Ris­ing dan­ger of 40C heat in UK – sci­en­tists

The Guardian - - Front Page - Damian Car­ring­ton En­vi­ron­ment editor

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.”

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