Influence of Atlantic and Pacific Sea Surface Temperatures on Heat-Related Mortality in the United States

The frequency and magnitude of extreme summer temperature events in the United States have increased in the past few decades. Long-term exposure to extreme summer temperatures can be detrimental to human health, due to potential risks of dehydration and thermoregulation strains on the cardiovascular system, which may often lead to heat-related mortality (HRM). The summer climate of the United States is influenced by variability in Atlantic and Pacific sea surface temperatures, driven in part by Atlantic Multidecadal Oscillation (AMO) and El-Nino Southern Oscillation (ENSO), respectively. However, the influence of AMO and ENSO on HRM in the United States has not been investigated. Here the longest time series of HRM spanning the past five decades is analyzed in relation with AMO and ENSO. We find that HRM doubled in the early-1990s, coinciding with the positive phase of the AMO. Furthermore, we note a positive association between the variability in HRM and summer temperatures across all regions of the United States, with the strongest association found over the Southern United States. Therefore, this research suggests that variability in Atlantic and Pacific sea surface temperatures has both a nationwide and regional impact on HRM in the United States. Hence, by understanding variability in sea surface temperatures, the future burden of heat-attributed emergencies during extreme summer temperature events can be reduced not only for the United States, but also worldwide. Plain Language Summary Changes in Atlantic and Pacific sea surface temperatures are known to have an influence on recent rising regional and large-scale summer temperatures in the United States. Extreme summer temperatures are detrimental to human health, some of which can result in heat- related mortality. We show the relationship of Atlantic and Pacific sea surface temperature variability on U.S. heat-related mortality. We find that on decadal scales, the number of heat-related mortality coincide with changes in Atlantic and Pacific sea surface temperatures. Future work is needed to understand the implications of multidecadal and interannual variability in sea surface temperatures on heat-related mortality worldwide.