The severe heat waves experienced in June and July have resulted in 2,300 fatalities across London and 11 other European cities, nearly tripling the death toll attributed to climate change. While assessing the effects of climate change on heat-related deaths typically takes months, scientists have now devised a rapid method for analysis.

In late June, a series of high-pressure “thermal domes” led to extreme temperatures in Western and Central Europe, reaching around 35°C to 40°C in London. Paris recorded temperatures as high as 46°C, while parts of Spain and Portugal also faced similar conditions. The intense heat caused nuclear reactors to shut down in Switzerland, France, and Italy. In response to worker fatalities caused by the heat, outdoor work was prohibited during peak temperatures.

Researchers at the World Weather Attribution Network utilized weather data to assess how severe the heatwave would have been without climate change, comparing that with observed conditions. They integrated a study from the London Faculty of Hygiene, which illustrated the relationship between daily temperatures and increased death rates in European cities, along with their own findings. This framework was then applied to actual temperatures, calculating the potential fatalities due to climate change during this heat wave.

By estimating the period from June 23 to July 2, the researchers concluded that 2,300 individuals perished due to the heat in cities like Barcelona, Budapest, Frankfurt, Lisbon, London, Madrid, Milan, Paris, Rome, Sassari, and Zagreb. Analysis indicated that even under cooler climate conditions, there would have been approximately 700 deaths. However, climate change raised temperatures by as much as four degrees, contributing to an additional estimated 1,500 fatalities. Heat remains one of the deadliest forms of extreme weather, often exacerbating existing health conditions and going unrecognized on death certificates.

This marks the first study to swiftly quantify climate-related fatalities following a heat wave. Specifically, in London, climate change was responsible for 171 out of 235 heat-related deaths. “For me, [the impact of] climate change feels more tangible,” remarked team member Freedérique Otto from Imperial College London. “It is essential for policymakers to take action.”

“Currently, we’re nearing dangerously high temperatures affecting more people,” stated team member Ben Clark of Imperial College London. Notably, 88% of the fatalities were individuals over 65, the most vulnerable demographic.

Experts suggest that this study might underestimate the death toll, as it relies on data from cooler climates. Christie Ebi from Washington University in Seattle expressed concern over future extreme temperatures, stating, “I am uncertain about what will happen when we reach these extreme levels.”

In response to the rising temperatures, the government has issued more heat wave warnings; however, emergency response plans and infrastructure improvements are still necessary. In Milan, for instance, 499 deaths were reported, exacerbated by high air pollution levels that can worsen with rising temperatures. With 90% of fatalities linked to climate change, Madrid struggles with a lack of green spaces to mitigate urban heat effects.

Additionally, many buildings in London suffer from inadequate ventilation. Currently, measures such as providing drinking water at subway stations and halting non-essential vehicle usage during heat waves are being implemented. Otto emphasizes the importance of public awareness around heat risks, stating, “If you believe you are invincible, you’re not.”