Heat-related urban mortality attributable to human-induced climate change in Europe in summer 2026

Abstract The summer of 2026 was characterized by a series of extreme heatwaves across Western Europe, with both monthly and annual temperature records broken repeatedly across many countries from May onwards. Several government agencies took the unprecedented step of issuing near-real-time estimates of the mortality associated with the most intense heat events, reflecting the severity of the threat to public health. Here we combine probabilistic climate attribution with city- and age-specific temperature–mortality relationships to estimate heat-related mortality in 854 European cities during the summer months (June–August) and compare with counterfactual climate conditions representing a world without human-caused warming. We estimate 50,391 heat-related excess deaths across the 854 cities during the summer, with around two-thirds of these attributable to anthropogenic climate change. These results highlight the threat from human-caused warming and the need for rapid emissions reductions alongside preparation and adaptation measures.