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Sea ice minimum forecasts

Filed under: — gavin @ 17 July 2009

One of the interesting things about being a scientist is seeing how unexpected observations can galvanize the community into looking at a problem in a different way than before. A good example of this is the unexpectedly low Arctic sea ice minimum in 2007 and the near-repeat in 2008. What was unexpected was not the long term decline of summer ice (this has long been a robust prediction), but the size of 2007 and 2008 decreases which were much larger than any model had hinted at. This model-data mismatch raises a number of obvious questions – were the data reliable? are the models missing some key physics? is the comparison being done appropriately? – and some less obvious ones – to what extent is the summer sea ice minimum even predictable? what is the role of pre-conditioning from the previous year vs. the stochastic nature of the weather patterns in any particular summer?

The concentration of polar expertise on the last couple of questions has increased enormously in the last couple of years, and the summer minimum of 2009 will be a good test of some of the ideas that are being discussed. The point is that whether 2009 is or is not a record-setting or near-record setting minimum, the science behind what happens is going to be a lot more interesting than the September headline.

In the wake of the 2007 minimum, a lot of energy went in to discussing what this meant for 2008. Had the Arctic moved into a different regime where such minima would become normal or was this an outlier caused by exceptional weather patterns? Actually this is a bit of false dichotomy since they aren’t exclusive. Exceptional patterns of winds are always going to be the proximate cause of any extreme ice extent, but the regime provides a background upon which those patterns act. For instance, in the paper by Nghiem et al, they showed the influence of wind patterns in moving a lot of thick ice out of the Arctic in early 2007, but also showed that similar patterns had not had the same impact in other years with higher background amounts of ice.

This ‘background’ influence implies that there might indeed be the possibility of forecasting the sea ice minimum a few months ahead of time. And anytime there is the potential to make and test predictions in seasonal forecasting, scientists usually jump at the chance. So it proved for 2008.

Some forecasting efforts were organised through the SEARCH group of polar researchers, and I am aware of at least two informal betting pools that were set up. Another group of forecasts can be found from the Arctic ice forecasting center at the University of Colorado. I personally don’t think that the intrinsic worth of a successful prediction of overall sea ice extent or area is that societally relevant – interest in open shipping lanes that might be commercially important need much more fine-grained information for instance – but I think the predictions are interesting for improving understanding of Arctic processes themselves (and hopefully that improved understanding will eventually feed into the models and provide better tests and targets for their simulations).

What was particularly interesting about last years forecasts was the vast range of forecasting strategies. Some were just expert guestimates, some people used linear regression on past data, some were simply based on persistence, or persistence of the trend. In more mature forecasting endeavours, the methods tend to be more clustered around one or two proven strategies, but in this case the background work is still underway.

Estimates made in June 2008 for the September minimum extent showed a wide range – from around 2.9 to 5.6 M km2. One of the lowest estimates assumed that the key criteria was the survivability of first year ice. If one took that to be a fixed percentage based on past behaviour, then because there was so much first year ice around in early 2008, the minimum would be very low (see also Drobot et al, 2008). This turned out not to be a great approach – much more first year ice survived than was predicted by this method. The key difference was the much greater amount of first year ice there was near the pole. Some of the higher values assumed a simple reversion to trend (i.e. extrapolation forward from the long-term trend to 2008).

Only a couple of the forecasts used physics-based models to make the prediction (for instance, Zhang et al, 2008). This is somewhat surprising until one realises how much work is needed to do this properly. You need real time data to initialise the models, you need to do multiple realisations to average over any sensitivity to the weather, and even then you might not get a range of values that was tight enough to provide useful information.

So how did people do? The actual 2008 September minimum was 4.7 M km2, which was close to the median of the June forecasts (4.4 M km2) – and remember that the 2007 minimum was 4.3 M km2. However, the spread was quite wide. The best estimates used both numerical models and statistical predictors (for instance the amount of ice thicker than 1m). But have these approaches matured this time around?

In this year’s June outlook, there is significantly more clustering around the median, and a smaller spread (3.2 to 5.0 M km2) than last year. As with last year, the lowest forecast is based on a low survivability criteria for first year ice and I expect that this (as with last year) will not pan out – things have changed too much for previous decades’ statistical fits on this metric to be applicable. However, the group with the low forecast have put in a ‘less aggressive’ forecast (4.7 M km2) which is right at the median. That would be equal to last year’s minimum, but not a new record. It would still be well below the sea ice trend expected by the IPCC AR4 models (Stroeve et al, 2008).

There is an obvious excitement related to how this will pan out, but it’s important that the thrill of getting a prediction right doesn’t translate into actually wanting the situation to get worse. Arctic ice cover is not just a number, but rather a metric of a profound and disruptive change in an important ecosystem and element of the climate. While it doesn’t look at all likely, the best outcome would be for all the estimates to be too low.

858 Responses to “Sea ice minimum forecasts”

  1. 451
    Hank Roberts says:

    Max (manacker),

    I looked up more recent work from the same author you cited and pointed to it — this is how to read science.

    What source are you relying on? Why do you trust your source?

    If you’re posting references from some blog or discussion, they’re not complete and you’re not getting good information.

