MAR 24, 2014 12:00 AM PDT

More Bad News for the Greenland Ice Sheet

Scientists have been observing the decline of the Greenland Ice Sheet with great concern for some time now. A recent report in Nature Climate Change suggests that the last area of this sheet that was thought to be stable is in fact receding, and these changes are likely to contribute to greater ice loss and significant rising of the sea level.

The bitterly cold conditions of northeast Greenland have historically kept the ice sheet relatively stable in this area, compared to losses in other parts of Greenland. However, it appears that even northeast Greenland is succumbing to warming mechanisms.

The research team from Ohio State University's GNET (Greenland GPS Network) project studied the Zachariae ice stream, which provides a conduit from the ice basins in the interior of the ice sheet to open water. This ice stream opens out into a bay that is generally stopped up by floating portions of ice that impede flow. The ice has receded in recent years, thus allowing greater flow of ice from the basin.

In essence, this could become a vicious cycle. As the outlet glacier continues to retreat from both higher air temperature and flow dynamics, more of the upstream ice is lost, causing an even greater susceptibility to flow.

Not only are changes taking place, they are taking place quickly. This ice stream has receded approximately 12 miles within the last ten years. That is an alarming rate-for reference, the Jakobshavn ice stream, considered to be one of the swiftest glaciers ever, took around 150 years to recede 22 miles.

GNET researchers were able to measure the mass loss in the northeast Greenland ice by physical displacement. Bedrock is weighed down by the collective weight of ice above it, and as the ice is lost the bedrock will rise proportionately. Using feedback from more than 50 GNET-controlled stations up and down the coast of Greenland, the team was able to combine the displacements of the bedrock and satellite-based measurements of ice density to determine the mass displacement.

In the period between April 2003 and April 2012, approximately 10 billion tons of ice per year was lost in the northeastern Greenland ice stream. The troubling implication for scientists is that due to the connection between this stream and the center of the Greenland ice reservoir, changes on the outside margins of the ice sheet can have a detrimental effect on areas located deep within the center of the sheet. Thus, scientists are concerned that ice loss could accelerate even more rapidly-and rightly so.

With the conclusion that none of the areas of the Greenland ice sheet are fully stable, scientists will continue to monitor this area for any future changes and acceleration of ice loss. Since the Greenland ice cap is composed of the world's second largest amount of frozen fresh water (behind Antarctica), the potential for coastal effects from rising sea levels is significant should this trend continue, or accelerate.
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