Dartmouth researchers have released a study showing climate change-fueled extreme heat has cost the world economy trillions of dollars since the early 1990s.
As global leaders gather for a major climate summit in Egypt, Dartmouth PhD candidate Chris Callahan, who led the research, says the study shows climate change impacts aren’t just a future projection.
“I think there is in some cases still a perception that it is this far off threat,” he said. “Our work and other recent work has illustrated the degree to which we are already living in a world that has been irrevocably changed by our emissions and that is already having cascading effects around the globe.”
The study also focuses on the ways that heat across the world exacerbates existing inequalities. Poorer nations, which are disproportionately warmer and have generally contributed less to global warming than wealthier nations, are hurt much more by increases in extreme heat.
“Increases in extreme heat due to warming are disproportionately due to the emissions of higher income places that have also not been as substantially harmed by heat waves,” he said. “We think that sort of illustrates this global pattern of inequality in climate impacts.”
Callahan says the research demonstrates the need for funding to compensate poorer nations for the past harms they’ve experienced due to climate change – a crucial aspect of the discussions at the climate summit, COP27, which began Sunday.
The study found that economic losses from extreme heat between 1992 and 2013 likely total between $5 trillion and $29.3 trillion globally.
Heat waves can reduce crop yields, limit productivity, and make people sick. But Callahan says they also have a host of more subtle effects that can still cost a lot of money.
“People fall off ladders more frequently and otherwise injure themselves at work more frequently when it's hot,” he said. “People honk their horns at each other more when it's hot. Major League Baseball umpires get calls wrong more when it's hot.”
Over the summer, Callahan published another paper that quantifies how individual countries have affected other countries’ economies through their greenhouse gas emissions. His team found that the United States alone is responsible for $1.9 trillion in economic losses in tropical countries.
The researchers say adaptations to heat will be necessary, and their study shows that targeting adaptation resources at the few hottest days of the year could provide disproportionate benefits.
Sharing the burden of those adaptations among wealthy countries could help the world economy as a whole, said Justin Mankin, another researcher on the study.
