As Thanksgiving approaches and leaves and temperatures start to fall across the country, heat waves are probably the last thing on anyone’s mind. But ever since the Fifth Assessment Report by the UN’s Intergovernmental Panel on Climate Change was released in September, a group of researchers from the Rollins School of Public Health at Emory University in Atlanta have been using these latest projections to understand the rising human toll of a warmer future.
Their findings are sobering. Heat waves will kill about ten times more people in the Eastern United States in 45 years than they did at the turn of this century. In 2002–2004, an average of 187 people in the eastern third of the U.S. succumbed to heat waves. By 2057–2059, that number will rise to over 2,000. The study results were published online this week in the journal Environmental Health Perspectives.
According to the U.S. Centers for Disease Control, 660 people die nationwide from heat waves each year, making it the leading cause of weather-related mortality in the country. The CDC defines heat waves as “several days of temperatures greater than 90° F; warm, stagnant air masses; and consecutive nights with higher-than-usual minimum temperatures.” The severe heat wave of July 1995 in Chicago was blamed for 700 deaths and perhaps as many as 333 people died in California in July 2006 as the state was gripped in unrelenting heat.
The researchers used two climate change projections for the Eastern United States, both taken from the IPCC’s Fifth Assessment Report, which projects that air temperatures will rise by 3.2 to 11.52 degrees by the end of the century.
The “low-medium” greenhouse gas emissions scenario assumes significant reductions in carbon pollution, while the “more extreme” scenario assumes a rate of greenhouse gas emissions similar to the current rate.
Under the “low-medium” scenario, heat wave-related deaths would increase by 1,403 per year. If current emissions continue, however, there could be an additional 3,556 deaths. The number of deaths is linked to the frequency of heat waves. Of the 1,700 counties included in the study, about ten percent will experience four or more heat waves per year under the low emissions projections. If 2057 looks more like the higher emissions estimate, nearly 27 percent of the counties will have to deal with at least four heat waves each year.
Florida, Louisiana, Georgia, Massachusetts, New York and New Jersey were identified by the researchers as the states that will witness the biggest spikes in heat-related mortality.
Outdoor workers, the elderly, children, and those without access to shelter are most vulnerable to heat exhaustion, heat syncope, heat stroke and heat cramps.