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Arctic sea ice minimum discussions

Filed under: — gavin @ 1 September 2011

Here is a continuation of the last Arctic sea ice discussion as we get closer to the 2011 minimum. All figures will update continuously.

JAXA Sea ice extent and area:

Cryosphere Today sea ice concentration:

Estimated sea ice volume from UW PIOMAS (updated every month):

143 Responses to “Arctic sea ice minimum discussions”

  1. 101
    Hank Roberts says:

    I asked
    > Is there a correlation between the year’s sea ice and the
    > year’s observations of methane bubbling out of the shallow seabed?

    D’oh. When there’s ice covering the area, is anyone in a position for observing bubbles of methane coming up? or taking sea water samples for dissolved methane? So “observation of an increase” may be “increasing observation” rather than an actual change in what’s bubbling up.

    Further aside — we need to distinguish thawing of old methane clathrate from creation of new methane by organisms in the mud layer. And I recall some methane is coming up from deeper in the sediments where it’s warmer and then freezing out near the surface of the sediments because they’re colder due to sea water. Carbon isotopes should tell old from recent carbon.

  2. 102
    Hank Roberts says:

    Another aside — noting how the sea ice volume appears to be a new low record already.

    For an interesting misrepresentation of how much sea ice is hidden from the satellites, sunk deep below the water line, you can’t do better than the cover picture of Spencer’s book:,204,203,200_PIsitb-sticker-arrow-click,TopRight,35,-76_AA300_SH20_OU01_.jpg

    Anyone want to figure how much of that iceberg would actually show to a satellite? Hint — it wouldn’t be in that narrow vertical orientation.

  3. 103
    G.S. Williams says:

    It seems to me that with all your scientific discussion about the sea ice extent or area is not all that important. whether or not it is frozen, surely, is of little consequence. If it all melts, it makes little difference to the sea-level, so, why the problem.

    I am not a trained scientist, but I like to thing that I am a reasonably intelligent person and I find your discussion quite interesting, but, as a layman, I would like to know what is the situation of the areas of Land-Ice floes. I believe that these areas have amb ient air temperatures of -30 deg and -40 deg. Is that correct? If it is , then there can be no problem with regard to the land-ice melting. Would you agree?

  4. 104
    J Bowers says:

    What gets me puzzled is how Arctic SIE just came in as the second lowest for the month in the 1979 to 2011 satellite record, yet the Northwest Passage and the Northern Sea route weren’t open in 2007 IIRC (correct me if I’m wrong). I know currents and winds move it all about, but it just doesn’t add up. Or is area what I should be looking at?

  5. 105
    Joe Cushley says:


    a) Albedo. Look it up.

    b) No. Look it up.

    Are you Dickie Bird in disguise? Start Here button, top left of Home Page.

  6. 106
    Hank Roberts says:

    > G.S. Williams
    > I believe … is that correct?


    Can’t get a post with links past the spam filter right now, but if you put your own question into a Google search box, you’ll find plenty of information contradicting what you believe. You might ask whoever you got those ideas from where they found them.

    Try asking again in the open thread, and people can help you find more.

  7. 107
    WhiteBeard says:

    # 102 – Hank,

    I suspect you’ve been bitten by a berg bug. The book cover illustration overstates draft for a berg (at least one without an immensely high content of very dense minerals) by an order of magnitude or so, and bergs are a tiny fraction of the sea ice, by any measure, that are floating around.

    For the first time I noticed some pressure ridging of the Arctic Ocean’s ice pans from the bridge of the USCGC Healy at 88 North at on the 6th giving some variation to the ice’s cross section.

    Perhaps more representative, with the Canadian Louis S. St-Laurent in the distance just below the horizon mid frame, is the one at:

    The Lemont-Doherty Earth Observatory has links to the hourly images where the form of the ice is plain to see.

  8. 108

    #103–Well, a lot of things change when the sea ice goes.

    1) Most obviously, it’s a serious problem for the animals that use it as habitat: polar bears, walrus, ringed seals. Decapitating the food chain has been observed to cause cascading, unpredictable effects all the way down that chain, so we don’t know quite what will happen should those species suffer population crashes. However, the Inuit won’t like it much, as they still take seals for food.

    2) Increased coastal erosion is a predictable (and, actually, already observed) consequense: the land itself will be changed.

