Banner
    Petermann Ice Island - Now There Are Two
    By Patrick Lockerby | September 10th 2010 06:29 PM | 30 comments | Print | E-mail | Track Comments
    About Patrick

    Retired engineer, 60+ years young. Computer builder and programmer. Linguist specialising in language acquisition and computational linguistics....

    View Patrick's Profile
    Petermann Ice Island - Now There Are two

    Petermann Ice Island (2010) has now broken into two parts.   The smaller island is about 80 km2.  It is the thinner of the two and is likely to melt away first.  Based on the labels already in use in comments1, I shall designate the larger island as Petermann 2010-A and the smaller one as Petermann 2010-B.


    Petermann Ice Islands A and B
    image source: http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201009091609.ASAR.jpg

    The importance of the Petermann Glacier calving to climate science is not so much that it happened, but that it was predicted to happen.  Quite a few predictions were made by people working independently as individuals or groups and using different techniques for prediction.


    Science and Prediction


    Science is of such great use to society because of its powers of prediction.  Dmitri_Mendeleev predicted the existence of eight elements - since discovered - from his observations of the systematic sets of properties of other chemical elements.  The planet Neptune was discovered in 1846 when astronomers searched for a planet in a region where one was predicted to exist based on mathematical models of the Newtonian mechanics of our solar system.


    The ability to extrapolate and interpolate data is what makes the logical processes of science so powerful and so useful to humanity.  Every day, doctors base their prognosis - a prediction of the future - on the patient's past history and present symptoms.


    The incontestable fact that the calving was predicted using the scientific method - and that it happened - is a public demonstration of the power of science to predict the future.  This evidence of the validity of the scientific method should be enough to convince any rational person that when climate scientists from the world's nations agree that the world's climate is changing, then it is changing.  The insurance industry is founded on the idea that risk assessment is a viable economic activity.  Professional insurers - level headed business people - accept the scientific evidence of the reality of global warming and climate change2,3.


    The Petermann Glacier Calving 2010

    I have already given credit to others for their predictions and observations in previous articles, such as Petermann Ice Island Revisited.  Here, I shall focus on my own predictions to give a context to the current event: the breaking in two of the ice island..

    I first predicted the imminent calving of Petermann Glacier, July 17th 2010, in my article Arctic
    Ice July 2010 - Update #3
    : " I predict some dramatic calving this year.



    The image, which I published July 17th shows where I expected to see fractures develop due to mechanical forces in the ice.  I then predicted, in Arctic Ice July - Update #4, July 22nd 2010, "The Petermann ice tongue looks primed to lose a few fairly large floes any day now."  I meant that I expected a large area to break up into substantial ice islands. 

    The calving was first reported as a news item on August 5th 2010 here at science20.com in
    Arctic Newsflash! Petermann Ice Tongue Loses Huge Chunk, 24 hours before any other news outlet.  I was surprised that the area which I had predicted to calve survived calving intact.

    The ice island drifted towards Nares Strait but then ceased drifting.  The ice island is tapered from front to back, as is the entire glacier tongue.  The Petermann Fjord has never been fully surveyed.  The surveys which have been conducted reveal a sill across the fjord with a depth of about 200m at the edges to 350 or 450m at the center4.  If the sill is surmounted by piles of glacial debris, especially at the edges, this could impede the movement of an ice island of sufficient depth.  The deepest, hindmost part of the ice island is about 200m thick5.


    A gentle Bump

    Observing that the ice island moved forward again shortly after a spring tide - September 27th - I suggested that it might not move much again until the next spring tide - September 8th.  It appears to me that the ice island moved forward until its 'notch' stuck against Joe Island.  There was no journalistic 'smash' or 'crash' of ice against land.  The ice island was travelling at a very low speed.  Even so, given the huge mass, the momentum would have been sufficient to cause the mass to break across a pre-existing weak point. 

    I had already predicted that the ice island would not stay in one piece for long.  It hasn't.



    Petermann Ice Island (2010)

    Note the meltpools and streams on the surface.  There are many cracks and stress points, so this ice island is most unlikely to stay in one piece for long.  However many pieces it breaks into, those pieces will be impacted by hundreds of icebergs from the rapidly calving Humboldt Glacier  in passing through Kane Basin.  A series of ever-smaller ice islands will - I suggest - move in a stop-start fashion as they follow currents and continually run aground.

