A new paper by Bougamont et al suggests that the sub-glacial surface in much of Greenland is more muddy than rocky in structure, so that as basal water accumulates, it will melt and become slippery. This means that the Greenland ice sheet may fail more quickly than recent estimates have indicated, which in turn have been faster than earlier estimates made before the role of basal water was understood.
A brief report by Sophie Yeo at Responding to Climate Change provides an introduction to the story.
The upshot is that year-over-year variations (including steady increases) in surface melt maximum can contribute significantly to destabilizing the ice sheet. The authors do not venture a modified projection of Greenland ice sheet failure time scale. A time scale of just a few centuries was already on the table before this new research.
In the context of recent surprising and extreme decreases in Greenland albedo this gives us some substantial new reasons for concern about sea level. (Photo: Dr. Jason Box)