    3) Loss of sea ice will lead to increased regional warming due to two feedback mechanisms: increased water vapor (its a greenhouse gas par excellance, remember!) and the albedo feedback whereby the water of the Arctic Ocean absorbs greatly increased amounts of solar radiation during the summer.

    4) Land ice will be destabilized in some cases, so we can expect increased glacial calving and the like.

    J. Bowers, here’s a graph of the sea ice extent in the Canadian Archipelago. Note there’s basically no ice there this year, while in 2007 there was still rather a lot. The general answer to your question is that the ice distribution is different. Indeed, it’s never quite the same in any two years.

    For more on this, go to Neven’s Arctic Sea Ice blog (an easy Google away) and click on the “Daily Graphs” tab in the header. (The posted graph is one of the “Regional Graphs” found under a sub-menu there.)

  9. 109
    Hank Roberts says:

    For Whitebeard:

    Spencer’s cover picture looks like these, but rotated 90 degrees and sunk far beyond its floating depth:

    Pressure ridge in multiyear sea ice “Multi-year Arctic sea ice”

    Those aren’t as easy to find as they used to be:

    Coastal Engineering
    Volume 5, 1981-1982, Pages 159-169
    Received 4 February 1980; 14 January 1981.

    “This paper reviews an extensive body of published and unpublished literature to establish an estimate of the thickness in the ice cover of the Arctic Ocean…. It is concluded here that the maximum depth of ice likely to be encountered, (99% probability) is in the order of 50 to 55 ft (15 to 17 m).”

  10. 110
    EFS_Junior says:

    Well even if 2011 sets or almost sets a new record low for Arctic sea ice extent (and/or area).

    I can see the cherry pick from the Denialinati now …

    Presenter as years of record: 2007-2011 … also known as taking a Goddard Dump.

    Look see, no significant trend these last FIVE years, why has the Arctic STOPPED melting?

  11. 111

    #110–Hey, it’s almost as if you’ve seen that before somewhere!!??


  12. 112
  13. 113
    J Bowers says:

    Thanks Kevin (108)

  14. 114
    Thanes says:

    Kevin, came across a good phrase on Neven’s blog for one other, somewhat hypothetical phenomenon a melted arctic may lead to- PETM 2.0. Ice gone over methane clatrates and change in warm water circulation is pretty scary over 1 trillion tons of methane carbon

  15. 115
  16. 116
    prokaryotes says:

    @108 Kevin McKinney

    Impacts on ocean circulation, atmospheric weather phenomenon today suggest more high impact storms. The collapse of the food chain works with many stressors, one begins with clorophyll …

    Alarming 40% decline in phytoplankton – base of marine ecosystem
    By John – Posted on 31 July 2010

    The July 28 issue of NATURE has a disturbing new study with strong evidence that phytoplankton have declined 40 percent in the last 50 years. That is based on a study of 450,000 ocean samples taken over the last century. Phytoplankton are critical because they:

    are the base of the entire ocean food chain, analogous to grasses and grains supporting land animals
    produce half of our life-supporting oxygen
    sequester 100 million tons of carbon dioxide daily, offsetting a substantial amount of the greenhouse gas produced from the burning of fossil fuels.
    Dr. Boris Worm, a noted marine biologist at Dalhousie University in Halifax, Nova Scotia, headed the study team. They spent three years unearthing, filtering and analyzing available data on ocean transparency and chlorophyll concentration — common ‘proxies’ for phytoplankton abundance. After removing data on shallow coastal waters and any obviously erroneous — that is, biologically impossible — observations, the data set still included some 450,000 globally distributed measurements collected between 1899 and 2008.

    The findings add to concerns that climate change is dangerously altering marine ecosystems. “This is severely disquieting,” adds Victor Smetacek, a marine biologist at the Alfred Wegener Institute of Polar and Marine Research in Bremerhaven, Germany. “One must really digest the very magnitude of this decline and its possible implications.”

    Added Paul Falkowski, an oceanographer at Rutgers University in New Brunswick, New Jersey. “Clearly, 40% is a huge number. This implies that the entire ocean system is out of steady state, slowing down.”

    Since 1899, ocean transparency has been measured using a simple device called a ‘Secchi disk’ after the Italian astronomer who invented it in 1865. The disk is lowered into the sea and a depth measurement is taken at the point where observers lose sight of it. Using optical equations, the researchers compared Secchi depth measurements of ocean transparency to measurements of chlorophyll concentrations at research sites and within phytoplankton, and to satellite observations of ocean color.

