Rising danger of 40C heat in UK – scientists
The likelihood of the UK experiencing deadly 40C temperatures for the first time is “rapidly accelerating” because of the climate crisis, scientists have found. The research shows searing heat could be a regular occurrence by the end of the century unless carbon emissions are cut to zero. Global heating has already made UK heatwaves 30 times more likely and extreme temperatures led to 3,400 early deaths from 2016-19.
The highest temperature recorded in the UK was
38.7C, in Cambridge in July 2019, while the summer of 2018 was the joint hottest on record. The new analysis found an increasing risk of even higher temperatures.
Today, a high of 40C is expected once every few centuries. But this would be every 15 years in a medium emissions scenario, in which carbon cuts are made but not enough to meet the 1.5C or 2C limits agreed by nations in the 2015 Paris climate deal.
In a worst-case scenario, with emissions continuing unchecked, somewhere in the UK would reach 40C every three and a half years.
Research in 2019 that also used a medium emissions scenario to indicate that by 2050 London will have the same climate that Istanbul has today, Leeds will be like Melbourne, Cardiff like Montevideo in Uruguay, and Edinburgh like Paris. All these foreign cities have already broken 40C.
“The probability of recording 40C, or above, in the UK is now rapidly accelerating,” said the scientists in the study, published in the journal Nature Communications. Its lead author, Nikolaos Christidis, at the Met Office Hadley Centre, said: “The rate of change is remarkable.”
“Last year, we had the record temperature in the UK and [Public Health England] reported spikes in mortality,” Christidis said. “When these kinds of events happen, we have detrimental impacts to our transport infrastructure, agricultural catastrophes and water shortages.”
Prof Piers Forster, at the University of Leeds, who was not part of the Met Office study, said: “Heatwaves are a real risk to life in the UK, especially if we do not begin modifying our homes, workplaces and hospitals to manage their expected overheating.
However, he added: “We should note that in terms of heatwaves, the UK will get off lightly compared with most other nations,” said Forster. “Heatwaves in the major crop-growing regions of the world could have more profound effects, both globally and for the UK.”
The Met Office research combined temperature measurements across the UK with climate models to calculate the likelihood of an extreme temperature being reached.
The scientists also examined the likelihood of exceeding 35C. This occurs in the UK about every five years at present, but would be an annual occurrence by the end of the century in either emissions scenario.
The south-east and south regions of the UK are most affected by the rising heat, because other regions benefit more from the cooling influence of the Atlantic Ocean. The study found that many areas in the north for which 30C is extremely rare may exceed that level at least once per decade by 2100.
Some scientists argue that the high-emissions scenario is unrealistic given the action being taken by nations to at least curb carbon emissions. However, Forster said: “Fortunately, the increasing use of fossil fuels portrayed in [the high-emissions scenario] is unlikely, but the average temperature levels seen at the end of the century under this scenario still remain a real risk if some of the worst-case amplification effects come to pass, such as massive permafrost thawing.”