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Antarctica's ice sheet is melting 3 times faster than before

AP  |  Washington 

The melting of is accelerating at an alarming rate, with about 3 trillion tons of disappearing since 1992, an international team of experts said in a new study.

In the last quarter century, the southern-most continent's sheet a key indicator of climate change melted into enough water to cover to a depth of nearly 13 feet (4 metres), scientists calculated. All that water made global oceans rise about three-tenths of an inch (7.6 millimetres).

From 1992 to 2011, lost nearly 84 billion tons of ice a year (76 billion metric tons). From 2012 to 2017, the melt rate increased to more than 241 billion tons a year (219 billion metric tons), according to the study Wednesday in

"I think we should be worried. That doesn't mean we should be desperate," said University of California Irvine's Isabella Velicogna, one of 88 co-authors. "Things are happening. They are happening faster than we expected." Part of West Antarctica, where most of the melting occurred, "is in a state of collapse," said of the

The study is the second of assessments planned every several years by a team of scientists working with NASA and the Their mission is to produce the most comprehensive look at what's happening to the world's vulnerable ice sheets in and

Outside experts praised the work as authoritative.

Unlike single-measurement studies, this team looks at ice loss in 24 different ways using 10 to 15 satellites, as well as ground and air measurements and computer simulations, said of the in England.

It's possible that Antarctica alone can add about half a foot (16 centimeters) to by the end of the century, Shepherd said. Seas also rise from melting land glaciers elsewhere, Greenland's dwindling ice sheet and the fact that warmer water expands.

"Under natural conditions we don't expect the ice sheet to lose ice at all," Shepherd said. "There are no other plausible signals to be driving this other than climate change." Shepherd cautioned that this is not a formal study that determines human fingerprints on climate events.

Forces "that are driving these changes are not going to get any better in a warming climate," said Waleed Abdalati, a former NASA who wasn't part of the study team.

In Antarctica, it's mostly warmer water causing the melt. The water nibbles at the floating edges of ice sheets from below. Warming of the southern ocean is connected to shifting winds, which are connected to global warming from the burning of coal, and natural gas, Shepherd said.

More than 70 per cent of the recent melt is in

The latest figures show is losing relatively little ice a year about 31 tons (28 metric tons) since 2012. It was gaining ice before 2012. So far scientists are not comfortable saying the trend in will continue. It is likely natural variability, not climate change, and is probably going to be stable for a couple decades, said Joughin.

Another study in Nature yesterday found that ice sheet didn't retreat significantly 2 million to 5 million years ago when heat-trapping carbon dioxide levels were similar to what they are now.

Twila Moon, a at the who wasn't part of the studies, said "ice-speaking, the situation is dire.

(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)

First Published: Thu, June 14 2018. 03:00 IST