Future hotspots of compound dry and hot summers emerge in European
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.