Climate change accounted for an estimated 5,227 of 6,824 heat deaths in 90 Spanish cities this summer. Barcelona had Europe’s second-highest toll of additional deaths, while Madrid recorded the highest attributable share.
Nearly a third of the additional heat deaths across the study’s European region occurred between 17 June and 1 July, when average temperatures stood 5°C above the 1991-2000 average. Researchers estimate that climate change accounted for 5,227 of 6,824 heat-related deaths in 90 Spanish cities between June and August, or 77% of the estimated total.
Published in Nature, the study by researchers from Imperial College London and the London School of Hygiene and Tropical Medicine covered 854 European cities across 30 countries, with a combined population of about 173 million. Across those cities, it estimates 50,391 additional deaths from heat this summer. Roughly two-thirds, or 32,619, were attributed to additional warming caused by human greenhouse-gas emissions. Without that human-caused warming, around 32,000 people would have been spared.
These are modelled estimates of excess mortality, not a count of death certificates listing heat as the cause. Researchers combined temperature observations and population data with climate modelling and established temperature–mortality relationships. They compared the heat burden with a counterfactual climate without human-caused warming. The analysis estimates deaths associated with excess heat across the season, rather than deaths caused only by a single heatwave.
The researchers describe this as the highest number of heat deaths directly linked to the climate crisis in the past 26 years. The previous peak was about 31,000 in 2022; around 26,000 were recorded in 2003. Italy and France were also among the hardest-hit countries, alongside Spain. The worst impacts were concentrated in western and southern Europe. Italy’s estimated total was 13,303, while France recorded 7,268. Spain had 6,824 and Germany 6,340.
Barcelona recorded 1,587 additional deaths attributable to extreme heat, second among European cities after Milan, with 1,842. Madrid had 967 such deaths out of 1,067 estimated heat deaths in total. Its 91% share was the highest among the cities analysed.
Other Spanish city estimates include 262 climate-attributable deaths out of 355 in Valencia and 169 out of 264 in Zaragoza. Málaga recorded 84 of 111, while Seville had 77 of 109. Granada recorded 71 of 98.
The Agencia Estatal de Meteorología said summer effectively lasted four months, with summer-like temperatures in the second half of May and the first half of September. Spain also recorded 61 days with heatwave conditions, a national record. The study estimates that more than 6,000 people under 65 died from severe heat in the cities examined. The estimated toll was not confined to older people.
Clair Barnes, a study co-author and extreme-weather expert, said the figures indicate that 2026 was the deadliest summer for heat-related mortality across much of Europe. Pierre Masselot, a co-author and epidemiologist at the London School of Hygiene and Tropical Medicine, said European cities remain poorly adapted to heat. He pointed to the need for more green space and less pollution.
