Rising temperatures in the Arctic are now affecting even the northernmost reaches of the inland ice. This is one of the findings revealed by new measurements of the North-East Greenland Ice Stream (NEGIS), a giant glacier that has been losing ice mass progressively over the past 7–8 years. If this ice continues to melt, current models for the rise in global sea levels will have to be recalculated.
By Christoffer Muusmann
“It is well known that the inland ice has generally been melting at an increasing pace in recent decades. However, it is quite a surprise to discover that the contribution to this development from the north-easterly part of the inland ice has risen over the past 7–8 years.”
So says Associate Professor Shfaqat Abbas Khan from DTU Space with regard to the sensational new research findings that have just been published in the recognized scientific journal Nature Climate Change (link to the article).
The research conducted in the far north reveals that in as little as six years the edge of the North-East Greenland Ice Stream has retreated around 20 km. By way of comparison, it has taken the Jakobshavn Glacier more than 150 years to retreat approx. 35 km.
Challenges the climate models
In contrast to the other major glaciers on Greenland, the glacier area in the north-east of the country features an ice stream leading approximately 700 km directly into the inland ice. This means that changes in the edge of the glacier may affect the mass balance deep inside the centre of the inland ice.
"It is well known that the inland ice has generally been melting at an increasing pace in recent decades. However, it is quite a surprise to discover that the contribution to this development from the north-easterly part of the inland ice has risen over the past 7–8 years."
Associate Professor Shfaqat Abbas Khan, DTU Space
As such, the North-East Greenland Ice Flow will—on account of its enormous size—have a significant effect on the total mass balance of the inland ice in the future. In other words, huge volumes of ice may flow out into the sea from North-East Greenland—volumes that previous climate models have not taken into account. Shfaqat Abbas Khan explains what that may mean:
“Many of the model calculations used to estimate the contribution to future rises in sea level indicate that the north-eastern sector of the inland ice should remain stable and not contribute to any loss of mass. However, our results demonstrate that over the past couple of years we have reached a point where the loss of mass in the north-east is actually the second-highest in Greenland, exceeded only by the Jakobshavn Glacier. This means that the models have underestimated the contribution to the total loss of mass—and therefore also underestimate the future contribution to changes in sea levels from the inland ice.”
A self-perpetuating process
For many years, the giant outflow glaciers—the Jakobshavn Glacier in West Greenland and Kangerslussuaq in South-East Greenland—along with the north-western sector of the inland ice have been the predominant contributors to the loss of mass from the inland ice, while the north and north-eastern sections have not demonstrated much activity to date. The North-East Greenland Ice Stream covers an area amounting to 16 per cent of the inland ice, which is double that of the Jakobshavn Glacier.
Regarding the research findings, Professor Kurt H. Kjær, Science Director at the Center for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, says:
“We used a combination of old aerial photos from 1978 and modern satellite observations to identify changes in the height of the glaciers. We can see that the changes in height between 1978 and 2003 in North-East
Greenland was very limited, but the pattern then began to shift, with a clear acceleration in loss of mass after 2006. This acceleration has since continued and even increased. The increased loss of mass can be explained by a combination of warmer air in the summer and a rise in sea temperatures. This has reduced the extent of sea ice, which otherwise helps to stabilize the glaciers.” Professor Kurt Kjær continues:
“Our results also demonstrate that after 2009 both air and, in particular, sea temperatures have returned to the level from before 2006. At the same time, the sea ice has maintained its previous extent, although the loss in mass has increased even further. This indicates that a self-perpetuating feedback process may have been triggered, with consequences we cannot yet determine precisely.”
The research findings stem from a partnership involving the Technical University of Denmark, DTU, the Center for GeoGenetics at the University of Copenhagen, Aarhus University and international partners.