Dimensions of Accumulated Climate Events and All-Cause Preventable Mortality Across County Disadvantage

Although attention to the health implications of climate change is growing, little work explores either local risks or the health effects of long-term exposure to multiple, overlapping events. Understanding the health impacts of cumulative exposure to climate extremes at the subnational level is crucial to effective climate adaptation and public health interventions. This study examined county-level exposure patterns to extreme climate events, using an innovative cumulative index of extreme heat, drought, and storms and the association with county-level all-cause, age-adjusted premature mortality in the United States. Results demonstrate that counties with higher non-Hispanic Black populations, lower educational attainment, and higher poverty levels were associated with multiple, overlapping climate extremes. Our findings also indicate that exposure to climate extremes significantly increased the risk of premature mortality, even when controlling for socioeconomic vulnerability. Counties exposed to above-average levels of extreme heat, drought, and storms had 25 additional premature deaths per 100,000 residents compared with those experiencing none. These results demonstrate that although counties with vulnerable populations are more likely to be exposed to multiple climate change events, repeated and overlapping climate events serve as an additional potential form of cumulative disadvantage, contributing to preventable mortality beyond other known social and economic determinants. This research underscores the urgent need for locally targeted public health interventions and climate adaptation strategies, particularly in socially and environmentally vulnerable communities. Our index offers one such tool for decision-makers to identify at-risk counties and tailor responses to mitigate their health challenges.