Greenland's future may be written under North Sea - BBC

There are clues to the near-future behaviour of a warming Greenland, and perhaps even a warming Antarctic, buried under the North Sea.

We've known about these valleys (often called "tunnel valleys" because they were incised under the ice sheet) for some time, but only in recent years has their true scale become apparent.

In places, the channels are more like canyons - up to 150km long, 6km wide and 500m deep.

The new advance is in describing the erosional processes involved in cutting the valleys, the speed at which that happened, and the amount of water that could be drained by them.

Researchers from the British Antarctic Survey (BAS) worked with a team led from the University of Sheffield to decipher the valleys' development as the northern ice sheet advanced and then retreated, between about 27,000 and 19,000 years ago.

"We started seeing these smaller channels at the base of the very large tunnel valleys, which seemed to meander and migrate over time," explained BAS PhD student James Kirkham.

"We worked out, basically, that when you force all that water through these smaller channels, they can be extremely erosive.

Streaming large volumes of water under an ice sheet can have implications for its stability.

On the other hand, if that water can be expelled rapidly in discreet channels, it might allow the ice sheet to sit down more firmly on the rock bed, to steady it.

These are the scenarios now being considered for the future of the Greenland Ice Sheet.

If, in the coming decades, similar valleys are cut under Greenland as were incised under Northern Europe's ancient ice sheet, how will that play into the future stability of Greenland.