A major new study has found that climate change was responsible for nearly 70 per cent of heat-related deaths across Europe during the summer of 2025, effectively tripling the toll from extreme temperatures

Researchers estimate that 16,500 of the 24,400 heat deaths recorded across 854 European cities were directly attributable to climate change, which increased summer temperatures by as much as 3.6°C. The study, led by Imperial College London and the London School of Hygiene and Tropical Medicine, warns that the true number is likely much higher, as the data covers only around 30 per cent of the continent’s population.

The analysis identifies southern and eastern Europe as particularly hard-hit. During a single week in July, from the 21st to the 27th, countries such as Romania, Bulgaria, Greece, and Cyprus saw a surge in heat-related deaths. In those seven days alone, an estimated 950 people died, with daily temperatures reaching up to 6°C above seasonal averages.

Capital cities reported some of the highest death rates per capita. Rome, Athens and Bucharest recorded the most heat-related deaths relative to population size, a consequence of extreme temperatures combined with factors such as air pollution, ageing populations, and varying levels of preparedness.

Italy recorded the highest overall number of deaths linked to climate-driven heat, with 4,597 fatalities. Spain followed with 2,841, while Germany (1,477), France (1,444), the UK (1,147), Romania (1,064), Greece (808), Bulgaria (552), and Croatia (268) also reported significant tolls.

Despite high-profile incidents such as the deaths of outdoor workers in Spain and Italy most fatalities from heatwaves go unnoticed. Victims typically suffer from underlying health issues such as cardiovascular, respiratory, or kidney conditions that are worsened by extreme heat.

The findings come amid growing concern over Europe’s long-term vulnerability to rising temperatures. Around 70 per cent of Europeans live in urban areas, a figure expected to rise to 80 per cent by 2050. Cities can be up to 10°C hotter than surrounding rural areas due to the urban heat island effect, putting densely populated and lower-income neighborhoods at even greater risk.

Experts continue to call for adaptation policies such as flexible working hours, changes to school calendars, and expanded urban green spaces interventions that could help reduce heat stress and protect public health.

Although heat-health warning systems and emergency action plans are well established across much of the continent, this summer’s death toll underscores the urgent need for stronger and more equitable climate resilience measures.