Late last year and early this year, various news stories reported the demise of the Ayles Ice Shelf, Ellesmere Island. On Dec. 29, 2006, National Geographic reported Giant Ice Shelf Breaks Off in Canadian Arctic and on Jan 4, 2007, CNN reported the story. The catastrophe actually occurred in August 2005, but no one noticed reported it until 16 months later.
From the story:
The mass of ice broke clear 16 months ago from the coast of Ellesmere Island, about 800 kilometers (497 miles) south of the North Pole, but no one was present to see it in Canada’s remote north. Scientists using satellite images later noticed that it became a newly formed ice island in just an hour and left a trail of icy boulders floating in its wake. (Watch the satellite images that clued in ice watchers) ..
The event registered as a small earthquake on instruments stationed 150 miles (250 kilometers) away, Warwick Vincent of Quebec’s Laval University told the CanWest News Service.
The Washington Post reported the story here showing the following picture from NASA. The Ayles ice shelf is visible in the center of the photograph at the lower part of the open water. They reported:
Within days of breaking free, the Ayles Ice Shelf drifted about 30 miles offshore before freezing into the sea ice.
Here is a jpg showing the break-up (thanks , Mark – also see link in Mark’s post below):
A specialist scientist (Vincent) said that such an event was unprecedented in the tennnnnnnnnn years that he had been studying the area.
Interestingly, Hattersley-Smith 1967 (Arctic Circular 17, 13-14 noted up in Jeffries 1986) had previously observed that the Ayles Ice Shelf no longer existed. Jeffries 1986:
In 1966 only scattered ice islands and slivers of ice shelf were observed in Ayles Fjord (Hattersley-Smith 1967). Hattersley-Smith concluded that Ayles Ice Shelf no longer existed,
Jeffries 1986 went on to say that, as of 1986, it was known that the Ayles Ice shelf had actually moved 5 km out of Ayles Fjord, a position that it still occupied in 1984 (and presumably up to August 2005):
but this is now known not to be the case. Much of Ayles Ice Shelf, an area of about 100 km2, remains in the mouth of Ayles Fjord, but in a much more exposed position than in 1959.
So the calving of the Ayles Ice Shelf appears to have been at least a two-stage process – breaking off of its connection to land in the early 1960s and the most recent move into the polar ice pack.
Jeffries 1986 speculated that the cause of the original calving in the early 1960s coincided with a massive calving at the Ward Hunt ice shelf attributed to a coincidence of tidal and seismic events:
The cause of the massive calving of ice from Ward Hunt ice shelf has been attributed to the coincidence of tidal and seismic events in February 1962 that created a critical condition in the ice shelf and ultimately caused the calving event (Holdsworth 1971) …
Jeffries 2002 reports that, in some cases, multiyear landfast sea ice (MLSI) has re-occupied areas formerly occupied by ice shelves and may be incipient ice shelves.
References:
Jeffries, Martin O., 1986. Ice Island Calvings and Ice Shelf Changes, Milne Ice Shelf and Ayles Ice Shelf, Ellesmere Island, N.W.T.. Arctic 39 (1) (March 1986) http://pubs.aina.ucalgary.ca/arctic/Arctic39-1-15.pdf
Jeffries MO. 2002. Ellesmere Island ice shelves and ice islands. In Satellite Image Atlas of Glaciers of the World: North America, Williams RS, Ferrigno JG (eds). United States Geological Survey: Washington, DC; J147–J164. http://pubs.usgs.gov/prof/p1386j/iceshelves/iceshelves-lores.pdf (This is an interesting account of ice shelves).
Climate Audit 
30 Comments
I’ll use the S word. I am growing increasingly sceptical that all ice masses labeled “ice shelves” have been / are in fact of glacial origin at all (as opposed to be sea ice, especially heavily compressed sea ice mashed together with snow accumulations). It is very tricky trying to tell the difference between sea ice using aerial and space images, and even on the ground, unless the surface is free of snow cover, it’s still tricky.
Sadlov, many of the Canadian ice shelves are explicitly NOT of glacial origin – Ive seen this stated in many of the sources Ive read.
RE: #2 – then they are not ice shelves. They are shorefast sea ice.
Steve S – if you look at Jeffries’ articles (or other similar) articles, they distinguish between glacial ice shelfs and sea-ice ice shelves. I don’t think that there’s any misconception on this particular count. The Ellesemere ice shelves appear to be pretty unusual though.
Sadlov, they BEGIN as shorefast sea ice, and are thickened and built by accumulations of snow over time in to stable thick shelves.
There is no secret about this – it is basic to the discussion about these ice shelves.