    If you’re searching the actual science then picking older papers and ignoring newer ones, you’re doing the cherrypicking — selecting what supports your beliefs, from older papers, rather than saying what’s currently known.

    Always check the references, look at citing papers for more recent work, and discuss what’s known.

    When you don’t say where you get your information, I have to check every claim you make. So far, consistently, your claims aren’t well supported, mostly being older papers or partial selections from them.

  2. 452
    Susan Anderson says:

    sidd
    Thanks for the maps/projections, right on point. I’d still love to see real current topography under all that ice, but not if it requires a large amount of computer capability.

    PBS last night; Lonnie Thompson “The Real Iceman” on tropical glaciers, mentions Quelccaya (I think it was a rerun from 2007):
    http://www.pbs.org/wgbh/nova/sciencenow/0405/04-real-nf.html

    This is good too; varied resource guide packed with pictures and information:
    http://www.pbs.org/wgbh/nova/mtblanc/vanishing.html

    hot dam’ I was just getting ready to take a break and leave it to better minds than mine, then new riches emerge.

    (Forget feeding the trolls, they won’t (can’t) stop, and will continue until doomsday – what they practice is not science. They love something to argue with.)

  3. 453
    Jim Bouldin says:

    Manacker says “Hank Roberts (430), You spent a lot of time talking about cherries but saying essentially nothing.

    No, he didn’t say “essentially nothing”, he provided a reference to a study on Russian Arctic sea ice extent and dynamics.

    And even if he did, saying nothing beats the hell out of ignoring significant components of the carbon cycle, fabricating numbers, lying, and refusing to accept contradictory evidence by people who know a lot more about climate science than you do. All of which are your signature on this site.

  4. 454
    Susan Anderson says:

    Some observations from the reality of a seascape painter. I have to watch this stuff because it affects my work and I kind of like numbers and statistics at the lowest level.

    1. Tides in the northern hemisphere are bigger at the new moon than the full moon in summer, and the reverse in winter. That would be the sun.

    2. Tides accelerate in the middle. If I set up to paint below high tide mark in Cornwall with a nearly 24 foot tide, I have to remember at the midpoint between high and low tide, the increase will not be 4 feet per hour but much more (say 8 feet). Day lengths do the same thing, more increase in the middle, flattening at the ends (and some weird wobble).

    I don’t know if or how these factoids might be useful …

  5. 455
    sidd says:

    Ms. Anderson:
    Re;Greenland subglacial topo
    The dataset I used is from Bamber, available at
    ftp://sidads.colorado.edu/pub/DATASETS/BAMBER_THICKNESS/

  6. 456
    Rod B says:

    Mark, yes there are double tide bulges on the front side and the back side, but none on the centerline. Backside tides arise from the moon’s gravitational pull on the whole earth (centripetal and van der Waals force stuff) being greater than the differential tidal pull on the ocean water which then tends to go in a lesser arc than its earthen container… more or less.

    True, a neutron star’s gravitational attraction would beat hell out of the water’s compression/expansion resistance. Plus, as I said, the moon does that too: pulling up on the water and then having water on the side flow in to fill in the lower pressure/density. It’s just less than noticeable or measurable — much less than a um.

    This is fun, but aren’t we starting to bore everyone else and wearing out our welcome?

  7. 457
    CTG says:

    “I’d prefer to see photos from space of the massive melt ponds and moulins in Greenland prior to 1979, and especially in the 1930-1940’s where thermometer records indicate significant warmth.”

    So now BobFJ (aka the Kamikaze Denial Troll) wants to see shots from space taken in the 1930s, or else AGW is not real.

    Right.

    I think this illustrates quite clearly that there is no amount of evidence in the world that is ever going to convince you, Bob.

  8. 458
    BobFJ says:

    Gavin, Reur response on my 436:

    [Response: Does it really take me to point out that there weren’t any ‘shots from space’ in 1851? The photo was taken in 2004 and the lines for the historical extent are drawn on using observed data. – gavin]

    Well actually Gavin it was a joke; partly because you did not provide a source link for the image, (see link in 3, below), that might have explained some of the issues apparent on the image, which in part I suggest are, briefly:

    1] The retreat in the interval 1929-1931 was probably greater in mass than that in the final 2004-2006 period.
    2] The retreat in the five intervals 2001-2006 was extremely erratic year by year.
    3] The retreat in the interval 1964-2001 is about the smallest in area, but the longest in duration, see composite image:
    http://farm3.static.flickr.com/2573/3775490997_b6e8c91f72_o.jpg
    However it matches the longest most significant temperature rise in the 150 years, if we take the HADCRUT NH annual average temperatures. (Whereas, earlier colder periods had very much greater retreats).

    For more detail, 5 possible explanations of the complex dynamics, and other remarks, see my 436

  9. 459
    Mark says:

    “True, a neutron star’s gravitational attraction would beat hell out of the water’s compression/expansion resistance.”

    Rod, you’re talking out your 7th planet.

    There’s no compression/expansion going on with the tide thing at all.

