Global warming may have caused the death of 1,500 people during the last heatwave in Europe
Between June 23 and July 2, Western Europe experienced an exceptional heatwave. Researchers calculated that there were 1,500 additional deaths due to human-induced global warming, which contributed to these extreme temperatures.
June 2025 was the hottest June ever recorded in Western Europe, the European Copernicus service announced on July 8. And June 30, a new monthly daily record, was “one of the hottest summer days ever recorded” on the continent.
“ A heat dome with high atmospheric pressure has driven an extreme heatwave from western to central Europe, with temperatures reaching almost 35°C in London, 40°C in Paris, and 46°C in parts of Spain and Portugal,” reports New Scientist . This exceptional ten-day heatwave has caused numerous deaths, the majority of which would not have occurred without global warming, according to an analysis that has also just been published.
To understand the impact of global warming, researchers from the Grantham Institute at Imperial College London and the London School of Hygiene and Tropical Medicine (LSHTM) estimated how intense the heatwave would have been in twelve European cities if climate change had not existed, and were able to calculate the number of additional deaths caused by climate change.
In these twelve cities (Athens, Barcelona, Budapest, Frankfurt, Lisbon, London, Madrid, Milan, Paris, Rome, Sassari, and Zagreb), they estimated that there were 2,300 heat-related deaths between June 23 and July 2. They calculated that “ the heatwave would still have killed 770 people in a cooler world. But with climate change increasing temperatures by up to 4°C, 1,500 more people died,” the British weekly reports.
“ Milan was the worst-hit city, with 317 of the 499 heat-related deaths attributed to climate change, followed by Paris and Barcelona. In London, there were 273 heat-related deaths, 171 of which were attributed to human influence on the climate ,” lists The Guardian .
“ Heatwaves don't wreak havoc like wildfires and storms,” Ben Clarke, one of the study's co-authors, told the British newspaper. He continued:
“They are silent devastators. A change of just 2 to 3°C can mean the difference between life and death for thousands of people.”
Since heat is not an official cause of death, linking rising temperatures to mortality is not straightforward. Furthermore, the vast majority (88%) of these deaths are among people over 65, and “ deaths occur primarily in homes and hospitals, away from public view ,” Climate Home News points out .
Attribution studies typically take a long time to establish this connection. In this case, the researchers decided to publish their analysis before it had been peer-reviewed by other scientists, as is usually the case. Friederike Otto, a climate scientist at Imperial College London , said, “It was important to publish studies quickly because the topic is often discussed immediately after a heatwave. ”