Animation (2006) Ayles Ice Break
http://heartspring.net/ayles_ice_shelf_iceburg.html
Animation (2001-2003) Ellesmere Island, Disraeli Fjord
http://heartspring.net/ellesmere_island_ice_shelf.html
“Ellesmere Island contains a range of unique aquatic ecosystems: ice shelves, epishelf lakes, meromictic lakes and tundra ponds. The perennial ice types in these ecosystems are at critical thresholds of sensitivity to climate forcing. All of these environments are now showing evidence of pronounced climate impacts, and movement across these thresholds.” – DR Mueller, WF Vincent, M Rautio & P Van Hove Centre d’àÆ”¬°tudes Nordiques, Université Laval – MO Jeffries, Geophysical Institute, University of Alaska Fairbanks
Here’s the full Vincent quote:
Imagine that – unprecedented for over tennnnn years.
RE: #5 – ” they BEGIN as shorefast sea ice, and are thickened and built by accumulations of snow over time in to stable thick shelves.”
How can any sea ice feature be considered stable? That is an oxymoron.
How can any “sea-ice” shelf be adequately dated? Dating of the ice itself only reveals the date at which the sea ice formed, NOT the date when it bacame landfast.
Sadlov – They turn into a grounded shelf. They become thickened and stationary.
HOW stationary they become is part of the dating question, of course.
The Ellesmere shelfs appear to be tangent rather than grounded. The articles describe accretion to the ice shelfs from below (which is inconsistent with grounding in the greater part of the ice shelf) and ablation from above. It’s an interesting concept – that’s how the arctic cod fossils and sponge fossils move to the surface. Grabbed by a temporary touchdown and then moving upward as ice is accreted from below and ablated from above. Interesting, n’est-ce pas?
I was just looking at the photo again and suddenly realized that the calfing shown in the mini-movie isn’t the largest one documented in the photo. Look just above the shelf that is moving at the one already partly embedded in the sea ice. Then look at its bottom edge and compare that with the fjord at the right side of the picture. It’s a perfect fit. And actually the movie shows this berg moving a bit too.
One of the things that I didn’t realize until I started on these threads is that, in geological terms, the polar ice pack moves like Smokey and the Bandit. It’s my understanding that Arctic ice floes in the Transpolar Drift will go from Siberia to the Fram Strait and melt in the Atlantic in 4-5 years (ones that get caught in the Beaufort Gyre may have a 20 year circuit on top of that but they still spin into the Atlantic). At a rate of say 1000 km/year, we’re talking of movements of a few km/day.
Also the Arctic Ocean is stratified with a reverse thermocline – underneath a thin veneer of cold fresh water is relatively warm Atlantic water.
Has anyone noticed that there’s another ice island that has attached itself to the sea ice after coming from just east of the Ayles Ice Shelf?
re: #14
See #12.
“The event registered as a small earthquake on instruments stationed 150 miles (250 kilometers) away, Warwick Vincent of Quebec’s Laval University told the CanWest News Service.”
How do we know the earthquake happened after the ice shelf calved away? Why can’t it be the other way around?
“A specialist scientist (Vincent) said that such an event was unprecedented in the tennnnnnnnnn years that he had been studying the area.”
Ten years is like a pimple on an elephant’s butt in geological time frame.
RE: #9 – Great point – an accretion feature presents quite a challenge in terms of stating an operational definition as to just what terms such as “age” and “date” even mean. Some sort of “mean” date using a black box weighting, the oldest “date,” the newest? Etc.
RE: #13 – it’s a jungle up there, figuratively speaking. Scouring, huge tangential/sheer forces punctuated by massive compressive events (both wind driven and collision driven). The bergs and floes scour. I’d liken it to a major river that is subject to seasonal freezing. The shorefast, shelf fast and glacier fast ice masses are akin the shorefast ice in a river during the spring break up.
A possibly useful link for this and other Ellesmere / Arctic sea ice related discussions:
http://arctic.atmos.uiuc.edu/cryosphere/
I am wondering about the delay in reporting of the event. You state that “no one noticed” for 16 months. Do you mean the media, or the researchers? I ask this because L. Copeland is quoted in a Dec. 2006 National Geographic article:
Was the ice shelf break-up known to have occurred by most in your field? If not, why was the news of such a major event not released earlier?
I don’t know anything more about the timing of this than I read in the news. From the article, my first take was that the researchers had only recently noticed the event from examining satellite imagery, but, examining this more closely, it does appear,as you say, that researchers did notice it some time ago and didn’t report it until now.
RE:20 It was released as supporting evidence to the plight of the “stressed” polar bears. 🙂
FYI – there’s a sea ice (meltdown) related thread over at RC just now …
Here’s a post of mine, awaiting the censor’s approval:
“Given the PDO, I have some issues with using 1980 – ~ present as the basis for trend line analysis. Truth is we are still unraveling the PDO (and other cyclical down leg) based decline(s) from 1976 (last PDO flip to positive phase) on, from the overall AGW(ish) decline. Once someone is able to successfully deconvolute the AGW(ish) decline from the cyclicals, then we’ll be talking.
by Steve Sadlov”
This is the RC thread, guest commentary by Cecilia Bitz from U Wash:
http://www.realclimate.org/index.php/archives/2007/01/arctic-sea-ice-decline-in-the-21st-century/
Have at it folks, especially the extrapolations …. 😉
Nova (PBS) had an excellent documentary on the Franklin expedition of 1845 to get through the NorthWest Passage.
