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    Petermann Glacier Calving 2010 - Update
    By Patrick Lockerby | August 11th 2010 11:18 AM | 25 comments | Print | E-mail | Track Comments
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    Retired engineer, 60+ years young. Computer builder and programmer. Linguist specialising in language acquisition and computational linguistics....

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    Petermann Glacier Calving 2010 - Update

    Before I discuss the recent calving of the Petermann Glacier ice tongue, I want to give credit to the many scientists who were studying, predicting and observing this event.  If I miss anyone out, please advise by email or comment and I will edit this article accordingly.

    The scientists who deserve credit, in no particular order:

    Humfrey Melling at DFO submitted a detailed science article to the Journal of Geophysical Research - Oceans just a few weeks before the event, and so missed the chance of including the calving in his article.

    Luc Desjardins, Senior ice and iceberg forecaster, Environment Canada - http://www.ec.gc.ca/
     - forecast the event August 01 2010.

    Trudy Wohlleben
    observed the event August 05 2010.

    Other scientists predicted or observed the event, and I will gladly add their names here as I come to know of them.

    Scientists often have to go through layers of bureaucracy before they can issue press releases, the more so if funded by the taxpayer.

    I am retired and work alone from home.  Nobody gets to stand in the way of my freedom of speech.  There are no editors to change my articles, thanks to .  I was very lucky to be able to publish my forecasts and my observations ahead of others.  As I wrote in a comment to  LiquidPublication - Publishing Without The Peer Review Hassle

    We need a new credit mechanism.  Science  needs to determine credit according to a weighted system of peer - reviewed credits which examine the person or group's methodology and its contribution to the scientific method.  In such a system, I would expect to get joint credit with at least four other persons or teams for predicting the ice island and would be about 3rd or 4th in the list of live event observers.
    And now, an update

    The Petermann Glacier flows quite slowly compared to many other marine outlet glaciers - a mere 1km per annum.


    image source:
    http://www-radar.jpl.nasa.gov/glacier/Greenland/greenland.html

    Even at 1km per annum, the pressures built up by ice restrained by fjord walls is immense.  There appears to be some kind of obstruction about 81N 62W.  With the complete loss of sea ice on the other edge, an offset force on the ice was inevitable, as was the calving.  I am surprised that this Giant tabular berg survived intact: the shock forces which arise when pressure is released are usually sufficient to ensure at least some fragmentation in any material.

    Another factor which I considered was the behaviour of ice from tributaries.  One would expect the lateral pressure of the main stream to be sufficient to integrate the tributary ice into a fairly smooth flow.  It appears to me, however, that there has been at the ice edge what would be called a turbulent flow in the case of a liquid.  In engineering terms it is chatter: the stop-start or slow-fast motion that causes damage between two surfaces in relative motion.

    Finally, there has been substantial meltwater flowing through the ice tongue.  One would normally expect run-off to flush away from the calving front.  Instead, the runoff appears to have penetrated under the ice sufficiently far back as to add to any warm current penetration and so promote underside melt.

    Now that the giant berg has calved, any runoff which does not fall through moulins and fissures and promote further thinning will flow into the gap between the new calving front and the new tabular berg.  I suggest this will promote further thinning and calving from the new calving front and from the rear of the berg.

    The old fissure in the ice tongue was widely expected to be the point of calving.  My own view was that it was in a zone of strong lateral compression, and so was not likely to be a point of calving until after substantial calving further downstream.  With the loss of backpressure from the August 05 calving, a new area is now likely to calve.  Much depends on the melt of the ice in the eastern margin.  Given the recent shocks, it will take little melting to release a new giant tabular iceberg.

    If the area downstream of the fissure survives the remainder of the melt season without calving, which I think is doubtful, then the back pressure from sea ice and the forward pressure from the glacier may combine to increase the lateral compression.  If the tongue becomes firmly wedged then I suggest that it may survive another year or two without calving.  However, if the forward pressure induces rotation, as it did August 04 2010, then we will see another calving event.