  10. 460
    Brian Dodge says:

    BobFJ 30 July 2009 at 5:56 PM

    “Thirdly, as glaciers retreat inland, typically the gravitational gradient increases, (but probably not uniformly)” [true] “which should result in further acceleration of retreat over time, in a warming regime.” [nope]
    As the environment warms, glaciers lose mass more quickly at the front than it is replaced by flow from upstream, so the front retreats, If it retreats far enough that increases in the gravitational gradient increase the flow rate, it can result in a new equilibrium, where the higher flow balances out the higher loss rate; if there is an environmental fluctuation like a strong La Nina, the glacier front may even advance. Obviously, a higher flow has to be supplied by higher accumulation to maintain balance over the long term, or the ice sheet which supplies the glacier will disappear. In Greenland, mass is accumulating at high elevations, but disappearing at lower elevations through surface ablation and accelerating glaciers; the overall result is net mass loss. Positive albedo feedback with the loss of Arctic summer ice cover and polar amplification of global warming will continue to increase Greenland mass loss.

    “Using satellite radar interferometry observations of Greenland, we detected widespread glacier acceleration below 66° north between 1996 and 2000, which rapidly expanded to 70° north in 2005. Accelerated ice discharge in the west and particularly in the east doubled the ice sheet mass deficit in the last decade from 90 to 220 cubic kilometers per year. As more glaciers accelerate farther north, the contribution of Greenland to sea-level rise will continue to increase” Changes in the Velocity Structure of the Greenland Ice Sheet Eric Rignot and Pannir Kanagaratnam http://www.sciencemag.org/cgi/content/abstract/311/5763/986

    “Fourthly, I would think that moraine grinding (smoothing) will have had greater predominance over the millennia, upstream and higher up the glacier, resulting in freer flow, from creep and sliding, the further the glacier retreats.”
    I don’t know about this, but if true, it will give positive feedback and make some ice sheets less stable to warming. Greenland sits in a bowl so this doesn’t apply here; it’s ice on ice (or maybe turtles, all the way down).

    “Fifthly, it has even been posited that if the termination shortens, such as in the break-up of ice shelves, that the flow-rate increases.” It has actually already been observed and published. see http://www.nasa.gov/pdf/121653main_ScambosetalGRLPeninsulaAccel.pdf
    Glacier acceleration and thinning after ice shelf collapse in the Larsen B embayment, Antarctica
    T. A. Scambos, J. A. Bohlander, C. A. Shuman, and P. Skvarca
    GEOPHYSICAL RESEARCH LETTERS, VOL. 31, L18402, doi:10.1029/2004GL020670, 2004

  11. 461
    Rod B says:

    Mark, That’s what I’ve been saying…

  12. 462

    re: #440

    Dear wili,

    You have stated the problem perfectly.

    If you want to talk about this further, you can get in touch with me via my blog profile.

    You can also try to push people here to discuss this, which is IMO a very good idea, and it is high time.

  13. 463
    Jacob Mack says:

    The science shows we influence weather and climate to a high degree of certainty. The science shows that mean global temperature has risen from recent (recent as in global recent, not human recent) pre-industrial periods. The science shows that GHG and aerosols hurt the atmospheric boundary conditions and human health above certain optimum levels. The clomate science shows that AGW is real. The models still need a lot of work and the prediction ability is still poor. The science does not show repeatable and validated evidence of a tipping point coming anytime soon, but the paleoclimate data and archaeological finds do show that tipping points have existed in this planet’s history.

  14. 464
    BobFJ says:

    Rod B, Reur 377, sorry for delay, but thankyou for your thoughtful comments on my 367 that was addressed primarily to Kevin McKinney. He wrote in part in his 300 concerning comparative albedos of water and ice:

    Albedo is not only an issue at optical wavelengths, but at infrared wavelengths. Back radiation in the infrared will not be reflected by the water due to angle of incidence–and, according to Kiehl & Trenberth ‘98, this is an input roughly twice as large as direct insolation.

    If I fully understood what you wrote, I agree with you, but reiterate that my understanding of Kevin’s comments was that either he or K & T (?) infer that IR back radiation will result in HEATING of the oceans. However, since infrared is (you agree) only absorbed in the skin of the water, and re-emission is an instantaneous process, there is virtually no opportunity for the slower downward process of conduction to take place. Thus, although it IS a very different process, it is somewhat similar IN EFFECT to reflection.
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    I also sought clarification from Kevin on his source….. Like for instance I can’t find K & T ‘98, which might simply be a typo on his part. I also asked everyone, if they disagreed with the two defining graphics that I linked to. (although they were from an academic QM paper)
    You are the only one to respond. Again, thankyou for your positive comments.

  15. 465
    Mark says:

    “Mark, That’s what I’ve been saying”

    Then what is all this about there needing to be compression to make a bulge in post 438:

    “Given the geometry, the only way a rising bulge of that kg can form is if the moon’s gravitational pull is sufficient to expand that kg.”

    ?

  16. 466
    Mark says:

    “However, since infrared is (you agree) only absorbed in the skin of the water, and re-emission is an instantaneous process,…”

    But conduction of heat from the ground into air is only done at the skin surface. Yet that doesn’t stop a lot of heat going into the atmosphere.

    So why do you think it such an impediment to ocean warming here?

  17. 467

    I think somewhere up-thread there were questions regarding ice extent errors?

