Hat-tip to Twemoran and the Idiot Tracker ( I had to read it in two places within 15 minutes of each other to get the significance of this):
Canadian Ice Shelves Breaking up at High Speed
As Patrick Lockerby noted back in April:
The oldest non-glacial ice in the northern hemisphere is a small remnant of the former Ellesmere Ice Shelf which began forming about 5500 years ago. That remnant is breaking up. Where the ice shelf has vanished the fjords are free of perennial ice for the first time in 3000 to 5500 years. It seems likely that very soon the oldest non-glacial ice will be a mere 5 years old, or less.
And in the seminal paper by Polyak et al 2010, History of sea ice in the Arctic, it says:
The severity of present ice loss can be highlighted by the breakup of ice shelves at the northern coast of Ellesmere Island, which have been stable until recently for at least several thousand years based on geological data.
Here are the visuals (found on this web page from Carleton University):
Map of Ellesmere Island ice shelves on August 8th 2005: Ice shelves are outlined in black. Blue denotes the coast of Ellesmere Island. Left to Right: Serson, Petersen, Milne, Ayles, Ward Hunt and Markham, MODIS images from the Rapid Response Project at NASA/GSFC. Maps courtesy of Derek Mueller, Carleton University.
By July 21st 2011 the Serson Ice Shelf was divided into Serson A and B. The Ayles and Markham Ice Shelves had completely disappeared:
After this year's melting season Serson B is all but gone on August 26th 2011, and now it's the large Ward Hunt Ice Shelf that has been divided into a western and eastern part.
Again, from the Carleton University web page:
The Serson Ice Shelf was reduced from 205 km2 to two separate remnant sections in 2008: Serson A, a 42 km2 floating glacier tongue and Serson B (35 km2) just to the north. This past summer, the Serson A was reduced to a 25 km2 and the Serson B was reduced to 7 km2.
Last year, the Ward Hunt Ice Shelf was 340 km2 with its central area broken into pieces. This past summer, the central area disintegrated into drifting ice masses, leaving two separate ice shelves: a western (227 km2) and an eastern (74 km2) Ward Hunt Ice Shelf.
In 1906, the Ellesmere Island ice shelves were an estimated 8900 km2 and were reduced to 1043 km2 over the last century. The total extent of Ellesmere ice shelves is now 563 km2 or 54 per cent of what it was prior to the loss of the Ayles Ice Shelf in August 2005.
Edit: Below in the comments Michael Fliss has some great links with animations of calving events of various shelves in 2008.
And here's the accompanying press release:
(Ottawa) – Canadian ice shelves are changing at an unexpected rate, with almost 50 per cent lost in the last six years, experts say.
Carleton University’s Derek Mueller says this summer has resulted in the near-complete loss of one important ice shelf and the largest remaining shelf separated into two distinct remnants.
“This is our coastline changing,” says Mueller, a researcher in the Department of Geography and Environmental Studies. “These unique and massive geographical features that we consider to be part of the map of Canada are disappearing and they won’t come back.”
After taking stock of this summer’s changes using satellite imagery, Mueller notes that the ice shelves have declined appreciably nearly every summer since 2005. This rapid attrition will have lasting effects, he says.
This summer alone, most of the Serson Ice Shelf broke away and the Ward Hunt Ice Shelf has now split into two separate pieces. This ice loss equals up to three billion tonnes or about 500 times the mass of the Great Pyramid of Giza.
“Since the end of July, pieces equaling one and a half times the size of Manhattan Island have broken off,” says Luke Copland, researcher in the Department of Geography at the University of Ottawa. He warns that oil companies need to sit up and take notice as more icebergs will be floating down from the North and may threaten rigs in locations such as the Beaufort and Chukchi seas.
Mueller blames a combination of warmer temperatures and open water for recent ice shelf calving. “The ice shelves were formed and sustained in a different climate than what we have now. As they disappear, it implies we are returning to conditions unseen in the Arctic for thousands of years.”
