Climate change drove heat extremes in 195 countries last year

Euronews

30-05-2025

Human-caused climate change added an average of 30 days of extreme heat for about half of the world's population over the past year, according to a new study.
That amounts to four billion people exposed to prolonged, dangerous temperatures. And the findings single out fossil fuel emissions as the cause of the blistering heat.
The study, published ahead of Heat Action Day on 2 June, comes from a collaborative attribution analysis by World Weather Attribution, Climate Central and the Red Cross Red Cross Climate Centre. Researchers examined temperature data from 247 countries and territories between May 2024 and May 2025 and found that, in 195 of them, climate change at least doubled the number of days classified as 'extreme heat.'
'This study needs to be taken as another stark warning. Climate change is here, and it kills,' says Dr Friederike Otto of Imperial College London and World Weather Attribution (WWA).
To understand the influence of climate change, scientists first defined 'extreme heat' as days when temperatures exceeded the 90th percentile of the averages between 1991 and 2020. In other words, the hottest 10 per cent of days during that period. Then they tallied how many such days occurred in each country between May 2024 and May 2025.
Next, they used climate models to simulate a world without human-induced warming. By comparing both sets of data, they were able to quantify just how many additional extreme heat days could be attributed directly to climate change.
The difference was staggering. In many parts of the world, global warming didn't just increase temperatures. It made once-rare heatwaves a near-daily occurrence.
Aruba, for example, suffered 187 days of extreme heat in the past year. Without climate change, the island's population would have endured just 45 such days.
Researchers identified 67 extreme heat events globally last year. They focused on four: Central Asia in March 2025, South Sudan in February 2025, Mexico, the US and Central America in June 2024 and the Mediterranean in July 2024.
In every case, they found that climate change made the back-breaking heat more likely or more severe.
'Climate change is clearly challenging life on every continent,' says Dr Mariam Zachariah, a WWA researcher at the Centre for Environmental Policy at Imperial College London.
'These frequent, intense spells of hot temperatures are associated with a huge range of impacts, including heat illness, deaths, pressure on health systems, crop losses, lowered productivity and transport disruptions,' she adds.
Europe is among the regions already suffering the most visible and deadly consequences of human-induced climate change.
Last summer, wildfires and heatwaves swept through southern Europe. Scientists warned that climate change made them three times more likely.
Greece endured deadly Juneheatwaves triggered by climate change that strained hospitals and caused mass evacuations from tourist destinations. Over the past two summers, extreme heat has led authorities to close the Acropolis – the country's most-visited site, attracting millions each year – during the hottest hours of the day.
In July,southeastern Europe experienced its longest heatwave on record, lasting 13 consecutive days and affecting 55 per cent of the region.
Prolonged heat in Spain, France and Italy caused transport disruptions, strained power grids and forced schools to shut early.
In total, the record-breaking heat is thought to have killed more than47,000 people in Europe in 2024.
The outlook continues to be grim, too. Climate experts project23 million additional temperature-related deaths in Europe by 2099 if warming continues unchecked.
'The evidence for the link between climate change and heatwaves is undeniable,' says Roop Singh, head of urban and attribution at the Red Cross Red Crescent Climate Centre.
'Through our interactions, we know that people are feeling the rise in heat, but they don't always understand that it's being driven by climate change, and that it will continue to get much, much worse.'
Despite the mounting pressure it places on global populations, heat remains one of the most underappreciated consequences of the climate crisis.
Climate change was found to have caused41 additional days of dangerous heat in 2024, unleashing what researchers called 'unrelenting suffering' across the globe.
That suffering isn't always visible.Prolonged exposure to extreme heat has been linked to accelerated ageing and damage at the cellular level.
For the next generation, the picture is even more alarming.
A recent study estimated that83 per cent of five-year-olds will live through far more frequent and intense heatwaves than any previous generation.
'There is no place on Earth untouched by climate change – and heat is its most deadly consequence,' said Dr Kristina Dahl, vice president for science at Climate Central.
'We have the science to quantify how fossil fuel emissions are reshaping our daily temperatures – and putting billions at risk.'
The landslide that buried most of a Swiss village this week is focusing renewed attention on the role of global warming in glacier collapses around the world and the increasing dangers.
How glaciers collapse - from the Alps and Andes to the Himalayas and Antarctica - can differ, scientists say. But in almost every instance, climate change is playing a role.
In Switzerland, the mountainside gave way Wednesday near the village of Blatten, in the southern Lötschental valley, because the rock face above the Birch Glacier had become unstable when mountain permafrost melted, causing debris to fall and cover the glacier in recent years, said Martin Truffer, a physics professor at the University of Alaska Fairbanks who studies how glaciers move.
While the debris insulated the glacier and slowed melting, its weight caused the ice to begin moving - which accelerated dramatically a few weeks ago.
Authorities ordered the evacuation of about 300 people, as well as all livestock, from the village in recent days, 'when it became clear that there's a whole mountainside that's about to collapse,' said Truffer, who is from Switzerland.
Lakes that form at the base of glaciers as they melt and retreat also sometimes burst, often with catastrophic results.
Water can even lift an entire glacier, allowing it to drain, said Truffer, adding that Alaska's capital of Juneau has flooded in recent years because a lake forms every year on a rapidly retreating glacier and eventually bursts.
In 2022, an apartment building-sized chunk of the Marmolada glacier in Italy's Dolomite mountains detached during a summer heat wave, sending an avalanche of debris down the popular summer hiking destination, killing 11.
A glacier in Tibet's Aru mountain range suddenly collapsed in 2016, killing nine people and their livestock, followed a few months later by the collapse of another glacier.
There also have been collapses in Peru, including one in 2006 that caused a mini tsunami; most recently, a glacial lagoon overflowed in April, triggering a landslide that killed two.
'It's amazing sometimes how rapidly they can collapse,' said Lonnie Thompson, a glacier expert at the Ohio State University. 'The instability of these glaciers is a real and growing problem, and there are thousands and thousands of people that are at risk.'
Scientists say melting glaciers will raise sea levels for decades, but the loss of inland glaciers also acutely affects those living nearby who rely on them for water for drinking water and agriculture.
Scientists say greenhouse gases from the burning of fossil fuels such as coal have already locked in enough global warming to doom many of the world's glaciers - which already have retreated significantly.
For example, glaciers in the Alps have lost 50 per cent of their area since 1950, and the rate at which ice is being lost has been accelerating, with 'projections ... that all the glaciers in the Alps could be gone in this century,' Thompson said.
Switzerland, which has the most glaciers of any country in Europe, saw 4 per cent of its total glacier volume disappear in 2023, the second-biggest decline in a single year after a 6 per cent drop in 2022.
A 2023 study found that Peru has lost more than half of its glacier surface in the last six decades, and 175 glaciers disappeared due to climate change between 2016 and 2020, mostly due to the increase in the average global temperature.
A study published Thursday in Science said that even if global temperatures stabilized at their current level, 40 per cent of the world's glaciers still would be lost.
But if warming were limited to 1.5 degrees Celsius - the long-term warming limit since the late 1800s called for by the 2015 Paris climate agreement - twice as much glacier ice could be preserved than would be otherwise.
Even so, many areas will become ice-free no matter what, Truffer, the University of Alaska expert.
'There's places in Alaska where we've shown that it doesn't take any more global warming,' for them to disappear, Truffer said. 'The reason some ... (still) exist is simply because it takes a certain amount of time for them to melt. But the climate is already such that they're screwed.'