Melt­ing Arc­tic ice cap could al­ter global ther­mo­stat

Kuwait Times - - HEALTH & SCIENCE -

ABOARD CCGS AMUND­SEN, Canada: The Arc­tic ice cap is melt­ing faster than ever be­fore, threat­en­ing to push so much fresh wa­ter into the North At­lantic that it could dis­rupt how the ocean reg­u­lates global tem­per­a­tures, a promi­nent oceanog­ra­pher has warned. As the head of a 40-mem­ber cli­mate mis­sion to the Arc­tic aboard the Cana­dian Coast Guard ice breaker Amund­sen, Bel­gian re­searcher Roger Fran­cois is con­cerned about how the pace of cli­mate change may af­fect the fu­ture of deep wa­ter pools and cur­rents, and how this im­bal­ance may worsen the ef­fects of global warm­ing.

Over the course of the past two mil­lion years, tem­per­a­tures have risen and fallen in 100,000year cy­cles, with a sheet of ice form­ing over the Arc­tic cap each time fol­lowed by a rapid melt, he told AFP. The last warm­ing oc­curred be­tween 20,000 and 15,000 years ago, and led at that time to a rise in sea level of 130 me­ters (425 feet). “This re­ally is the trend with the thaws in Green­land and Antarc­tica,” said Fran­cois, who is a pro­fes­sor at the University of Bri­tish Columbia in Van­cou­ver.

“The big­gest dif­fer­ence with to­day is the time scale. It has never been faster.” Each cy­cle is marked by an in­crease in car­bon in the at­mos­phere. At the last change, the rate of car­bon diox­ide in the air in­creased from 180 parts per mil­lion to 280 ppm over 5,000 years. Un­til the In­dus­trial Rev­o­lu­tion, the level re­mained at 280 ppm, and since then it has sky­rock­eted to more than 400 ppm in 2015, he ex­plained. “If we con­tinue this way, and that’s what seems to be hap­pen­ing, we’ll end up by the end of the cen­tury with rates we have not had since the days of the di­nosaurs, the Me­so­zoic Age,” with 1,000 ppm, Fran­cois warned.

‘Feed­backs’

The last deglacia­tion, or dis­ap­pear­ance of ice from an area that was formerly cov­ered by it, was fol­lowed by a much longer than usual pe­riod of cli­mate sta­bil­ity, which al­lowed Homo sapi­ens to flour­ish. “Our civ­i­liza­tion, as we know it, is ac­tu­ally a direct re­sult of cli­mate change,” said Fran­cois. At the heart of this cli­mate are“deep wa­ter”masses that are cre­ated in the North At­lantic off Green­land when sur­face sea­wa­ter evap­o­rates and cools as wind blows over it, re­sult­ing in in­creased salin­ity. The re­main­ing wa­ter be­comes heav­ier and more dense and sinks into deep basins. The wa­ter then flows south­ward along deep abyssal plains and back, cre­at­ing cur­rents that are “a ma­jor mech­a­nism for trans­port­ing heat from the equa­tor to the poles,” said Fran­cois. With the melt­ing of the ice cap, di­lu­tion in the sea of ice­bergs made of fresh wa­ter “low­ers salin­ity, and makes more dif­fi­cult the for­ma­tion of deep wa­ter masses,” he ex­plained. But if the heat trans­fer be­tween the equa­tor and the poles is in­ter­rupted be­cause this deep wa­ter cir­cu­la­tion is bro­ken, then “high lat­i­tudes be­come much colder,” he said. Such a sce­nario al­ready hap­pened dur­ing the last global warm­ing.

“It was still colder in early deglacia­tion than dur­ing the Ice Age in north­ern Europe in par­tic­u­lar,” said the oceans re­searcher. Chang­ing of the deep wa­ter for­ma­tion is only one of sev­eral cli­mate phe­nom­ena that can am­plify the ef­fects of global warm­ing. These so-called “feed­backs” can cause cli­mate change to spi­ral out of control. An oft-cited ex­am­ple of this is the melt­ing of sea ice due to warm­ing ex­pos­ing darker seas that ab­sorb heat in­stead of re­flect­ing sun­shine, which has­tens warm­ing. — AFP

ARC­TIC OCEAN, at sea: Mem­bers of the Cana­dian Coast Guard as­sist sci­en­tists in de­ploy­ing a de­vice to col­lect sed­i­ment from the Arc­tic ocean seabed on board the CCGS Amund­sen ice-breaker Septem­ber 20, 2015, to study the com­po­si­tion of the Arc­tic Ocean. — AFP pho­tos

ARC­TIC OCEAN, at sea: Mem­bers of the Cana­dian Coast Guard as­signed to the CCGS Amund­sen, as­sist sci­en­tists to de­ploy a pump through the hull of the ship.

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