Tag: Arctic sea ice

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.

From Russia, with love

group_with-bennett.jpg The work of the Swedish and Russian team on the Yakov Smirnitsky has finally found its way into the mainstream media, with Steve Connor at the Independent in London reporting the final post at the ISSS-08 blog I’ve been linking to for the last month or two. It’s not good news – they’ve found dramatic evidence of “methane chimneys” – bubbles of methane emerging form the sea floor and reaching the surface (instead of dissolving), and recorded atmospheric concentrations 100 times the normal background level. Connor reports on an email exchange with the Swedish team:

“We had a hectic finishing of the sampling programme yesterday and this past night,” said Dr Gustafsson. “An extensive area of intense methane release was found. At earlier sites we had found elevated levels of dissolved methane. Yesterday, for the first time, we documented a field where the release was so intense that the methane did not have time to dissolve into the seawater but was rising as methane bubbles to the sea surface. These ‘methane chimneys’ were documented on echo sounder and with seismic [instruments].”

At some locations, methane concentrations reached 100 times background levels. These anomalies have been seen in the East Siberian Sea and the Laptev Sea, covering several tens of thousands of square kilometres, amounting to millions of tons of methane, said Dr Gustafsson. “This may be of the same magnitude as presently estimated from the global ocean,” he said. “Nobody knows how many more such areas exist on the extensive East Siberian continental shelves.

In his piece, Connor uses the “standard” global warming potential for methane of 20 times CO2 (actually 25 is the official IPCC number), and correctly notes the short atmospheric lifetime of the gas. However, over that short lifetime (around 12 years), CH4’s GWP is more like 70 times CO2. Current global methane level is about 1750 ppb (1.75 ppm), so using a GWP of 25 it has the same warming effect as 43.75 ppm CO2. On the shorter 10 year time scale, that’s more like 122 ppm CO2. But Semiletov and his team on the Yakov Smirnitsky have measured concentrations 100 times greater than “normal”, which implies a local warming effect equivalent to 12,200 ppm CO2.

Luckily, it’s getting dark up there, but methane release on that scale might slow down the winter cooling in the region of the chimneys. Methane seeps in lakes can keep holes open in winter ice, so if persistent holes start appearing in the satellite maps of sea ice over the Siberian seas, we’ll know there’s a big issue (the holes would have to be huge to be seen in the data). We urgently need more info on the extent of the problem. There’s a lot of methane under the Siberian seas – we can only hope it stays there.

The NZ Herald reprints the Independent story, and the Guardian puts its own spin on it (a note of caution). This is a story that needs wider coverage, more informed scientific debate, and great deal more study. I hope Connor’s piece doesn’t get dismissed as hype, or “alarmism”. You don’t need to be an alarmist to find this stuff alarming…

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.

Continue reading “I’m (possibly/probably) a loser”

You ain’t seen nothing yet

arctic_AMSRE_29808.png This year’s Arctic sea ice minimum is now officially the second lowest in the record according to the National Snow & Ice Data Center in the US. On August 26, the ice extent stood at 5.26m km2, dropping below 2005’s 5.32m km2. The melt season still has several weeks left to run, and there are now suggestions that this year’s final minimum could be close to – perhaps even beat – last year’s record.

The NSIDC announcement has attracted a flurry of attention, and the media has been out trawling the usual suspects for quotes. The BBC reports:

Researchers say the Arctic is now at a climatic “tipping point”. “We could very well be in that quick slide downwards in terms of passing a tipping point,” said Mark Serreze, a senior scientist at the Colorado-based NSIDC. “It’s tipping now. We’re seeing it happen now,” he told the Associated Press news agency.

Adding to the interest, the European Space Agency released some interesting Envisat images of the state of the sea ice, and warned:

Following last summer’s record minimum ice cover in the Arctic, current observations from ESA’s Envisat satellite suggest that the extent of polar sea-ice may again shrink to a level very close to that of last year.

Meanwhile, Scientific American notes that the northwest passage is now open, and the Environment News Service does an admirable job of pulling all the info together – including recent work on possible rapid climate change around the Arctic. Earlier this month I was prepared to accept that I was going to lose my two bets on a new record minimum this year, so what’s been going on up north to change the outlook so dramatically?

Continue reading “You ain’t seen nothing yet”

The cracks are showing

petermann_breakup-1_web copy.jpg Arctic warming is taking a toll on more than sea ice: two of Greenland’s largest glaciers have experienced significant breakups over the last month, according to researchers at Ohio State University. The Petermann glacier in the far northwest of the island has lost a 29 square kilometre chunk of its floating ice tongue, and a big crack further back suggests another large piece could be about to break off. Meanwhile, the Jakobshavn Isbrae on the west coast – the largest glacier in Greenland – has retreated further inland this summer than at any time in the last 150 years, and possibly up to 6,000 years.

Further south, a team led by Ted Scambos at the University of Boulder has examined the rate of ice loss from the glaciers of south east Greenland, previously thought to be too small to contribute much to the overall mass balance of the ice sheet. Using a combination of laser altimetry and satellite imaging, they estimate that the region is losing about 100 cubic kilometres per year, a substantial part of the overall loss.

While we’re up there, the Arctic sea ice is still melting fast. Cryosphere Today shows the current area to be 3.68m km2, homing in on last year’s record. The fat lady’s still in her hotel…