A new study conducted by public health experts across Europe found that 61,672 Europeans died from excruciating summer temperatures across the continent between May 30 and September 4 of last year.
Last summer, Europe experienced temperatures that soared to over 115 degrees Fahrenheit (over 46 degrees Celsius). Portugal reached a peak temperature in July of 47°C (116.6°F), though that temperature did not break its record temperature of 47.3°C in 2003.
The temperatures also caused the continent’s second-worst wildfire season on record, with nearly 17,000 fires having destroyed over 4 million acres (1.62 million hectares).
The deadly heat waves were fueled by climate change, with researchers finding that in every week of that summer, average temperatures consistently exceeded the baseline values of the previous three decades, with the highest heat hitting the continent between July 18 and July 24.
The countries that experienced the highest mortality rates included Italy, Greece, Spain and Portugal. Following those nations were Bulgaria, Croatia, Malta, Lithuania, Estonia and Romania.
“The Mediterranean is affected by desertification, heat waves are amplified during summer just because of these drier conditions,” said Joan Ballester, a study co-author and professor at the Barcelona Institute for Global Health.
In a separate study, researchers also found pollution from burning fossil fuels and other sources increased the death toll.
“We found 60% of the observed deaths can be attributed to climate change,” said Ana Maria Vicedo-Cabrera, the head of the climate and health research group at the University of Berne, and the lead author of the separate study. She praised Monday’s research., but warned the true death toll could be even higher.
Those who died from heat-related causes most likely already had existing health problems such as heart and lung disease. Researchers found that women, especially older women who are older than 80, were more likely than men to die, but that’s because women are more likely than men to live into old age which makes them vulnerable to the heat.
While some countries across Europe have implemented ways of tackling the heat, including warning systems and cooling green spaces across cities, researchers say last summer’s death toll is a sign those efforts are far from efficient.
“It’s an indication to those countries that they need to review their plans and see what is not working,” said Chloe Brimicombe, a climate scientist at Austria’s University of Graz.
Juan Declet-Barreto, a senior social scientist at the Union of Concerned Scientists who was not involved in Monday’s study, explained that expanding access to air-conditioning is the most important factor in preventing deaths caused by heatwaves.
But those efforts may not come soon enough this year. As El Niño increases in strength and affects the global climate—in combination with human-caused climate change, planet Earth already set its warmest record in June of this year since at least 1940.
The study was published in the journal Nature Medicine on Monday.