Anthropogenic heat release due to energy consumption exacerbates European summer extreme high temperature

Anthropogenic heat release (AHR) is the release of heat generated by anthropogenic energy consumption. The global mean flux of AHR is 0.03 W m(-2), while AHR is geographically concentrated and fundamentally correlates with economic activity; furthermore, AHR can reach a level sufficient for impacting regional even large-scale climate. In this study, the impacts of AHR on the summer European heatwaves (EHWs) are examined by using the Community Earth System Model version 1 (CESM1). The results show that in Europe, AHR increases the summer mean 2-m temperature by 0.26 degrees C and the surface minimum and maximum temperatures by 0.14 degrees C and 0.41 degrees C, respectively. AHR exacerbates the extreme high temperatures in the summer in Europe, increasing EHW days by 1-2 days in central and eastern Europe in the summer annually from 1992 to 2013. AHR strengthens the surface wind that flows from the ocean to the land in Europe by increasing the land surface temperatures. AHR decreases the lower-troposphere stability (LTS) and reduces the low-cloud amounts in Europe, which leads to more solar shortwave radiation reaching the surface. AHR affects water vapor and the surface energy balance in Europe, which impacts on European summer heatwaves further. AHR acts as a non-negligible factor for summer extreme high temperature in Europe and a potential factor impacting EHW days.