    The combined data suggest that phytoplankton biomass has decreased in eight of the ten ocean regions measured, with the largest rates of decline in the South and Equatorial Atlantic, the Arctic and the Southern Ocean. Only in the Indian Ocean has phytoplankton biomass increased — slightly in the north and more markedly in the south — since 1899.

    “The study adds to a growing body of global ocean research, all evidencing a fundamentally common result: the net effect of a warming ocean surface is a reduction in phytoplankton surface chlorophyll concentration,” says Michael Behrenfeld, a marine ecologist at Oregon State University in Corvallis.

  17. 117
    Hank Roberts says:

    > decline in plankton
    That’s more than a year old; it’s a serious issue (you want catastrophe? ask a starving whale). But look for more recent work. There’s more to this than that one article including some discussion: and look at the 2011 work reported.

    There’s a classic feedback possible there:
    and related articles for other species. See also Jeremy Jackson generally.

  18. 118
    Hank Roberts says:

    > plankton
    This is well worth reading:

    Hold onto your head while you read this:

    “when integrated over its entire area, the annual net photosynthetic production of the ocean is similar to that on land (around 50 Pg C yr−1)2. However, the biomass of phytoplankton responsible for this production is far smaller than its terrestrial plant counterpart. This difference implies a much faster turnover of the phytoplankton. Indeed, the entire global population of phytoplankton is replaced on average every two to six days….”

    There’s a fast feedback response to any environmental change!

  19. 119
    GlenF says:

    Here’s yet another plot of the PIOMAS series:
    And, fitting a curve (parabola) to the anomalies as others have done, you can project a summer zero towards the end of this decade:
    But the really interesting thing is that if you fit a curve to the raw volume data instead of the anomalies, you get an ice free arctic for half the year by the end of the next decade:

    That is less than 20 years away…

  20. 120

    #116–Troubling indeed, prokaryotes, and eminently worthy of comment.

    But what does it have to do with my response to the question of why the loss of sea ice matters?

    (Admittedly, there is a lot more that could be said on that topic than I said in my off-the-cuff response.)

  21. 121
    wili says:

    @120–why loss of sea ice matters

    I hope you have been reading the threads here.

    Loss of sea ice, beside the immediate effects on the animals in the region, is likely to dramatically change the weather patterns in much of the northern hemisphere. We are going from a polar region that was mostly ice and snow all year toward one that is open water half the year, and during that half, it is receiving constant sunlight. So there will be lots more water evaporated, which will both fall on surrounding land as rain and snow, and stay in the air as heat trapping water vapor. The further possible/probable consequences for this dramatic change are still being studied, afaik.

    An ice-free Arctic will also certainly change patterns of sea currents, but I am not up on studies that predict what might happen there. Changing patterns of sea currents will also greatly affect weather patterns.

    The effect of greatest concern to me is how ice-free waters expose seabed methane deposits in shallow parts of the continental shelves to warm water as the surface is warmed by the midnight sun and that surface warmth is agitated down to the few-meters-deep floor by the waves that can now freely propagate and grow across the unchained ocean.

    Ultimately, though, we can’t know all the consequences of turning an icy white top of the planet into a dark wet one, but they are likely to be profound.

  22. 122
    Hank Roberts says:

    > why the loss of sea ice matters

    Putting that into Google finds plenty, have you looked? Then try Scholar.

  23. 123
    rich f says:

    So I have a question and would appreciate if I wasn’t decried as a heretic as part of the answer. Since the arctic ice cap floats, it is subjected to currents which bring ocean heat content north. That being the case, I would think that the ocean ice extent in the southern ocean would be far better corrolated with changes in air temperature than the arctic, where (just based on the comparative heat content of water v. air) I have to believe that the heat transported north by the currents must have a significant impact on ice volume… So if the southern ocean ice volume isn’t changing, it makes me wonder whether the increase in ocean heat content over the past twenty years is a larger factor than than increase in air temperatures in the arctic (which could concievably be at least partially a by-product of less ice). Is there some inherent problem with my logic?

  24. 124
    flxible says:

    rich f
    Why do you think the southern ocean ice volume is not changing?
    Where have you found increasing air temperatures cited as the cause of ice loss?

