Expedition2010.Org Blog: Arctic is continuing down in a death spiral. Every bit of evidence we have says the ice is thinning

UPDATE: National Snow and Ice Data Center (NSIDC) director Mark Serreze slammed the anti-science disinformers yesterday:

There are claims coming from some communities that the Arctic sea ice is recovering, is getting thicker again. That’s simply not the case. It’s continuing down in a death spiral.

Every bit of evidence we have says the ice is thinning. That means there’s less energy needed to melt it out than there used to be.

Certainly the latest analysis from the Polar Science Center bears that out:

Arctic sea ice volume, extent, and area continue to shrink apace as we approach the dramatic end to this year’s melt season. The NSIDC tells me extent dropped to 4.76 million square kilometers today — which is below the majority of even the most recent expert predictionslogged with the Study of Environmental Arctic Change (SEARCH).

Here’s one of the sea ice graphs on the web I haven’t posted before, from the University of Bremen (click to enlarge), one of the resources that SEARCH recommends:

http://www.iup.uni-bremen.de:8084/amsr/ice_ext_n.png

An unexpected source suggested I ask NSIDC scientist Julienne Stroeve to explain what is going on. I did, and she replied:

We’ve dropped to 4.76 today.
All the old ice that was transported into the Chukchi Sea over the winter is gone and about 50% of the old ice in the Beaufort Sea remains.
Arctic-wide there has been a 60% reduction in ice ages 5+ years from the end of April to the end of August. Atmospheric circulation patterns in summer 2010 were not as favorable to ice loss as in 2007 and 2008, so this suggests that the ice may have been on the thin side.
I haven’t looked into detail on the SSTs, and there is compression towards the pole in the Chukchi that is contributing, but given the continued ice loss this month, which is double that of climatology, and faster than in 2007 and 2009 (but a bit slower than 2008), I’m thinking it’s a combination of warmer SSTs and thin ice that is continuing the current ice loss.

The water is warm — see Captain’s log from the Chukchi Sea: “The water temperature is 7.5 degrees. If we weren’t sailing, it would be a great temperature for a swim!”; “North of Point Hope. Water temperature: 9.0˚C.”
Sometimes it is the wind that helps push the ice together and drive down sea ice extent. This year’s rapid end-of-season extent drop is partly due to some compression, but appears to be driven more by warmer waters and thinner ice, which is not a big surprise — see Study: “It is clear … that the precipitous decline in September sea ice extent in recent years is mainly due to the cumulative loss of multiyear ice.”
Human emissions of greenhouse gases are warming the planet and polar amplification is accelerating that process in the Arctic.
Featured Comment (from Steve Bloom): Joe, I’ll suggest again posting this animation (by Jack Taylor via Neven’s Arctic sea ice blog) of UniBremen ice concentrations from 8/26 through 9/8. It demonstrates perfectly the thin and mobile ice conditions plus the effect of the dipole anomaly.
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