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Reservoirs of water found beneath Antarctic ice streams

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Trevor Proffitt
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« on: April 22, 2007, 12:03:40 am »

Reservoirs of water found beneath Antarctic ice streams
22:09 15 February 2007
NewScientist.com news service
Gaia Vince, San Francisco





Laser pulses bounced off the surface of Antarctica by NASA's ICESat mission have revealed numerous areas of ice that either rose or sank due to highly pressurised water flooding into or out of subglacial lakes beneath (Image: Fricker et al/Science)


Rivers of fast-flowing water are gushing beneath the West Antarctica ice sheet in an extensive arterial system of rapidly filling and emptying lakes, new satellite images have revealed.

Researchers had predicted that the western ice sheet would contain subglacial water stores, but the unprecedented scale of the network and the speed of the water has surprised them. Crucially, the lakes occur below fast-moving ice streams, which could have major implications for glacial melt rates and associated sea-level rises.

"We've found substantial lakes under ice that's moving a couple of metres a day. It's really ripping along," says Robert Binschadler of NASA's Goddard Space Flight Center in Maryland, US, who carried out the study with colleagues. He presented the research at a meeting of the American Association for the Advancement of Science in San Francisco, California, US.

The linked reservoir system was discovered beneath the Whillans and Mercer ice streams fast-flowing channels of ice that are major feeders of the continent's largest ice shelf, the Ross Ice Shelf. It may be that the ice streams themselves are eroding the ground beneath, making such water reservoirs more likely, Binschadler told New Scientist.

Fast-flowing ice streams are important predictors for climate change. Data from the streams can be used to calculate how Antarctic ice which comprises 90% of the world's ice stores will survive increases in temperature, and to help determine sea-level rises.

Lubricating streams
It is thought that the vast network of moving water will help lubricate the ice, carrying it from the relative protection of the sheet's interior to the floating edge, which could exacerbate melting.

In just the three years from 2003 to 2006, laser pulses bounced down from NASA's ICESat (Ice, Cloud, and land Elevation Satellite) mission discovered numerous areas of ice that either rose or sank due to highly pressurised water flooding into or out of subglacial lakes beneath.

The three most massive subglacial lakes measure up to 500 square kilometres. One of these Subglacial Lake Engelhardt drained a volume of 2 cubic kilometres in that period, while another Subglacial Lake Conway steadily filled by 1.2 cubic kilometres over the same timeframe.

Quick changes
"We didn't realise that the water under these ice streams was moving in such large quantities and on such short time scales. We thought these changes took place over years and decades, but we are seeing large changes over months," says Helen Fricker at the University of California San Diego's Scripps Institution of Oceanography in the US, who led the study.

During the period studied, the team saw a net gain in subglacial water, although it is too early to draw conclusions about how this will affect the stability of the ice sheet, Fricker says.

More than 150 subglacial lakes have been discovered, most through drilling narrow holes in the ice, which is limited and labour intensive (see Hidden Antarctica: Terra incognita).

The new satellite technique taken from 600 kilometres above the Earth's surface gives a far more comprehensive view of the ice sheet. "It is the most complete picture to date of what is going on beneath fast-flowing ice," Bindschadler says.

Journal reference: Sciencexpress (doi: 10.1126/science.1136897

http://www.newscientist.com/article.ns?id=dn11195
« Last Edit: April 22, 2007, 12:09:30 am by Trevor Proffitt » Report Spam   Logged

Trevor Proffitt
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« Reply #1 on: April 22, 2007, 12:11:31 am »

What lurks beneath Antarctic ice sheet
03 February 2007


 A DRUMLIN - a word so evocative of the whale-shaped hills of Ireland that it is best spoken with an Irish brogue - has been spotted forming for the first time under Antarctic ice.

Drumlins are formations left behind by glaciers and are commonly found in North America, Ireland and Finland. It was thought that they formed slowly beneath the ice from sediments left behind by an ice river.

