Europe's Summer Heat Killed More Than 50,000 People, and Climate Change Is Blamed for Two-Thirds of the Deaths

Blistering record heat across Europe this summer killed more than 50,000 people, and a new study has found that nearly two-thirds of that death toll was caused by human-caused climate change. Researchers modelled heat-related deaths for different age groups in 854 European cities during the repeated heat waves of June, July and August.

According to the study, 50,391 people died because of the warmer temperatures, and of those, 32,619 died because of the extra heat caused by the burning of coal, oil and gas. The study is set to appear in an upcoming issue of the journal Nature Health.

That figure is 71 percent higher than the previous deadliest summer on the researchers' record, 2022, when heat-related deaths in the same cities totalled 29,480. The authors also caution that this summer's figures are underestimates, because they do not count a deadly heat wave in May and cover only those 854 cities, which represent about 40 percent of Europe's population.

About one-third of the deaths occurred between June 17 and July 1, a particularly intense heat wave when temperatures were 9.5 degrees Fahrenheit (5.3 degrees Celsius) above normal, said study co-author Garyfallos Konstantinoudis, a biostatistician at Imperial College London.

Lead author Clair Barnes, a climate scientist at Imperial College London, said some European cities this summer saw temperatures as much as 21.6 degrees Fahrenheit (12 degrees Celsius) warmer than normal. '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.

By country, Italy, France, Spain and Germany had the highest death tolls. And according to the same team's study earlier this month tracking yearly summer heat deaths, Rome had the highest heat death total of any European capital between 2000 and 2025.

Barnes said Europe is the fastest-warming continent — although the Arctic, which is not a continent, is warming even faster — and is now 4.5 degrees Fahrenheit (2.5 degrees Celsius) hotter than in pre-industrial times. The underlying warming from burning fossil fuels raises everyone's temperatures, she said, and for many people that extra two and a half degrees is what tips temperatures from uncomfortable to dangerous and potentially deadly.

More than half of those who died were aged 85 or older, but the stifling temperatures also killed more than 800 people between the ages of 20 and 44, Konstantinoudis said.

The researchers explained how the numbers were produced. Heat deaths are underreported and often not listed on death certificates, so the team used an established scientific method: computer simulations of a world without climate change were compared with the deaths that actually happened this summer, and the difference is what global warming caused. A mathematical equation factoring in age and temperature for each city was also checked against real-time estimates from government agencies; for the May and June British heat waves, the team's calculation of 2,700 excess deaths closely matched the UK health statistics agency's figure of 2,800.

Outside experts who were not part of the study praised the methods as state-of-the-art. Dr. Howard Frumkin, former director of the US National Center for Environmental Health, said that as summers get hotter and the analytical tools for attributing deaths to heat get more accurate, the counts of heat-related deaths become both higher and more accurate. The study found the share of heat deaths attributable to global warming has grown from about 45 percent in the early 2000s to 65 percent now.

The experts' warning is clear: societies must prepare for the heat that can no longer be avoided, with urgent investment in heat early-warning systems, equitable access to low-carbon cooling and neighbourhood buddy systems that check on those most at risk — while rapidly reducing the fossil fuel use driving the crisis. As Dr. Jonathan Patz of the University of Wisconsin-Madison put it, adaptation alone is not enough: 'We can't just be mopping up the mess on the floor without thinking about turning the faucet off.'