AMOC Stability Amid Tipping Ice Sheets: The Crucial Role of Rate and Noise

• Main Authors: Sinet, Sacha, Ashwin, Peter, von der Heydt, Anna S., Dijkstra, Henk A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2023
• Subjects: article; Verlagsveröffentlichung; Greenland; West Antarctica; Antarc*; Antarctica; Ice Sheet
• Online Access: https://doi.org/10.5194/egusphere-2023-2661; https://noa.gwlb.de/receive/cop_mods_00070269; https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00068624/egusphere-2023-2661.pdf; https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2661/egusphere-2023-2661.pdf

The Atlantic Meridional Overturning Circulation (AMOC) has recently been categorised as core tipping element, for it is believed to be prone to critical transition under climate change, implying drastic consequences on a planetary scale. Moreover, the AMOC is strongly coupled to polar ice sheets via meltwater fluxes. On one hand, most studies agree on the fact that a collapse of the Greenland ice sheet would result in a weakening of AMOC. On the other hand, the consequences of a collapse of the West Antarctica ice sheet are less well understood. However, some studies suggest that meltwater originating from the Southern Hemisphere is able to stabilize the AMOC. Using a conceptual model of the AMOC and a minimal parameterization of ice sheet collapse, we investigate the origin and relevance of this stabilization effect in both the deterministic and stochastic cases. While a substantial stabilization is found in both cases, we find that important rate and noise-induced effects result in bifurcation-induced tipping approaches to be inaccurate for predicting the AMOC stability.