Extreme heat killed more than 50,000 people in European cities and towns this summer, according to peer-reviewed estimates released by scientists in London on Friday (the 23rd).

This is three times as many people as would have died if humanity had not heated the planet by burning oil, gas and coal, the researchers said. Their estimates suggest that the intense heat this summer was, by far, the deadliest in Europe this century.

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The findings, detailed in two studies in the journal Nature Health, are based on a combination of factors that influence heat-related health risks in specific locations, including demographics, socioeconomic indicators, and the availability of health services.

The estimates are not based on official death reports. Governments typically include fatalities from heatstroke, but not necessarily those resulting from cardiovascular and respiratory diseases that are exacerbated by extreme temperatures. This means that the true number of deaths from a heat wave is often undercounted.

Large parts of Europe sweated this summer under a series of heat domes, or extensive weather systems that allow heat to accumulate for days on end. The extra heat trapped around the Earth by greenhouse gas emissions makes temperatures during these events rise even higher, increasing health risks.

“Even in a pre-industrial climate, for some of these heat waves, we would expect to see high mortality,” said Clair Barnes, a climate scientist at Imperial College London and the lead author of both studies. “But this mortality was substantially pushed up by human-caused warming, mainly from burning fossil fuels.”

Temperatures rose repeatedly and relentlessly in many of Europe’s major cities this summer, exposing outdoor workers to dangerous conditions and leaving millions of others seeking relief.

Fire surges and fatalities

Furnace-like conditions fueled the largest wildfires in modern history in France and Spain, displacing 300,000 people. Overall, it was the hottest summer on record in Western Europe and the third hottest on the continent as a whole.

The authors of the new studies focused on mortality in 854 urban areas across 30 nations: the 27 European Union member states, plus the United Kingdom, Norway and Switzerland. These cities and towns account for about 40% of the total population of those countries, but are not necessarily representative of Europe as a whole. The researchers chose them because they were able to obtain the data needed to estimate heat-related mortality for every summer since 2000.

The scientists’ estimate of 50,391 deaths in these cities and towns this summer suggests a substantial jump in fatalities compared with previous years. Heat killed about 29,480 people in the second-deadliest summer, 2022, and 28,462 people in the summer of 2003, when devastating heat waves sparked widespread concerns about Europe’s readiness to cope with climate change.

To assess the role of human-caused warming in heat-related mortality, researchers first used climate computer models to simulate summer temperatures in a world in which nations would not have warmed the planet by burning coal, oil and gas. They then estimated the number of heat-related deaths across Europe in that hypothetical, cooler world.

Intensity Explains

The main reason for the estimated jump in mortality this year is simply the intensity of the heat this summer, which afflicted large swaths of the continent with extraordinary intensity for long periods, said Garyfallos Konstantinoudis, a climate scientist at Imperial College who contributed to the new studies.

The estimated number of deaths was significantly higher this summer compared with previous years, even after researchers accounted for increases in urban populations, Konstantinoudis said. This suggests that the 2026 jump was not due to demographic changes.

European governments are paying more attention to the dangers of scorching temperatures. One sign of this, Barnes said, is that health agencies in several nations, including the United Kingdom, France, Germany and Spain, began issuing heat death estimates while the summer was still underway.

This article was originally published in The New York Times.

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