    August 25 2010
    Petermann Ice Island Revisited

    The ice island has not survived the short, slow journey from Petermann Fjord to Nares Strait as a single mass.  The chance of the two parts not breaking up further when they move at speed into obstacles is effectively zero.
     
    In Nares Strait and Kane Basin there are many places where a tabular iceberg can run aground or be trapped.  Nares Strait is a warm water polynya.  Even when the sea freezes over, these ice islands will continue to be eroded from below by warm water.  In Kane Basin, until the sea freezes over these ice islands would be bombarded by hundreds of icebergs from Humboldt Glacier.

    Very soon now, even if the Nares Polynya remains as open water, the sea will begin to freeze in Baffin Bay.  These ice islands, or their fragments, will not travel far until next spring.


    Footnotes:
    [1]
    - credit to FrankD for alerting me to this event.  I am following the A, B designations he uses in his comment.

    [2] - http://insurance.lbl.gov/
    [3] - http://www.genevaassociation.org/PDF/Geneva_Reports/Geneva_report...

    [4] - Muenchow et al 2010

    [5] - "Recall that at the ice front the sea ice was less than 70 m thick and even at the rear of ice it is likely less than 200 m thick."  Comment by Mauri Pelto.


    Previous articles on Petermann Ice Island:

    Arctic Newsflash! Petermann Ice Tongue Loses Huge Chunk
    The Anatomy Of A Discovery - Petermann Glacier Ice Tongue Calving 2010
    Petermann Glacier Calving 2010 - Update
    Petermann Ice Island Revisited

    Comments

    Of some interest is the non-zero rate at which the island(s) moved along the channel, implying that the water current to the sea was at least that fast or faster, suggesting that a melt rate could be calculated.

    The ice island was sliding by Joe Island, which is the white dot, in the September 7th radar image:

    http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201009071527.ASAR.jpg

    but the lower section had a notch in it that may have struck Joe Island causing the ice island to break up.

    There has been some further calving at the Petermann glacier front, including one sizable chunk off the tongue that can be seen in the September 9th radar image posted by Patrick above that was not there in the September 7th image in link #1527 above.

    It is tiny compared to the Peterman 2010-A, but still much bigger than Joe Island.

    The "Petermann Glacier Fissure" shows up in the radar images. Perhaps Petermann Ice Island 2011 will separate from the glacier along this fault line.

    Looks like more stuff is falling off the leading edge of the Petermann Glacier in the Modis image (need to scroll down the image to see the glacier).

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010253...

    Clouds partially obscure Peterman 2010-A and 2010-B in the terra image and there is quite a bit of recent snow cover in the area of the glacier, but the radar images below show 2010-A as it has gone half way down the strait to the next island.

    http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201009101531.ASAR.jpg

    http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201009101713.ASAR.jpg

    The front-left? corner of Petermann 2010-B appears to be still in contact with the tiny white dot that is Joe Island.

    Lake Hazen on Ellesmere Island can be seen in the full radar image just above and to the left of the Petermann ice islands.

    http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201009091609.ASAR.jpg

    It became ice free shortly before July 27th in this image (need to scroll down the image to the lake and the Petermann ice tongue before the calving event))

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010208...

    It is starting to show signs of ice as of September 10th in the radar image in the link for #1713 above.

    After Joe Island, there are three more Islands for Peterman 2010-A to negotiate in the Nares Strait.

    http://upload.wikimedia.org/wikipedia/commons/f/f8/Nares_strait_border_%...

    The big island that was referred to in the previous post is Franklin Island. Just before Franklin is another small island called Hans Island (which may be similar in size to Joe Island - pictures of Joe below, note - Joe may not be significant enough to have its own wikipedia page)

    http://www.meltfactor.org/blog/?p=244

    http://www.davewalshphoto.com/_MG_0272-_mirage_nares_strait_20090714-_fa...

    http://gliving.com/wp-content/uploads/2007/11/greenland-warming-01.jpg

    Hans Island pictured below (1.3 km2 or .5 miles2) has its own wikipedia page as it is subject to a territorial dispute between Denmark and Canada.

    http://members.virtualtourist.com/m/p/m/22091e/

    http://www.panoramio.com/photo/3811522

    Below Franklin is another small island called Crozier Island. Franklin and Crozier are considered part of Greenland (according to Wikipedia) .

