Melt­ing of Green­land’s ice ‘off the charts,’ study shows

Iran Daily - - Cultural Heritage & Environment -

Green­land’s mas­sive ice sheets con­tain enough water to raise global sea lev­els by 23 feet, and a new study shows that they are melt­ing at a rate ‘un­prece­dented’ over cen­turies – and likely thou­sands of years.

The study, pub­lished in the sci­en­tific jour­nal Na­ture, found that Green­land’s ice loss ac­cel­er­ated rapidly in the past two decades af­ter re­main­ing rel­a­tively sta­ble since the dawn of the In­dus­trial Rev­o­lu­tion in the mid-1800s, CNN wrote.

To­day, Green­land’s ice sheets are melt­ing at a rate 50 per­cent higher than pre-in­dus­trial lev­els and 33 per­cent above 20th-cen­tury lev­els, the sci­en­tists found.

“What we were able to show is that the melt­ing that Green­land is ex­pe­ri­enc­ing to­day is re­ally un­prece­dented and off the charts in the longer-term con­text,” said Sarah Das, an as­so­ciate sci­en­tist at the Woods Hole Oceano­graphic In­sti­tu­tion and a coau­thor of the study.

To de­ter­mine just how fast Green­land’s ice is re­treat­ing com­pared with the past, sci­en­tists used a drill the size of a traf­fic light pole to take ice core sam­ples.

The sam­ples were taken from sites more than 6,000 feet above sea level, giv­ing the re­searchers a win­dow into melt­ing on the ice sheet over the past sev­eral cen­turies.

A new study shows that Green­land’s ice sheet is melt­ing at an ‘un­prece­dented’ rate.

In the wake of Oc­to­ber’s dire re­port from the UN In­ter­gov­ern­men­tal Panel on Cli­mate Change warn­ing that civ­i­liza­tion has just more than a decade to stave off cli­mate catas­tro­phe, The re­port spells more bad news for the planet, es­pe­cially the mil­lions of peo­ple liv­ing near the world’s oceans.

Melt­ing from Green­land’s ice sheet is the largest sin­gle driver of global sea level rise, which sci­en­tists pre­dict could swamp coastal cities and set­tle­ments in the com­ing decades.

Eight of the 10 largest cities in the world are near coasts, and 40 per­cent to 50 per­cent of the global pop­u­la­tion lives in coastal ar­eas vul­ner­a­ble to ris­ing seas.

The study also found that Green­land’s ice loss is driven pri­mar­ily by warmer sum­mer air and that even small rises in tem­per­a­ture can trig­ger ex­po­nen­tial in­creases in the ice’s melt rate.

“As the at­mos­phere con­tin­ues to warm, melt­ing will out­pace that warm­ing and con­tinue to ac­cel­er­ate,” said Luke Trusel, an as­sis­tant pro­fes­sor at Rowan Uni­ver­sity and study coau­thor. Ac­cord­ing to Trusel, the cur­rent thought in the sci­en­tific com­mu­nity is that there is a tem­per­a­ture thresh­old that could trig­ger a point of no re­turn for the even­tual melt­ing of Green­land and Antarc­tica’s ice sheets. And though we don’t know ex­actly what that tem­per­a­ture tip­ping point is, ‘what’s clear is that the more we warm, the more ice melts’.

“Once the ice sheets reach these tip­ping points, it’s thought that they’ll go into a state of ir­re­versible re­treat, so they’ll be re­spond­ing to what we do now for cen­turies and mil­len­nia into the fu­ture,” Trusel said.

Das stressed that although cli­mate science of­ten fo­cuses on the fu­ture im­pacts of warm­ing, the find­ings show that the cli­mate is al­ready un­der­go­ing hugely sig­nif­i­cant changes.

“Cli­mate change – whether it’s in Green­land or in your back­yard – is al­ready here and al­ready hap­pen­ing and al­ready im­pact­ing peo­ple. It’s not some­thing that’s com­ing in the fu­ture, and this study re­ally drives home that point,” she said.

Pub­lished by cnn.com

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