    The new ice island has drifted towards Nares Strait only a little so far.


    MODIS/Aqua 2010/223 08/11/10 14:35 UTC
    image source:
    http://rapidfire.sci.gsfc.nasa.gov/realtime/single.php?2010223/crefl2_14...

    The ice island may be grounded.  However, if it drifts far enough to expose only its tip to the bergs flowing in Nares Strait then it will be gradually eroded.  If it drifts substantially then it will be exposed to impacts which will promote fractures and break-up.  However, in my opinion, if it drifts so as to block Nares Strait it will serve as a barrier to ice loss from Lincoln Sea.  As ice jams up against the barrier it will form an obstruction to ice loss far more effective than an ice bridge.  This will have significant impact on Arctic sea ice loss and will promote ice compaction along the north coasts of Ellesmere Island and Greenland.

    Finally: how many times must it be said?  This ice island will not directly add an iota to sea level - it was already afloat when it calved.  Indirectly, if it allows Petermann Glacier to accelerate, which is highly likely, then that effect will contribute to sea level rise.  Also, any hazard to shipping will be confined to Nares Strait for some time to come.  Media reports of this ice island ending up intact in the Atlantic are just plain daft.  It would be easier for an elephant to escape from the zoo through the keyhole.

    Edit:
    I have published a further update:
    Petermann Ice Island Revisited
    -----------------------------------------
    This article was an update to:
    Arctic Newsflash! Petermann Ice Tongue Loses Huge Chunk
    and
    The Anatomy Of A Discovery - Petermann Glacier Ice Tongue Calving 2010


    More Arctic and related articles:
    The ChatterBox Arctic Index

    Comments

    Good work! Would you be willing to make a prediction about when summertime Arctic ice melts completely? Even pessimistic ("pessimistic", by the business-as-usual standard) estimations vary quite a bit.

    BTW, if I remember correctly, you mentioned a while ago that you're planning to write about how Arctic ice loss affects the Gulf Stream (I assume you meant trans-Atlantic atmospheric patterns rather than thermohaline overturning). Could I politely ask you to give a short preliminary summary about your ideas/estimations on that phenomenon? That's a topic I've been trying to gather information about, with quite meager results so far. (Living in the far north, my interest is not only academic...) Thank you in advance!

    logicman
    Mark:  you just caught me before I log out for a well-earned nap.  :-)

    I recall a scientist talking recently about the Pacific and Atlantic inflows meeing in the middle of the Arctic.  Things would get really nasty if that happened.  I'll try to find the reference later and post it here.

    Would you be willing to make a prediction about when summertime Arctic ice melts completely?

    2011:
    Reduced ice cover affects sea temperatures, in turn affecting Arctic current flows and air movements. Thinner ice, instead of piling up as pressure ridges due to compression effects, cracks into sections due to tension and agitation effects.
    The Arctic is virtually ice-free by late summer: there is open water at the North Pole.
    Global Cooling : Beyond Parochialism
    Thanks for the quick answer. It seems that this article is related to the subject?
    http://www.whoi.edu/page.do?pid=16900&tid=282&cid=29428

    (Disclaimer: I've only just begun to study Arctic climate, so my questions may appear somewhat uninformed.)

    So is there the risk that less salty Pacific waters, flowing into the Arctic basin, may disrupt the Atlantic thermohaline circulation? In that case, the most important questions would be:
    How far geographically would the effects reach?
    What would the seasonal temperature impact be in different parts of Europe and North America?
    How fast would these effects take place?

    I'm sure no one has certain answers, but phenomena like these are the most crucial aspects of climate change. I do appreciate the time and work you put into researching Arctic climate.