    Regarding error considerations on Artic ice extent, Walt Meier (NSIDC):

    First, one has to separate out error in concentration in a given grid cell vs. total extent. The concentration is indeed on the order of 5%, upwards of 20% or more during summer. The higher summer error is due to surface melt on the ice depressing the total concentration. The instrument also underestimates thin ice and this can also lead to an underestimation. These do have a potentially significant effect when adding up total ice area. That is one reason why we generally suggest not using total area, but rather total ice extent (ice of at least 15% concentration).

    However, while the instrument isn’t terribly accurate at providing the exact concentration, it does a much better job of discriminating ice (of any concentration above 15%) from ice-free water. Because of the melt water (or thin ice), you can potentially depress the concentration from say 25% to maybe 10% and that takes away ice from the extent calculation that should be included. However, in most cases sea ice very quickly goes from no-ice to well above 30% concentration, so any such effect is usually limited to at most 2 or 3 pixels along the ice and thus the effect on total ice extent are much smaller than 20% and most of the time smaller than 5%. I would generally put this at 1-3% at most during summer, even smaller during winter.

    But the news is even better than that. Note that these errors are generally biases (i.e., an underestimation) and the bias at a given time of year is pretty consistent. Thus, if one is most concerned about change from year to year and/or long-term trends, any consistent bias is not a factor. This is the difference between “absolute error” (measurement vs. truth) and “relative error” (uncertainty of a measurement relative to other measurements). Relative errors result uncertainties of measurements of change, but absolute error does not do so if most of the absolute error is bias as in the case with sea ice extent.

    Based on comparisons of sea ice extents from different instruments of a similar type, we estimate relative errors of +/- 30,000 sq km or less. For summer extents, this is less than 1%; for winter is is less than 0.5%. Changes in summer extents of more than 10% per decade are far beyond these error levels. Thus there is extremely high confidence that these changes are real and not significantly affected by instrument or algorithm error.

    We actually have an FAQ entry relating to this issue, which you are free to pass along to anyone interested:

    http://nsidc.org/arcticseaicenews/faq.html#error_bars

  18. 468
    BobFJ says:

    Mark, Reur 466, thankyou for your thoughtful question;
    The topic in 464 was about the effect of back radiation or incoming EMR (infrared) and its virtual inability to penetrate water, and thus not cause significant HEATING because downward conduction is a very slow process compared with re-emission from the skin. This is unlike sunlight (EMR) which penetrates water well, including its near infrared, and is thus converted to HEAT, some lagging long term, and some being quickly lost back to the atmosphere, in three main processes.

    I seem to recall that some 11% of HEAT loss from the surface as thermals is typically estimated, and I guess that sounds reasonable. The rest is via up-welling infrared EMR, and evapo-transpiration. (HEAT loss)

  19. 469
    BobFJ says:

    Martin Vermeer, returning to your 398/p9, you wrote:

    [1] Fortunately most denialists are not very smart, and BobFJ’s combination of cock-sure assertions using lots of difficult words combined with elementary errors immediately got my neck-hairs up.
    [2] I wonder if he finally understood the silliness of using pictures that had solar limb darkening digitally removed in trying to prove it doesn’t exist… I sure hope the readership here got the message.

    And in your 445/p9, you wrote:

    #422 BobFJ: sigh…

    I guess this means that you were unhappy with my 442.
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    [1] I think that part of the misunderstanding is that you did not consider why I bold emphasised the word fundamental in something early-on, quoting exactly:
    “The fundamental solution as to why the sun appears to have uniform brightness [from ocular observation with eye protection] presented despite that it is a sphere, is that its surface emits EMR equally in ALL directions, hemispherically…”

    Now let me give you a demonstration of the use of the word fundamental in this context. You may well have heard of the common idea of ’black body radiation of the sun’. However, it is severally an imperfect statement, but WRT limb darkening, take a look at this article by Courtney Seligman
    professor of astronomy. In particular, notice that on the figure, he gives the black body curve of the sun at 5780K
    http://cseligman.com/text/sun/blackbody.htm
    However, in the area of limb darkening, the plasma is obviously “colder” in the tangential direction. Do solar scientists ever mention this when talking of the sun temperature being 5780K? No, I don’t think so.
    Do you now understand the significance of fundamental?
    Did you also notice my use of the conditional word ‘appears‘, with respect to ocular capability in my phrase: appears to have uniform brightness?
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    [2] I also draw your attention to this exchange:

    BobFJ #292: don’t sweat it… I won’t try to teach you anything against your will ;-)
    “Now that has me [BobFJ] more than puzzled. For example, are you suggesting that the SOHO MDI image of the sun of quality 151 KB, (or you can click for a 657 KB enhancement), is inferior to the 9.65 KB “depiction” in Wiki’, and that it does not show a difference?

    Bear in mind that when I look at the sun through my arc-welding mask, it looks uniform in colour, and that the MIDI SOHO image shows only slight limb darkening, which would not be observable ocularly. (they also described it as what you see in visible light)

    I asked a simple question, stating that I did not understand what you were infering. Typically, you obfuscated and applied derision, rather than give a proper answer. An apology from you would be appropriate.

  20. 470
    BobFJ says:

    Sorry, correcting my part[2] above to Martin Vermeer, html tags wrong.

