Tag: glacier

Tipping and other points

During the Copenhagen kerfuffle a lot of interesting stuff hit the web: here’s something that deserves a bit more air – a Proceedings of the National Academy of Science (PNAS) special issue on tipping elements in the earth system, edited by John Schellnhuber, the director of the Potsdam Institute for Climate Impact Research in Germany.

Tipping elements (or points, as Malcolm Gladwell would have them) are changes that once started take on a life of their own, and can’t easily be returned to their original state. In the climate system that might be the rapid loss of an ice sheet in a few decades or hundreds of years, while regrowing it might take many thousands. The PNAS special issue deals with nine: dust production in the Bodélé Depression in Chad, ENSO, Arctic sea ice and ice sheets, the Atlantic Meridional Overturning Circulation, deep ocean hydrates (not shallow sea bed, Siberian methane) — David Archer dubs them a “slow tipping point”, the Amazon rainforest (no “Amazongate” here, just a confirmation that concern is justified), monsoons, oceans, and policy responses to the climate challenge. And the best thing is that all the articles are available online, free (click on the link above). Schellnhuber contributes an introduction, and the Potsdam press release also provides a good overview. For some introductory thoughts, check out Tim Lenton’s discussion here.

Another recent example of a real tipping point is the Pine Island Glacier in West Antarctica. Recent modelling suggests that the glacier’s grounding line retreated beyond a ridge in 1996, and is now free to retreat by several hundred kilometres inland. This could happen in a hundred years and result in the loss of half of the ice in the glacier — enough to raise sea level by 24cm. New Scientist reports:

Observations already show that the model severely underestimates the rate at which PIG’s grounding line is retreating, says Katz. “Ours is a simple model of an ice sheet that neglects some important physics,” says Katz. “The take-home message is that we should be concerned about tipping points in West Antarctica and we should do a lot more work to investigate,” he says.

Amen to that.

Oops, he did it again

It pays to beware of leaving hostages to fortune: saying or doing something that might cause you some embarrassment in the future. There’s a very fine example in this recent blog post by Ian Wishart, titled “Top 10 global warming myths exposed“. It takes the form of a piece Wishart has submitted to the Coromandel Chronicle, taking exception to a column by Thomas Everth [PDF]. He begins:

In a blatant effort to mislead and scare your readers, Green blogger Thomas Everth makes more errors in the first 200 words of his recent global warming diatribe than I have made in my last three books totalling around 400,000 words.

As hostages go, that’s pretty impressive. Wishart proceeds to find fault with ten of Everth’s opening points, but does he make a few mistakes of his own in the process? I’m going to take a long, hard look: is that hostage feeling lucky?

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Ain’t no mountain high enough

Tutoko.jpg

New Zealand’s glaciers are continuing to lose mass according to this year’s aerial survey of the Southern Alps by NIWA scientists. The figures released today show that over 2008-9 the glaciers lost much more mass through melt and calving than they gained from snowfall. From the press release:

NIWA Snow and Ice Scientist Dr Jordy Hendrikx says weather patterns over the course of the year from April 2008 to March 2009 meant that overall the glaciers had lost much more ice than they had gained. This was mainly due to the combination of above normal temperatures and near normal or below normal rainfall for the Southern Alps during winter, and La Niña-like patterns producing more northerly flows creating normal-to-above normal temperatures, above normal sunshine, and well below normal precipitation for the Southern Alps particularly during late summer.

NIWA have also released some of the wonderful pictures taken by Dr Hendrikx during the flights. The photo above shows Mt Tutoko (the highest mountain in Fiordland), with the Donne glacier tumbling down its flanks towards the Hollyford valley and calving into a lake. Below is Mt Aspiring with the Bonar glacier on the left. Must be one of life’s finer jobs — being paid to fly around the magnificent scenery of the nation’s spine. See also: TV One’s report on this year’s flights, and HT’s coverage of last year’s figures.

BonarAspiring.jpg

Titanic days

Awesome (defined as extremely impressive or daunting; inspiring great admiration, apprehension, or fear) time-lapse pictures of the calving face of the great glacier at Ilulisat, Greenland pouring ice into the ocean — the single biggest ice discharge of any northern hemisphere glacier. Greenlanders reckon this is where the iceberg that sank the Titanic originated. The ice face is huge — the helicopter at the beginning of the clip gives some sense of scale — but the ice is actually 1,000 metres thick at that point. This clip is only an appetiser for the Extreme Ice Survey‘s James Balog providing more detail, and showing many more truly awe-inspiring images in a recent TED talk. Well worth 20 minutes of anyone’s time — as Balog says, it’s hard to ignore the evidence of what’s happening up North.

[Hat tip to Riatsala in a comment yesterday]

(Arctic) Change is now

The World Wide Fund for Nature (WWF) has just published a new report on climate change in the Arctic — Arctic Climate Feedbacks: Global Implications [PDF], and it’s a fascinating read. Over the last two years I’ve blogged regularly on the changes being seen in the Arctic — sea ice reductions, melting of the Greenland ice sheet, the danger of increased carbon release from permafrost and sea floor methane hydrates, and the possible impacts on northern hemisphere weather patterns and climate. WWF’s report — written by some of the leading names in the field (including Serreze, Stroeve, Cazenave, Rignot, Canadell, and for the methane hydrate chapter Shakhova and Semiletov) — pulls together all those strands to paint a picture of a region undergoing rapid change. The authors provide a fully-referenced review of our current understanding of the processes at work as the pole warms, with chapters covering atmospheric circulation feedbacks, ocean circulation changes, ice sheets and sea level, marine and land carbon cycle feedbacks, and sea floor methane hydrates. It’s compelling stuff, and well worth reading in full, but for this post I want to focus on the excellent overview of methane hydrate feedbacks provided by Natalia Shakhova and Igor Semiletov.

Continue reading “(Arctic) Change is now”