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By New Scientist and Press Association

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The risk of days with sweltering 40°C heat in the UK could rise significantly by the end of the century without action to drive down greenhouse gas emissions, the UK’s Met Office has warned.

Climate change caused by human activity is already pushing temperatures to new heights, with 38.7°C in Cambridge in July 2019 the highest ever recorded in the UK.

Those new records prompt the question of whether 40°C heat is on the horizon for the UK, with heatwaves posing a potentially severe risk to people’s health.

Researchers at the Met Office Hadley Centre have used a detailed, local-scale data set based on observations to assess the likelihood of future hot spells in the face of high or medium levels of greenhouse gas emissions.

Currently, the chances of temperatures reaching 40°C anywhere in the UK are extremely low. But if emissions continue at high levels, worsening climate change, the UK could see days with 40°C heat every three to four years on average by 2100.

Temperatures exceeding 35°C in the UK currently occur once every five years on average, but that could rise to every other year with high emissions.

If the world takes action on emissions in line with commitments in the international Paris Agreement to limit global temperature rises to 1.5°C or 2°C above pre-industrial levels, the risk of extreme heat in the UK would be much lower, according to the team.

The south-east of the UK is the most likely place to eventually see 40°C temperatures, with 35°C temperatures already becoming increasingly common in the region.

But the study also found that areas in the north, where it is extremely rare to see days that reach 30°C, may exceed that temperature at least once a decade by 2100.

“We found that the likelihood of extremely hot days in the UK has been increasing and will continue to do so during the course of the century, with the most extreme temperatures expected to be observed in the south-east of England,” says Nikolaos Christidis at the Met Office.

“Climate change has already influenced the likelihood of temperature extremes in the UK,” says Christidis. “The chances of seeing 40°C days in the UK could be as much as 10 times more likely in the current climate than under a natural climate unaffected by human influence.”

Journal reference: Nature Communications, DOI: 10.1038/s41467-020-16834-0

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