    [2] I also draw your attention to this exchange:

    BobFJ #292: don’t sweat it… I won’t try to teach you anything against your will ;-)

    “Now that has me [BobFJ] more than puzzled. For example, are you suggesting that the SOHO MDI image of the sun of quality 151 KB, (or you can click for a 657 KB enhancement), is inferior to the 9.65 KB “depiction” in Wiki’, and that it does not show a difference?

    Bear in mind that when I look at the sun through my arc-welding mask, it looks uniform in colour, and that the MIDI SOHO image shows only slight limb darkening, which would not be observable ocularly. (they also described it as what you see in visible light)

    I asked a simple question, stating that I did not understand what you were infering. Typically, you obfuscated and applied derision, rather than give a proper answer. An apology from you would be appropriate.

  21. 471
    Larry N says:

    Re# 467

    Regarding ice area over ice extent. Over the past week, ice area has slowed down quite a bit, with the past few days showing a melt rate of 35-40K per day. Meanwhile the ice extent has shown a greater decrease.

    From looking at the sattilite photos, it appears that the ice in the east siberian sea is becomming more disperse, however it is still above 15% and this is depressing the actual true melt rate.

    The 15% crieteria may be a little low, and it would be interesting if mutliple crieteria was given like 15%, 25%, 40%.

    It may be a mute point, as by the end of the melt season, the ice appears to have a well defined boundary, or at least it has during the past several melt seasons.

    I do expect a few more 100-150k melt days, as the ice in the disperse ice in the east siberian sea drops below 15% concentration.

    Maybe with the release of 1 meter sat photos, hopefully the modeling of sea ice area and extent, can be better modelled, and the results will begin to converge better.

  22. 472

    #467 John, Is there a push for:

    Ice Volume publications
    Total energy input in melting the ice
    How much temperature loss this gives
    Average sea surface temperature of the entire Arctic ocean

    A few of these items in the form of data would be useful…

  23. 473
    Phil. Felton says:

    Re #464
    If I fully understood what you wrote, I agree with you, but reiterate that my understanding of Kevin’s comments was that either he or K & T (?) infer that IR back radiation will result in HEATING of the oceans. However, since infrared is (you agree) only absorbed in the skin of the water, and re-emission is an instantaneous process, there is virtually no opportunity for the slower downward process of conduction to take place. Thus, although it IS a very different process, it is somewhat similar IN EFFECT to reflection.

    Re-admission is not an instantaneous effect, far from it there is time for many deactivating collisions with other water molecules during the emission lifetime of the excited state. Consequently the energy of an absorbed photon is rapidly shared through the surrounding molecules.

  24. 474

    BobFJ writes:

    The topic in 464 was about the effect of back radiation or incoming EMR (infrared) and its virtual inability to penetrate water, and thus not cause significant HEATING because downward conduction is a very slow process compared with re-emission from the skin.

    The relative speed is completely irrelevant in this context! For a given thermal conductivity, heat transfer by conduction depends solely on the difference in temperature. For your model to be correct, the skin of the ocean would somehow have to maintain a markedly different temperature from the water one millimeter below it. Trust me, it doesn’t.

  25. 475
    Mark says:

    “Bear in mind that when I look at the sun through my arc-welding mask, it looks uniform in colour,”

    And you eyeball is an EXCELLENT photometer, isn’t it…

    Look, the earth looks flat on the wild plains or out on a large lake, doesn’t it.

    Does that mean the earth is flat?

  26. 476
    Dave says:

    How do you respond to recent papers that sea ice losses are due to wind shifts, not warming in the north Atlantic?

  27. 477

    Re #476 where Dave asks “How do you respond to recent papers that sea ice losses are due to wind shifts, not warming in the north Atlantic?”

    Which papers?

    In any case, the reason more ice is lost from the Arctic due to wind is that the ice is now thinner and so has broken into smaller pieces which are more likely to be blown about. In other words, it is not a matter of winds OR warming. It is a matter of winds AND warmer oceans AND warmer air due to greenhouse warming.

    HTH,

    Cheers, Alastair.

  28. 478
    Hank Roberts says:

    Dave asks:

    > how do you respond to recent papers … wind shifts, not warming …

    Let’s take your question as an example.

    Paste your question into the Search Box for Google Scholar. Here, thus:

    http://scholar.google.com/scholar?hl=en&scoring=r&q=sea+ice+losses+are+due+to+wind+shifts%2C+not+warming+in+the+north+Atlantic%3F&as_ylo=2008

    Look at the first hit:

    GLACIOLOGY: Winds, Not Just Global Warming, Eating Away at the Ice Sheets
    RA Kerr – Science, 2008 – sciencemag.org
    … drove more waters from the Irminger Sea near Iceland …

    So — Dave — Compare:

    You: “wind shifts, not warming in the north Atlantic”
    Science: “Winds, not just global warming”

    Perhaps you’re thinking of some other “recent papers” — if so, which ones? What’s your source, and why are you relying on it?

  29. 479
  30. 480

    #472 Wayne Davidson

    As far as I know they are still trying to model ice volume over the past 100 years (or so) but that has many challenges.

