Study links hu­man ac­tions to spe­cific Arc­tic sea ice melt

Kuwait Times - - HEALTH & SCIENCE -

Driv­ing a gas-pow­ered car about 90 miles - the dis­tance be­tween New York and Philadel­phia - melts about a square foot of Arc­tic sea ice in the crit­i­cal month of Septem­ber, ac­cord­ing to a new study that di­rectly links car­bon pol­lu­tion to the amount of ice that’s thaw­ing.

At cur­rent car­bon emis­sion lev­els, the Arc­tic will likely be free of sea ice in Septem­ber around mid-cen­tury, which could make weather even more ex­treme and strand some po­lar an­i­mals, a study pub­lished Thurs­day in the jour­nal Science finds.

The study cal­cu­lates that for ev­ery ton of car­bon diox­ide put in the air, there’s 29 square feet less of sea ice (for ev­ery met­ric ton, there’s 3 square me­ters less) dur­ing the cru­cial month when the Arc­tic re­gion is least frozen. Us­ing ob­ser­va­tions, sta­tis­tics and 30 dif­fer­ent com­puter mod­els, the study au­thors show heat-trap­ping gases cause warm­ing and the melt­ing of sea ice in a way that can be trans­lated into a sim­ple math­e­mat­i­cal for­mula.

Clear lin­ear re­la­tion­ship

There’s “a very clear lin­ear re­la­tion­ship” be­tween car­bon diox­ide emis­sions and sea ice re­treat in Septem­ber, es­pe­cially at the south­ern bound­ary edges, said study lead author Dirk Notz, a cli­mate sci­en­tist at Max Planck In­sti­tute for Me­te­o­rol­ogy in Ger­many.

“It’s very sim­ple. Those emis­sions from our tailpipes and our coal-fired power plants are all go­ing into the at­mos­phere,” said study co-author Juli­enne Stroeve, a cli­mate sci­en­tist at both the Na­tional Snow and Ice Data Cen­ter in Boul­der, Colorado, and Univer­sity Col­lege, Lon­don. “It just in­creases the warm­ing at the sur­face. So the ice is go­ing to re­spond to that. The only way it can do that is to move fur­ther north.”

Rut­gers Univer­sity marine sci­en­tist Jen­nifer Fran­cis, who wasn’t part of the study, said the link is so clear and di­rect that “we know be­yond a shadow of a doubt that Arc­tic sea ice is dis­ap­pear­ing be­cause of in­creased car­bon diox­ide.”

Stroeve and Notz cal­cu­lated that the aver­age Amer­i­can each year is re­spon­si­ble for car­bon emis­sions that lead to melt­ing around 538 square feet (50 square me­ters) of Septem­ber sea ice. “I’ve stood on sea ice many times, and the idea that I’m re­spon­si­ble for 500 square feet of its de­struc­tion each year is dev­as­tat­ing,” Univer­sity of Wash­ing­ton cli­mate sci­en­tist Ce­cilia Bitz, who wasn’t part of the study but also praised it, said in an email. “That is the size of my front yard!”

On aver­age, each Septem­ber, there’s about 33,670 square miles (87,200 square kilo­me­ters) less Arc­tic sea ice than the year be­fore, al­though it varies year to year, ac­cord­ing to a 37-year trend line cal­cu­lated by the Na­tional Snow and Ice Data Cen­ter. —AP

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