In the fastest-melting region of Antarctica, the melting rate of glaciers -- the region's biggest contributor to sea level rise -- has tripled in the last decade, a new study indicates.
Due in large part to ongoing global warming, glaciers in West Antarctica's Amundsen Sea Embayment are losing ice faster than is any other portion of the frozen continent, scientists say.
"The mass loss of these glaciers is increasing at an amazing rate," says Isabella Velicogna, a scientist a the University of California, Irvine, who also works with NASA's Jet Propulsion Laboratory in Pasadena, Calif.
With sea levels rising around the word, keeping track of such glacial melt takes on a new urgency, says Velicona, co-author of a study of the Antarctica melting appearing in the journal Geophysical Research Letters.
"It's critical that we maintain this [observing] network to continue monitoring the changes," she says. "Because the changes are proceeding very fast."
The researchers considered two factors of the melting of the glaciers of West Antarctica; total amount of ice loss, and the rate of that loss.
Analysis found that each year for the last two decades the glaciers have lost an average 83 gigatons of mass. To put that in perspective, Mount Everest weighs around 161 gigatons, so the Antarctic glaciers have been losing an Everest-size amount of water every two years for the last 20 years, the researchers say.
And the rate of loss is speeding up, they report; since 1992 it has increased 6.1 gigatons every year.
The researchers used a number of data sources, including satellite, laser and radar measurements, to come up with what they say is an "authoritative estimate of the amount and the rate of loss" of ice.
The melting of the glaciers in the Amundsen Sea region could be one step in a chain reaction that could result in a catastrophic collapse of West Antarctica's ice sheet, causing dangerous increases in sea levels around the globe, scientists warn.
Warm ocean currents can thin so-called "grounding lines" that hold glaciers to the sea-bed once they move off the continent, keeping them from breaking away and escaping into the open ocean.
"[As] ocean heat eats away at the ice, the grounding line retreats inland and ice shelves lose mass," NASA scientists explained in a release from the space agency. "When ice shelves lose mass, they lose the ability to hold back inland glaciers from their march to the sea. ... In this equation, more ice flows to sea every year and sea level rises."
The process has probably reached a state where it's irreversible, says Eric Rignot, another UC Irvine researcher.
"We feel it is at the point that it is ... a chain reaction that's unstoppable," he says.