    Last I heard, the ice volume >2 year ice is down to 9.8% and losing that thick ice at 10% per year. You can find more on NSIDC http://www.nsidc.org

    http://www.ossfoundation.us/projects/environment/global-warming/myths/images/arctic
    images have source links in the descriptions

    The modern satellite measurements are helping us understand what is going on now though.

    http://www.ossfoundation.us/projects/environment/global-warming/myths/images/arctic/20070822_oldice.gif/image_view_fullscreen

    The sea surface temps and temps at depth are measured, dig around google, there are tons of SST sites in NASA and elsewhere.

    http://www.noaanews.noaa.gov/stories2009/20090717_juneglobalstats.html
    http://www.nasa.gov/topics/earth/features/icesat-20090707.html

    Google is your friend :)

    Here are some I use

    http://www.emc.ncep.noaa.gov/research/cmb/sst_analysis/
    http://www.nhc.noaa.gov/aboutsst.shtml
    http://www.nodc.noaa.gov/dsdt/oisst/
    http://www.cdc.noaa.gov/map/clim/sst.shtml
    http://www.cdc.noaa.gov/data/gridded/data.noaa.ersst.html
    http://www.nodc.noaa.gov/dsdt/sst_ani.htm
    http://polar.ncep.noaa.gov/sst/
    http://polar.ncep.noaa.gov/sst/oper/Welcome.html
    http://www.opc.ncep.noaa.gov/sst/goessst2.shtml
    http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/sstanim.shtml
    http://coralreefwatch.noaa.gov/satellite/current/sst_anomaly_2m.html
    http://www.aoml.noaa.gov/phod/cyclone/data/at.html
    http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/gsstanim.shtml
    http://www.pmel.noaa.gov/tao/jsdisplay/
    http://lwf.ncdc.noaa.gov/oa/climate/research/sst/sst.php
    http://noaasis.noaa.gov/NOAASIS/ml/sst.html
    http://www.csc.noaa.gov/crs/cohab/hurricane/sst.htm
    http://polar.ncep.noaa.gov/sst/oper/global_sst_oper0.png
    http://polar.ncep.noaa.gov/sst/oper/global_anomaly_oper0.png
    http://polar.ncep.noaa.gov/sst/oper/namer_sst_oper0.png
    http://data.giss.nasa.gov/gistemp/graphs/
    http://lwf.ncdc.noaa.gov/oa/climate/research/trends.html

  31. 481
    Martin Vermeer says:

    BobFJ #470, congratulations, you just invented “limb darkening denial”.

    Spare me the concern trolling. I don’t care if you understand me or not, or if you’re fake dumb or the genuine article. The readership here understands you very well by now, trust me.

  32. 482
    Susan Anderson says:

    Wili in 440 speaks for me:

    “Which brings us back to the life-and-death issue again:

    “What are the likely effects of a total or even near total melt of the Arctic Ocean going to be on agriculture and other crucial systems?
    ….
    “We are not just fascinated at watching the Arctic melt because it is abstractly and scientifically interesting. We are riveted to charts on Cryosphere Today and other sources because we are watching our earth change into a different kind of planet, and we can’t be sure what this mean for us and our children.

    “I would still like any clear and accurate information (or even well-informed speculation) that the good folks here could provide. I have read many of the books on the subject for the general public, but I do find some climatological jargon in published papers a bit hard to follow.”

    That said, replies to persistent (and professional looking) pseudo-skeptics provide a wealth of varied information.

  33. 483

    #482 Susan Anderson

    Susan, as the summer ice subsides the Arctic amplification (polar amplification) is reasonably expected to accelerate. This will have multiple effects the expected ramifications include further latitudinal shift and accelerated warming.

    Latitudinal shift and warming have different but related ramifications

    Droughts, floods, extra large snowstorms in higher latitudes, inability for infrastructure to follow shift due to economic limitations, et cetera.

    Of course northern hemisphere accelerated warming will exacerbate the Greenland ice melt and accelerate sea level rise.

    That warming will of course influence the oceans and they will begin to warm faster placing more H2o into the atmosphere, and further exacerbating the acceleration of warming.

    http://www.ossfoundation.us/projects/environment/global-warming/summary-docs/2009-may-leading-edge

    http://www.ossfoundation.us/projects/environment/global-warming/security

    Read up on feedbacks on RC and elsewhere

    http://www.ossfoundation.us/projects/environment/global-warming/feedbacks

    * http://www.epa.gov/climatechange/glossary.html#ClimateFeedback
    * http://www.ncdc.noaa.gov/oa/climate/gases.html

  34. 484
    Alastair McDonald says:

    Re #482

    Susan,

    You are not the first to try and get the scientists to answer the question “What are the likely effects of a total or even near total melt of the Arctic Ocean going to be on agriculture and other crucial systems?”

    Willi wrote “Is this somehow off topic? Is it too uncertain to discuss? Or too scary to discuss?”. The answer seems to be “Yes, yes, yes.”

    But two scientists have now faced up to the truth. See Brierley and Kingsford described here.

  35. 485
    BobFJ says:

    Phil. Felton 473, you wrote WRT infrared absorption by water:

    Re-admission is not an instantaneous effect, far from it there is time for many deactivating collisions with other water molecules during the emission lifetime of the excited state. Consequently the energy of an absorbed photon is rapidly shared through the surrounding molecules.

