A Sleeping Giant Awakens – University of Copenhagen

GeoGenetics > News > A Sleeping Giant Awakens

17 March 2014

A Sleeping Giant Awakens

Arctic warming has now reached the northernmost regions of the Greenland Ice Sheet. By far the largest drainage basin, the Northeast Greenland ice stream has over the last 6-7 years lost an increasing quantity of ice. This presents a problem for the climate models. In the calculations of future sea level rise, experts do not recognize the large amounts of ice flowing into the sea from Northeast Greenland. New Danish-led research points out the serious shortcomings in the latest issue of the scientific journal Nature Climate Change.

Catchments of the Northeast Greenland Ice Stream (NEGIS), Jakobshavn Isbræ (JI), Helheim Glacier (HG) and Kangerdlugssuaq (KG) draped onto measured ice surface velocities. The NEGIS catchment covers c. 16% of the Greenland Ice Sheet and reaches c. 700 km into the interior.

Associate Professor Shfaqat Abbas Khan from the Technical University of Denmark says about this new exciting research:

"The fact that the mass loss from the ice sheet generally has increased over the last decades is well known, but the increasing contribution during the last 6-7 years from the northeastern part of the ice sheet is new and very surprising. This is due to the ice margin which over the last 5-6 years has retreated approx. 20km – for comparison, the Jakobshavn glacier has retreated approx. 35 km during a time span of 150 years. Unlike other large glaciers in Greenland, Northeast Greenland has an ice stream, which reaches almost 700 km directly into the core of the ice sheet. This implies that changes in the marginal areas can affect the mass balance deep in the center of the ice sheet. Doing so the Northeast Greenland ice stream, due to its huge size, will significantly change total mass balance for the ice sheet in the future."

When the researchers compare their findings with data from climate models, they can see that the dynamic contribution of the total mass loss from the ice stream i.e. contribution due to the glaciers flowing faster into the sea, has increased significantly in recent years.

And Shfaqat Abbas Khan continues:

"Many modeling approaches used to assess the contribution to future sea level rise shows that the northeastern sector of the ice sheet should be stable and not contribute to any mass loss. Our results show, however, that in the last few years a level has been  reached so that the mass loss in the northeast is the second largest in Greenland - second only to the Jakobshavn Glacier. This means that the models have underestimated the contribution to the total mass loss and thus underestimate Greenland's future contributions to global sea level change."

The front of Nioghalvfjerdsfjorden Glacier (79N fjord) captured in the summer of 2012.

The process has started – but where does it end?

Over the past several years, the major outlet glaciers, Jakobshavn Glacier in western Greenland, Kangerslussuaq in Southeast Greenland and the northwest sector of the ice sheet have been dominant contributors to the mass loss of the ice sheet. At the same time the north and north-east have shown little activity. The Northeast Greenland ice stream covers an area of 16% of the entire ice sheet, which corresponds to twice that of Jakobshavn Glacier.

Research Director, Professor Kurt H. Kjær, Center of Excellence for GeoGenetics at the Natural History Museum, University of Copenhagen, says about the research results:

"We have used a combination of old aerial photographs from 1978, and modern satellite observations to show glacier elevation changes. We can show that the elevation changes from 1978 to 2003 in Northeast Greenland have been very limited, succeeded by a change with a clear acceleration of mass loss since 2006, which has continued to increase ever since. The reason for the increased mass loss should be found within a combination of warmer summer air temperatures and warmer sea temperatures. This has reduced the extent of sea ice, which has a stabilizing effect on the glacier margins"

Kurt H. Kjær continues:

"Our results also show that by 2009 the air and especially sea temperatures dropped to the level before 2006. At the same time the sea ice recovered to the previous extent, while the mass loss continued to increase. This means that a process has started and we do not know where it ends."

The research results are part of a collaboration between the Technical University of Denmark (DTU), Center of Excellence for GeoGenetics at Copenhagen University and the University of Aarhus and international partners.