AMOC Weakening Shapes Ocean Heat Storage Patterns Under Strong Idealized Warming

Abstract

The ocean absorbs most of the excess heat induced by anthropogenic greenhouse gas emissions. Among the different processes, a key role has been attributed to the Atlantic Meridional Overturning Circulation (AMOC), both for heat uptake and redistribution among basins, yet a comprehensive view remains elusive. In this study, we investigate how a weakening of the AMOC would influence ocean heat storage in a warming climate by comparing two idealized experiments with two different AMOC evolutions from the global climate model EC-Earth3, after abrupt carbon dioxide quadrupling. We find that AMOC weakening influences both vertical and inter-basin heat redistribution. For a stronger AMOC decline, more heat is stored in the Indo-Pacific Ocean and in the intermediate ocean layers above 700 m, while less heat accumulates in the deeper ocean layers, especially in the Atlantic. Globally, we find a 3% increase in cumulated ocean heat uptake at the end of the simulations.