A recent study by British research organizations paints an alarming picture of the latest heatwave in Spain. Between June 23 and July 2, 2025, over 450 people died in Madrid and Barcelona. The shocking finding: climate change is believed to be responsible for the deaths of 394 of these victims. The study, published on Wednesday, July 9, 2025, and conducted by scientists from Imperial College and the London School of Hygiene and Tropical Medicine, highlights the severe impact of global warming on human health.
Europe’s Cities in Focus: A Comparative Analysis
For their analysis, the researchers examined twelve European metropolitan areas, selected based on their size, geographical location, and the fact that heat warnings were issued in all of them. In addition to the Spanish cities of Madrid and Barcelona, these included Lisbon, Paris, London, Frankfurt, Milan, Rome, Sassari (Sardinia), Athens, Budapest, and Zagreb. The results are clear: human-induced climate change has tripled the estimated number of heat-related deaths in these twelve cities.
In total, approximately 2,300 people died from extreme temperatures in the cities studied. Without the climate warming caused by the burning of fossil fuels, there would have been an estimated 1,500 fewer deaths. This means that climate change is responsible for a remarkable 65% of these additional deaths.
“Heatwaves are Silent Killers”: The Unseen Tragedy
“This study shows why heatwaves are known as silent killers,” explained Malcolm Mistry, Assistant Professor at the London School of Hygiene and Tropical Medicine. He emphasized that, while some deaths were reported in Spain, France, and Italy, thousands more are estimated to have died from the scorching temperatures, yet their deaths are not recorded as heat-related.
Local figures are equally concerning: in Madrid, approximately 118 people died from the effects of the heat during the period, with 108 of these deaths directly attributable to climate change. The figures for Barcelona are even more drastic, where 340 people succumbed to the high temperatures, and 286 of these deaths were linked to climate change.
Barcelona’s Increased Vulnerability: An Unexpected Comparison
An “interesting” comparison emerged between the two Spanish major cities: although Madrid was hotter with an average temperature of 30.16 degrees Celsius during the five-day sample period than Barcelona (29.04 degrees Celsius), the Catalan capital recorded a significantly higher number of deaths.
“This is a clear sign that there are significant differences in vulnerability between the two cities,” explained one of the responsible scientists at a press conference in Brussels. There is evidence that people in Barcelona are more vulnerable, possibly due to a higher proportion of single-person households, a factor not explicitly considered in the study.
Furthermore, Madrid, due to its inland location, suffers from a rapid increase in heatwave intensity, with temperatures approximately 3.68 degrees Celsius higher in the last recorded heatwave, compared to coastal cities like Lisbon, which saw an increase of only 1.13 degrees Celsius. The study highlights that the ocean warms slower than land, explaining the lower temperature increases in coastal regions.
Elderly Most at Risk: An Urgent Appeal
The study concludes that people over 65 years old are responsible for 88% of climate change-related deaths. This underscores that individuals with underlying health conditions are most at risk of premature death during heatwaves. The findings are an urgent appeal to policymakers and society to implement more effective measures to protect the population from the consequences of climate change, particularly vulnerable groups.
