Experts warn Antarctica’s ice sheet is melting faster than expected
WASHINGTON — The melting of Antarctica 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 last quarter-century, the continent’s ice sheet — a key indicator of climate change — melted into enough water to cover Texas to a depth of nearly 13 feet, scientists calculated. All that water made global oceans rise about 0.3 of an inch.
From 1992 to 2011, Antarctica lost nearly 84 billion tons of ice a year. From 2012 to 2017, the melt rate increased to more than 241 billion tons a year, according to the study Wednesday in the journal Nature.
“I think we should be worried. That doesn’t mean we should be desperate,” said Isabella Velicogna of the University of California, Irvine, one of 88 coauthors. “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 coauthor Ian Joughin of the University of Washington.
The study is the second of assessments planned every several years by a team of scientists working with NASA and the European Space Agency. Their mission is to produce the most comprehensive look at what’s happening to the world’s vulnerable ice sheets in Antarctica and Greenland.
Outside experts praised the work as authoritative.
Unlike single-measurement studies, this team looks at ice loss in 24 ways using 10 to 15 satellites, as well as ground and air measurements and computer simulations, said lead author Andrew Shepherd of the University of Leeds.
It’s possible that Antarctica alone can add about half a foot to sea level rise by the end of the century, Shepherd said. Seas also rise from melting glaciers elsewhere, Greenland’s dwindling ice sheet and the fact that warmer water expands.
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 University of Colorado ice scientist Waleed Abdalati, a former NASA chief scientist 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, oil and natural gas, Shepherd said.