Kaihui Song, Angel Hsu, Wei Peng, Ying Yu, Noah Kittner

Global warming increases health risks from heat exposure. Historical evidence suggests disproportionate impacts of heat exposure in different regions across socioeconomic groups in the US. However, little is known about the scale of potential disparities and which populations stand to be most vulnerable under different future climate scenarios. Here, we assess county-level heat exposure, measured by Heat Index (HI) from now to 2100, in the contiguous US using an ensemble of Integrated Assessment Models results that present five future warming and socioeconomic development pathways. Our results reveal stark spatial and sociodemographic disparities in present and future heat stress, mainly for people of color and those aged 65 and older. The large proportion of high-risk populations residing in the Southern US makes this region particularly vulnerable to increases in HI, future climate warming will further enlarge disparities between presently-disadvantaged sociodemographic groups. Our findings underscore the need for considering sociodemographic factors when developing climate adaptation plans and prioritizing policy responses for vulnerable communities.