Heat-related urban mortality attributable to human-induced climate change in Europe from 2000 to 2025

Anthropogenic climate change is increasing the frequency and intensity of extreme heat, with major implications for population health. Although previous studies have attributed heat-related mortality to climate change during individual events, the longer-term contribution of human-induced warming to urban mortality burdens across Europe remains poorly quantified. 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 summers of 2000-2025 under factual and counterfactual climate conditions. We estimate 430,365 heat-related deaths over the study period, with just over half of the modelled burden attributable to human-induced warming. The proportion of estimated heat deaths attributable to human-induced climate change shows a marked rise over time, increasing from 39% in 2000 to 68% in 2025. Although summer 2003 remains the second deadliest summer in absolute terms, summers with similarly large expected mortality burdens have become more frequent in recent years. These findings show that anthropogenic climate change has already greatly increased expected heat-related mortality across European cities, underscoring the need for both rapid emissions reductions and targeted local adaptation.