    Ooops, should have said Petermann 2010-B instead of A.

    Looks like "B" is already passed Hans and will easily pass to the east of Franklin.

    Wow, it is really moving.

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010254...

    west of Franklin, not east

    Colorado Bob
    Fire&Ice
    Volcanoes and frozen lands make an explosive combo

    Tens of thousands of years ago, says Mercurio, a graduate student at the University of Pittsburgh, this place was the heart of a roiling volcanic eruption. Molten rock bubbled up from a fissure in the Earth’s crust. On top of that lay hundreds of meters of ice. Lava met ice, and the result was an inferno.

    Heat from the eruption instantly boiled ice to steam, which ramped up the eruptive power like a pressure cooker blowing its top. Magma hitting the steam exploded into tiny fragmented bits, sending pillars of fine-grained ash billowing overhead.

    http://www.sciencenews.org/view/feature/id/63177/title/Fire_%2Bamp%3B_Ice
    Interesting, but what does a volcano on iceland along the mid-atlantic rift have to do with northern Greenland and the Nares Strait?

    I think there is some uncertainty or controversy about plate tectonics and the location of the Wegener fault in the Nares Strait.

    http://jgs.lyellcollection.org/cgi/content/abstract/146/6/913

    http://epic.awi.de/epic/Main?puid=31693&lang=en

    With local volcanic action some 58 + million years distant.

    http://www.springerlink.com/content/g122ur4617815052/

    logicman
    Thanks to all for the comments and links.  I apologize for not yet having the stamina to reply individually.  Please be assured - even when I don't log in, I lurk and absorb. :-)

    Here's the latest image of the Petermann Glacier area:


    Petermann 2010-A and Petermann 2010-B ice islands.

    MODIS image cropped and rotated from source
    crefl1_143.A2010254200000-2010254200500.250m.jpg

    Petermann 2010-A may be grounded and wedged against Joe Island.  The more sea ice that compacts into Petermann Fjord, the less likely it is - I suggest - that ice island Petermann 2010-A will be able to wriggle past Joe Island.

    Petermann Glacier has another large ice island ready to calve, but this is at a point where the fjord narrows, tending to create some back-pressure.  Although this area could calve at any time, I expect it to calve next spring, very soon after the sea ice melts in the fjord estuary.  By that time the glacier will have built up some forward pressure against the sea ice.

    In the past, Petermann Glacier has advanced and retreated due to natural cycles.  If global warming in general, and Arctic amplification in particular, have the effect of accelerating the retreat during this cycle, then I would expect a retreat to the grounding line by about 2015 to 2016.
    Patrick:

    Why do you expect a retreat back to the grounding line?

    I would not be so quick to predict this as the glacier's length trend is biased to retreat when it is long and biased to advance when it is short.

    It is clear that more Petermann calving will occur over the next year or so due the the existence of the fissure.

    However, based on the history of retreat and advance by the glacier and the unique forces acting on it, isn't it more likely that the glacier will advance down the fjord rather than retreat to the grounding line even with increased warming?

    The dynamics affecting the Petermann glacier are different than other glaciers as analyzed in this article:

    http://glacierchange.wordpress.com/2010/09/04/humboldt-glacier-retreat-g...

    Based on several sources, the glacier appears to have undergone a cycle of retreat and advance over the last 100 years. Is there any reason to believe that this cycle has stopped?

    By predicting such a retreat, you may be setting up a denier rebuttal fo AGW if the glacier advances rather than retreats as you are suggesting.

    Before predicting such a retreat consider the following:

    The fjord provides a protected natural channel for containing the floating glacier.
    The remaining portion of the glacier is considerably thcker than the portions which have calved.
    The glacier advance rate of 1 km per year may accelerate due to the loss of back pressure.
    Most of the melting (upwards of 80%) of the floating portion of the glacier has occurred from the bottom (basal melting).

