Uneven evolution of regional European summer heatwaves under climate change

Heatwaves (HWs) are extreme events magnified under climate change with critical implications for the human and environmental systems they impact. These phenomena are generally investigated as a large-scale effect over extensive regions. However, their regional -to -local characteristics and trends are responsible for the specific effects on local communities. This study presents a comprehensive analysis of the characteristics and evolution of regional HWs covering the 1950 to 2021 period across different European climates, central Europe (CE), France (FR), and the Iberian Peninsula (IP), including an analysis of the local and remote relationship between summer heat periods and winter -spring precipitation conditions. Our results confirm the general increase in frequency, intensity, duration, and spatial extent of the HW phenomena over the three domains but point out their uneven evolution under climate change. While a larger frequency increase in the number of heat periods affects IP and FR, it is over CE, where the largest frequency change is observed in the most recent decades. Over north-western FR and CE the most intense HW events have recently registered, further over CE HWs' long-lasting durations between five to six days have tripled from the sixties to recent decades. It is indeed over the latter that a substantial increase in human exposure to HW phenomena is observed. Probably, the unalike progressions are related to the proven differential rate of warming between the mean and hottest days at northern and southern European domains and the influence of soil conditions over IP on the development of summer heat periods over FR and CE.