Greenland Ice Sheet Continues to Thin

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Meltwater stream on the Greenland ice sheet. CREDIT: Roger Braithwaite via NASA

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The disappearing Greenland Ice Sheet continues to thin along its edges, and could soon open up in the north, according to the latest results of satellite and aerial studies presented here today at the annual meeting of the American Geophysical Union.

The broad view is that the entire Greenland ice sheet

is thinning, and has done so for 20 years, researchers reported at the

meeting. But regionally, Greenland presents a more complicated story.

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Portions of the giant ice cap, one of the biggest blocks of ice on

Earth, are melting faster than others, but a few places also seem to be

getting thicker, scientists said.

Greenland is now losing about 22 gigatons (22 cubic kilometers) of ice a

year, said Beata Csatho, a professor at the University of Buffalo in

New York. All of that melting ice adds to rising global sea levels, and

future melting is expected to further contribute to that rise.

The north of the ice sheet in particular presents a possible future

hazard should rapid thinning there continue. The northeast edge is

thinning rapidly, with potential for opening up the rest of the northern

portion of the ice to melt, Csatho said. The ice sheet could start

flowing like a river out to the north if the edges thin rapidly enough.

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The southeast part of the ice sheet is also melting at increasing

rates, Csatho reported. The data comes from satellites and NASA's

IceBridge campaign, which flies planes laden with instruments over both

the Arctic and Antarctic to fill a gap between the retirement of one

ice-monitoring satellite and the launch of another. (Dazzling Images from NASA's IceBridge)

While the southwest's famous Jakobshavn glacier

seems stable, researchers at the University of Texas at Dallas found

the Jakobshavn was rapidly thinning. The elevation change was 0.17

inches (4.34 millimeters) a year at the outlet glacier from IceBridge

data, which covers the past four years, said doctoral student Wenlu Qi.

Laser altimetry data indicates that the entire ice sheet continues to

thin even though snowfall over Greenland increased after the year 2000,

said Bill Krabill, principal investigator for NASA's Airborne

Topographic Mapper and a scientist at NASA's Wallops Flight Facility in

Wallops Island, Va.

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"It's a consistent story. There are a few areas of thickening that are

taking place, but anytime you get to the edge of Greenland, you are

seeing thinning," he said.

Krabill, who works with NASA's IceBridge campaign,

said the space agency just agreed to "re-wing" or replace the wings on

the sturdy P-3 aircraft that flies for IceBridge. The IceBridge mission

will "keep on to an extent" after the launch of ICESAT-2 for specific

data collection and ICESat-2 data validation, NASA told OurAmazingPlanet

in a tweet.Themodified P-3 flies daily missions through mid-May out of

Thule and Kangerlussuaq, Greenland to measure sea and land ice.

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