Here’s the latest imagery of the Wilkins Ice Shelf from the European Space Agency’s amazing “webcam from space” page (the ice shelf is the black structure running from top left to bottom right — sea shows as white). This image was captured on Jan 24th, and clearly shows the narrow 2km neck referred to in my recent post. Take a look at the “webcam” — the animation is regularly updated as new images are processed. In Hot Topic, I remarked how satellite views of the earth enable my senses to work overtime — this is a fantastic near real-time example.
According to Alister Doyle, Reuters’ man in Antarctica (now that’s a job I’d like to try…), what’s left of the Wilkins Ice Shelf is on “the brink of collapse with just a sliver of ice holding it in place“. Earlier this week, Doyle reported on a trip with the British Antarctic Survey to the remnants of the ice shelf:
“We’ve come to the Wilkins Ice Shelf to see its final death throes,” David Vaughan, a glaciologist at the British Antarctic Survey (BAS), told Reuters after the first — and probably last — plane landed near the narrowest part of the ice. […]
BAS scientists and two Reuters reporters stayed about an hour on the shelf at a point about 2 km wide.
“It’s very unlikely that our presence here is enough to initiate any cracks,” Vaughan said. “But it is likely to happen fairly soon, weeks to months, and I don’t want to be here when it does.”
The Dominion Post‘s Paul Easton picked up the report, and managed to turn it into a story about sea level rise. Rather odd, because Doyle explicity notes:
Loss of ice shelves does not raise sea levels significantly because the ice is floating and already mostly submerged by the ocean. But the big worry is that their loss will allow ice sheets on land to move faster, adding extra water to the seas. Wilkins has almost no pent-up glaciers behind it. But ice shelves further south hold back vast volumes of ice. “When those are removed the glaciers will flow faster,” Vaughan said.
Unfortunately for us all, the most recent research suggests that the West Antarctic is warming significantly, as this image from the cover of this week’s Nature demonstrates rather well:
(E Steig/NASA)
See also: Guardian (UK) on Steig et al, Reuters on summer rain on the Antarctic Peninsula and the clear air down there, and a Danish researcher finds yet another reason to project that sea level rise this century will exceed IPCC estimates. More on land ice and the Arctic next week.
Some summer reading for NZ prime minister John Key: Christopher, Viscount Monckton of Brenchley (“I’m no potty peer”) has penned another of his dippy epistles — an “open letter” in the next issue of Free Radical, an NZ libertarian publication. His last, to John McCain, was a triumph of hilariously overblown climate crank nonsense. This looks to be no more succinct, but has the publishers of FR chortling with excitement. From Not PC:
This is pure gold; the world’s leading climate ‘skeptic’ explains to NZ’s new Prime Minister that the apocalyptic vision of catastrophic anthropogenic climate change is a lurid and fanciful account of imagined future events that was always baseless, was briefly exciting among the less thoughtful species of news commentators and politicians, and is now thoroughly and scientifically discredited.
Thoroughly and scientifically? How exciting. Let’s take a look.
It’s my pleasure to welcome another guest writer to Hot Topic — Peter Barrett, professor of geology at Victoria University, deputy director of the Climate Change Research Institute and former director of VUW’s Antarctic Research Centre. He is also convener of the ANDRILL science advisory panel. Last week, the Dominion Post carried this challenging article from Peter, and as it is not available at the DP web site, he has kindly agreed to allow it to appear as a guest column here. I hope it won’t be the last.
The world economy appears to be heading into the worst recession in 60 years. The nominal wealth of global markets has almost halved in the last couple of months and the United States Government alone is shoring up its banking system with $US7.6 trillion. Commentators expect conditions will be difficult in the next few years and say we need to get the fundamentals right.
Severe downturns have happened before and our society has recovered. Each time, confidence and perception of wealth has grown to exceed tangible assets and credible wealth by a big margin, and the illusion could not be sustained. Each time we had to go back to the fundamentals.
At same time the global ecosystem has suffered from economic growth and rising population. The United Nation’s Millennium Ecosystem Assessment of 2005 found that more than 60 percent of the Earth’s ecosystem services were degraded by overuse and pollution. The importance of ecosystem services to our economic and social well being is now understood as fundamental, though progress is slow.
Summer’s arriving on the Wilkins ice shelf, and its disintegration continues. New cracks are threatening to destroy the ice “bridge” that’s been holding the ice shelf pinned between Charcot Island (top left) and the Antarctic peninsula. This picture, captured by the European Space Agency’s ENVISAT satellite on November 26, shows the new cracks (coloured lines) and the dates they first appeared (NASA version here). If the chunk of ice under “21 July” breaks away, the long thin bridge will lose support and follow suit, the ESA analysts say.
Meanwhile, a team lead by Richard Alley at Penn State has worked out that ice shelf calving – where icebergs break away at the edge of an ice shelf – is critically influenced by the rate at which the ice shelf is spreading out. The PSU release notes:
For iceberg calving, the important variable — the one that accounts for the largest portion of when the iceberg breaks — is the rate at which ice shelves spread, the team reports in the Nov. 28 issue of Science. When ice shelves spread, they crack because of the stresses of spreading. If they spread slowly, those cracks do not propagate through the entire shelf and the shelf remains intact. If the shelf spreads rapidly, the cracks propagate through the shelf and pieces break off.
When ice shelves break up, the glaciers that feed them can speed up noticeably, dumping more ice into the ocean. Over recent years, the role of water as a lubricant for glacier flow has been receiving a lot of attention (rubber ducks were recruited as under ice research tools in Greenland this year), and the BBC reports that a sub-glacial “flood” under the Byrd Glacier which feeds ice at the rate of about 20 billion tonnes a year into the Ross ice shelf caused that to increase to 22 billion tonnes over 2006. It has since returned to normal.
Up north, the NSIDC reports (Dec 3) that it continues to be warmer than average, even though the sea ice is now covering the whole Arctic ocean.
According to Alister Doyle, Reuters’ man in Antarctica (now that’s a job I’d like to try…), what’s left of the Wilkins Ice Shelf is on “the brink of collapse with just a sliver of ice holding it in place“. Earlier this week, Doyle 
