Researchers: Swamp & Stream Systems Under Antarctic Ice
July 14, 2013
By The Austin American-Statesman
A team of University of Texas researchers recently discovered a swamplike system of water under an Antarctic glacier the size of New Mexico -- a finding that might hold the key to how quickly the polar ice will melt and the seas will rise.
From a nondescript office at the J.J. Pickle Research Campus, sweltering in the midsummer heat like the rest of Central Texas, this research team has become renowned for its study of some of the coldest places on Earth -- not to mention Jupiter`s icy moon, Europa.
Their expertise on the Antarctic is not as improbable as it might seem. The frigid continent has a rare combination of land, sea and ice, and the UT group has specialists in each of those usually separate fields. Due to the university`s proximity to oil and natural gas drilling, UT has developed technology for detecting what is underground, similar to detecting what is under a glacier. And a supercomputer at the Texas Advanced Computing Center is able to more easily handle the data mapping the glacier.
"With the realization that ocean was eating these ice sheets away, (studying Antarctica) became an important Earth system problem" to solve, said Don Blankenship, who leads the research group and was a co-author on the paper about the swamp system discovery, published last week in the journal Proceedings of the National Academy of Sciences.
The recent findings by the UT Institute for Geophysics say scientists need to consider the form of water under the Thwaites Glacier, already among the fastest-melting in the world, to predict how quickly it will melt.
"The paper makes for the possibility of much better examination of (melting glaciers), and they`ve identified a potential risk," said Garry Clarke, a professor emeritus at the University of British Columbia who reviewed the report.
The discovery settles a debate about what the water under the Thwaites looks like, a more pressing question as global warming melts glaciers, the researchers said. The Intergovernmental Panel on Climate Change estimates that global ice melt raised the sea level by 2 inches over the past 20 years.
Graduate student Dusty Schroeder, the lead author of UT`s latest research, found that the glacier has two systems: the inner part is on top of a swamplike system of water, which, like a bald tire in the rain, has little traction with the glacier and allows it to move more quickly; the outer part is atop a streamlike system of water, which is likely to cause the ice to slow down on rock between the streams.
"This report gives you an idea of what processes are important. ... There are things that are important to how quickly a glacier melts, like the shape of the glacier or the temperature of the ocean. We add that how water underneath a glacier is moving is an important process," Schroeder said.
With most of the glacier a mile or more below sea level, the Thwaites would also be the single largest contributor to global sea level rise if it melts entirely, Blankenship said. The glacier alone can contribute to a meter of sea level rise. Once the roughly 60 miles of the glacier on the streamlike water melt, there is nothing holding back the larger part of the glacier that is on the faster swamplike area, Blankenship said.
It may seem unlikely that water exists under miles-thick blocks of ice in the coldest parts of the planet. But the water exists for a few reasons, said Duncan Young, a co-author of the report. Pressure of the ice on the rock causes some melting, similar to how a skater`s blade melts ice. Also, the Earth`s natural heat and friction between ice and rock warm the bottom of the glacier to temperatures slightly below the melting point of ice. And the pressure of miles of ice on top of the ground lowers the melting point, allowing water to exist in below-freezing temperatures.
The UT group built the model of the subglacial water using radar imagery collected from 80 flights over Antarctica about nine years ago. A specially equipped airplane performed the flights over about 3 1/2 months, giving researchers a trove of data that has been used for other research, Young said. The flights and the equipment for the airplane cost the institute between $5 million and $10 million, Blankenship said.
Copyright Austin American-Statesman (TX) 2013
Story Image: Fred Walton of NOAA captured this image of Gletscher Glacier in Antarctica (Wikimedia Commons)
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