Summer heat deaths in 854 European cities more than tripled due to climate change

Resources

• Publications

• Action hub

• Climate change FAQs: causes, impacts and action

• Grantham Institute blog

• Background briefings

• Podcasts

Topics: Impacts and adaptation
Type: Institute reports and analytical notes
Publication date: September 2025

Download

• Summer heat deaths in 854 European cities more than tripled due to climate change [PDF]

Summary

Climate change intensified summer temperatures across Europe and led to an additional 16,500 more deaths compared to a summer that hadn’t been heated by human activities.

Focusing on 854 European cities, this study found climate change was responsible for 68% of the 24,400 estimated heat deaths this summer by increasing temperatures by up to 3.6°C.

The analysis was led by researchers at Imperial College London and London School of Hygiene & Tropical Medicine, who warn 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. It follows a study by the same team that found climate change could have tripled the death toll of a July heatwave in Europe.

Using modelling, historical mortality records and peer-reviewed methods, the study provides early estimates of this summer’s fatalities and underscores why extreme heat is known as a “silent killers” – the majority of heat-related deaths go unreported, while official government figures can take months to appear, if they are released at all.

Key points

• Across the cities, climate change was behind 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 (a full breakdown of the results with all countries and confidence intervals is given in the notes).

• In capital cities, climate change led to an additional 835 heat deaths in Rome, 630 in Athens, 409 in Paris, 387 in Madrid, 360 in Bucharest, 315 in London and 140 in Berlin.

• People aged 65 and over made up 85% of the excess deaths, highlighting how hotter summers will become increasingly deadly for Europe's aging population.

• While policies are needed to protect people from heat, a rapid shift away from fossil fuels is the most effective way to avoid hotter and deadlier summers.