‘Re­ally ex­treme’ global weather event leaves sci­en­tists aghast

The Timaru Herald - - WORLD - PETER HANNAM

UNITED STATES: Cli­mate sci­en­tists are used to see­ing the range of weather ex­tremes stretched by global warm­ing, but few episodes ap­pear as re­mark­able as this week’s un­usual heat over the Arc­tic.

Zack Labe, a re­searcher at the Univer­sity of Cal­i­for­nia at Irvine, said av­er­age daily tem­per­a­tures above the north­ern lat­i­tude of 80 de­grees had bro­ken away from any pre­vi­ous record­ings in the past 60 years.

‘‘To have zero de­grees at the North Pole in Fe­bru­ary – it’s just wrong,’’ said Amelie Meyer, a re­searcher of ice-ocean in­ter­ac­tions with the Nor­we­gian Po­lar In­sti­tute. ‘‘It’s quite wor­ry­ing.’’

The so-called Po­lar Vor­tex – a zone of per­sis­tent low pres­sure that typ­i­cally keeps high-lat­i­tude cold air sep­a­rate from re­gions fur­ther south – has been weak­en­ing for decades.

In this in­stance, ‘‘a mas­sive jet of warm air’’ was pen­e­trat­ing north, send­ing a cold burst south­wards, said Meyer, who has re­lo­cated to Ho­bart to re­search the south­ern hemi­sphere and is hosted by the In­sti­tute for Marine and Antarc­tic Stud­ies.

‘‘The anom­alies are re­ally ex­treme,’’ An­drew King, a lec­turer in cli­mate sci­ence at the Univer­sity of Mel­bourne, said. ‘‘It’s a very in­ter­est­ing event.’’

Warm, moist air is pen­e­trat­ing much fur­ther north than it would nor­mally at a time when the North Pole is in com­plete dark­ness.

Cape Mor­ris Jes­sup, the world’s most northerly land-based weather sta­tion, in Green­land, touched 6 de­grees C on Sun­day, about 35C above nor­mal for this time of year.

Robert Ro­hede, a Zurich-based sci­en­tist with Berke­ley Earth, posted on Twit­ter that Cape Mor­ris Jes­sup had al­ready recorded 61 hours above freezing so far in 2018.

The pre­vi­ous record was just 16 hours, recorded to the end of April in 2011.

‘‘Parts of Green­land are quite a bit warmer than most of Europe,’’ King said.

The cold snap will see tem­per­a­tures sink moder­ately be­low freezing in Lon­don each day un­til Fri­day. How­ever, cities such as Ber­lin will dive to as low as mi­nus 12C, and Moscow to mi­nus 24C.

With a weak jet stream, sur­face winds are tak­ing an un­usual course – bring­ing snow from the east and prompt­ing some com­men­ta­tors to dub the event the ‘‘Beast from the East’’.

‘‘For Bri­tain and Ire­land, most weather sys­tems would typ­i­cally blow in from the west, but [yes­ter­day] we will see a cold front cross Bri­tain from the east,’’ King said.

Along with the un­usual warmth over the Arc­tic, sci­en­tists are mon­i­tor­ing the re­treat of sea ice in the Ber­ing Sea. The ice cov­er­age in the re­gion was now at lev­els pre­vi­ously seen only in May or June, Labe posted on Twit­ter, cit­ing data from the US Na­tional Snow and Ice Data Cen­tre.

While cli­mate change it­self is only likely to have ex­ac­er­bated re­gional weather vari­abil­ity, the long-term shrink­age of sea ice had a re­in­forc­ing ef­fect on global warm­ing in a re­gion al­ready warm­ing faster than any­where else on the planet, King said.

Ice re­flects sun­light back to space. When it melts, the sea ice ex­poses more of the dark ocean be­neath, which then ab­sorbs that so­lar ra­di­a­tion, adding to the warm­ing.

Sea ice cov­er­age is cur­rently at or close to record low lev­els in both the Arc­tic and Antarc­tic.

The im­pact of the rel­a­tively warm air in the Arc­tic could play out for months to come. Multi-year ice was likely to be thin­ner and more cracked, lead­ing to a faster melt when spring ar­rived, said Meyer, who will be­gin work later this year at the ARC Cen­tre of Ex­cel­lence for Cli­mate Ex­tremes.

While re­searchers had pegged 2050 as a pos­si­ble year when the Arc­tic will be­come ice-free, this win­ter and the pre­vi­ous one – also un­usu­ally warm – had thrown those es­ti­mates out, she said.

‘‘It’s go­ing much faster than we thought.’’ – Fair­fax


‘‘It’s just wrong’’: This week’s un­usual burst of heat in the Arc­tic.

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