    Due to the loss of a large area subject to underwater melting, isn't it possible that the mass balance of the floating glacier will become positive with more ice being pushed into the fjord than melts on an annual basis and the glacier will once again advance down the fjord?

    From a global warming perspective, the recent calving of the Petermann glacier is not significant even though it is certainly dramatic.

    Of greater concern is the effect of AGW on the mass of the portion of the Greenland ice cap that is drained by the glacier. The NASA gravity-sensing satellite GRACE has detected that the Greenland ice sheet has been losing ice at an accelerating rate. This measurement is of greater significance than the lenght of the Petermann glacier in the fjord.

    The dynamics of the ice cap are different from the floating arctic ice in its sensitivity to global warming. It is possible that global warming could result in increased snowfall on the Greenland Ice Cap as the moisture content of the air increases (in part this moisture increase will occur as there is less sea ice to block the uptake of water vapor into the atmosphere and the atmosphere capacity to hold water vapor increases due to troposphere warming). This might result in an increase in mass for the ice cap. Very little melt occurs in the central portion of the ice cap, so increasing snowfall could result in mass increases. There are some indications that the very cold central ice cap of Greenland has been increasing even though the mass of the ice cap in the lower regions has declined.

    So I would caution anyone making a prediction that the floating portion of the Petermann glacier would disappear as it appears that the further back it retreats the greater the likelyhood that future advances of the glacier will occur.

    Looking at the DMI COI images of this area, it looks like Petermann 2010-B might have grounded briefly on the coast of Ellesmere Island before wriggling free again. A radar pic taken a little before the MODIS image Patrick has posted shows taht it tracked very close to the coast and then veered sharply back towards the centre of the channel, having *just* cleared Franklin Island.

    It *might* get caught on the next island (Crozier) but I don't think so.

    My impression is that Peterman-A is on the move.

    http://rapidfire.sci.gsfc.nasa.gov/realtime/single.php?A102551120

    Look out Kane Basin, Petermann-B is about to arrive.

    Sure is Will,

    Latest MODIS false colour image puts it past Crozier Island.
    http://ocean.dmi.dk/arctic/images/MODIS/Kennedy/201009121210.NOAA.jpg

    The image is a bit funky, and its easier if you compare it to a true colour image.

    Tomorrow, it should enter Kane Basin (the next section of Nares Strait, immediately to the left off the picture posted by Patrick at 9/11/10 20:00).

    On that same image, you can see what seems to be a big floe moving through the Lincoln Sea towards the mouth of Robeson Channel (the north end of Nares Strait). I have no idea where it came from or how thick it is; it doesn't show up well on radar so I think its probably not a big solid chunk, but it *might* act as an ice bridge and block export through Nares Strait. Stay tuned viewers....

    FrankD:

    Thanks for your posts.

    The big chunks have previously shattered upon entering the Nares Strait.

    Neven has an animation of the Nares Strait from earlier in the year on his site:

    http://neven1.typepad.com/blog/2010/06/nares-strait-animation-part-1.html

    and in the comments section on Patrick's site:

    http://www.science20.com/chatter_box/arctic_ice_august_2010_update_3

    I am not sure which chunk you are tracking, but these radar images from August 15 to date may help.

    http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201008151548.ASAR.jpg

    http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201008182239.ASAR.jpg

    http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201008221710.ASAR.jpg

    http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201008271616.ASAR.jpg

    http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201008301615.ASAR.jpg

    http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201009022306.ASAR.jpg

    http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201009051626.ASAR.jpg

    http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201009081631.ASAR.jpg

    http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201009111645.ASAR.jpg

    The chunks you are looking at may be an illusion due to heavy snow cover that makes several of the chunks appear as one solid piece. Compare the August 22nd aqua image with yesterday's image:

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010234...

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010255...

    The radar image for the Kane basin (which was taken about 12 hours before the image you reference) shows Petermann-B to the left of Franklin Island and above Crozier Island in the upper right corner of the image.

    http://ocean.dmi.dk/arctic/images/MODIS/Kane/201009120059.ASAR.jpg

    Thanks again for your posts.

    Oopsie!

    Already has entered Kane Basin: http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010255...

    It is honking along!

    Todays image

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010256...

