The changing dynamics of population exposure to extreme heat in the contiguous United States from 2001 to 2020

The increasing population exposure to heat extremes in recent decades represents a formidable challenge to urban sustainability. Yet, less is known about the spatial and temporal dynamics of extreme heat events accompanied by the changing climate and the associated human exposure. In this study, we create a series of cartograms to reveal the spatial and temporal changes of population exposure to extreme heat in the contiguous United States from 2001 to 2020. Findings demonstrate a notable spatial shift in exposure from northern to southern regions over the two-decade period, with the worrying trend of prolonged extreme heat in some counties with large populations. While the majority of the population experienced fewer than 18 days of extreme heat annually, the spatial shift was accompanied by increasing population exposure to prolonged extreme heat. Results underscore the urgent need for spatially targeted climate adaptation policies to effectively mitigate the adverse impacts of heat extremes.