Extreme Heat Related Mortality: Spatial Patterns and Determinants in the United States, 1979–2011

Extreme heat has been responsible for more deaths in the United States than any other weather-related phenomenon over the past decade. The frequency and intensity of extreme heat events are projected to increase over the course of this century. In this work, we examine historical patterns of extreme heat exposure and mortality in the continental United States. We examine spatial variation in the mortality response to exposure, consider the contribution of key demographic and socio-economic factors in driving heat-related mortality, and test three different extreme heat thresholds using a national-level spatial autoregressive model and a geographically weighted regression approach. We find that the mortality response to exposure is higher in areas that do not routinely experience heat extremes, and that exposure itself is a stronger driver of heat-related mortality across the larger urban areas of the Midwest and Northeast. The importance of demographic/socio-economic factors varies substantially over space, and results are robust across alternative measures of heat extremes, suggesting that no single definition is necessarily superior. The baseline relationships established here are potentially useful for future predictions of exposure and heat-related mortality under alternative population and climate change scenarios, and may aid policy makers and planners in implementing effective adaptation and mitigation strategies.