Heat-Related Deaths Around The World Top Half A Million A Year: Study

Soaring temperatures are killing nearly 550,000 people around the world each year, part of a heat death toll that's climbed more than 20% on a population-adjusted basis since the 1990s, according to the latest edition of the Lancet's annual report on climate and health.

"That's approximately one heat-related death every minute throughout the year," says Ollie Jay, a heat and health expert at the University of Sydney and a co-author of the new report. "So this is a really startling number." 

It's the first year that the medical journal has reported the total number of global heat-related deaths, which it calculated through recent advances in methods to estimate heat-related deaths and better access to detailed death data in different countries. (The Lancet has previously shared percentage increases in such deaths.)

The new numbers come during a year of record-setting temperatures around the world. In Europe, residents and summer tourists were scorched by heatwaves over the summer, while parts of Asia and the US were also gripped by extreme heat.

The report - the Lancet's ninth - reflects work by 128 researchers globally and across 71 organizations. They found that most days of heat wave conditions people around the world experienced over the last five years wouldn't have happened without climate change.

Hotter conditions are taking a toll not just on human health but also the economy. Lost labor productivity related to heat caused an estimated $1 trillion in income losses in 2024, equivalent to nearly 1% of global gross domestic product. Sleep lost at night to high temperatures also increased by a record 9% in 2024, according to the report. 

Jay says scientists fear that parts of the world are nearing so-called physiological tipping points, when it's so hot and humid that people can no longer survive. That concern has been stoked by accelerating climate change, and by new evidence that serious risks may begin at cooler and drier conditions than previously thought, he added. In Latin America, for example, heat-related deaths have more than doubled since 2000, with around 13,000 such deaths occurring a year, according to a Lancet report focused on the region that was also released on Tuesday.

"We're potentially reaching these limits in different parts of the world at an alarming rate or approaching them," Jay says. "It's something that needs urgent action."

Other climate threats

The scientists tracked a variety of indicators to assess the health threats posed by climate change, looking at heat and other extreme weather-related health risks along with a changing climate's influence on infectious disease transmission. 

Most of these health-focused indicators have reached record levels since they began monitoring them. Exposure to miniscule particles released into the air by wildfires, for instance, hit a high in 2024, leading to more than 150,000 deaths globally - more than ever before. 

The mosquito-borne tropical disease dengue, meanwhile, has seen its worldwide average transmission potential surge by nearly half since the 1950s as warmer and wetter conditions enable the insects to spread to and survive in more places. 

There were some more promising findings, including that global exposure to a type of fossil fuel pollution has decreased nearly 20% over the last decade and a half as many developed nations burn less coal. 

Still, overall, the findings present a picture that is "very bleak," said  Marina Romanello, executive director of the Lancet initiative that produced the report.

"We're really, really worried from the scientific perspective because we do have the data and there's no denying how grave the situation is," she added.

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