    The Petermann Glacier flows quite slowly but is rate of advance is bigger now than in 2002
    an offset force on the ice was inevitable, as was the calving, yep but not a big calving of 18 cubic km in a few hours
    in 1991 fragmented in several pieces und the volume is smaller
    the question of volume versus area is the big problem all the people point that in 1961-1962 a big calving occur
    but 600 square km, but is a event that occur in 8 months and with a ice sheet of 50 m of medium thickness

    this is a big event
    only if Sermeq Kujalleq or the other two big continental glaciers calves till september, this is a significative
    calving
    that there has been at the ice edge what would be called a turbulent flow,?
    in this case is a mass flow the turbiditic caracteristics in a fluid are with a different coeficient of drag , than in this case is bigger

    Now that the giant berg has calved, any runoff which does not fall through moulins and fissures and promote further thinning will flow into the gap between the new calving front and the new tabular berg. I suggest this will promote further thinning and calving from the new calving front and from the rear of the berg....its possible the calving of 61-62 in elsmeere island take since August to April of 62, with episodes of fragmentation during the fall
    and september is far away 18 cubic kilometres c'est superbe

    The old fissure in the ice tongue was widely expected to be the point of calving. My own view was that it was in a zone of strong lateral compression, and so was not likely to be a point of calving until after substantial calving further downstream. With the loss of backpressure from the August 05 calving, a new area is now likely to calve. Much depends on the melt of the ice in the eastern margin. Given the recent shocks, it will take little melting to release a new giant tabular iceberg.....
    .i supose that small ones have a bigger probability of occurrence

    well i doubt that the ice that is release this year melt in 2011 , ice free arctic a decade more at least

    logicman
    Anome:  thanks for the 'added value', I'll look those points up.  I don't agree that this berg has bought us a decade.  Two years at most.  After that, this berg will have fragmented and drifted too much to contribute to blocking ice loss in Nares Strait - but that is just one person's opinion.  Let's wait and see what others have to say about it.

    I think that Humboldt Glacier has calved more than normal this year, and has more to go.

    Ones to watch: Zachariea and 79N, both of which sit in a shared basin below sea level.
    Colorado Bob
    Patrick ... Keyhole indeed .  But it is a summer of hot and hype, so why not ?
    Here's another image I saved ....... The world's largest tundra fire from 3 summers ago :



    Colorado Bob
    I would really like to know if anyone has followed this event . If there was ever a study area carved out by nature this patch between these two stream beds is it.  Question #1 .... Did this area thaw faster than the surrounding area ?
    logicman
    Colorado Bob:  I covered this in Arctic Ice August 2010.   The Anaktuvuk River Fire of 2007 has been totally dwarfed in scale by the recent fires in Russia.

    I know of no studies on albedo and snow melt.  However, tundra recovery has been studied extensively.
    In 2007, the Anaktuvuk River Fire (ARF) became the largest recorded tundra fire on the North Slope of Alaska. The ARF burned for nearly three months, consuming more than 100,000 ha.

    Fire Behavior, Weather, and Burn Severity of the 2007 Anaktuvuk
    River Tundra Fire, North Slope, Alaska

    Jones et al
    http://www.bioone.org/doi/abs/10.1657/1938-4246-41.3.309

    Basic Statistics on North Slope Tundra Fires in Alaska
    Eric Miller, 21 June 2010

    To date in 2010, eleven fires have been detected on the North Slope. There has been some interest in the fire activity and whether it is abnormal. Here I provide some basic statistics on North Slope fires since 1969 to provide some context. There have been 34 recorded fires on the north slope. Early season fires tend to be smaller and burn for only a single burn period. Mid-season fires have potential to burn longer and to a greater area if conditions allow fire to penetrate and hold overnight in the duff.  Fires are carried by the accumulation of cured, dead sedge foliage. The mean and median fire size is 60-80 acres. The lightning season is mid-June to late July. Strike density decrease exponentially from the foothills of the Brooks Range out to the coastal plain. Although fire frequency has increased in the last 40 years, the size of the fires detected has simultaneously decreased which suggests it may be explained by increased aircraft traffic and by better remote sensing technology.
    http://fire.ak.blm.gov/content/effects/Basic Statistics on North Slope Tundra Fires in Alaska.pdf

    This file was unavailable when I checked.  Try Google search for Basic Statistics on North Slope Tundra Fires in Alaska.pdf and view cache in html.

