Extreme heat is a killer. A recent heat wave shows how much more deadly it’s becoming
Extreme heat is a killer and its impact is becoming far, far deadlier as the human-caused climate crisis supercharges temperatures, according to a new study, which estimates global warming tripled the number of deaths in the recent European heat wave.

For more than a week, temperatures in many parts of Europe spiked above 100 degrees Fahrenheit. Tourist attractions closed, wildfires ripped through several countries, slot aztec palace and people struggled to cope on a continent where air conditioning is rare.

The outcome was deadly. Thousands of people are estimated to have lost their lives, according to a first-of-its-kind rapid analysis study published Wednesday.

A team of researchers, led by Imperial College London and the London School of Hygiene and Tropical Medicine, looked at 10 days of extreme heat between June 23 and July 2 across 12 European cities, including London, Paris, Athens, Madrid and Rome.

They used historical weather data to calculate how intense the heat would have been if humans had not burned fossil fuels and warmed the world by 1.3 degrees Celsius. They found climate change made Europe’s heat wave 1 to 4 degrees Celsius (1.8 to 7.2 Fahrenheit) hotter.

The scientists then used research on the relationship between heat and daily deaths to estimate how many people lost their lives.

They found approximately 2,300 people died during ten days of heat across the 12 cities, around 1,500 more than would have died in a world without climate change. In other words, global heating was responsible for 65% of the total death toll.

"The results show how relatively small increases in the hottest temperatures can trigger huge surges in death," the study authors wrote.

Heat has a particularly pernicious impact on people with underlying health conditions, such as heart disease, diabetes and respiratory problems.

People over 65 years old were most affected, accounting for 88% of the excess deaths, according to the analysis. But heat can be deadly for anyone. Nearly 200 of the estimated deaths across the 12 cities were among those aged 20 to 65.

Climate change was responsible for the vast majority of heat deaths in some cities. In Madrid, it accounted for about 90% of estimated heat wave deaths, the analysis found.