Amplified Midlatitude European Heatwave Trends Linked to Anthropogenic Forced Atlantic Multidecadal Variability-like Warming and Decreased Aerosol Emissions

Midlatitude Europe stands out as a prominent heatwave hotspot, characterized by accelerated upward trends in both summer surface air temperature and heatwave days. Remarkably, these trends surpass the global land average by approximately 2.6 and 2.3 times since 1979. Through dynamic adjustments applied to reanalysis datasets, we found that one-third of these trends resulted from externally forced circulation changes, characterized by a zonal dipolar circulation exhibiting an anticyclonic pattern over Europe. These observed circulation changes are primarily induced by a Rossby wave response triggered by the warming of sea surface temperatures in the North Atlantic, resembling the Atlantic Multidecadal Variability pattern. The ensemble simulations from the sixth phase of the Coupled Model Intercomparison Project indicate that these sea surface temperatures are dominated by the greenhouse gases, with additional contributions from a reduction in aerosols. Additionally, the stronger air temperature response in midlatitude Europe to the reduced aerosols further amplify summer warming, contributing to the rapid increased frequency of heatwave days. These findings offer evidence of important anthropogenic forcing impacts on the rapid surge of heatwaves in Europe, with important implications for potential adaptation strategies and risk management.