LONDON

Summer heat deaths in European cities have more than tripled this year as a result of human-caused climate change, a new study revealed on Wednesday.

This summer, extreme heat caused by climate change killed two out of every three people in 854 European cities, according to the research conducted by Imperial College London and the London School of Hygiene and Tropical Medicine.

Scientists identified 16,469 deaths from hot weather caused by greenhouse gases, noting that June-August 2025 was the fourth warmest summer season on record, 0.9°C above the 1990-2020 average.

The study found that climate change was responsible for 68% of the 24,400 estimated heat deaths this summer, with temperatures rising by up to 3.6°C.

Researchers warned that the result is only a snapshot of the death toll linked to extreme heat, as the cities studied represent about 30% of Europe's population.

The sobering findings follow a study conducted by the same team, which discovered that climate change could have tripled the death toll from a July heatwave in Europe.

Climate change was responsible for 4,597 of the estimated heat deaths in Italy, 2,841 in Spain, 1,477 in Germany, 1,444 in France, 1,147 in the UK, 1,064 in Romania, 808 in Greece, 552 in Bulgaria, and 268 in Croatia.

Climate change caused an additional 835 heat-related deaths in Rome, 630 in Athens, 409 in Paris, 387 in Madrid, 360 in Bucharest, 315 in London, and 140 in Berlin.

It also noted that people aged 65 and up accounted for 85% of the excess deaths, highlighting how hotter summers will become increasingly hazardous for Europe's aging population.

The study suggested that, while policies are required to protect people from heat, a rapid transition away from fossil fuels is the "most effective" way to avoid hotter and deadlier summers.