by their mutual interactions. However, while an AMOC destabilization driven by Greenland Ice Sheet (GIS) meltwater release is well documented, the consequences of a West Antarctic Ice Sheet (WAIS) tipping on the AMOC remain unclear. In the Earth System Model of Intermediate Complexity CLIMBER-X, we perform experiments where meltwater fluxes representing plausible tipping trajectories of the GIS and WAIS are applied. We find that WAIS meltwater input can increase the AMOC resilience to GIS meltwater. In particular, we show that this stabilizing effect can cause the AMOC recovery and, for the first time in a comprehensive model, totally prevent an AMOC collapse. Moreover, we find this stabilzation to occur for ice sheet tipping trajectories that are relevant under high future greenhouse gas emission scenarios.