    Some more free pdf resources:
    http://www.iarc.uaf.edu/workshops/terrestrial_team/indiv_pdf/permafrost_...

    Tundra Fire Regimes in the Noatak River Watershed, Alaska: 1956-83
    http://pubs.aina.ucalgary.ca/arctic/Arctic38-3-194.pdf
    Hi Patrick,

    Zachariae movements

    Note there is a cracking at the northern outlet of the Zachariae Glacier (just south of 79), just between the 2 islands, whether the pressure is coming from Zachariae or 79, is hard to tell, due to clouds on the Modis Aqua 08:46 image, you better have a look.

    Regards Espen

    logicman
    Espen: Thanks for the heads-up.  I'll check for the latest images later.  I am just writing up my newest Arctic ice update.  I decided to deal with these two glaciers in a separate article.

    Here is an image which I saved August 10 and will be using:

    Zachariea and 79N glaciers.
    detail from MODIS Rapidfire Arctic mosaic
    Arctic_r02c03.2010222.terra.250m.jpg
    I wrote Modis Aqua 08:46 image the correct image is Modis Aqua 08:45 image.
    The cracks are placed where you have the lover Red ice tonques lineon your image.

    Espen

    logicman
    Espen: do you mean MODIS terra 08:45 UTC?

    There is a lot of action in that area today.  It's 4pm UK time.  Time for this old fossil to get his afternoon nap. :-)

    I'll try to find an image with the least artifacts and cloud and post it soon.

    Meanwhile, I just posted Arctic Ice August 2010 - Update #2.
    Hi Patrick

    No it is Modis Aqua 08:45 buthere is the link :
    http://rapidfire.sci.gsfc.nasa.gov/realtime/single.php?2010224/crefl2_14...

    Regards Espen

    It appears that the Petermann Ice Island is still moving towards Nares Strait and is not grounded. Initially it seemed to be rotating anti-clockwise, but on the MODIS pix between day 225 and 226 it swung back clockwise. The tip moved about 2 kilometres, although only about 500m of that was forward progress.

    It could be grounded, but it seems more like its bouncing from once side of the fjord to the other. The wides part is just clearing the narrowest part of the fjord, and is moving into the section where the fjord flares appreciably. If, as it seems, it is still afloat, it will shortly get to the point where getting stuck in the fjord through size alone is unlikely. It seems to be making progress forwards at about 1 km per day in the 9 days since it broke. At that rate, the nose at least should be well into Nares Strait before September.

    logicman
    FrankD:  thanks!  I haven't had time to check today.  Your input is greatly appreciated.

    The ice island is from an ice tongue which tapers in depth from the grounding line to the calving front.

    The lower 80 km (in length) and 1300 km2 (in area) of the glacier is afloat. This makes it (by area) the largest floating glacier in the Northern Hemisphere. The ice front is not impressive,unlike the faster outlet glaciers. The calving front protrudes a mere 5-10 m above sea level, reflecting the fact that the ice at the front is only 60-70 m thick. Further up-glacier, the ice at the grounding line is 600-700 m thick.

    Mauri Pelto
    http://www.realclimate.org/index.php/archives/2008/10/what-links-the-ret...

    Petermann Ice Island (2010) will, accordingly, be tapered in longitudinal section.  If, as I suspect, there is at least one bar at the entrance to Petermann Fjord, then the ice island will ground at some stage.

    If it merely 'pokes out its tongue', then the race is on to see whether ice forms, protecting it and  locking it in place, or if one or more ice floes banging into it break off a major part.

    If satellite images show motion in steps a multiple of ~12 hours apart - from local tides - , that would strongly suggest the presence of a bar of glacial debris.
    Good points Patrick, I'd forgotten the importance of the underwater profile, of both the fjord and the island, and just assumed it would continue to move into deeper water.

    Your tidal indicator is correct, but personally I haven't seen images close enough together in time to see that (though they may well be out there).