    OK, perhaps I should have said ‘almost instantaneous’, and it is of course complicated. E.g. re-emission is not a perfect description of what happens according to QM theory. For instance one particular photon being absorbed is end of story for that photon, and subsequent emissions are in other photons from varying energy levels. Sure there is a lot of activity in the skin of the water as a consequence of incoming infrared, but as you say: …rapidly shared through the surrounding molecules….
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    474 Barton Paul Levenson also wrote:

    The relative speed is completely irrelevant in this context! For a given thermal conductivity, heat transfer by conduction depends solely on the difference in temperature. For your model to be correct, the skin of the ocean would somehow have to maintain a markedly different temperature from the water one millimeter below it. Trust me, it doesn’t.

    Actually, as with most things in nature, they turn-out to be more complicated than at first sight.
    The skin of the water has complex dynamics, the obvious being; the interface conditions, temperature, air humidity, wave action, wind, and evaporation. The most important WRT your observation is the latter. Global estimates of HEAT loss from the surface from evapo-transpiration have been made up to 50% of the total#. Thus since this is the largest cooling effect, and since it takes place from the skin, it infers that the water below the skin would be warmer. Thus, there is a problem WRT to your comment and thermo’law2.
    However, for the skin, I suggest that what with the other dynamics below, that some of the higher energy molecules may be transported downwards resulting in an effect that might be called conduction for want of a better word. It doesn’t end there; for instance, any surface HEATING would be combative to convective heat loss from below.
    # http://chriscolose.wordpress.com/2008/12/10/an-update-to-kiehl-and-trenberth-1997/#comment-981

  36. 486
    Doug Bostrom says:

    BobFJ 1 August 2009 at 6:13 PM

    “The topic in 464 was about the effect of back radiation or incoming EMR (infrared) and its virtual inability to penetrate water, and thus not cause significant HEATING because downward conduction is a very slow process compared with re-emission from the skin.”

    Hey, Wingman Bob, if I point an infrared source at an iron ingot and meanwhile the infrared source remains constant, will only the first millimeter or so become warmer, assuming the ingot is cooler than the source?

    Come to think about it, where -does- your zone of heat impermeability begin? A millimeter? A centimeter? Kilometers down?

    How does this magic work? And how do we commercialize it?

    Seriously, that is probably the single most ignorant assertion I’ve heard on this site, and that’s saying a lot.

  37. 487
    Doug Bostrom says:

    Further BobFJ’s discovery of heat impermeability, do we taxpayers get a rebate for all the money wasted on Apollo PLSS sublimator systems? What a fraud! The suits would have re-radiated perfectly well without all that plumbing! After all, the wavelengths impinging on the suit couldn’t penetrate that first magic millimeter (centimeter/kilometer/parsec) of material and thus the money on cooling was wasted, right?

  38. 488
    BobFJ says:

    Phil. Felton & Barton Paul Levenson, cc Kevin Mckinney.
    Further my 485, I recapitulate, that this all arose from an exchange I had with Kevin Mckinney, (my 367, and his 300), and that the more recent stuff is really a nitty-gritty diversion to that of the bigger basic ask I had in my 367 that still remains in a state of ???????????????????????????????:

    Kevin McKinney Reur 300, in part, you wrote concerning comparative albedos of water and ice:
    Albedo is not only an issue at optical wavelengths, but at infrared wavelengths. Back radiation in the infrared will not be reflected by the water due to angle of incidence–and, according to Kiehl & Trenberth ‘98, this is an input roughly twice as large as direct insolation.
    I was intrigued by your reference to K & T ‘98, because it seems to be a very simplistic statement. So, I Googled around but could not find it. Could you please check your reference; is it the wrong year maybe? Also, Trenberth and his colleague Kiehl have independently authored other works …. ?
    [discussion in my 367 excluded here for brevity]
    …So, what was K & T (?) on about?
    Kevin, please clarify your sources.… I‘m very interested.

  39. 489
    Mark says:

    “Actually, as with most things in nature, they turn-out to be more complicated than at first sight.”

    Not complicated to significantly change BPL’s statement.

    No matter how much you want it to.

  40. 490
    Phil. Felton says:

    Phil. Felton & Barton Paul Levenson, cc Kevin Mckinney.
    Further my 485, I recapitulate, that this all arose from an exchange I had with Kevin Mckinney, (my 367, and his 300), and that the more recent stuff is really a nitty-gritty diversion to that of the bigger basic ask I had in my 367 that still remains in a state of ???????????????????????????????:

    It doesn’t really matter why you got the science wrong it gets corrected.
    Your original question appears to be how to find K&T, your problem might be that it was actually published in ’97.
    http://www.atmo.arizona.edu/students/courselinks/spring04/atmo451b/pdf/RadiationBudget.pdf

  41. 491

    #274 #293 #304 #320 #349 (Bof_FJ, manacker, Rod B, Kevin McKinney)

    Sorry, to have missed the discussion. My point was meant to be general in nature so I hope it was not unduly misleading. The loss of arctic ice will allow the Arctic ocean to absorb more heat energy.

