0 Another one bites the dust

Another ice shelf bites the dust, to little surprise in the polar community. In this case, it's the Wordie ice shelf, and you can see a photo and a short write up at:
http://www.reuters.com/article/environmentNews/idUSTRE5332BU20090404

The reason I'm not surprised, and anybody who has been reading the science is not surprised, is that we knew years ago that warming was going to lead to the breakup of ice shelves. See, for example:

Rapid disintegration of the Wordie Ice Shelf in response to atmospheric warming, by C. S. M. Doake & D. G. Vaughan. That was 1991. You do have to remember that glaciologists are used to things that move at glacial speeds.

The breakup was more specifically tied to atmospheric warming in a more recent (1996) paper by D. G. Vaughan & C. S. M. Doake Recent atmospheric warming and retreat of ice shelves on the Antarctic Peninsula. The authors cite the earliest suggestions of problems for Antarctic ice shelves in a warming world as Mercer's 1978 paper
West Antarctic ice sheet and CO2 greenhouse effect: a threat of disaster. Rather drastic title. But it serves to both establish that the collapse of these ice shelves due to CO2-induced climate change is an old issue, and to provide yet another example of a scientist in the 1970s who was not expecting 'another ice age' any time soon.

The scientific question left on ice shelf collapses on the Antarctic peninsula is not whether, but which one is going to go next, and how soon. For the ice shelves farther to the pole -- which are the big ones and of the greatest concern (the reason for the 'threat of disaster' in Mercer's title) for the future, we still have several scientific questions about whether, and what happens how fast if they do go.

Some folks are making comments which mix up sea ice and ice shelves. Please don't do that! See my note about ice types for the simple differences between the sorts of ice.

It's also been mentioned that the breakup of ice shelves can't change sea level. This isn't actually true. I'll take up the details in two notes to come. First, why it isn't true (you can get ahead by reading the Sea Level Change FAQ -- same process that means sea ice can change sea level applies to ice shelf ice). Second, why it is someone else published it first, even though I had the answer 10 years earlier. A bit of how science is done, and reminder that scientists are fallible.