The dangerous 32C heat that will be endured by people in the south-east of England on Saturday will have been made 100 times more likely by the climate crisis, scientists have calculated.
Global heating, caused by the burning of fossil fuels, is making every heatwave more likely and more intense. The 32C (89.6F) day forecast on Saturday would have been expected only once every 2,500 years without the climate crisis, the researchers said, and June heatwaves are now about 2-4C (3.6-7.2F) hotter than in the past.
The heat is expected to cause premature deaths, particularly among older and vulnerable people. More than 10,000 people died before their time in summer heatwaves between 2020 and 2024, according to the UK Health Security Agency, and the UK government has been heavily criticised for failing to properly prepare people for extreme weather.
Prolonged heat is especially dangerous as it gives no time for people’s bodies to cool off. Maximum temperatures in the south-east are expected to be above 28C for three consecutive days. The scientists said this heatwave was made 10 times more likely by the climate crisis.
Dr Ben Clarke at Imperial College London, who was part of the research team, said the culprit for the extreme heat was clear. “This weather just wouldn’t have been a heatwave without human-induced warming,” he said.
Climate breakdown drove the annual global temperature in 2024 to a new record and carbon dioxide emissions from coal, oil and gas are still rising. If that continues for just two more years, passing the internationally agreed limit of 1.5C above preindustrial levels will be inevitable, intensifying the extreme weather already taking lives in the UK and across the globe.
Clarke said: “With every fraction of a degree of warming, the UK will experience hotter, more dangerous heatwaves. That means more heat deaths, more pressure on the NHS, more transport disruptions, and tougher work conditions. The best way to avoid a future of relentless heat is by shifting to renewable energy.”
Dr Friederike Otto, also at Imperial College London, said: “It is really important to highlight this early summer heatwave because the impacts of heat are still severely underestimated, and the UK is not prepared for this type of weather.” The Climate Change Committee, the government’s official advisers, said in April that the UK’s preparations for adapting to a changing climate were “inadequate, piecemeal and disjointed”.
Otto said: “Heatwaves are called the silent killer, because we don’t see people dropping dead on the street, but killers they are. In Europe in 2022, more than 60,000 people died in the summer from extreme heat.”
Maja Vahlberg at the Red Cross Red Crescent Climate Centre said: “Sadly most people die from heat indoors and alone, especially older people and those with underlying health conditions, such as lung or heart disease.”
Prof Mike Tipton, a physiologist at Portsmouth University, said: “The human body is not designed to tolerate prolonged exposure to this sort of extreme heat. It is undeniable that climate change is now costing British lives. Those politicians and commentators who pour scorn on climate action should reflect on this fact because, until we stop emitting greenhouse gases, these episodes are only likely to become more extreme.”
The extremely dry spring, combined with soaring temperatures, means the UK is also facing a high risk of wildfires, said Theodore Keeping, also at Imperial College London: “We’ve already seen the highest burnt area on record in the UK this year.” People should take extreme care with fires, barbecues and cigarettes, he said.
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The rapid study of the role of global heating in the predicted weekend heatwave compared the likelihood of the high temperatures in today’s hotter climate with that in the cooler preindustrial period. The team, part of the World Weather Attribution group, was also able to reuse detailed climate modelling undertaken for a similar heatwave in 2022, speeding up their conclusions.
They said older people were at greatest risk from the high temperatures, but that others with existing vulnerabilities could also be affected, with the effectiveness of some medications being changed by the heat or affecting people’s ability to cool down.
Sweating is how the body cools so it is vital to drink plenty of water, the researchers said. Closing windows and curtains during the day and opening them in the cool of the night can help keep temperatures in homes down, they said. A recent study estimated that 80% of UK homes overheat in the summer.
Temperatures in the UK rose above 40C for the first time in 2022. The Met Office said on Wednesday that the UK had a 50/50 chance of temperatures soaring to 40C again in the next 12 years as the climate crisis worsens and that 45C could not be ruled out.
Extreme heat is more deadly than floods, earthquakes and hurricanes combined, according to a report by the insurance giant Swiss Re published on 12 June. “Up to half a million people globally succumb to the effects of extreme heat each year,” it said.
“Extreme heat used to be considered the ‘invisible peril’ because the impacts are not as obvious as of other natural perils,” said Jérôme Haegeli, chief economist at Swiss Re. “With a clear trend to longer, hotter heatwaves, it is important we shine a light on the true cost to human life, our economy, infrastructure, agriculture and healthcare.”
