Climate scientists have expressed shock at the UK’s smashed temperature record, with the heat soaring above 40C for the first time ever on Tuesday.
Researchers are also increasingly concerned that extreme heatwaves in Europe are occurring more rapidly than models had suggested, indicating that the climate crisis on the European continent may be even worse than feared.
Temperature records are usually broken by fractions of a degree, but the 40.2C recorded at Heathrow is 1.5C higher than the previous record of 38.7C recorded in 2019 in Cambridge.
About 2,000 heatwave deaths a year have occurred on average in the UK over the last decade, as well as widespread disruption to work, schools and travel. Scientists said the latest record showed that slashing carbon emissions, and rapidly upgrading the UK’s overheating homes and buildings, was more urgent than ever.
Prof Peter Stott, at the Met Office, said: “I find it shocking that we’ve reached these temperatures today in 2022, smashing the previous record set only in 2019.”
His research in 2020 showed there was a chance of the UK hitting 40C due to global heating. “But we calculated it as a relatively low likelihood – a roughly one in a hundred chance – albeit that those chances are increasing rapidly all the time with continued warming,” Stott told the Guardian. “Breaking 40C today is very worrying; we’ve never seen anything like this in the UK and it could be that the risk of such extreme heat is even greater than our previous calculation showed.”
The risk was certainly rising rapidly, said Dr Nikos Christidis, who also worked on the 2020 study: “The main message is that this event is becoming more and more common and by the end of the century it will no longer be an extreme.”
The role of human-caused global heating appears clear, as the scientists estimated that chances of breaking 40C in the UK without it would be less than 0.1%. Dr Friederike Otto at Imperial College London said 40C “would have been extremely unlikely or virtually impossible without human-caused climate change”.
Otto added: “While still rare, 40C is now a reality of British summers.”
“Climate change is driving this heatwave, just as it is driving every heatwave now,” she said. “Greenhouse gas emissions, from burning fossil fuels like coal, gas and oil, are making heatwaves hotter, longer-lasting and more frequent.”
Prof Hannah Cloke, at the University of Reading, said: “The all-time temperature record for the UK has not just been broken, it has been absolutely obliterated.
“Even as a climate scientist who studies this stuff, this is scary.”
“I wasn’t expecting to see this [40C] in my career,” said Prof Stephen Belcher, at the Met Office.
Climate scientists are concerned that the rise in extreme weather may be occurring faster than expected. “In Europe, climate models do underestimate the change in heat extremes compared to observations,” said Otto. “There are still problems with climate models that we don’t quite understand yet.”
Prof Michael Mann, at Pennsylvania State University in the US, said his research suggested that climate models failed to adequately link many extreme summer weather events to climate change.
“This is because of processes that are not well-captured in the models but are playing out in the real world – eg, the impact of warming on the behaviour of the summer jet stream that gives us many of the extreme heatwaves, floods, droughts, wildfires we’re seeing,” he said. “It suggests that models, if anything, are underestimating the potential for future increases in various types of extreme events.”
There were explanations for “crazy heat” extremes happening after only just over 1C of global average warming, said Prof Stefan Rahmstorf, at the Potsdam Institute for Climate Impact Research in Germany. First, land is heating much faster than the oceans, which cover 70% of the planet and dominate the global average.
Second, changing weather patterns could deliver greater extremes in temperature, he said. “Europe is a heatwave hotspot, exhibiting upward trends that are three to four times faster compared with the rest of the northern midlatitudes. The reason? Changes in the jet stream.” Third, the slowdown of a key Atlantic Ocean current tends to increase summer heat and drought in Europe.
While 40C broke a benchmark in the UK, researchers in continental Europe, which is also in the grip of the heatwave, are now considering 50C. “In France, one cannot rule out 50C being reached in the coming decades,” said Prof Robert Vautard, at Sorbonne University. “For France, Spain, and many other countries, the current historical record is within 5 degrees of 50C, and we know such a jump is possible.”
Climate action remained vital, said Otto: “Whether [40C in the UK] will become a very common occurrence or remains relatively infrequent is in our hands and is determined by when and at what global mean temperature we reach net zero. Heatwaves will keep getting worse until greenhouse gas emissions are halted.”
“It is also in our hands whether every future heatwave will continue to be extremely deadly and disruptive,” she said. “We have the agency to make us less vulnerable and redesign our cities, homes, schools and hospitals and educate us on how to keep safe.”