Scale-dependent response of the urban heat island to the European heatwave of 2018

Extreme heat continues to be a pressing challenge of the changing climate. The impacts extreme manifest on two different spatio-temporal scales: (1) episodic continent-wide heatwaves (HWs) and (2) city-scale urban island (UHI). As HWs are becoming more frequent, longer, severe, they pose serious implications increased public health risks at city scale, have adverse agricultural terrestrial/aquatic ecosystems regional scale. Here we offer fresh perspective HW as forcing that invokes dynamic, heterogeneous, scale-dependent responses evident in inter intra-urban islets. A numerical simulation 2018 European including surface air temperature-based UHIs six agglomerations, with high-resolution focus Paris, serves our case study. We find mean nighttime UHI intensities reduced for inland cities but coastal cities. Our examination islets reveals major findings: (i) homogenizes temperatures during daytime (reduces variance), (ii) most significant scale large, spatially discontiguous nighttime. These results underscore need move beyond prevalent HW-mean intensity characterization toward islet analyses aid targeted mitigation.