Climate Change Tripled Heat Deaths in European Heatwave

The European summer had barely started this year, when the region was hit by the first severe heatwave of the season. Across the continent, authorities triggered heat health alerts, as large parts of Western Europe struggled to cope with sweltering temperatures in the last days of June and the first days of July.

There is strong scientific consensus that climate change is increasing the frequency and intensity of heatwaves globally, with Western Europe already experiencing an increase in extreme heat events in recent years. Studies have shown that human-induced global warming has made heatwaves in the region far more likely, with temperatures like the ones observed in the last few weeks in countries like France, Italy, Spain and the UK being much less likely without climate change.

Scientists from the Grantham Institute for Climate Change and the Environment at the Imperial College of London have conducted a rapid study to estimate the impact of climate change on the number of heat-related excess deaths caused by the latest heatwave across 12 European cities. The researchers used established epidemiological models to estimate heat-related excess deaths under the actual observed/forecast temperatures and conditions and compared them to a counterfactual scenario for which they deducted the estimated increase in heat extremes caused by a 1.3 degree Celsius increase in global mean surface temperature from the actual temperature levels.

In 10 of the 12 locations (i.e. excluding Milan and Lisbon), the increases in extreme temperatures due to climate change varied between 2 to 4 degrees Celsius, making a huge difference in how the heat is experienced and, more importantly, in how it impacts the human health. As our chart shows, the added temperature also makes a big difference in heat-related excess mortality, nearly tripling the estimated number of excess deaths across the 12 cities in the recent heatwave. Interestingly, the added heat stress caused by climate change had a similar effect on excess deaths across all age groups. While those aged 75 and older are naturally most at risk, deaths attributable to climate change accounted for around 60 percent of estimated excess deaths in all age groups.

In conclusion, the autors found that roughly 1,500 of the 2,300 estimated heat deaths in the recent heat wave, or 65 percent, were a result of climate change increasing the heat by 1 to 4 degrees Celsius, meaning the death toll was roughly tripled by the effects of climate change.