    Be that as it may, it swung back anticlockwise today (Day 227), the nose moving aboubt 3 kms left (south), while moving about 1.5 kms forward in the fjord. The aft end looks to have whacked the RH (north) wall of the fjord. It could well be scraping its keel (I presume the bottom of the fjord would be covered in a debris field of mud and dropstones), but I don't think its fully grounded. If anything the movement looks like it might be catching on a succession of obstacles.

    If it does continue to pachinko from side to side like the last few days, its going to take a pounding - you can already see the sides, especially the right (north) side, are getting pretty beaten up. We'll see over the next few days, I guess. If it continues to fishtail down the fjord as it is now, it won't take long to get into Nares Strait.

    Colorado Bob
    the importance of the underwater profile, of both the fjord and the island, and just assumed it would continue to move into deeper water.

    One other unknown , the amount of melt water being discharged into the fijord under the glacier.  My guess, there's one hell of a lot of water flowing into the fijord.
    Hi Patrick,

    I believe your "small" floating property in the top of North West Greenland, soon will leave its neighborhood, that's within days, so you better watch up.

    Regards Espen

    Looks like Petermann Ice Island is hooked up - its sharp rotation with little or no forward movement suggests its hung up on the left (south) side. That could be just the southerly current in the Nares Strait pushing it around, but that seems to have eased today (Day 228), so it looks like it might be scraping its a***.

    *climb down* :-(

    Man, it walloped the fjord walls today - that would have put some shockwaves through it! And Petermann appears to be shedding more bergs, as you predicted, Patrick.

    Any chance of an update of Ellesmere Island Ice Shelf update with the next Petermann update?

    Today's satellite offers a relatively cloud free shot.

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010230...

    logicman
    Any chance of an update of Ellesmere Island Ice Shelf update with the
    next Petermann update?

    Will: I'll try to cover that topic soon. Neven may beat me to it, he is already discussing the topic in comments:
    http://neven1.typepad.com/blog/2010/08/sea-ice-extent-update-25-the-time...

    Tip of the hat to FrankD for the link to this image:

    image source:
    http://ice-glaces.ec.gc.ca/app/WsvPageDsp.cfm?ID=11893&Lang=eng
    Pat I have been working on a bit of Petermann Glacier material today. Comparing the key rift from 2008 and from 2010 The annotations for the images identify supraglacial stream channels the spread of the rift that I labelled as Rift C in 2008 in the 2009 blog update to the 2008 RC article. I am sure you have examined this rift, and I would look forward to your excellent visual presentations of such.

    logicman
    Mauri, I have been working on a new article about Petermann Glacier in the wider context of Arctic warming.  I just logged in after reading your 2009 blog update to your 2008 Realclimate article. 
    I am very grateful to you for the mentions and links to my articles.

    As I have commented elsewhere, illness has slowed me down, but I am getting back on track.  In the new article I will propose that retreat to tributaries will add to acceleration of the main stream in proportion to the contribution that each separate component stream makes to the lateral pressures downstream of the tributary.  Those pressures would relate - I suggest - to the appearance of tributary stream widths in satellite images.

    I'll be using this excellently large NASA image to illustrate my points:
    http://earthobservatory.nasa.gov/IOTD/view.php?id=45306&src=iotdrss

    I look forward to your continued examination. In the post above one aspect that is not quite on target is the runoff aspect. There are several very long and long lived supraglacial streams that indicate a lack of moulins and difficulty of meltwater penetrating to the base on the lower floating tongue sections. Some of the streams drain into rifts. The temperature of this water is also unlikely to help much with sub-glacial melt. The role of tributaries is interesting. Usually they are stabilizers, but as you note they seem to create what you call a chatter, creating a melange of sea ice and glacier pieces. So clearly they are not serving the stabilizing role well. There is only one tributary and it is the largest coming in on the north side that seems to really add to the ice stream and forces some higher velocities as the main ice stream seems to be constricted and flows around it in the velocity maps. However, immediately downstream of this an area of low velocity and the melange begins.