According to the latest edition of The Lancet’s annual report on climate and health, rising temperatures are killing about 550,000 people worldwide each year, part of the heat death toll, on a population-adjusted basis since the 1990s.
“That’s one heat-related death every minute of the year,” says Ollie Jay, a heat and health expert at the University of Sydney and co-author of the new report. “So that’s a really shocking number.”
This is the first year that the medical journal has reported the total number of global heat-related deaths, which it estimates is due to recent advances in estimating heat-related deaths and better access to detailed death data in different countries. (Such deaths have previously been compiled by the Lancet by percentages.)
The new numbers come during a year of record-setting temperatures around the world. In Europe, residents and summer tourists were scorched by heat waves during the summer, while parts of Asia and the Americas were also gripped by extreme heat.
Read more: At least 16,500 heat deaths in Europe this summer due to climate change
The report – Lancet’s ninth – reflects the work of 128 researchers globally and in 71 organisations. They found that people around the world did not experience more heat wave conditions in the past five years without climate change.
Hotter conditions are taking a toll not only on UNHOMN health but also on the economy. Heat-related labor productivity is expected to account for an estimated $1 trillion in 2024, equivalent to about 1% of global gross domestic product. According to the report, nighttime sleep was lost to higher temperatures in 2024.
Jay says scientists worry 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. He added that this concern has been underscored by accelerating climate change, and by new evidence that colder and drier conditions may trigger serious threats than previously thought. In Latin America, for example, heat-related deaths have doubled since 2000, according to a Lancet report focusing on the region, also released Tuesday.
“We’re potentially reaching or dangerously close to these limits in different parts of the world,” Jay says. “This is something that requires immediate action.”
Other climate risks
Scientists tracked a number of indicators to assess health risks from climate change, looking at other extreme health risks related to heat and weather, as well as the impact of a changing climate on the transmission of infectious diseases.
Most of these health-based indicators have reached record levels since they began monitoring them. Exposure to microscopic particles released into the air by forest fires, for example, reached a peak in 2024, causing more than a half million deaths globally – more than ever before.
The mosquito-borne tropical disease dengue, meanwhile, has seen its average worldwide transmission potential increase by about half since the 1950s as warmer and wetter conditions enable the insects to spread and survive in more places.
There were some more promising findings, including that global exposure to one type of fossil fuel pollutant has fallen by about 20 percent over the past decade and a half as many developed countries burn less coal.
Still, overall, the findings paint a picture that is “very bleak,” said Marina Romanello, executive director of the Lancet Initiative, which produced the report.
“We’re really, really worried from a scientific point of view because we have the data and there’s no denying how serious the situation is,” he added.
Photo: A member of the emergency military unit works to extinguish a forest fire next to a village in Pepin, province of Orense, Spain, on August 19, 2025. Photo credit: Pablo Blazquez Domingos/Getty Images
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