The study attributes 32,619 modeled heat-related excess deaths in 854 European cities during June through August 2026 to human-caused climate change, out of an estimated total of 50,391.
The analysis was conducted by researchers at Imperial College London and the London School of Hygiene & Tropical Medicine (LSHTM). The overall estimate has a 95% empirical confidence interval of 46,026 to 53,878 deaths. The portion attributed to climate change ranges from 26,078 to 38,237, or 53% to 73% of the total. These are modeled excess deaths, not counts of death certificates listing heat as the cause.
To isolate the effect of human-caused warming, researchers calculated mortality under summer 2026 temperatures and under a modeled climate scenario without that warming. They applied existing city- and age-specific evidence on temperature and mortality to each scenario, then treated the gap between the estimates as the climate-change share.
The 854 urban areas are in the European Union’s 27 member states, the United Kingdom, Norway and Switzerland. Their combined population is about 172.7 million, or roughly 40% of the population in the 30 countries. The report says the urban sample cannot be used to calculate a direct total for the continent.
The largest age-group estimate was 22,502 deaths among people aged 85 or older, about 45% of the modeled total. Researchers estimated about 833 deaths among adults aged 20 to 44. Southern Europe had the highest regional heat-mortality rate. Italy had the largest modeled country toll, with 13,303, followed by France with 7,268, Spain with 6,824 and Germany with 6,340.
The June 17–July 1 period accounted for nearly one-third of the modeled summer deaths. Average daily temperatures across the cities during those two weeks were 5.3°C above the 1991–2020 average. The same analysis estimated 29,480 heat-related excess deaths in the cities in 2022 and 28,462 in 2003.
Dr. Pierre Masselot, an assistant professor, statistician and epidemiologist at LSHTM, said, “It is becoming increasingly clear our cities are poorly adapted to rising heat.” The researchers called for emissions cuts and stronger local protections, including heat alerts, better preparation of homes and health facilities, and expanded shade and green space. LSHTM linked the warming behind the heat risk to greenhouse gas emissions, primarily from fossil fuels.