    Maybe this is a better way to illustrate the point

    http://svs.gsfc.nasa.gov/vis/a010000/a010000/a010021/index.html

  42. 492
    Chris Dudley says:

    Susan (#482),

    The answer to the question “what are the effects of substantial loss of sea ice?” looks to be that it all happens in a package. There are obvious local effects such as a big change of habitat for many Arctic creatures and perhaps one may attribute some local heating to change in albedo but you are worried about agriculture and for that you need to look at global models. Once you do that, the particulars of the sea ice loss will not be all that apparent. Drought in the US Southwest and Southeast are part of the whole warming pattern. Greater precipitation in the Northeast would also be a part of the global pattern. The IPCC report tries to describe what models indicate will be the changes on a subcontinent scale. Changes over the whole Earth feed into these predictions, not just the Arctic.

  43. 493
    G. Karst says:

    July (month end averages) NSIDC

    1980 Southern Hemisphere = 16.1 million sq km
    1980 Northern Hemisphere = 10.4 million sq km
    Total = 26.5 million sq km

    2008 Southern Hemisphere = 16.6 million sq km
    2008 Northern Hemisphere = 9.0 million sq km
    Total = 25.6 million sq km

    2009 Southern Hemisphere = 16.6 million sq km
    2009 Northern Hemisphere = 8.8 million sq km
    Total = 25.4 million sq km

  44. 494
    Mark says:

    And at the south pole, where is the sun?

    So it will be cold because there’s no solar heating for the greenhouse gasses to keep in.

    Now look again at your figures:

    1980 Northern Hemisphere = 10.4 million sq km
    2008 Northern Hemisphere = 9.0 million sq km (1.4 million lower in 28 years = 0.05 million per year)
    2009 Northern Hemisphere = 8.8 million sq km (0.2 million lower in 1 year)

    Looks like the rate of melting is increasing to me!

  45. 495
    Hank Roberts says:

    > July
    Compare the proportions.

    Of course it’s silly to cherrypick individual years when you can look at the overall trends over the long term.

  46. 496

    Re #490 where Phil. Felton posted a link for BobJ to K&T 1992. BobJ also asked for any later papers and K&T 1992 is about to be updated with this.

  47. 497
    dave p says:

    It does seem as if the melting has stalled in the last few days. In the bearents sea the ice seems to be increasing again. If this continues it may not reach the 2008 levels.

  48. 498
    G. Karst says:

    #495,#494 Mark, Hank Roberts:

    Everyone has seen the graphs, however, I find it a useful exercise to examine the numerical values. One can get so used to visual aids and anomaly trends, that we lose track of the actual values. Since we cannot process large columns of numbers, it becomes necessary to 3 or 4 columns. I choose current, last year, 30 yrs. ago as a fair snapshot. Beyond that, it is hardly cherry picking.

    As Mark points out “Looks like the rate of melting is increasing to me!”. He is entirely right for this July. I shouldn’t have to remind either one of you, that this is a monthly average report. Last month indicated the reverse. If you do not find the exercise useful, just use the scroll wheel to pass. That is what it is for!

  49. 499
    Gareth says:

    Susan #482 & willi,

    I share your concern about the impact of reductions in summer sea ice on northern hemisphere weather patterns. As changes in climate can be expressed as changes in the patterns of weather, not just as gradual warming, increase in rainfall etc, it’s very important to get some kind of idea of how the flows of atmosphere around the planet might change – what meteorologists might call the general circulation response. There are a few papers around on the subject (the most recent I’ve seen is Deser et al The Seasonal Atmospheric Response to Projected Arctic Sea Ice Loss In the Late 21st Century, submitted to the Journal of Climate earlier this year (a preprint can be found on the web)).

    A couple of key points seem to be emerging. The first is that during periods of rapid ice loss there is a corresponding rapid warming on the land around the Arctic, for a very substantial distance inland (1,000km, from memory). This warming is likely to be seen mainly in autumn and winter, but still has nasty implications for the stability of permafrost and potential positive carbon cycle feedbacks. This goes hand in hand with an increase in precipitation in winter – more snowfall. Both effects are related to the impact of having open oceans close to land: as they lose heat during the autumn/early winter freeze, that heat goes into the atmosphere and can be moved south. At the same time, that warmer air carries more water vapour from the open oceans, adding to snow fall. Open oceans are also conducive to increased storminess.

    It’s less clear what impacts this will have on the patterns of weather – storm tracks, positions of regions of high pressure, and so on. Deser et al find some responses – a pattern similar to the negative phase of the North Atlantic Oscillation in winters over the north Atlantic – but don’t speculate on what that might mean for North America and Europe. A lot more work is obviously needed…

  50. 500

    I would add to Gareth that if the Arctic seas warms by a few degrees, Greenland’s Glacier base, its very foundation, is directly in contact with these oceans. A lesson already learned by the collapse of Ward Hunt Ice shelf, despite still quite cold Arctic winters, the shelf drifted away from shore. Weather wise, its very hard to imagine an Arctic Ocean without ice, but Iceland’s current weather may be what is in store for the greater Arctic lands,
    at least for the ice free periods, this will ultimately mean a different weather world West of the rockies all the way to the Atlantic. More like fall weather of the last 50 years lasting for a great chunk of winter. We have already experienced what is to come. Not bad if you hate winter, but coming along with far reaching ramifications,
    affecting all. What is worrisome is the unknown in these ramifications.