Gone too soon

SIOJune2009iceages.jpg The June Sea Ice Outlook forecasts for the Arctic sea ice September minimum extent have been released today by SEARCH. Most groups are picking a minimum close to last year’s 4.7m km2, but the melt season is starting with an unusually small amount of multi-year ice. The report suggests that there is “a small but important probability of a major sea ice loss event this year, given that the ice is thinner and younger than previous years, combined with a possibility of atmospheric conditions that cause significant ice retreat.” The full range of forecasts is shown in this chart:


The range of individual outlook values is from 4.2 to 5.0 million square kilometers. All estimates are well below the 1979–2007 September climatological mean value of 6.7 million square kilometers. Half of the responses are in the range of 4.9–5.0 million square kilometers; the remaining estimates are in the range of 4.2–4.7 (Figure 1, above). The uncertainty / error values, from those groups that provided them, are close to 0.5 million square kilometers, thus many of the values overlap.

Interestingly, the forecasts showing the lowest minima are based on sea ice modelling driven by atmospheric forcings and initialised with current sea ice conditions. The projection by Jinlun Zhang (next to lowest in the chart) suggests that even with conditions like last year — that is, without the Transpolar Express of warm southerlies that set up in 2007 — the 2007 record could fall. On the other hand, a Russian scientist suggest thats Pacific sea surface temps could be priming a cooler pattern than last year.

The full report [PDF] is a very interesting read for all ice watchers (and gamblers). On this guide to the form, it looks as though I’ll lose my bets – but the weather over the next two months will be the deciding factor. Do I feel lucky…?

[Michael Jackson RIP]

Come a little bit closer


Estimates of when the Arctic will be substantially ice free in summer used to be out towards the end of this century. In 2007, the IPCC’s fourth report suggested that there would still be a fair amount of summer ice in the 2080-90s, but the record minima of recent summers have been forcing a rapid review of that expectation. We’ve had “rough” estimates of perhaps the 2030s, and even a suggestion it could happen as early as 2013 (follow the sea ice tag for earlier posts). A new paper by Wang and Overland in this week’s Geophysical Research Letters takes a more quantitative approach, by using six models and priming them with the sea ice state after the dramatic melt seasons of 2007 and 2008 (NOAA press release):

The area covered by summer sea ice is expected to decline from its current 4.6 million square kilometers (about 2.8 million square miles) to about 1 million square kilometers (about 620,000 square miles) – a loss approximately four-fifths the size of the continental U.S. Much of the sea ice would remain in the area north of Canada and Greenland and decrease between Alaska and Russia in the Pacific Arctic.

You can see the ice distribution in the small image at the top of the post (click on it for the larger original). The paper’s abstract tells us when this might happen:

Using the observed 2007/2008 September sea ice extents as a starting point, we predict an expected value for a nearly sea ice free Arctic in September by the year 2037. The first quartile of the distribution for the timing of September sea ice loss will be reached by 2028.

I interpret that to mean that the central expectation is 30 years, but some models suggest it could be a decade earlier. I wonder what effect that might have on the permafrost and methane hydrates… AP coverage here. Meanwhile, the NSIDC has declared this winter’s maximum extent was reached on February 28th, at 15.14 million km2 — the fifth lowest winter maximum in the record. They note:

The six lowest maximum extents since 1979 have all occurred in the last six years (2004 to 2009).

The betting season is now open. I’m on double or quits with Stoat (aka wmconnolley when he shows up here), but as he’s offering 2-1 to newcomers, I might be back to evens. I think I’m also betting with malcolm (Vibenna) again… I won’t offer any sort of form guide until later in the season, but (as ever) I’m hoping to lose, but at least half expecting not to.

[Jay & The Americans]

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.

Santa’s blues

Polarbear.jpg What’s a Christmas icon to do, when all the ice at the North Pole disappears in summer? This startling question is posed by the latest flush of media attention to events in the Arctic. First there was a National Geographic story on June 20th speculating that the North Pole would be ice free this summer (note: this is nothing to do with record minima, just do with ice around the pole itself). This was picked up by CNN, who went to Mark Serreze of the NSIDC in Boulder, Colorado for comment:

“We kind of have an informal betting pool going around in our center and that betting pool is ‘does the North Pole melt out this summer?’ and it may well,” said the center’s senior research scientist, Mark Serreze. It’s a 50-50 bet that the thin Arctic sea ice, which was frozen in autumn, will completely melt away at the geographic North Pole, Serreze said.

And then everything went quiet, until The Independent in Britain (referred to as The Indescribablyoverhyped on climate matters by Stoat) picked up the story and ran with it under the headline – Exclusive: no ice at the North Pole:

It seems unthinkable, but for the first time in human history, ice is on course to disappear entirely from the North Pole this year.

They seem to be having problems with their choice of tense, and quite how they can justify the “exclusive” tag escapes me… The Drudge Report noticed, and then everyone in the world had to have a go [Telegraph, AP(*)]. Andy Revkin at DotEarth covers it well, and RealClimate chips in with its own analysis. It won’t be long before the usual denialist sites will be spluttering with indignation, despite the fact that the North Pole has a very good chance of being open ocean this summer – even if a new record minimum is not set.

None of this has any relevance to the odds of my winning my various sea-ice bets, but it does give me a chance to post a few interesting Arctic-related links from the last week… As part of its beat-up, The Independent went to Peter Wadhams, professor of ocean physics at Cambridge University, for his impressions on the changes in the Arctic, and the BBC’s been carrying a blog from Liz Kalaugher aboard a Canadian icebreaker that over-wintered near Banks Island. Interesting stuff – note Liz’s comments about the weather. Meanwhile, across the melting ice, the Russian defence establishment is beginning to get worried about the impact of melting permafrost.

(*) The AP story uncovers this truly remarkable and hitherto unnoticed fact: “That pushed the older thicker sea ice that had been over the North Pole south toward Greenland and eventually out of the Arctic, Serreze said. That left just a thin one-year layer of ice that previously covered part of Siberia.” So that ice has somehow left the land and started floating towards the Pole. Be afraid, be very afraid…