Quantifying heat exposure reduction from adaptation and mitigation in 21st century US cities

The continued increase in the duration, frequency, and intensity of heat waves is especially problematic in cities, where more than half of the world’s population lives. We combine decadal scale regional climate modeling simulations with projections of urban expansion, emissions of greenhouse gases and population migration to examine the extent to which adaptation and mitigation strategies, in isolation and in tandem, can reduce population heat exposure across end-of-century US cities. We show that some cities respond more favorably to adaptation while others respond more favorably to mitigation. Our results indicate that the reduction in the number of extreme heat hours due to adaptation and mitigation varies during the daytime portion of the diurnal cycle but is largely independent of the hour of the day during nighttime. We emphasize the importance of adaptation and mitigation strategies through examination of their synergistic interaction to inform development of climate resilient urban development pathways.