Dynamical evolution of extremely hot summers in Western Europe in response to climate change

The study of the statistical and dynamical characteristics of extreme and very extreme events in the climate system is impaired by a strong under-sampling issue. Here we use a rare events algorithm to massively increase the number of extremely hot summers simulated in the state-of-the-art IPSL-CM6A-LR climate model under present and future anthropogenic forcings. This allows us to reach precise climatological results on the dynamics leading to centennial hot summers. We demonstrate that the dynamics leading to these hot summers tend to be more local and less large scale-organized with climate change. In the future, high temperatures are still reached via a large anticyclone, but anomalies do not extend as far longitudinally as in the present and arise mainly as a result of an increase in the intensity of surface heat fluxes.