Summer heat waves killed 50,000 Europeans, study finds

Extreme heat across Europe this summer killed more than 50,000 people, a new study reveals. The research indicates that nearly two-thirds of those deaths resulted directly from human-caused climate change. This total represents the deadliest summer on record for the continent.

The study analyzed heat-related mortality in 854 European cities during June, July, and August. Researchers estimated that 50,391 people died due to warmer temperatures. Of that total, 32,619 deaths were linked to the additional heat generated by burning coal, oil, and gas. The findings are scheduled for publication in an upcoming issue of the journal Nature Health.

The death toll for this summer is 71 percent higher than the previous record set in 2022. In 2022, the same research team counted 29,480 heat-related deaths. The authors note that the current figures are likely an underestimate because they exclude a deadly heat wave in May. The analysis also covers only 854 cities, which house approximately 40 percent of Europe's population. Italy, France, Spain, and Germany recorded the highest number of deaths.

A specific period between June 17 and July 1 accounted for about one-third of the total deaths. During those weeks, temperatures ran 5.3 C above normal levels, according to Garyfallos Konstantinoudis, a co-author and biostatistician at Imperial College London. While more than half of the victims were aged 85 or older, the heat also killed more than 800 people between the ages of 20 and 44.

Clair Barnes, the lead author and a climate scientist at Imperial College London, stated that some cities experienced temperatures 12 C above normal. She explained that infrastructure in much of Western and Northern Europe is not designed to handle the temperatures seen today due to human-caused warming. Europe is now the fastest-warming continent, sitting 2.5 C hotter than in pre-industrial times. Barnes said this extra warming can shift temperatures from uncomfortable to dangerous and potentially deadly.

The team separated natural heat from climate-driven heat by running computer simulations of a world without climate change. They compared these simulations with the actual deaths recorded this summer. The gap between the two scenarios represents the effect of global warming. Barnes noted that the share of heat deaths attributable to warming has risen from about 45 percent in the early 2000s to 65 percent now.

Heat deaths are often underreported and rarely appear on death certificates, so the researchers used statistical modeling to account for age and each city's optimal temperature. This optimal temperature is the point at which the fewest deaths occur. The team checked their results against government estimates, which mostly matched. For the heat waves in Britain in May and June, the model produced 2,700 excess deaths, while the UK's health statistics agency reported 2,800.

Several outside experts described the methods as state-of-the-art. Dr. Howard Frumkin, former director of the National Center for Environmental Health in the U.S., observed that summers are getting hotter while attribution tools become more accurate. He said these trends together produce higher and more reliable counts. Experts emphasized that adaptation efforts must go hand in hand with cutting emissions.

Dr. Courtney Howard, president-elect of the Canadian Medical Association, called for investment in early-warning systems and equitable access to low-carbon cooling. She also suggested neighborhood buddy systems for people most at risk. Dr. Jonathan Patz of the University of Wisconsin-Madison stressed the need to address fossil fuel burning. He said society cannot keep mopping up the mess on the floor without thinking about turning the faucet off.