Times are tough for the massive ice sheets of Antarctica these days with the latest report that the giant floating ice shelves that form a fringe along the continent's coast are beginning to melt and deteriorate much faster than scientists once believed.
For hundreds of thousands of years these shelves of ice have served as a doorstop for the entire Antarctic ice sheet, holding back millions of cubic miles of glaciers from surging to the sea. Now, however, they are losing much of their size much faster than originally believed.
In a study published in the journal Science, researchers from the Scripps Institution of Oceanography at the University of California at San Diego found that the ice shelves of the Antarctic have been losing volume at an increasing rate for the past 18 years.
Most of the loss has occurred in West Antarctica, where losses have accelerated 70 percent in the past decade. In two particularly vulnerable regions, the shelves are actually 18 percent thinner than they were in 1994. Overall, the average volume change accelerated from "negligible loss" between 1994 and 2003 to "rapid loss" of around 300 cubic kilometers per year between 2003 and 2012. To put that loss in perspective, that is nearly 10 time the volume of Lake Mead, the reservoir created by the Hoover Dam.
But according to study co-author Helen Amanda Fricker, the overall volume of the sheets should stay the same, but something is indeed out of balance. According to Fricker, the ice shelves are being eaten away from above by warmer air and from below by the warmer water, and they're not being replenished fast enough by the ice behind them.
The study is based on analysis of satellite images from the European Space Agency, and researchers were quick to point out that the short time span of the study and the distance of the observations makes it difficult to draw conclusions.
"While it is fair to say that we're seeing the ice shelves responding to climate change, we don't believe there is enough evidence to directly relate recent ice shelf losses specifically to changes in global temperature," Fricker said
Unlike the loss of glacial ice, melting ice shelves do not contribute to rising sea levels because they are already floating in the water.
"This is just like your glass of gin and tonic. When the ice cubes melt, the level of liquid in the glass does not rise," the study's lead author, Fernando Paolo said.
But, while the loss of floating ice won't increase the sea levels in the oceans, the loss of these shelves could allow the massive glaciers to begin flowing directly into the sea which most certainly would drastically effect sea levels across the globe.
"That's the key concern from our new study," said Fricker.
