HEAT WAVESClimate Change-Driven Heat Waves Have Cost Global Economy Trillions Since the 1990s

Massive economic losses due to sweltering temperatures brought on by human-caused climate change are not just a problem for the distant future. A Dartmouth study published Oct. 28 in the journal Science Advances has found that more severe heat waves resulting from global warming have already cost the world economy trillions of dollars since the early 1990s—with the world’s poorest and lowest carbon-emitting nations suffering the most.

Geography professor Justin Mankin and doctoral candidate Christopher Callahan, Guarini ’23, combined newly available, in-depth economic data for regions worldwide with the average temperature for the hottest five-day period—a commonly used measurement of heat intensity—for each region in each year. They found that from 1992 to 2013, heat waves statistically coincided with variations in economic growth and that an estimated $16 trillion was lost to the effects of high temperatures on human health, productivity, and agricultural output.

The findings stress the immediate need for policies and technologies that protect people during the hottest days of the year, particularly in the tropics and the Global South where the world’s warmest and most economically vulnerable nations are located, the researchers report.

“Accelerating adaptation measures within the hottest period of each year would deliver economic benefits now,” says Callahan, who is the study’s first author. “The amount of money spent on adaptation measures should not be assessed just on the price tag of those measures, but relative to the cost of doing nothing. Our research identifies a substantial price tag to not doing anything.”

The study, “Globally Unequal Effect of Extreme Heat on Economic Growth,” is the among the first to specifically examine how heat waves affect economic output, says Mankin, the study’s senior author and an assistant professor of geography. “No one has shown an independent fingerprint for extreme heat and the intensity of that heat’s impact on economic growth. The true costs of climate change are far higher than we’ve calculated so far.”

“Our work shows that no place is well adapted to our current climate,” Mankin says. “The regions with the lowest incomes globally are the ones that suffer most from these extreme heat events. As climate change increases the magnitude of extreme heat, it’s a fair expectation that those costs will continue to accumulate.”