The news comes two weeks after another study, also published in Nature, concluded that deep, warm ocean currents are driving ice loss in Antarctica. Researchers at the British Antarctic Survey said the warm water that is reaching Antarctica's western coast is carving out the bottoms of the floating ice shelves that help hold back the flow of glaciers in land (ClimateWire, April 26).
That the new papers suggest the same process could begin in the Weddell Sea by the end of the century is a surprise to researchers who have long considered the Filchner-Ronne Ice Shelf to be a relatively stable portion of the vast Antarctic ice sheet.
"This particular paper takes another part of West Antarctica that is generally thought of to be very safe and demonstrates that is not at all the case," said David Holland, an oceanographer at New York University.
"The word I would use myself is 'shocking,'" he said. "It doesn't mean this will happen this century, but these papers present the realistic possibility that it will."
Ted Scambos, senior scientist at the University of Colorado's National Snow and Ice Data Center, agreed. "I think it is a fairly profound discovery," he said. "What the study is showing is that new areas of Antarctica that we thought were slow and stable could be vulnerable by the end of the century."
Harder to determine is just how quickly the sea level would rise if warm water does begin to erode the ice shelf, experts said.
Because the ice shelf itself is already floating, its melt would not raise sea level. Thawing the portion of the ice sheet grounded on the newly discovered subglacial basin would raise the seas by centimeters, Siegert said.
But eventually, if the flow of ice from areas well-grounded on land begins to accelerate, that could have major consequences for sea level, he predicted, potentially causing ice streams in other areas to respond by speeding up or changing direction.
It is still a guessing game, said Scambos, who said looking that far into the future depends on a lot of "what-ifs."
Asked to hazard his own guess, he estimated that the process of melting and ice loss described in the new analyses could raise seas 2 to 3 meters (6.5 to 10 feet) over thousands of years.
"There's a lot of potential sea-level rise tied up in that area," Scambos said. "And once these things begin, they are very hard to undo."
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500