Severe heat waves caused by climate change have cost the world trillions of dollars since the 1990s, according to a Dartmouth College study published in October in Science Advances. The world’s poorest countries, which are also least responsible for carbon emissions, have suffered the most, the study reported.
Between 1992 and 2013, heat waves statistically coincided with variations in economic growth, and about $16 trillion was lost as a result of high temperatures on human health, productivity, and agricultural output, the report concluded. The study, “Globally Unequal Effect of Extreme Heat on Economic Growth,” was conducted by Assistant Professor of Geography Justin Mankin and 2023 doctoral candidate Christopher Callahan. For each world region and year, economic data was combined with average temperatures for the hottest five-day period, a commonly used measurement of heat intensity.
Countries in the tropics and the global South, which are the world’s poorest and hottest, have been hit the hardest, the study found.
“Accelerating adaptation measures within the hottest period of each year would deliver economic benefits now,” said Callahan. “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 is among the first to show a correlation between heat waves and economic output. “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,” Mankin said.
In previous research, heat waves have been included among other extreme weather events – flooding, for instance – but they are unique, according to Callahan. “Heat waves are one of the most direct and tangible effects of climate change that people feel, yet they have not been fully integrated into our assessments of what climate change has cost and will cost in the future. We live in a world that has already been altered by greenhouse gas emissions. I think our research helps demonstrate that.”