    The inherent problem I see with your logic is, something as complex as oceanic ice behavior is not a logic problem.

    Your question, clear of “logical connections”, seems to be: For Arctic ice loss, is the increase in ocean heat content over the past twenty years a larger factor than increase in air temperatures?

    In my non-scientist view, the answer would be Yes, a larger factor, not the only one, and north being a seperate collection of complexities than south.

  25. 125
    wili says:

    Rich f. Ocean currents are probably playing a role, but there are others. Note that the Arctic is an ocean surrounded by land, while the Antarctic is a continent surrounded by ocean. They are polar opposites in more ways than the literal one. So one would not expect them to behave the same way. Also, the majority of land is in the Northern Hemisphere, so that is also where the largest sources of GHG’s and black carbon come from. Once these factors take hold, albedo change can play a strong reinforcing or ‘feedback’ role. And then there are feedbacks like methane starting to bubble out of tundra lakes and the shallows of continental shelves.

    It is rarely a good idea to look at just one system, such as ocean currents.

    (Others can perhaps give more technical–and perhaps accurate?–explanations.)

  26. 126
    prokaryotes says:

    When was the last time that the arctic was ice free? And when was the last time when the north pole was basically ice free (with remaining melt spots in the surrounding areas)?

  27. 127
    prokaryotes says:

    @120 Kevin McKinney (Admittedly, there is a lot more that could be said on that topic than I said in my off-the-cuff response.)

    Sorry, if that wasn’t clear but it was meant as supplemental data.

  28. 128
    Pete Dunkelberg says:

    Currents merit lots of attention. Outgoing currents must be matched by incoming currents, which might help explain conditions found under the receding lip of the Pine Island Glacier (my PIG link’s not handy).

  29. 129
    flxible says:

    prokaryotes – re ice free arctic: arctic ice history

  30. 130
    Hank Roberts says:

    For Rich F: Often if you simply put your question into a search box you’ll find you can check what you assume is true against what’s been published. Looking at the science journals _will_ give you _different_answers_ than you get from the average opinion blog.


    Second result is this one:

    “Rapid bottom melting widespread near Antarctic ice sheet grounding lines
    E. Rignot… – Science, 2002 –
    The undersides of ice streams flowing from the Antarctic continent typically melt into the ocean where they cross the grounding line and begin to float as ice shelves and ice tongues (1). Unlike melting under the grounded ice sheet, processes beneath floating glaciers are governed …
    Cited by 186 ” <– often a clue it's worth reading; click the link on the search results page to see those papers, which have subsequently referred to this one. Follow the work through from 2002 to the present day that way.

    Someone said they'd checked and you're real, that should help people give you calm answers. The site here gets a lot of "homework help" requests, and a lot of people who heard something from some guy at a bar and want to repeat it prominently — so distinguishing yourself from them will get you somewhere.

    Note one thing people really will respect — if you use the "Open Thread" for your general questions, instead of putting them in a topic with a specific focus. Look in the right sidebar and at the top of the page for links.

    Lots of us here are just generally interested readers, many are (like me) not scientists, just trying to understand what's being written; the real scientists who are formal Contributors are named in the sidebar and the 'About' info again at top of page.

  31. 131
    cRR Kampen says:

    It is done: 2007 is promoted to ‘just another year of decline’.

  32. 132
    John Nissen says:

    @ #108, Kevin, and #125, Wili,

    Kevin listed some repercussions of sea ice disappearance:


    1) Most obviously, it’s a serious problem for the animals that use it as habitat: polar bears, walrus, ringed seals. Decapitating the food chain has been observed to cause cascading, unpredictable effects all the way down that chain, so we don’t know quite what will happen should those species suffer population crashes. However, the Inuit won’t like it much, as they still take seals for food.

    2) Increased coastal erosion is a predictable (and, actually, already observed) consequense: the land itself will be changed.

    3) Loss of sea ice will lead to increased regional warming due to two feedback mechanisms: increased water vapor (its a greenhouse gas par excellance, remember!) and the albedo feedback whereby the water of the Arctic Ocean absorbs greatly increased amounts of solar radiation during the summer.

    4) Land ice will be destabilized in some cases, so we can expect increased glacial calving and the like.

