EGU24-5278, updated on 08 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

The role of a weakening AMOC in shaping future Euro-Atlantic atmospheric circulation

Andrea Vito Vacca1,3, Katinka Bellomo1,2, Federico Fabiano2, and Jost von Hardenberg1,2
Andrea Vito Vacca et al.
  • 1Politecnico di Torino, Turin, Italy
  • 2National Research Council, Institute of Atmospheric Sciences and Climate, Italy
  • 3IUSS Pavia, Pavia, Italy

Climate change simulations predict a weakening of the Atlantic Meridional Overturning Circulation (AMOC). In the North Atlantic, where the deep convection occurs, the AMOC has a particularly marked influence. Here, the AMOC decline could have significant implications for the evolution of weather patterns, resulting in societal risks for densely populated areas of Europe. 

We employ the Weather Regime framework to analyse the change in the daily variability of large-scale atmospheric circulation in three coordinated experiments from the CMIP6 archive (i.e., ssp2-4.5, ssp5-8.5 and abrupt-4xCO2). We find that models that simulate a larger AMOC decline feature a net increase in NAO+ regime frequency and persistence compared to models that simulate a smaller AMOC decline. We show that this is due to the influence of a reduced warming of the subpolar North Atlantic (SPNA) on mean geopotential height, caused by the AMOC weakening. We further show that this also causes the storm track to strengthen due to an increased baroclinicity of the atmosphere in the region, with possible consequences on future extreme events.

Overall, our results suggest that the evolution of the Euro-Atlantic atmospheric circulation depends on the AMOC decline. We conclude that ocean circulation is a main driver of NAO variability in projections of future climate change, in addition to previously known drivers. 

How to cite: Vacca, A. V., Bellomo, K., Fabiano, F., and von Hardenberg, J.: The role of a weakening AMOC in shaping future Euro-Atlantic atmospheric circulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5278,, 2024.