Andrea Boehnisch

and 4 more

Compound dry and hot extremes (CDHE, such as recent summers 2015, 2018 and 2022 in Europe) have wide ranging impacts: Heat exacerbates moisture shortages during dry periods whereas water demand rises. Climate change will likely increase the intensity, frequency, and duration of CDHE events in Europe. However, current studies focus on drivers and impacts in coarse-resolution global climate models and likely miss spatial details of CDHE characteristics. To overcome this issue, we exploit a regional 50-member single-model initial condition large ensemble (SMILE) at 12 km spatial resolution. Hence 1000 model years per 20 year-periods provide an extensive database of CDHE and robust estimations of their occurrence changes across Europe in high geographical detail. CDHE occurrences are investigated in a current climate and at two global warming levels (+2 °C, +3 °C). We identify Northern France, Southern Germany, Switzerland, Southern Ireland, and the western coasts of the Black Sea with currently low CDHE frequencies as emerging hotspots. These regions experience a tenfold occurrence increase under global warming conditions. Apart from Western Europe, temperature is the dominant contributor to frequency increases. Furthermore, tail dependencies strengthen in regions with high CDHE frequency increases. In European agricultural areas, soil moisture shows very strong negative correlations with CDHE extremeness. Last, our results suggest a halving of CDHE in a +2 °C world compared to a +3 °C world, highlighting the necessity of climate mitigation with respect to this hazard type.