Climate scientists have already established that Europe’s sweltering summer was the hottest on record. Now they are saying it was likely the deadliest as well, with their models showing that the extreme heat led to more than 50,000 excess deaths in cities alone.
The continent has endured five scorching heat waves since May, with record-shattering temperatures in several countries. On the whole, it was about 5.2 degrees Fahrenheit (2.9 degrees Celsius) above the 1991 to 2020 average. Some days exceeded the norm by nearly 22 degrees F, or 12 degrees C. Researchers modeled the impact of those extremes across 854 urban areas, representing roughly 40 percent of the population, and the 2026 data, released today, showed that this summer was by far the deadliest on record.
“We’re seeing significantly higher modeled deaths,” said Clair Barnes, an extreme weather and climate change researcher at Imperial College London’s Centre for Environmental Policy. The next closest years were 2022 and 2003, with 29,000 and 28,000 excess deaths, respectively.
Climate change is making extreme heat more likely, frequent, and persistent. As the mercury climbs, conditions become increasingly dangerous, Barnes said, with even fractions of a degree dramatically raising health risks. She and her colleagues attributed some two-thirds of the 50,000 deaths in their study, which the journal Nature Health will publish next week, to human-caused warming.
“Any one of those heat waves would have been deadly, but we’ve had five,” Barnes said, compared to maybe one or two most years. “It’s not just summer. It’s been turbocharged by climate change and now it’s dangerous.”
The teams’ method of attributing extreme heat deaths to climate change is pretty standard, said Kai Chen, faculty director of the Yale Center on Climate Change and Health, who was not involved in the study. Researchers, he explained, essentially modeled the temperatures and associated death levels Europe would have experienced with and without climate change, then reported the difference.
“This tells people that climate change is not a distant threat anymore,” said Chen, who was also struck by how quickly the analysis was released. “That is critical information to communicate in near-real time.”
Europe saw an especially searing stretch from June 17 to July 1, when daily average temperatures across the entire region were more than 9 degrees F, or 5 degrees C, above the 30-year average. Schools closed, public transit networks shuttered, wildfires erupted, and preparedness plans were put to the test. The heat even disrupted the Tour de France.
Overall, southern and western Europe bore the brunt of this summer’s heat impacts, with Italy seeing the greatest number of modeled excess deaths at 13,303, followed by France at 7,268. One reason Europeans are so vulnerable to heat deaths, said Chen, is that air conditioning is less prevalent than in the United States, where his research shows that the amenity can cut fatalities by more than half.
The elderly are at a particularly elevated risk, as heat can exacerbate underlying conditions. The latest modeling reflected that, with all but about 6,000 of the excess deaths occurring in those over 65 years old. “People don’t realize how dangerous extreme heat can be,” said Barnes. “It’s really important to bring home those risks.”
The World Health Organization called 2026 a “dress rehearsal” for what’s to come, and Barnes thinks research like this can help raise public awareness about the importance of preparing for extreme heat and the need to mitigate climate change. The research, Barnes noted, can also be used to project dangers ahead of coming heat to help authorities plan. “There’s no reason,” she said, “that the model couldn’t be run on forecast temperatures.”
Barnes hopes to expand her work to include other parts of the world too, especially historically marginalized regions such as Africa, where people often feel the effects of heat but may not attribute them to climate change. Limited data availability could impede those efforts in some places, she said. Those numbers do, however, mostly exist for the United States, where Chen is among those trying to implement this type of analysis.
“That will be very important for the U.S. conversation too,” he said. “It can raise awareness and motivate policy action.”
