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Greenland Ice Sheet: "More than 50 hidden lakes" discovered



  Meltwater from the top of the Greenland ice sheet can reach the bed.

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NASA / Goddard / Maria-José Viñas

Photo caption

Meltwater from above on Greenland Icecap can find its way to the bed

Scientists have identified more than 50 new lakes with liquid water under the Greenland Ice Sheet.

So far, only four lakes have been discovered.

The Antarctic hides 470 lakes under its ice, but this latest study from the UK and the US proves this. The North Pole region also has its share.

They are by no means that big. The largest in the south, the Vostoksee, is 250 km long. Greenland's largest subglacial lake is only 6 km long.

For a number of reasons, vast expanses of water can accumulate beneath a kilometer-thick ice sheet.

Pressure from above and geothermal heat from below can sustain a liquid. Surface meltwater also flows into bed and collects in hollows.

Researchers are interested in finding such lakes because they say something about the hydrology (water network) of an ice sheet and its movement.

Water acts as a lubricant, and as the world warms, the forecast of future sea-level rise is determined by modeling the speed at which the ice slips toward the ocean.

Greenland's ice would increase the global sea level by a total of 7 meters to melt.

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NASA / Operation IceBridge / John Woods

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Nasa's IceBridge operation mapped the Geenland ice sheet

Jade Bowling of Lancaster University manually inspected 570,000 km of ice-permeable radar data collected by Nasa's IceBridge program in Greenland.

The US Space Agency has regularly flown an instrumented aircraft over the ice sheet to map its inner layers and the shape of the bedrock. Liquid water has a telltale backscatter pattern in radar data.

The PhD student identified 54 candidate lakes in this search. "Unlike the sub-glacial lakes in the Antarctic, which are typically grouped around (inner) ice pieces, these new Greenlandic lakes are mostly at the edge of the ice sheet under relatively slow ice and are largely stable," she told BBC News.

"They are also much smaller than those in Antarctica (1

.4 km average length compared to 11 km)."

In addition to the 54 Radar Lakes, two other candidates in search of strong altitude changes in the Antarctic were found new ArcticDEM dataset.

This elevation model was created from high-resolution satellite photos. Mrs. Bowling sees some places where the ice surface has collapsed, presumably because a lake below has seeped away.

"These" active "lakes fill up and drain, which makes the ice lift up and down, seems to be rare," said co-author Dr. Stephen Livingstone. "But we speculate that the signal from active subglacial lakes near the edge of the ice sheet is actually lost because much superficial meltwater gets into bed.

" This water may flush the lakes on a seasonal basis through very efficient channels , The edges can only be a very dynamic area. "

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Andrew Sole / Sheffield University

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The new study brings the total number of known lakes to 60

In Antarctica, a number of lakes, including Vostok, were the target of scientific drilling.

The idea is that some of the oldest and most stable lakes contain ancient organisms that were captured during the formation of the ice sheet.

The chemistry of water and the nature of sediments should also provide valuable insights into past environmental conditions.

Prof. Martin Siegert of Imperial College London made an attempt to explore the subglacial Lake Ellsworth of Antarctica.

He commented to BBC News, "As the ice sheet has probably changed massively in the last ice age cycle, these Greenlandic Lakes are unlikely to be very old, hence the kind of questions you may have Lake Vostok / Ellsworth will differ from what you could achieve by drilling into a Greenland lake depth, topographical location, basal sediment).

"An analysis of which lakes look best from an exploration point of view seems a logical next step to be. If the scientific return is strong enough, an exploration mission could follow. "

Ms. Bowling and co-worker have published their analysis of Greenland's subglacial lakes in the journal Nature Communications.

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Pete Bucktrout / BAS

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One or two of the lakes could become drill targets


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