WASHINGTON: Antarctica's melting is accelerating at an alarming rate, with about 3 trillion tons of ice disappearing since 1992, an international team of ice experts said in a new study.
In the past quarter century, the southernmost continent's ice sheet, a key indicator of climate change, has melted into enough water to cover Texas to a depth of nearly 13 feet (4 meters), the scientists calculated. All that water caused the global oceans to rise about three-tenths of an inch (7.6 millimeters).
From 1992 to 2011, Antarctica 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 Wednesday's study in the journal Nature.
“I think we should be concerned. That doesn't mean we should be desperate, ”said Isabella Velicogna of the University of California Irvine, 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 co-author Ian Joughin of the University of Washington.
This 2010 photo provided by researcher Ian Joughin shows crevasses near the edge of the Pine Island Glacier in Antarctica.
The study is the second of evaluations planned every several years by a team of scientists working with NASA and the European Space Agency. Its mission is to produce the most complete view of what is happening to the world's vulnerable ice sheets in Antarctica and Greenland.
External experts praised the work as authoritative
Unlike single measurement studies, this team analyzes ice loss in 24 different ways using 10 to 15 satellites, ground and air measurements and computer simulations, said lead author Andrew Shepherd of the University of Leeds in England. .
It's possible that Antarctica alone could add about half a foot (16 centimeters) to sea level rise by the end of the century, Shepherd said. The seas are also rising from the melting of land-based glaciers elsewhere, the shrinking Greenland ice sheet, and warmer water expanding.
"Under natural conditions, we don't expect the ice sheet to lose ice at all," Shepherd said. "There are no other plausible signs to drive this other than climate change."
Shepherd cautioned that this is not a formal study determining human fingerprints in weather events.
The forces "that are driving these changes are not going to improve in a warm climate," said Waleed Abdalati, an ice scientist at the University of Colorado, a former NASA chief scientist who was not part of the study team.
In Antarctica, it is mainly warmer water that causes the melt. The water nibbles at the floating edges of the ice sheets from below. The warming of the southern ocean is linked to changing winds, which are connected to global warming from burning coal, oil and natural gas, Shepherd said.
More than 70 percent of the recent melting is in West Antarctica.
The latest figures show that East Antarctica is losing relatively little ice per year _ about 31 tons (28 metric tons) _ since 2012. It was gaining ice before 2012.
So far, scientists are not comfortable saying that the trend in East Antarctica will continue. Natural variability, not climate change, is likely, and East Antarctica will likely remain stable for a couple of decades, said study co-author Joughin.
The human race on the planet is facing extinction. If the ice of Antarctica melts, the sea level will rise to drown all the continents. Sanjoy pandey
Another study in Nature found on Wednesday that the East Antarctic ice sheet did not recede significantly between 2 and 5 million years ago, when levels of heat-trapping carbon dioxide were similar to what they are now.
Twila Moon, a research scientist at the National Snow and Ice Data Center who was not part of the studies, said that "when talking about ice, the situation is dire.
Original article (in English)