Greenland ice sheet losing mass on northwest coast (w/ Video)

Mar 23, 2010
New research indicates ice loss in Greenland is moving up the northwest coast. Credit: Greenland

(PhysOrg.com) -- Ice loss from the Greenland ice sheet, which has been increasing during the past decade over its southern region, is now moving up its northwest coast, according to a new international study.

Led by the Denmark Technical Institute's National Space Institute in Copenhagen and involving the University of Colorado at Boulder, the study indicated the ice-loss acceleration began moving up the northwest coast of Greenland starting in late 2005. The team drew their conclusions by comparing data from NASA's Gravity and Recovery Climate Experiment satellite system, or GRACE, with continuous GPS measurements made from long-term sites on bedrock on the edges of the sheet.

The data from the GPS and GRACE provided the researchers with monthly averages of crustal uplift caused by ice-mass loss. The team combined the uplift measured by GRACE over United Kingdom-sized chunks of Greenland while the GPS receivers monitor crustal uplift on scales of just tens of miles. "Our results show that the ice loss, which has been well documented over southern portions of Greenland, is now spreading up along the northwest coast," said Shfaqat Abbas Khan, lead author on a paper that will appear in .

This video is not supported by your browser at this time.
A video animation of Greenland's northwest coastline ice loss from 2003 to 2009 produced by CU-Boulder's Wahr

The team found that uplift rates near the Thule Air Base on Greenland's northwest coast rose by roughly 1.5 inches, or about 4 centimeters, from October 2005 to August 2009. Although the low resolution of GRACE -- a swath of about 155 miles, or 250 kilometers across -- is not precise enough to pinpoint the source of the ice loss, the fact that the ice sheet is losing mass nearer to the ice sheet margins suggests the flows of Greenland outlet glaciers there are increasing in velocity, said the study authors.

"When we look at the monthly values from GRACE, the ice mass loss has been very dramatic along the northwest coast of Greenland," said CU-Boulder physics Professor and study co-author John Wahr, also a fellow at CU-Boulder's Cooperative Institute for Research in Environmental Sciences.

"This is a phenomenon that was undocumented before this study," said Wahr. "Our speculation is that some of the big glaciers in this region are sliding downhill faster and dumping more ice in the ocean."

Other co-authors on the new GRL study included Michael Bevis and Eric Kendrick from Ohio State University and Isabella Velicogna of the University of California-Irvine, who also is a scientist at NASA's Jet Propulsion Laboratory. GRL is published by the American Geophysical Union.

A 2009 study published in GRL by Velicogna, who is a former CU-Boulder research scientist, showed that between April 2002 and February 2009, the Greenland ice sheet shed roughly 385 cubic miles of ice. The mass loss is equivalent to about 0.5 millimeters of global sea-level rise per year.

"These changes on the Greenland ice sheet are happening fast, and we are definitely losing more ice mass than we had anticipated, " said Velicogna. "We also are seeing this ice mass loss trend in Antarctica, a sign that warming temperatures really are having an effect on ice in Earth's cold regions."

Researchers have been gathering data from GRACE since NASA launched the system in 2002. Two GRACE satellites whip around Earth 16 times a day separated by 137 miles and measure changes in Earth's gravity field caused by regional shifts in the planet's mass, including ice sheets, oceans and water stored in the soil and in underground aquifers.

"GRACE is unique in that it allows us to see changes in the ice mass in almost real time," said Velicogna. "Combining GRACE data with the separate signals from GPS stations gives us a very powerful tool that improves our resolution and allows us to better understand the changes that are occurring."

Changes in Greenland's ice mass as measured by NASA's Gravity Recovery and Climate Experiment (Grace) mission between September 2005 (left) and September 2008 (right). Image credit: NASA/JPL

In addition to monitoring the Thule in northwest Greenland as part of the new GRL study, the team also is taking data from GPS receivers in southern Greenland near the towns of Kellyville and Kulusuk. An additional 51 permanent GPS stations recently set up around the edges of the should be useful to measure future crustal uplift and corresponding ice loss, said Wahr.

"If this activity in northwest Greenland continues and really accelerates some of the major in the area -- like the Humboldt Glacier and the Peterman Glacier -- Greenland's total could easily be increased by an additional 50 to 100 cubic kilometers (12 to 24 cubic miles) within a few years," said Khan.

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User comments : 6

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joefarah
1.4 / 5 (10) Mar 23, 2010
Great... I really can't wait until all of the ice in the world is gone... then the Global Warming enthusiasts will have nothing more to harp about.
meeker
Mar 23, 2010
This comment has been removed by a moderator.
CouchP
2.5 / 5 (2) Mar 23, 2010
How is it certain that crust uplift is caused by ice mass loss?
jgelt
2.2 / 5 (6) Mar 23, 2010
So where is the supposed 0.5 mm/year sea level rise worth of meltwater vanishing?
Royale
5 / 5 (3) Mar 24, 2010
it's apparently not vanishing if an island was just overflowed in the bay of bengali (yet another of several) there's an article out today on physorg.
mary_hinge
5 / 5 (2) Mar 25, 2010
So where is the supposed 0.5 mm/year sea level rise worth of meltwater vanishing?


No, it isn't 'vanishing' despite what the anti-science blogs might tell you..http://sealevel.c...obal.jpg
LuckyBrandon
not rated yet Mar 26, 2010
If there are talking 12-24 cubic miles of ice loss over a few years, then why does the linked video show the majority of greenland losing ice since 2003...?
It'll be amazing when greenland is actually green so at least its name will be accurate...