It’s Getting Hotter: A Cross-City Comparison of Heat and Heat-Related Climate Indicators in the US

Abstract Background During the past few summers, record-breaking temperatures have created heat health emergencies. As heat waves become more frequent, the summer hot season is also getting longer and climate fueled disasters more frequent, largely impacting those most vulnerable. Methods Using new data from the Big Cities Health Coalition (BCHC) data inventory (BCHI), an equity focused cross-city data platform, we describe and compare climate data and impacts on health. BCHC is the forum for the leaders of the US’ largest metropolitan health departments, serving 1 in 5 americans. Results Across 35 big cities in the U.S., heat waves, defined as unusually hot weather for at least two consecutive nights, have increased 3-fold compared to decades ago. As heat waves become more frequent, the summer hot season is also getting longer; the season average is currently 30 days longer than it was decades ago. Heat waves are just one among many threats to health from climate change. These conditions are already having profound wide-ranging impacts on our ecosystem and health, worsening air quality and fueling disasters. Climate-related disasters are federally declared and include severe storms, hurricanes, floods and wildfire. Platform data reveal that climate-related disasters are occurring every two years in BCHC cities and last for approximately 30 days. Conclusions All cities have been impacted by the climate crisis albeit more intensely in cities that are already the hottest in the U.S. and more vulnerable to climate disasters. These cities have already experienced a disproportionate number of heat waves, climate-related disasters, and worse air quality. Climate-related disasters can become humanitarian emergencies, destroying essential city infrastructure needed to maintain safe drinking water, sanitation and safety; they also can have long-term negative effects on health and wellbeing. Key messages • Cross-city data comparisons are a critical tool in assessing climate change in the US. • Heat waves are having increased impact on health in US urban environments.