Europe's Summer Heat Killed More Than 50,000 People, and Climate Change Caused Two-Thirds
A study in Nature Health puts the toll across 854 cities at 50,391, a 71% jump over the previous deadliest summer, in 2022.
Blistering record heat in Europe this summer helped kill more than 50,000 people, with nearly two-thirds of the toll blamed on human-caused climate change, a new study found.
Researchers modeled heat-related deaths by age group in 854 European cities during repeated heat waves in June, July and August. They found that 50,391 people died from warmer temperatures, and that 32,619 of them died because of the extra heat caused by burning coal, oil and gas. The work is due in an upcoming issue of Nature Health. The total is 71% higher than the previous deadliest summer, 2022, when the same researchers counted 29,480 deaths. They produced a separate study earlier this month tracking yearly summer heat deaths in those cities.
The figures are likely underestimates. They leave out a deadly heat wave in May, and they cover only the 854 cities, which hold about 40% of Europe's population. About a third of the deaths came between June 17 and July 1, when temperatures ran 9.5 degrees Fahrenheit (5.3 Celsius) above normal, said co-author Garyfallos Konstantinoudis, a biostatistician at Imperial College London. Italy, France, Spain and Germany had the highest death tolls. Of all European capitals, Rome has had the highest heat death total from 2000 to 2025, according to the earlier study.
Lead author Clair Barnes, a climate scientist at Imperial College London, said parts of Europe are simply not built for this. "Much of Western and Northern Europe, our infrastructure is just not designed to cope with the sort of temperatures that we are seeing now because of the effects of human-caused warming," she said. Some cities this summer ran 21.6 F (12 C) warmer than normal. Europe is the fastest-warming continent, she said, and is 4.5 F (2.5 C) hotter than before the industrial era. "For many people, it's certainly the case that that extra two-and-a-half degrees of warming is what's going to tip those temperatures from uncomfortable to dangerous and potentially deadly," Barnes said.
The victims skew old, but not entirely. More than half of those who died were 85 or older, yet the heat also killed more than 800 people between ages 20 and 44, Konstantinoudis said.
To split natural heat from climate-driven heat, the team ran computer simulations of a world without climate change and compared them with the deaths that occurred. The difference is the share attributed to global warming. That share has grown from about 45% in the early 2000s to 65% now, Barnes said. The researchers also had to estimate the base count statistically, because heat deaths are underreported and often don't appear on death certificates. Several outside experts called the methods state of the art. The calculation uses an equation applied in earlier peer-reviewed studies, based on the age and temperature profile of each city and a local optimal temperature at which the fewest people die.
Howard Frumkin, a former director of the National Center for Environmental Health in the U.S. who was not part of the study, said two trends are converging. "Summers are getting hotter, and the analytical tools for attributing deaths to heat are getting more accurate," he said. "Together, these two trends yield increasingly high and increasingly accurate counts of heat-related deaths."
Jonathan Patz of the University of Wisconsin-Madison, who also was not involved, said adapting is only part of the answer. "We can't just be mopping up the mess on the floor without thinking about turning the faucet off," he said. Cooling and protection for vulnerable people are needed, he said, but so is cutting fossil fuel burning at the root.