Now, however, Andy Smith of the British Antarctic Survey (BAS) and his colleagues have made a surprise discovery: they have seen a drumlin forming in less than a decade. They visited the Rutford Ice Stream in West Antartica three times between 1991 and 2004. Each time, they used echolocation to map out the shape of the river bed 2 kilometres below the surface of the ice. The most recent data revealed a big lump of sediment, 10 metres high and 100 metres wide, that "plainly wasn't there last time we looked [in 1997]", says team member David Vaughan. The team does not yet know the lump's length.

The sediment looks as if it is being dragged along the underside of the ice sheet as it moves towards the sea. "What is surprising is that big lumps of sediment are being moved around wholesale rather than being slowly accumulated," says Vaughan (Geology, vol 35, p 127).

From issue 2589 of New Scientist magazine, 03 February 2007, page 17

http://www.newscientist.com/article.ns?id=mg19325895.400
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Trevor Proffitt
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« Reply #2 on: April 22, 2007, 12:18:07 am »

Article Preview
Hidden Antarctica: Terra incognita
29 November 2006
Gabrielle Walker
Magazine issue 2580
Deep under the ice continent is a world no one expected.


Seen from the outside, Antarctica is a desert, frozen and all but lifeless. Dig below the surface, however, and you will find deep secrets. Thousands of metres beneath Antarctica's forbidding facade, at the place where ice meets rock, lies a land that is exotic, dynamic and above all, wet. Water courses around Antarctica's soft underside; it collects in deep, dark lakes, spills out into streams and rivers, and forms wetlands and marshes that have not seen the sun for millions of years.

"Antarctica has two faces," says geologist Robin Bell from Lamont Doherty Earth Observatory in New York. "It has the face it shows to the world and it has the one on the inside. And the inside face could be the one that really matters."

Where there is water, there is also ...


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Trevor Proffitt
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« Reply #3 on: April 22, 2007, 12:19:49 am »

Antarctica 2004
 
Other Antarctica Links


 

Virginia Institute of Marine Science (VIMS) http://www.vims.edu

National Science Foundation Polar Programs http://www.nsf.gov/od/opp/

Long Term Ecological Research (LTER) http://www.lternet.edu/

Palmer Long Term Ecological Research (PAL LTER) http://www.lternet.edu/sites/pal/

Rawls Byrd Elementary School http://www.wjcc.k12.va.us/rb/

Raytheon http://www.rpsc.raytheon.com/

R/V LM Gould http://www.rpsc.raytheon.com/science/marine/lmg/index.htm

Sea Ice
animation: http://www.icess.ucsb.edu/~sharon/anim_mon.html
overview: http://www.crseo.ucsb.edu/lter/projects/si_wap/Plots/lc7901c_ext.pdf
summary: http://www.crseo.ucsb.edu/lter/projects/si_wap/


Global Warming:
USNews: http://pal.lternet.edu/biblio/2000/00usnews.html
Aquarian Times: http://pal.lternet.edu/biblio/2002/Aquarian_Times/article.pdf
EPA: http://yosemite.epa.gov/oar/globalwarming.nsf/content/ImpactsPolarRegions.html\
PBS/NOVA online: http://www.pbs.org/wgbh/nova/warnings/


History
http://antarcticaonline.com/antarctica/history/history.htm
http://www.antarctica.ac.uk/About_Antarctica/Treaty/treatyperu.html
http://geography.about.com/library/cia/blcantarctica.htm

 
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Trevor Proffitt
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« Reply #4 on: April 22, 2007, 12:20:44 am »

That's for all those people who think that Atlantis was in Antarctica!
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sevens
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http://www.dalamatiacity.com


WWW
« Reply #5 on: April 22, 2007, 06:32:10 am »

Or entry into the hollow earth!
sevens
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Trevor Proffitt
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« Reply #6 on: April 23, 2007, 01:23:38 am »

I'm betting there's some room to get around inside the earth, but we know that most of it is made up of magma and other stuff! 

Or do we..?
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