    Nothing to hit as it hugs Ellesmere Island until it gets down to Pirn Island.

    Should be Pim not Pirn.

    Colorado Bob

    Melting sea ice forces walruses ashore in Alaska



    Story here
    Colorado Bob



    September 13, 2010


    Our favorite climate de-crocker, Peter Sinclair has a new video on the Arctic:

    Climate Progress
    "Nothing to hit as it hugs Ellesmere Island until it gets down to Pirn Island"

    Except for Ellesmere Island, itself, of course. It looks like it ran 60 kilometres in the last two days and then ran agound. At least, its very close to the shore - its a bit hard to tell if its still moving much.

    Still watching....

    Patrick and FrankD:

    What do you make of the fast transport of ice through the Nares Strait?

    Looks like FrankD's big ice island entered the Robeson Channel (Nares Strait) from the Lincoln sea around September 11th

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010254...

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010256...

    Then it looked like it might attach itself to the entrance of Newman Bay (Bugt) as it went by

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010257...

    (Check out the break-up on Ellesmere Island of eastern? end of Ward Hunt ice shelf near Ward Hunt Island which can be seen in this image)

    These maps have the name references:

    http://www.geus.dk/program-areas/raw-materials-greenl-map/greenland/gr-m...

    http://www.geus.dk/program-areas/raw-materials-greenl-map/greenland/gr-m...

    http://www.geus.dk/program-areas/raw-materials-greenl-map/greenland/gr-m...

    but today's image shows it sailing down the Nares Strait through the Davis Basin.

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010258...

    It shows up in this radar image of September 14th:

    http://ocean.dmi.dk/arctic/images/MODIS/Lincoln/201009142329.ASAR.jpg

    but I can not make it out in the earlier radar images I posted to FrankD on September 13th.

    So far, it looks like it will sail to the West of Petermann 2010-A. Doubtful this would do much to 2010-A since 2010-A is likely to be much thicker.

    Snowfall may be making some of these ice islands look bigger as the snow can cover fracture lines. The ASAR radar image appears to show the ice in a more broken appearence than the aqua and terra images.

    Reference to Davis Basin should read Hall Basin

    Looks like Petermann 2010-B is on the move.

    http://ocean.dmi.dk/arctic/images/MODIS/Kane/201009161548.ASAR.jpg

    A portion of Petermann 2010-A is located between Greenland and the white dot that is Joe Island which may keep it trapped in Hall Basin just outside the glacier entrance, but who knows?

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010258...

    Petermann 2010-B free of land contact in the Kane basin and generally headed for Smith Sound

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c02.2010258...

    logicman
    Thanks to all for the updates and for keeping this going while I've been short of energy.

    Here's the latest images.

    Petermann 2010-A seems to have snugged itself in for a while:


    Petermann 2010-A wedged at fjord mouth.
    cropped from Arctic_r03c03.2010258.terra.250m.jpg


    Petermann 2010-B has passed Kane Basin, but may yet come to a halt.  The general trend of the wind is along Nares Strait, but there are many eddies.  The most likely fate for Petermann 2010-B is to be grounded close to Pim Island.   The arrow below shows the thinner front of the ice island.  The deeper stern will cause the ice island to yaw as it is driven by the wind.  This motion could help to drive the ice island hard aground where the water shoals.


    Petermann 2010-B approaching Pim Island.
    cropped from crefl1_143.A2010258180000-2010258180500.250m.jpg
    GOING WITH THE FLOW

    Petermann 2010-B appears to be headed away from Ellesmere and Pim Island and toward Greenland.

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c02.2010260...

    Will it make it through Smith Sound to Baffin Bay?

    Petermann 2010-A may still be trapped by Joe Island as it rotates counterclockwise and a huge ice island floats by:

    http://rapidfire.sci.gsfc.nasa.gov/subsets/?subset=Arctic_r03c03.2010260...

    Most of the ice flow near Petermann 2010-B has been hugging the coast of Ellesmere Island. Odd that it drifted toward Greenland. It may drift back to Ellesmere before getting to Baffin Bay

    Will bear in mind that most of the ice flowing down Nares is only a few metres thick whereas Petermann B has some depth and might be influenced by the deeper currents rather than surface flows/wind.