Extreme heat in Western Europe has been increasing at a rate faster than predicted by climate models. This study shows that atmospheric circulation changes, specifically more frequent southerly flows, contribute significantly (0.8 °C out of 3.4 °C per global warming degree) to this trend. None of the 170 climate model simulations analyzed successfully captured the observed trend, suggesting either an underestimation of circulation response to external forcing, an underestimation of low-frequency variability, or both. This highlights the need for caution when using climate model projections for heatwave adaptation.

Robert Vautard, Julien Cattiaux, Tamara Happé, Jitendra Singh, Rémy Bonnet, Christophe Cassou, Dim Coumou, Fabio D'Andrea, Davide Faranda, Erich Fischer, Aurelien Ribes, Sebastian Sippel, Pascal Yiou