Tag: ice

Freezing

NSIDCmultiyear081004.gif With this summer’s Arctic sea ice minimum done and dusted, the first analyses of the season are beginning to appear. The NSIDC’s latest press release suggests that ice volume decline continued:

NSIDC Research Scientist Walt Meier said, “Warm ocean waters helped contribute to ice losses this year, pushing the already thin ice pack over the edge. In fact, preliminary data indicates that 2008 probably represents the lowest volume of Arctic sea ice on record, partly because less multiyear ice is surviving now, and the remaining ice is so thin.”

Click on the thumbnail above to see the big picture on multi-year ice reduction. The large area of red first year ice will obviously become second year ice next year, but the continuing reduction in thicker, older ice sets the stage for further big losses the next time the Arctic has a warm summer. The European Space Agency confirms this, quoting US National Ice Centre Chief Scientist Dr Pablo Clemente-Colón:

Although last year’s summer sea ice minimum extent record was not broken, a record amount of the thickest multiyear sea ice was actually lost this season impacting the thickness of the sea ice presently found around the North Pole region and setting the stage for more minimum or near-minimum records in upcoming years.

The ESA also provide some nice images…

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Every loser wins

The Arctic sea ice has started its autumn freeze up. Both the NSIDC and Cryosphere Today metrics show significant increases over their minima for the year, and so I’ve settled my debts to Malcolm and William “Stoat” Connolley. To settle Malcolm’s bet, I have donated $40 to Women’s Refuge (they’re sending a receipt, which I will happily post when it arrives if Malcolm so wishes), but with William I have elected to go “double or quits” on next year’s minimum. He does get a signed copy of Hot Topic though, and it should be with him by the weekend or early next week. To ensure carbon neutrality for the airmail shipping, I will plant an extra tree in the truffière… 😉

So what are the prospects for next year? Will the ice consolidate a little more, hover around the 2007 and 2008 level, or beat 2007? My gut-feel (and, in the absence of further info on how the ice finished this summer, that’s all it is) is that the odds remain roughly 50/50 on a new record. A warmer winter than last, or a sunnier summer is all that it might take to cause greater loss. So I’m happy with my double or quits – at least for the time being.

NSIDC September 24th update here (note continuing reduction in multi-year ice). NASA reports that ice loss in August was fastest ever seen – and produced an excellent animation of ice coverage over the year (in right column, third image down). Meanwhile, ice loss from Greenland is also increasing (there should be much more concrete info later this year when the 2008 summer season reports start appearing), and a team at Ohio State University are beginning the Arctic System Reanalysis project, which will “merge a decade of detailed atmospheric, sea, ice and land surface measurements into a single computer model-based synthesis. The coupling of these immense data sets will produce complex and instructive descriptions of the changes occurring across the normally frigid, remote region.” The project will generate about 350 TB of data. Won’t run on my Macbook Pro, then… Plus there’s some learning about ice going on at the blog of a real ice man – Bob Grumbine’s More Grumbine Science here.

Ain’t no mountain high enough

LonnieThompson.jpg It’s not often you get discussion of ice cores over the breakfast muesli, but Kim Hill’s Saturday Morning show on Radio NZ National today featured a long chat with Lonnie Thompson, the renowned paleoclimatologist who has spent most of his career drilling into high altitude ice caps and glaciers to investigate past climate. The blurb to Mark Bowen’s book about Thompson claims that he “has spent more time in the death zone— the environment above eighteen thousand feet— than any man who has ever lived.” It’s a fascinating 30 – 40 minutes, well worth a listen for the insight he provides into the changes taking place in the cryosphere. Audio will be here later on today.

I’m (possibly/probably) a loser

200809NSIDCmin.pngThe National Snow & Ice Data Centre in the USA has declared that this year’s minimum Arctic sea ice extent has been reached – 4.52 million square kilometres on September 12th, only 390,000 km2 more than the record 2007 minimum (and 2.24 m km2 below the 1979-2000 average minimum). It looks as though their line may bump along the bottom of the graph for a while, so there may be some potential for that number to reduce a little. Their figure for Sept 12 is 9.4 percent above the 2007 minimum, so unless there’s some unprecedented melt over the next couple of weeks, I am prepared to accept that I have lost my bet with Malcolm (see comments here and at Poneke! here), which was based on NSIDC numbers. My cheque book is at the ready.

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Beat the retreat

MarionArawata.jpg New Zealand’s glaciers lost 2.5 km3 (2.2 billion tonnes) of permanent ice from April 2007 to March 2008, leaving 44.9 km3 of ice in the Southern Alps – the lowest amount since NIWA began regular surveys 32 years ago. The picture (credit: “Mr Ice” Trevor Chinn, click for larger image) shows the Marion Glacier in the Arawata Valley in South Westland which has recently retreated above its proglacial lake. The annual survey uses a fixed wing aircraft to record the height of the snowline at the end of summer (and Trevor gets to take the pix). Jim Salinger, NIWA’s principal scientist, says that the survey shows that the glaciers had lost a lot more ice than they had gained over the preceding winter [press release]:

“As a result of La Niña conditions over New Zealand, more easterlies, and warmer than normal temperatures, there was less snowfall in the Southern Alps and more snowmelt. The higher the snow line, the more snow is lost to feed the glacier. On average, the snow line this year was about 130 metres above where it would need to be to keep the ice mass constant.”

More below the fold…

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