Climate change added 41 days of dangerous heat around world in 2024

"The finding is devastating but utterly unsurprising: Climate change did play a role, and often a major role in most of the events we studied, making heat, droughts, tropical cyclones and heavy rainfall more likely and more intense across the world, destroying lives and livelihoods of millions and often uncounted numbers of people," Friederike Otto, the lead of World Weather Attribution and an Imperial College climate scientist, said during a media briefing on the scientists' findings. "As long as the world keeps burning fossil fuels, this will only get worse."

Millions of people endured stifling heat this year. Northern California and Death Valley baked. Sizzling daytime temperatures scorched Mexico and Central America. Heat endangered already vulnerable children in West Africa. Skyrocketing southern European temperatures forced Greece to close the Acropolis. In South and Southeast Asian countries, heat forced school closures. Earth experienced some of the hottest days ever measured and its hottest-yet summer, with a 13-month heat streak that just barely broke.

To do its heat analysis, the team of volunteer international scientists compared daily temperatures around the globe in 2024 to the temperatures that would have been expected in a world without climate change. The results are not yet peer-reviewed, but researchers use peer-reviewed methods.

Some areas saw 150 days or more of extreme heat due to climate change.

"The poorest, least developed countries on the planet are the places that are experiencing even higher numbers," said Kristina Dahl, vice president of climate science at Climate Central.

What's worse, heat-related deaths are often underreported.

"People don't have to die in heat waves. But if we can't communicate convincingly, 'but actually a lot of people are dying,' it's much harder to raise this awareness," Otto said. "Heat waves are by far the deadliest extreme event, and they are the extreme events where climate change is a real game changer."

This year was a warning that the planet is getting dangerously close to the Paris Agreement's 1.5 degrees Celsius (2.7 degrees Fahrenheit) warming limit compared to the preindustrial average, according to the scientists. Earth is expected to soon edge past that threshold, although it's not considered to have been breached until that warming is sustained over decades.

The researchers closely examined 29 extreme weather events this year that killed at least 3,700 people and displaced millions, and found that 26 of them had clear links to climate change.

The El Niño weather pattern, which naturally warms the Pacific Ocean and changes weather around the world, made some of this weather more likely earlier in the year. But the researchers said most of their studies found that climate change played a bigger role than that phenomenon in fueling 2024's events. Warm ocean waters and warmer air fueled more destructive storms, according to the researchers, while temperatures led to many record-breaking downpours.

Jennifer Francis, a climate scientist at the Woodwell Climate Research Center in Cape Cod who wasn't involved in the research, said the science and findings were sound.

"Extreme weather will continue to become more frequent, intense, destructive, costly, and deadly, until we can lower the concentration of heat-trapping gases in the atmosphere," she said.

Significantly more climate extremes could be expected without action, the United Nations Environment Program said in the fall, as more planet-warming carbon dioxide has been sent into the air this year by burning fossil fuels than last year.

But the deaths and damages from extreme weather events aren't inevitable, said Julie Arrighi, director of program at the Red Cross Red Crescent Climate Center and part of the research.

"Countries can reduce those impacts by preparing for climate change and adapting for climate change, and while the challenges faced by individual countries or systems or places vary around the world, we do see that every country has a role to play," she said.