WASHINGTON — A dramatic increase in heat-related deaths will sweep major U.S. cities in coming summers, according to an analysis released Wednesday by the Natural Resources Defense Council, an environmental advocacy group based in New York.
“This is a wake-up call,” said Daniel Lashof, director of NRDC’s climate and clean air program. “Climate change has real life-and-death consequences.”
Rising temperatures across the U.S. will result in more than 150,000 deaths by the end of the century, according to the NRDC, which based its report on a recent study published in the journal of the American Meteorological Society.
The study examines the historical relationship between heat and mortality and relies on National Center for Atmospheric Research climate models to project future scenarios.
Louisville, Ky., will be hardest hit, according to the study, with an anticipated increase of 18,988 heat-related deaths by the end of the century, followed by Detroit and Cleveland. Boston rounds off the top 10 most affected cities with a projected increase of 5,715 deaths by the end of the century.
Cities in cooler climates are at higher risk of heat-related deaths because of unexpected fluctuations in summer temperatures, according to the report. In hotter climates, where the temperature is more constantly elevated, cities and their residents are better able to adapt, according to Larry Kalkstein, a co-author of the study and a geography professor at the University of Miami.
For Vermonters, the threat from heat is present but muted, according to Dr. Stephen Leffler, emergency physician and chief medical officer at Fletcher Allen Health Care.
Vermont’s prevalence of green space and lack of large urban areas helps deter prolonged stretches of uninterrupted heat—one of the biggest causes of heat-related illnesses and death.
“We’re lucky here that most of the time it cools back down in the evenings,” Leffler said. “We don’t have the huge heat sink problems like the big cities where the asphalt gets really hot and it stays over 100 degrees all day and all night.”
The NRDC study assumes a steady increase in temperatures over the century, does not factor in population growth and does not take into account an increase in adaptive measures that cities may take in the face of rising temperatures.
The projections are a significant jump from National Weather Service data that shows that in 2011, 206 people died in the U.S. from extreme heat, up from 138 in 2010. The 10-year average for heat-related deaths is 119, according to the National Weather Service.
But the standard methodology for recording heat-related fatalities, Kalkstein said, underestimates the actual death toll of extreme heat.
Medical examiners consider only a few factors, particularly body temperature, in determining heat as cause of death, he said. They typically do not include heart attacks and respiratory failure that may have resulted from extreme temperatures, he said.
“In our evaluations, we clearly see the spikes in heart attacks and some other causes of death during an excessive heat event,” according to Kalkstein. “So we would define the deaths in that spike as heat-related.”
Lashof and Kalkstein urged city officials to take action in the face of extreme weather events. Enacting policies that reduce the emission of heat-trapping gasses and developing programs that help the public during heat waves can go a long way towards minimizing fatalities they said.