Climate crisis: UK temperatures could regularly hit 40C by end of the century, Met Office study warns

A Met Office study into temperature trends in the UK has found within the next 80 years the UK could regularly experience temperatures of 40C as global greenhouse gas emissions continue to rise, driving the increased likelihood of heatwaves.

Currently the highest temperature ever recorded in the UK is 38.7C, which was set in Cambridge in July 2019.

The Met Office researchers said the record prompts the question of whether exceeding 40C is now within the possibilities of the UK climate.

The authors said the research indicates that while the current chance of seeing days above 40C is “extremely low”, by the year 2100 under a high emissions scenario the UK could see 40C days every three to four years.

But if emissions are reduced in line with the Paris Climate Agreement, the future probabilities are expected to be considerably lower.

The return time for the 40C threshold is reduced to around 15 years by 2100 under a medium-emissions scenario.

Lead author Dr Nikos Christidis said: “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 southeast of England.

“Climate change has already influenced the likelihood of temperature extremes in the UK. The chances of seeing 40C 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.

“The likelihood of exceeding 40C anywhere in the UK in a given year has also been rapidly increasing, and, without curbing greenhouse gas emissions, such extremes could be taking place every few years in the climate of 2100.”

At the moment summers with daily maximum temperatures exceeding 35C currently happen once every five years on average, but could happen almost every other year by 2100 under a high emissions scenario.

Co-author and head of the Met Office National Climate Information Centre Dr Mark McCarthy, said: “This research shows human-caused climate change has set us on a course to see temperature extremes in the UK that would be highly unlikely under a ‘natural’ climate, although urgent action to reduce emissions now can significantly reduce the occurrence of extreme high temperatures in the UK in the future.”

He added: “Analysis shows that in some parts of the southeast between 1960 and 2019 the hottest days of the year have already increased by 1C each decade, showing the UK is already on a warming trend when it comes to heat extremes.”

The chances of 40C days are focused around the southeast of the UK, with temperatures above 35C becoming increasingly common in this region too.

But the study also found that by 2100 many areas in the north for which 30C is currently extremely rare or unlikely may exceed 30C at least once per decade.

The Met Office said the findings from this research are important to help plan for future extremes, informing effective adaptation and mitigation strategies to limit impacts on UK society.

“Heatwaves are extreme weather events, but research shows that climate change is making these events more likely,” the authors said.

“A scientific study by the Met Office into the summer 2018 heatwave in the UK showed that the likelihood of the UK experiencing a summer as hot or hotter than 2018 is a little over one in 10. It is 30 times more likely to occur now than before the industrial revolution because of the higher concentration of carbon dioxide in the atmosphere.”

The research authors said the new analysis is consistent with the findings from the UKCP18 climate projections, which show a greater chance of hotter, drier summers in the UK and that under certain emissions pathways temperatures exceeding 40C in the UK may become common by the end of the century.

They said: “Urgent action to reduce emissions now can significantly reduce the occurrence of extreme high temperatures in the UK in the future.”