London: A new rapid analysis reveals that climate-driven pollution tripled the death toll during the severe heatwave that swept across Europe from 23 June to 2 July, claiming an estimated 2,300 lives in just 12 major cities.
According to researchers from the World Weather Attribution group, about 1,500 of these deaths were directly linked to climate breakdown caused by human-induced global warming.
Cities such as Milan, Paris, Barcelona, and London recorded the highest numbers, with Milan alone accounting for 317 of 499 heat-related deaths linked to climate change. In London, 171 of the 273 heat deaths were attributed to global heating.
The study, which is not yet peer-reviewed, used established epidemiological models to estimate mortality and compared current death tolls with those in a hypothetical world without human-driven global warming.
Experts described the event as a ‘quietly devastating’ crisis, warning that heatwaves often go unnoticed compared to other natural disasters because their impacts are less visible.
Dr. Malcolm Mistry from the London School of Hygiene & Tropical Medicine noted that, while only a few deaths were officially reported in Spain, France, and Italy, the actual toll runs into the thousands.
Older adults were most affected, with 88 percent of the climate-attributed deaths occurring in those over 65. Co-author Ben Clarke from Imperial College London said a mere increase of 2–3°C could determine life or death for thousands, highlighting the urgent need to address heat as an underestimated public health threat.
The findings indicate that climate breakdown caused temperatures to rise by up to 4°C in some areas, greatly intensifying health risks. Researchers warned that the models may not fully reflect recent adaptations to heat, as they are based on pre-2019 mortality data.
The death toll from this Europe heatwave is higher than some of Europe’s worst recent disasters, made worse by climate change, including the 2024 floods in Spain that killed 224 people and the 2021 floods in north-west Europe that left 243 dead. Typically, an average of 44,000 heat-related deaths occur across Europe each year, but the figures from just these 12 cities suggest this summer could be particularly deadly.
Adding to the concern, Copernicus, the EU’s Earth observation agency, reported that June 2025 was the third hottest June globally. The western Mediterranean experienced an ‘exceptional’ marine heatwave, with sea surface temperatures reaching a record 27°C.
The rise in ‘tropical nights,’ where temperatures don’t drop below 20°C, made resting difficult for people in affected areas like Spain, which saw up to 24 tropical nights, far above average.
Samantha Burgess, Deputy Director of Copernicus’s climate change service, warned that intensifying heat stress is becoming the norm across Europe.
A separate analysis from Mercator Ocean, which runs Copernicus’s marine services, revealed that nearly two-thirds of the Mediterranean Sea is now experiencing marine heatwaves categorized as strong or higher, the most widespread occurrence ever recorded.
Marine heatwaves are known to disrupt marine life, causing fish stress and killing off essential underwater plants, contributing to recurring mass-mortality events in the Mediterranean. According to Karina Von Schuckmann of Mercator Ocean, the repeated emergence of marine heat stress is worsening ecosystem vulnerability over time, compounding the environmental crisis.
Scientists and experts urge governments and policymakers to treat extreme heat as a growing health emergency and to adopt immediate climate action to prevent escalating human and ecological loss in the years to come.
MOST READ | UK to ban NDAs that silence harassment and abuse victims
