How much AMOC weakening would cool Europe in a warming climate?

Abstract
The Atlantic Meridional Overturning Circulation (AMOC), which regulates Earth’s heat transport, is projected to weaken, with European cooling being the most widely discussed impact. It is therefore striking that so little is known about the net temperature effect of AMOC-induced cooling and global warming across Europe. A set of 72 new Earth system model simulations with freshwater hosing alongside anthropogenic forcings reveals a remarkably linear and scenario-independent effect of additional AMOC weakening on European temperatures. Here, we show that this finding can be used to move beyond uncertainties in AMOC projections by inferring the end-of-century magnitude of AMOC weakening that would cool a given European region under different levels of global warming. This analysis reveals that sizeable parts of Europe could cool below preindustrial temperatures in low-emissions scenarios with substantial AMOC weakening. Under high emissions, however, most regions would not experience net cooling, or would do so only at very high magnitudes of AMOC weakening. A multi-model extension indicates that the magnitudes of AMOC weakening leading to regional net cooling are less uncertain than suggested by existing model evidence, paving the way for a more targeted discussion of the concrete impacts of a given scenario of AMOC weakening.

Recommended citation: Alastrué de Asenjo, E.*, Schaumann, F.* (under review). "How much AMOC weakening would cool Europe in a warming climate?" (*equal contribution)