PNNL

Abstract

Urbanization increases air temperature and reduces relative humidity. The combined impact of these changes on large-scale heat stress disparities remains unknown due to observational and modeling bottlenecks. Using high-resolution urban-resolving numerical model simulations, we show pervasive disparities in all-sky average maximum summertime air temperature and operational metrics of heat stress across US cities, with higher potential heat stress exposure in poorer and primarily non-white census tracts. 94% of the US urban population (225 million) live in cities where heat stress burdens the poor and heat stress inequities between white and non-white populations is strongly associated with residential segregation. Similarly, historically redlined neighborhoods show systematically higher heat stress than their non-redlined counterparts, demonstrating how historical segregation impacts present-day environmental inequalities. Our results provide quantitative estimates of physiologically relevant heat stress disparities at the US national scale, but also stress the importance of choosing appropriate variables to accurately monitor them.