    [end quote]

    To this I would add:

    5) Following from (3) there will be increased thawing of permafrost on land, leading to growing emissions of CO2 and methane – probably mostly methane. There is of the order of 1600 Gt of carbon locked up, double the amount already in the atmosphere [1]. It has been estimated that 30% permafrost will thaw by 2050 [2].

    6) Also following from (3) there will be warming of the shallow seas on the continental shelves, particularly the East Siberian Arctic Shelf (ESAS) where methane hydrate conditions have become critical, and, according to Shakhova et al [3], up to 50 Gt of methane could be released “at any time”, e.g. if there were an earthquake. A release of this size would multiply atmospheric methane by a factor of 11 (referred to as “methane x 11” [4]), causing a climate forcing of the order of 10-20 W/m, almost certainly resulting in a methane feedback and runaway global warming. Forgive me for shouting but:


    7) Following from the warming (3) and the calving (4), the Greenland Ice Sheet (GIS) will produce 6 or 7 metres of sea level rise.

    8) Together with (7), there is mutual feedback between GIS and the West Antarctic Ice Sheet (WAIS), because the sea level rise lifts the base of the ice sheets where they meet the sea, causing ice sheet acceleration. According to Hansen, gravity measurements from satellite show that GIS ice sheet mass loss is doubling per decade [5].

    The albedo feedback, mentioned in (3), is extremely important, and will produce a net flux of the order of 1-2 petawatts of positive climate forcing when all the sea ice has gone. It’s producing about 40% of that now, which will rise to about 70% when the end-summer ice disappears (in 2015 according to PIOMAS exponential trend of sea ice volume) and near 100% when gone during 6 months of the summer (in 2020 or 2021 according to same model).

    This climate forcing produces an accelerated local warming, and is generally considered the cause of the “polar amplification” of global warming. From temperature data, the local temperature could be rising at 4-6 times the global average rate.

    The initiation of the Arctic warming is due to two main factors: local CO2 greenhouse gas effect and the warming of the Northern Atlantic currents flowing into the Arctic. The latter currents are fed from the Gulf Stream.

    The Arctic sea ice is generally accepted as crucial for the cooling of the planet, and implicated in the amplification of the Milankovitch cycles through cyclic variations in the warming of the mid-latitude Northern Hemisphere, which feed through the Gulf Stream into the Arctic and initiate positive feedback amplification, which is then cut off when there is a meltwater pulse to divert the Gulf Stream southwards and/or halt the Atlantic Meridional Overturning Circulation (AMOC), as happened at the start of the Younger Dryas.

    Basically, I believe we are at the point of breaking the amazing mechanism that has kept the temperature of the planet within certain limits over the whole of the ice ages – some 2.5 million years. We’ve broken it by injecting a colossal pulse of CO2 into the atmosphere – producing a greater concentration than in the past 15 million years or so. The sea ice is now amplifying the warming effect of this pulse, which is greater than the warming effect at the positive part of the Milankovitch cycle.

    Is the situation totally hopeless? Is the game over? No, not if we recognise the nature of the problem, and use geoengineering technology to cool the Arctic by one or two petawatts of negative forcing, however unsavoury one feels that to be – tampering with nature, playing God, cheap fix, etc.

    “Sometimes we have to do what’s required” – Sir Winston Churchill






  33. 133
    Petter H says:

    Univ of Bremen has recorded a record minimum aa of 8 sept 2011. They are confident NSIDC will follow suit.

  34. 134
    L. David Cooke says:

    Hey All,

    Just wanted to interject a curiousity, given the current seasonality of insolation, what is the perdicted minimum polar ice coverage. It would seem that in the “Paleo” record there was a possibility of tropical conditions; however, it would also appear to be related to geo-specific positioning and ocean currents.

    So given current and near future techtonic pisitioning if the continents, ocean circulation, variations in the 250mb air currents and planetary tilt in relation to the current TSI imbalace has anyone predicted the probable polar ice minimum? Certainly it will not be absent with 6 months of less then 268K, at even 7 deg. F greater then the current minimum, there should easily be enough heat loss in the region to create a great seasonal mass of ice. If it remains in a land locked/bordered region such as the Canadian Maritime Is. would it not be likely to remain at similar levels for the next 100 years? Or would insolation and warm winds be sufficient to reduce the mass further. I would suspect that we may be seeing the min. with the given conditions.

