A new study by researchers at Imperial College London and the London School of Hygiene & Tropical Medicine estimates that climate change was responsible for roughly 16,500 heat-related deaths across 854 European cities during the summer of 2025.
The study reveals that global warming made temperatures an average of 2.2°C hotter from June to August, leading to a tripling of the death toll compared to a world without human-caused warming. Rome suffered the highest estimated number of deaths at 835, followed by Athens with 630 and Paris with 409.
While the research covers only about 30% of Europe’s population, experts warn that the actual death toll is likely higher. Heatwaves were notably severe in countries like Spain, where August saw record temperatures and devastating wildfires.
The findings underscore the urgent need for climate action to protect vulnerable populations, especially the elderly, who accounted for over 85% of the excess deaths.
This summer was Europe’s fourth hottest on record, highlighting the growing threat of extreme heat events fueled by rising global temperatures.