The temperature at which a heatwave is announced has been redefined
The Met Office is increasing the temperature at which it declares a heatwave in eight counties in England.
A heatwave is announced by the forecasting body whenever an area surpasses a set temperature for at least three days in a row.
Climate change has caused average temperatures to rise, so the heatwave level has now risen by 1C in eight areas.
The old limits were based on data between 1981 and 2010 and the new ones use temperatures from 1991 and 2020.
In Berkshire, Bedfordshire, Buckinghamshire, Cambridgeshire, Hertfordshire and Surrey, the limit has increased from 27C to 28C. Meanwhile, it has gone from 26C to 27C in Lincolnshire and from 25C to 26C in the East Riding of Yorkshire.
Throughout the UK, the Met Office’s heatwave limit varies from 25C to 28C. Until now, London had been the only region with a 28C limit, but it has now been joined by Surrey, Bedfordshire, Buckinghamshire, Cambridgeshire, Hertfordshire and Berkshire.
The head of the Met Office National Climate Information Centre, Dr Mark McCarthy, said: “Temperature rise has been greatest across parts of central and eastern England where they have increased by more than 1C in some locations, while further north, areas of Scotland and Northern Ireland have seen temperatures rise by closer to 0.7C.
“Although heatwaves are extreme weather events, research shows that climate change is making these events more likely.”
The Met Office carried out a study into the 2018 UK heatwave and discovered it was 30 times more likely to happen now than in 1750. This is because there is now a greater concentration of carbon dioxide, which is a greenhouse gas, in the atmosphere.
Dr McCarthy explained: “As greenhouse gas concentrations increase, heatwaves of similar intensity are projected to become even more frequent, perhaps occurring as regularly as every other year.”
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“Although heatwaves are extreme weather events, research shows that climate change is making these events more likely,” Dr Mark McCarthy, head of the Met Office National Information Centre