"System change is now inevitable. Either because we do something about it, or because we will be hit by climate change. '...

"We need to develop economic models that are fit for purpose. The current economic frameworks, the ones that dominate our governments, these frameworks... the current economic frameworks, the neoclassical, the market frameworks, can deal with small changes. It can tell you the difference, if a sock company puts up the price of socks, what the demand for socks will be. It cannot tell you about the sorts of system level changes we are talking about here. We would not use an understanding of laminar flow in fluid dynamics to understand turbulent flow. So why is it we are using marginal economics, small incremental change economics, to understand system level changes?"

Friday, April 3, 2009

Wilkins Ice Shelf Disintegration proceeds



The narrow ice bridge that was all that was attaching the Wilkins Ice Shelf to Charcot Island has apparently cracked all the way through, though not in the intuitively obvious place, and large areas of the ice sheet are breaking off and forming icebergs. This is the second such event that has been observed, the precedent being further equatorward at the Larsen B site. While thus far the present event has been somewhat less abrupt than its predecessor, it is now comparable in scale and may continue deeper into the embayment now that the neighboring island no longer acts as a buttress.

(Most readers who follow the climate system will recognize that this does not contribute to sea level directly but will reduce the flow resistance of neighboring glaciers and thus will contribute to sea level rise in the future.) (Update: it actually does contribute a little bit.)

There are spectacular satellite photos of the event at the European Space Agency site.

Hat tip to Huntsville, Alabama's WHNT TV meteorologist Dan Satterfield.

6 comments:

WAH said...

In fact, it is not quite true that floating ice does not change sea level when it melts. This is because the density of the fresh water from the melted ice is lower than that of sea water. The effect is tiny, but still real. There was a nice paper about it last year in GRL, see http://www.agu.org/pubs/crossref/2007/2007GL030784.shtml

Dano said...

Ayup. Yet another indicator. Will society wake up, take notice, and act? (word verification says 'phythead', so signs are neutral)

Best,

D

Horia said...

amasing!
Can anybody explain why this ice shelf stayed with zero changes during almost a year ,and it totally desintegrated only in few hours?

David B. Benson said...

Horia --- First breakup was in Decemeber 2008. Its the end of summer there now.

Steve Bloom said...

IIRC the Wilkins is a (rarish) sea ice-based shelf without much glacier input.

chriscolose said...

WAH is correct about the density differences resulting in some sea level rise, but the difference is pretty negligible. I'm not even sure if this matters in climate prediction models