Ice loss from Northeastern Greenland underestimated

By 2100, the Northeast Greenland Ice Stream could cause sea levels to rise by up to 15.5 millimeters - six times as much as climate models have predicted so far. This is the finding of an international research team with the participation of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). In a recent study, the group evaluated GPS data from a monitoring network on Northeast Greenland Ice Stream that covers an area extending up to 200 kilometers inland. The region is upstream of Nioghalvfjerdsbræ and Zachariae Isstrøm and is difficult to access for expeditions. The scientists combined this GPS data with height measurements from the CryoSat-2 satellite mission and high-resolution numerical modeling. "With our many years of expertise in processing CryoSat-2 data, we were able to make a significant contribution here" reports Dr. Veit Helm, an expert in satellite altimetry at AWI. 

"Our data show us that what we see happening at the front reaches far back into the heart of the ice sheet. We can see that the entire basin is thinning, and the surface speed is accelerating. Every year the glaciers we've studied have retreated further inland, and we predict that this will continue over the coming decades and centuries. Under present day climate forcing, it is difficult to conceive how this retreat could stop," says first author Shfaqat Abbas Khan, a professor at the Technical University of Denmark (DTU Space).

Previous models made it difficult to estimate how much ice Greenland's glaciers are losing and how far into the ice sheet this process extends. This is because the inland ice is difficult to access for observations, limiting accurate predictions. Using a combination of remote sensing, in situ observation and modeling, the researchers have now been able to show in their study how the Northeast Greenland Ice Stream is changing not only at its edge, but also far into its interior. "The close combination of these three approaches allows great progress and is key to model glaciers, their dynamics and their impact on sea level realistically," says co-author Prof. Angelika Humbert, a glaciologist at AWI.

AWI has been conducting in-situ and airborne observations at Zachariae Isstrøm and its neighbor Nioghalvfjerdsbræ for many years to gather important information about glacier evolution. This will allow them to fill data gaps and enable more robust simulations of glacier dynamics.

Original publication

Shfaqat Abbas Khan, et. Al.: Extensive inland thinning and speed-up of North-East Greenland Ice Stream. Nature (2022). DOI: 10.1038/s41586-022-05301-z