Arctic ice shelves, old and thick, are relatively rare. They are markedly different than sea ice, which is typically less than a few metres thick and survives up to several years. Canada has the most extensive ice shelves in the Arctic along the northern coast of Ellesmere Island. These floating ice masses are typically 40 metres thick (equivalent to a 10-storey building), but can be as much as 100 metres thick. They thickened over time via snow and sea ice accumulation, along with glacier inflow in certain places, and are thought to have been in place over most of the past several thousand years .
Mueller and Copland’s research into ice shelf changes is funded by the Natural Sciences and Engineering Research Council of Canada and ArcticNet. Natural Resources Canada’s Polar Continental Shelf Program provided logistical support for the research conducted in the Canadian Arctic.
Background:
The degradation of the Serson Ice Shelf was noted by the Canadian Ice Service, Environment Canada at the beginning of August (http://www.ec.gc.ca/glaces-ice/). CIS provided imagery that was important for the delineation of the current ice extent.
The Ellesmere Island ice shelves are known to harbour unique microbial life, which are particularly vulnerable to the impacts of climate change.
Professor Warwick Vincent, director of the Centre for Northern Studies at Laval University, has studied these organisms since 1998. His team is based each summer at Ward Hunt Island in Quttinirpaaq National Park to monitor the ecological shift from ice-dependent to open water ecosystems.
Professor John England, an NSERC Northern Chair at the University of Alberta, has inferred that the ice shelves have been in place for up to 5,500 years from examining driftwood and other materials that he found behind them.
The Serson Ice Shelf is named after Harold Serson (1926-1992) a scientist with the Defence Research Board who contributed to the study of ice shelves and related phenomena along the northern coast of Ellesmere Island.
Images and maps are available at:
http://http-server.carleton.ca/~dmueller/iceshelves/summer2011.html
Soon it will not be worth giving them names. Or maybe better Costa del Serson or Costa del Hunt?
Posted by: Espen | September 28, 2011 at 20:01
Poignant to think that Harold Serson's colleagues probably thought that they were honoring him in quasi-permanent fashion.
"Sic transit gloria mundi"--but not always quite that suddenly.
Posted by: Kevin McKinney | September 28, 2011 at 22:04
Thanks for the giant plug, Neven!
There is a very high resolution image of the remnants of the Ward Hunt ice shelf in 2010 over at NASA.
http://earthobservatory.nasa.gov/IOTD/view.php?id=45463
MODIS images show that the break-up continued after the date of the NASA image - August 18 2010.
The large remaining piece is bonded at each end to ice domes. The lines between the shelf ice and the dome ice can just about be seen in some MODIS images.
I have had my eye on this area throughout summer. The shelf appears to have some fissures but overall it hasn't budged.
MY best guess is that because it is so well bonded to solid ice at each end it will not detach as spectacularly as other shelves but will first break up in situ. Maybe as early as next summer.
Posted by: logicman | September 28, 2011 at 22:24
Maybe a future post around this topic could be titled:
"We did it to our Shelves"
Posted by: Andrew Xnn | September 28, 2011 at 22:59
CBC coverage of the story is here:
http://www.cbc.ca/news/technology/story/2011/09/28/north-ice-shelves.html
The written copy adds nothing to Neven's post, but there is a video interview with Dr. Mueller that is of interest.
Posted by: Kevin McKinney | September 28, 2011 at 23:44
I noticed this new post this morning but at work they still have me on IE6 and I am not supposed to comment at blogs.
Anyway, I seem to remember that when the Arctic becomes "ice free" they actually expect some ice to remain, the stuff that would be toughest to melt. I thought it was the Canadian shelves. Maybe someone can correct me if I was wrong. In either case it looks like this permanent ice is much more frail than that.
Trying to find out I did some digging in news archives and while I didn't find what I was looking for I did find this bit which may be of interest:
Neven, thank you for this year's coverage of the Arctic, for covering this story, and for keeping this blog open even as the Arctic does its annual "recovery."Posted by: Timothy Chase | September 29, 2011 at 03:33
How much ice is in the Ellesmere ice sheets on land? With the ice shelves breaking up, the glaciers will flow faster into the ocean. Will that raise the oceans by milimeters? Or inches?