    Even if the darkside radiative energy doubled and the GAT increased another 0.7 with a regional rise of another 7 deg. F, it would seem unlikely for insolation to increase. Warm winds seem to not significantly effect shaded snow in our region would it be more significant in the polar region?.

    My observations suggests it actually depends on the surface upon which ice sits for warming to significantly expedite it state change. Has anyone attempted an experiment to suggest a melt rate for ice on a porous surface in which the applied heat is in the form of surface winds to help us understand the efficiency of transfer of heat contained in the air towards the forcing of the state change of ice? (I suspect this value will prove to be relatively small.) At least with those efficiency of energy transfer values we can begin to ID root cause/prevention measures should we wish to change the inevitable.

    Dave Cooke

  35. 135
    Hank Roberts says:

    > Has anyone attempted an experiment to suggest a melt rate for ice on a
    > porous surface in which the applied heat is in the form of surface winds

    Predict how long a ski resort could stay open in the spring, for example?

  36. 136
    L. David Cooke says:

    Hey Hank,

    In Switzerland, a plastic cover surrounding a grooming tractor sitting beside a tree in 2005 preserved the snow there all year. Based on plastic cover tests done near moulins in Greenland, the ice was 1/2 meter thicker and harder over a period of a week. Insolation or it’s preventation has been proven to increase ice durability by 6 months. Hence, dense cloud cover could add potential durability, if the oceans were also sufficiently shaded. A broad covering of Sargasso seaweed and a +VE or +NAO goes a long way to preserving sea ice.

    To me that is a major issue, what is changing the synoptics so drastically, that Blocking Highs and Cutoff Lows have increased both in population and duration. To have the Azores/Bermuda High in retrograde to the point it Centers in Western Carolina or SW Georgia is way abnormal. A deg. C more warmth in the GoM or Caribbean Sea is not going to cause that, nor is 134ppm more CO2,

    A swollen N. Jet Stream which has deviated nearly 20 deg. from it’s former Summer average, now that is something to explore…

    Dave Cooke

  37. 137
    John Brookes says:

    Minimum reached?

  38. 138
    ccpo says:

    I’m going to go out on a limb and say yes for extent and area, possibly not for volume, but also likely yes. If the clouds disappear for the next ten days, we might see some more downward trends, but the AO is positive, so…

  39. 139
    wili says:

    Has anyone else seen this:

    “Commercial shipping through the Northeast Passage over the last couple weeks has reported the seas bubbling as if they were boiling. Their observations have been reported to the science ministry who have sent scientists to investigate.”

    Does anyone know about this source? Is it usually reliable?

    Does anyone else find the notion of “seas bubbling as if they were boiling” a bit…disconcerting?

  40. 140
    ccpo says:

    139 wili says:

    Does anyone else find the notion of “seas bubbling as if they were boiling” a bit…disconcerting?

    Yes, but expected. What was it, two years ago they reported a tripling in the number of thermokarst lakes?

    The problems are very complex, but the answer are exceedingly simple: Reforestation, regenerative agriculture, food forests, reduced consumption (based in smaller, semi-autonomous communities) and some sort of sustainable/steady-state economy (See Steve Keen for possible economic modeling of the steady-state), etc.

  41. 141
    harvey says:

    I dont speak russian, but they have lots of research into the arctic methane release and permafrost… Im sure their research will be very usefull once translated to english..

  42. 142
    WA Piper says:

    Why is there nothing on this site regarding Antarctic ice accretion?

    [Response: What Antarctic ice accretion? (land ice, sea ice) – gavin]

  43. 143

    There is strong evidence of freezing in the center of the Arctic Ocean ice pack (colder than -11 C), but unlikely likewise at its edges, there was in the last few days displacement of multi-year ice in the Canadian archipelago Northern channels. Very much pushed by a significant cold low pressure system. Daily winds have favored less flushing quite a lot lately, but the melt was really big , would have been seen much more as such if the winds were more in line with the sea current., Dominance of surface adiabatic lapse rates, with scant presence of inversions may persist over the wider open very warm arctic ocean. This gives rather thick lower clouds dominating the entire Arctic, but is rather a sign that the sea is feeding back some heat it acquired over the summer. I suspect that the coming re-freeze would be not as fast as 2007 because of an overall lesser melt of multi-year much less salty ice and by also the warmer seas fueling a quasi total cloudy state.