Tril­lion-ton ice­berg breaks off Antarc­tica

‘We’re not aware of any link to hu­man-in­duced cli­mate change’

Kuwait Times - - FRONT PAGE -

An ice­berg the size of Delaware, one of the largest on record, was set adrift after snap­ping off a West Antarc­tic ice shelf that is now at in­creased risk of col­lapse, sci­en­tists said yes­ter­day. A crack in the Larsen C ice shelf, a drift­ing ex­ten­sion of the land-based ice sheet, fi­nally broke through after inch­ing its way across the ice for­ma­tion for years. The calv­ing of ice shelves oc­curs nat­u­rally, though global warm­ing is be­lieved to have ac­cel­er­ated the process. Warmer ocean wa­ter erodes the un­der­belly of the ice shelves, while ris­ing air tem­per­a­tures weaken them from above. The calv­ing cre­ated an ice­berg about 5,800 square kilo­me­ters (2,200 square miles) big, with a vol­ume twice that of Lake Erie, one of the North Amer­i­can Great Lakes. It is about 350 me­ters (1,100 feet) thick.

“The ice­berg weighs more than a tril­lion tons, but it was al­ready float­ing be­fore it calved away so has no im­me­di­ate im­pact on sea level,” said a team of re­searchers from the MIDAS Antarc­tic re­search project. It will likely be named A68. “The calv­ing of this ice­berg leaves the Larsen C Ice Shelf re­duced in area by more than twelve per­cent, and the land­scape of the Antarc­tic Penin­sula changed for­ever,” the team added. Sep­a­ra­tion oc­curred some­where be­tween Mon­day and yes­ter­day, and was recorded by a NASA satel­lite.

Ice­bergs calv­ing from Antarc­tica are a reg­u­lar oc­cur­rence. But given its size, this be­he­moth will be closely watched for any po­ten­tial risk to ship­ping traf­fic. The fate of the berg is hard to pre­dict. It may stay in one piece, or break up. “Some of the ice may re­main in the area for decades, while parts of the ice­berg may drift north into warmer wa­ters,” said lead in­ves­ti­ga­tor Adrian Luck­man. Ac­cord­ing to the Euro­pean Space Agency, ocean cur­rents could drag the berg, or pieces of it, as far as the Falk­land Is­lands, post­ing a threat for ships in the Drake Pas­sage. Records show that large ice­bergs from the west­ern Wed­dell Sea, where Larsen C is, tend to make their way into the Antarc­tic Cir­cum­po­lar Cur­rent, which flows clock­wise from west to east around the south­ern­most con­ti­nent, or into the South At­lantic.

Will it col­lapse?

This may heighten the risk of the re­main­ing shelf dis­in­te­grat­ing. Float­ing ice shelves are fed by slow-flow­ing glaciers from land. With­out them, the glaciers would flow di­rectly into the ocean. With its new shape and size, Larsen C may be less sta­ble than be­fore, the team warned. “There is a risk that Larsen C may even­tu­ally fol­low the ex­am­ple of its neigh­bor, Larsen B, which dis­in­te­grated in 2002 fol­low­ing a sim­i­lar riftin­duced calv­ing event in 1995,” they said. Larsen A col­lapsed in 1995. If the glaciers held in check by Larsen C were to spill into the Antarc­tic Ocean, it would lift the global wa­ter mark by about 10 cen­time­ters (four inches), other re­searchers have said.

Swansea Univer­sity glaciol­o­gist Martin O’Leary, an­other MIDAS project mem­ber, said this is the fur­thest back Larsen C’s ice front has been in recorded his­tory. “We’re go­ing to be watch­ing very care­fully for signs that the rest of the shelf is be­com­ing un­sta­ble,” he said in a state­ment. “In the en­su­ing months and years, the ice shelf could ei­ther grad­u­ally re­grow, or may suf­fer fur­ther calv­ing events which may even­tu­ally lead to col­lapse-opin­ions in the sci­en­tific com­mu­nity are di­vided,” added Luck­man.

“Our mod­els say it will be less sta­ble, but any fu­ture col­lapse re­mains years or decades away.” Hu­man ac­tions have lifted av­er­age global air tem­per­a­tures by about one de­gree Cel­sius (1.8 de­grees Fahren­heit) since pre-in­dus­trial lev­els, ac­cord­ing to sci­en­tists. Antarc­tica is one of the world’s fastest-warm­ing re­gions. O’Leary said “we’re not aware of any link to hu­man-in­duced cli­mate change” for the lat­est calv­ing.—AFP

SWANSEA, WALES, United King­dom: This hand­out im­age re­ceived from Swansea Univer­sity shows an illustration de­pict­ing an ice­berg de­tach­ment from the Larsen C Ice Shelf.—AFP

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