Greenland Ice Sheet Failure May Be More Rapid Than Previous Estimates

Michael Tobis

Michael Tobis, editor-in-chief of Planet3.0 and site cofounder, has always been interested in the interface between science and public policy. He holds a doctorate from the University of Wisconsin - Madison in Atmospheric and Oceanic Sciences where he developed a 3-D ocean model on a custom computing platform. He has been involved in sustainability conversations on the internet since 1992, has been a web software developer since 2000, and has been posting sustainability articles on the web since 2007.

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.

box-snow-3-630

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)

Comments:

Jumping the gun a bit (I haven't read the paper: couldn't find a free copy) but how would more slippery bedrock significantly increase the ice-sheet's loss to the sea? Greenland's bedrock forms a mostly enclosed basin:

http://www.sott.net/image/s7/149597/full/Greenland3.jpg

One could imagine how, with the land shaped like that, the effect might even work the other way: that slippery bedrock might help send it all back uphill somehow.

Or are they only talking about one corner of Greenland? The NW Petermann outlet, perhaps?

A very striking image, thanks! However, your argument reminds me of the day after Katrina, wherein the headlines stated "New Orleans Dodged a Bullet" and the text explained said "the levees only broke in two places".

All it takes is one.

Oh well, just a thought.

It turns out they were looking at the Russell Glacier, one of the lesser plugholes.

http://www.aber.ac.uk/greenland/Russell.shtml

I think what they've found is that mushier bedrock prevents the increase in rock/ice friction you get when subglacial drainage channels are eroded in harder bedrock. So a strictly local effect - though one that might be relevant to other Greenland glaciers.