We live on a barrier island, every inch counts!
Posted by: Rich and Mike Island | September 29, 2011 at 06:46
Below is a favorite image of mine of Dr. Derek Mueller wading in a meltwater lake of the Markham Ice Shelf. This is the true image of our graphs, our math, our maps of bright, false colors: The meeting of two ends of the food chain that need each other.
http://www.people.trentu.ca/~dmueller/iceshelfloss2008/markham.html
Posted by: Michael Fliss | September 29, 2011 at 07:54
It is just stunning to see in the animations below how rapidly, in only days, these massive areas of ice break away from the ice shelf where they have been secured for thousands of years and stream towards the Beaufort Sea.
http://www.people.trentu.ca/~dmueller/iceshelfloss2008/serson.html
http://www.people.trentu.ca/~dmueller/iceshelfloss2008/wardhunt.html
Posted by: Michael Fliss | September 29, 2011 at 08:06
A unique ecosystem was lost with the crumbling of the Ward Hunt Ice Shelf and the destruction of its epishelf lake. The change was sudden and gone was the chance to study microbial communities that form the base of the food chain from which arctic ocean life draws its energy.
http://earthobservatory.nasa.gov/Features/wardhunt/
Posted by: Michael Fliss | September 29, 2011 at 08:13
Thanks for those great links, Michael!
And thanks to you too, Timothy.
Posted by: Neven | September 29, 2011 at 08:37
Ward-Hunt's bifurcation was noted on September 11th on this blog, it was still holding together on the 9th.
The discussion was in the historical minimum in sea ice extent tread. ;-)
Posted by: Twemoran | September 29, 2011 at 20:40
Here's an article about 2002 observations regarding the breakup of the Ward Hunt Ice shelf:
http://earthobservatory.nasa.gov/Features/wardhunt/
"Changes became apparent in the 1950s when ice-shelf investigators examined early 20th-century records of Arctic explorer Robert Peary. “It was already clear there was a vast region — much greater than today — of thick, ancient ice floating on the ocean. We estimate that this ice has now retreated by about 90 percent relative to Peary’s observations,” said Vincent."
Posted by: Andrew Xnn | September 29, 2011 at 22:26
Here's a 1986
http://pubs.aina.ucalgary.ca/arctic/Arctic39-1-15.pdf
"The largest observed ice island calving occurred at Ward Hunt Ice Shelf (Fig. l ) , where almost 600km2 of ice broke away at some time between August 1961 and April 1962 (Hattersley-Smith, 1963)."
and
"During the period 1959-74 some 48 km2,involving 3.3 km3, of ice calved from Milne and Ayles ice shelves and the
remainder of Ayles Ice Shelf moved some way out of the mouth of Ayles Fiord. Although the total loss of ice from these events is
much less than the massive loss from Ward Hunt Ice Shelf, it still constitutes a considerable loss, indicating the ice shelves remain unstable and prone to disintegration. In 1982 Area B (Fig. 2B) was severely fractured and considered likely to disintegrate. This had occurred by spring 1985. Despite the large change at the front of Ward Hunt Ice Shelf in 1962, the ice front remains changeable, since between 1980 and 1983 a total of about 80 km2 of ice was lost,including three large ice islands (Jeffries and Serson, 1983).
Any ice front can be expected to be unstable,and the periodic calving of ice islands and thick sea ice might be a normal process akin to, but smaller scale than, iceberg calvings from a glacier. Further losses from the ice shelves and landfast sea ice of northern Ellesmere Island are to be expected, and it is clear that there is a quite rapid degeneration of thick sea ice where calvings occur."
Posted by: Andrew Xnn | September 29, 2011 at 22:41
Neven,
Just posted a response to your post, which follows on from Andrew Xnn's point about the earlier Vincent paper of 2001.
http://dosbat.blogspot.com/2011/09/loss-of-ellesmere-ice-shelves.html
In my usually rambling style I digressed to address Pierre over at Tamino's.
Posted by: Chris Reynolds | September 30, 2011 at 21:55