In a sign of over­heat­ing world, arc­tic sea ice dips to record low

To­tal float­ing at top of world shrank by an amount the size of Maine

The Denver Post - - NEWS - By Seth Borenstein

wash­ing­ton» The frigid top of the Earth just set yet an­other record for low lev­els of sea ice in what sci­en­tists say is a sig­nal of an over­heat­ing world.

The ex­tent of float­ing ice in the Arc­tic hit a new low for win­ter: 5.57 mil­lion square miles. That’s about 35,000 square miles — an area about the size of Maine — be­low 2015’s record. Last year had a shade more than 2015, but nearly a tied record.

This puts the Arc­tic in a “deep hole” as the cru­cial spring and sum­mer melt sea­son starts and more re­gions likely will be ice­free, said Mark Ser­reze , di­rec­tor of the National Snow and Ice Data Cen­ter in Colorado, which re­leased the find­ings Wed­nes­day.

“It’s a key part of the Earth’s cli­mate sys­tem, and we’re los­ing it,” he said. “We’re los­ing the ice in all sea­sons now.”

At the other end of the world, Antarc­tica, where sea ice reaches its low­est point of the year in March, also hit a record low mark. Antarc­tic sea ice varies widely un­like Arc­tic sea ice, which has steadily de­creased.

The ice data cen­ter mea­sures how wide sea ice ex­tends based on satel­lite imagery. It’s harder to mea­sure the thick­ness and over­all vol­ume, but data from the Univer­sity of Wash­ing­ton show that as of late last month ice vol­ume lev­els were down 42 per­cent from 1979, said po­lar sci­ence cen­ter chief Axel Sch­weiger.

Sev­eral sci­en­tists called the sea ice loss dis­turb­ing.

“It’s ev­i­dence that the cli­mate at the top of the world con­tin­ues to change faster than any­where else on Earth with im­pacts to us that are still frankly un­known,” Penn State me­te­o­rol­ogy pro­fes­sor and re­tired ad­mi­ral David W. Tit­ley , said in an e-mail.

Sci­en­tists blame a com­bi­na­tion of nat­u­ral ran­dom weather and man-made global warm­ing from the burn­ing of coal, oil and gas. The win­ter of 2016-17 was un­usu­ally toasty, and the Arc­tic saw three “ex­treme heat waves,” Ser­reze said.

A new study this month in the jour­nal Na­ture Cli­mate Change found that nat­u­ral causes can ex­plain 30 to 50 per­cent of plung­ing Septem­ber sea ice lows, while Serezze and oth­ers give cli­mate change an even big­ger role in sea ice loss.

A rel­a­tively new idea — that still di­vides me­te­o­rol­o­gists — links the shriv­el­ing ice cap at the North Pole to a weaker po­lar vor­tex and weak and am­bling jet stream, which can mean more ex­treme weather for a good part of the rest of the world.

“Re­cent cold spells and big snow­storms that we have ex­pe­ri­enced over the past few win­ters have oc­curred when the po­lar vor­tex is weak,” top win­ter weather fore­caster Ju­dah Co­hen of the pri­vate At­mo­spheric En­vi­ron­men­tal Re­search in Lex­ing­ton, Mass., said.

It’s not just the weather. As more re­gions be­come free of ice, ship­ping lanes will open in the Arc­tic, there will be more drilling for oil and gas and more over­all eco­nomic ac­tiv­ity. And that may mean ris­ing ten­sions be­tween coun­tries over newly avail­able re­sources, Ser­reze said.

This im­age, pro­vided by the National Snow and Ice Data Cen­ter and NASA, shows how low sea ice lev­els were in the Arc­tic this win­ter, alarm­ing cli­mate sci­en­tists. Dur­ing the win­ter, Arc­tic sea ice grew to 5.57 mil­lion square miles at its peak, but that’s the small­est amount of win­ter sea ice in 38 years of record keep­ing. National Snow and Ice Data Cen­ter and NASA

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