Sensitivity and vulnerability to summer heat extremes in major cities of the United States

Abstract Many cities are experiencing more frequent extreme heat events during summer because of the global temperature rise and the urban heat island effects. Yet, how the rising temperature impacts urban residents differently is still not clear. Here we leveraged urban microclimate modeling to map the Universal Thermal Climate Index (UTCI), a more complete indicator of human heat stress at an unprecedentedly fine spatial resolution (1 m) for 14 major cities in the United States. We also examined the sensitivity and vulnerability to summer heat across different socioeconomic and racial/ethnic groups in these cities, finding that income level is most consistently associated with heat stress. Results show that a hypothetical 1 ºC increase in air temperature would have a substantial impact on human heat stress, with impacts that differ across cities. The results of this study can help us better evaluate the impact of extreme heat on urban residents.