Of course there is no way through the passage unless you time it perfectly and hit the straights on August 7th and get into the Pacific by early September. Assuming of course that a northerly wind doesn’t push sea ice into the straights and stop you in your tracks for three years like happened to Franklin, his 2 ships and 129 crew.
Eventually, the polar ice caps are melting myth will go away. But the global warmers have already won the day and the myth will be with us until an OBJECTIVE scientist proves that nothing out of the ordinary is ocurring.
If you want to know what is really happening, ask the oil companies if they are building any oil tankers that are capable of taking the oil out of the Beaufort Sea. There is lots of oil there and the pipelines are already full. One of them built three in the early 1980s and abruptly went bankrupt when they found out the extremely expensive ice-breaking oil tankers had no hope of getting out even 1 barrel of oil.
Ask shipping companies if they are planning on moving any product through the NorthWest passage because the sea ice is melting.
In other words, ask the money people who put their money where their mouth is what is going on (ie. the people who really do their research.) They just laugh at the sea ice predictions.
They do not laugh at the global warming predictions however. Because they already know that some politician (who has fallen for these myths) is going to make them reduce emissions, go green. The money people know they have already lost the day and they are getting as ready as they can for the day when a politician watching the polls (based on the public falling for these myths) slaps the big regulation on their industry.
RE: #25 – Assuming that the decline in sea ice at late summer extent minima that seems to have been measured since the late 1970s is partially or wholly due to AGW (as yet unproven and technically indistinguishable from other possibilities such as multidecadal cycles) I would be open to a scenario whereby the extent at the minimum is reduced enough to allow NW Passage navigation most years. But I think the linear extrapolations of 25 or 30 years of data down to zero are incredibly naive and fail to recognize the fact that the more you try to increase the summer melt, the more you start to run up against very old and difficult-to-melt ice, not to mention the innate limitations imposed by the characteristics of the Arctic Ocean, sun angles and continental configurations. At worst, again, assuming AGW driven decline is the main mechanism, a decaying exponential is far more likely. Once the minimum extent reaches a certain value it is likely to not get much lower than that. Many assumptions in what I’ve laid out. It will be quite interesting to see what happens with sea ice extent at summer minima once we have solidly flipped back into a negative PDO phase. Only the last bits of the previous negative phase were covered by satellite data and that was mostly visual band as acceptable remote sensing technology really did not start until the early 1970s.
I posted this before, but here is the sea ice in the Beaufort Sea on July 25th in 2005 and 2006.
Real actual pictures from the visible spectrum gives you a better idea of what is really happening compared to the IR or radar satellite images which are subject to the bias of the climate change researcher producing the data and the software program used to generate the images.
I certainly wouldn’t trust Michael Mann’s chart of sea ice decline for example.
http://earthobservatory.nasa.gov/NaturalHazards/shownh.php3?img_id=13738
Re: #24 Cecilia Bitz from U Wash says
“Because the system is chaotic, the natural variability in each run is random and uncorrelated from one run to the next. When an ensemble of runs is averaged, the natural variability is reduced in the ensemble mean, and it is easier to detect a significant trend.”
As an earth scientist with experience in conducting computer simulations of complex natural systems ie oil and gas reservoirs with complex geological and geochemical variables, I am amazed at the reliance of climate change models on repetetive error cancellation as an accepted means of data verification. That applies to Mann’s use of self-proving statistics in deriving “acceptable” data for the “Hockey Stick” as well. In my business we would call that fudging the data.
My observation is that Cecilia will not likely generate a meaningful model without determining which of the variables is responsible for which change, a formidible task, indeed! It’s a computer model and she appears to be assuming that the multiple runs of a simple system will emulate an indescribably complex one. We’ll run it ’til it’s right!
To quote Steve “Repeating wrong numbers does not make them right”
Happy Summer Solstice everyone! The sun angle has peaked in the NH. Of course, realized warmth lags this by a bit, someplaces quite a bit, others not as much. The realized melt back of sea ice tends to lag it by 60 – 85 days. All eyes are on the Arctic, to observe what happens this year. The first year in a long time where we appear to be in a negative PDO. Also, a seemingly cooling Atlantic at the same time. When was the last time we had a cooling Atlantic and negative PDO at the same time?
I usually don’t normally post on many Blogs, still I just has to say thank you… keep up the amazing work. Ok regrettably its time to get to school.
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