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17 April 2014 12:48 pm ,
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Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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Gigantic Remelted Ice Mass Discovered Below Antarctic Ice Sheet
3 March 2011 5:41 pm
Unless the South Pole melts, no one is ever going to see the Gamburtsev Mountain Range. The "Antarctic Alps" has been encased beneath the East Antarctic Ice Sheet for millions of years. Yet thanks to radar and other technologies, scientists have begun to peer through the ice. And in a new study, they've uncovered startling insights into how it formed.
Until now, researchers have assumed the vast majority of the ice that makes up ice sheets forms as snowflakes compact over millions of years. But that may not be the whole story, according to the first major finding from data gathered as part of a seven-nation project known as the Antarctica's Gamburtsev Province (AGAP).
AGAP's focus in the new study was on the so-called "Dome A" region of the Gamburtsev range, the high point of the East Antarctic sheet. To image the ice below the frigid surface, scientists used two Twin Otter aircraft equipped with ice-penetrating radars, laser ranging systems, gravity meters, and sensors that measure magnetic fields. The planes scanned the surface in north-south flights spaced 5 kilometers apart, crossing in east-west lines every 33 kilometers.
Previous studies have found temperatures below the ice sheet, caused by the warmth of the planet below, that could melt water. But scientists thought there was much less meltwater, playing a far less important role in ice sheet structure, than the new work suggests. According to the observations, massive ice blocks seem to form when liquid water—propelled by the pressure of the ice—moves up the steep walls of the Gamburtsev mountains, says lead author and glaciologist Robin Bell of Lamont-Doherty Earth Observatory of Columbia University in Palisades, New York. As the water rises, it encounters lower temperatures and less pressure from overlying ice, so it refreezes.
In all, refrozen meltwater may be responsible for as much as half the thickness of the ice sheet over large areas, the team reports online today in Science. (Bell says clues suggest the same process occurs in Greenland and on the west side of the Antarctic ice sheet.)
It's too early to know whether this new finding means that global warming will melt ice sheets slower or faster than scientists have predicted. But the work does suggest that current models of ice sheet dynamics are missing a huge factor, said glaciologist Donald Blankenship of the University of Texas, Austin. "The take-home message of this work is that [the bottom of ice sheets] can no longer be ignored" in the models, he says.