Accelerating ice flow at the onset of the Northeast Greenland Ice Stream

A new study finds that the North East Greenland ice stream is not as stable as previously thought and that this will affect its future evolution. Mass loss near the ice-sheet margin is evident from remote sensing as frontal retreat and increases in ice velocities. Velocities in the ice sheet interior are orders of magnitude smaller, making it challenging to detect velocity change. Here, we analyze a 35-year record of remotely sensed velocities, and a 6-year record of repeated GPS observations, at the East Greenland Ice-core Project (EastGRIP), located in the middle of the Northeast-Greenland Ice Stream (NEGIS). We find that the shear margins of NEGIS are accelerating, indicating a widening of the ice stream. We demonstrate that the widening of the ice stream is unlikely to be a response to recent changes at the outlets of NEGIS. Modelling indicates that the observed spatial fingerprint of acceleration is more consistent with a softening of the shear margin, e.g. due to evolving fabric or temperature, than a response to external forcing at the surface or bed.

Automated summary

A new study reveals the instability of the North East Greenland ice stream and its potential impact on future evolution. By analyzing remote sensing data and GPS observations, researchers find that the shear margins of the ice stream are accelerating and widening, which is likely due to the softening of the shear margin caused by evolving fabric or temperature, rather than external forcing.