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An update on the Arctic sea-ice

Filed under: — rasmus @ 26 August 2012

We noted earlier that the Artic sea-ice is approaching a record minimum. The record is now broken, almost a month before the annual sea-ice minima usually is observed, and there is probably more melting in store before it reaches the minimum for 2012 – before the autumn sea-ice starts to form.

The figure shows annual variations in the area of sea-ice extent, and the x-axis marks the time of the year, starting on January 1st and ending on December 31st (for the individual years). The grey curves show the Arctic sea-ice extent in all previous years, and the red curve shows the sea-ice area for 2012.

(The figure is plotted with an R-script that takes the data directly from NSIDC; the R-environment is available from CRAN)

UPDATE on the update The National Snow and Ice Data Center announced today (August 27th, 2012) that the 2007 record has now been broken by their more conservative 5-day running average criterion. They also note that “The six lowest ice extents in the satellite record have occurred in the last six years (2007 to 2012).”

343 Responses to “An update on the Arctic sea-ice”

  1. 51
    kristiina says:

    For the list of potential effects:
    As the ice melts and spreads evenly as fluids tend to do, the tectonic plates are going to go through a lot of adjustment. Meaning earthquakes.

  2. 52
    Donald Dresser says:

    Here is an idea for graphically displaying the concept that the loss of Arctic ice will lead to more persistent weather — choose two cities in the Northern Hemisphere from substantially different longitudes and plot the difference between their weekly highs over an extended period of time. This curve should show a change in behavior over the most recent 20 to 30 years.

  3. 53
    michael sweet says:

    This was posted on Nevens’ blog. I didn’t copy the hot links.

    For those wondering about the NIC estimates (as can be seen here:, NIC produces operational ice analyses, focused on using many data sources of varying quality and quantity to detect as much ice as possible, even small concentrations. NSIDC’s passive microwave data may miss some low concentrations (it uses a 15% concentration cutoff), particularly during melt. So it’s not unusual for NIC/MASIE to show more ice, though it’s more than in other years because the low concentration ice is scattered over a much larger area.

    An important point is that NIC/MASIE, while picking up more ice, is produced via manual analysis and the data quality and quantity varies. So the product is not necessarily consistent, particularly from year-to-year. NSIDC’s product is all automated and consistently processed throughout the record. So there may be some bias, but the bias is consistent throughout the timeseries. This means that comparison of different years, trend values, and interannual variability are more accurate using NSIDC.

    Hope this info helps.

    Walt Meier

  4. 54
    dbostrom says:

    john byatt says: 26 Aug 2012 at 10:52 PM Tell him that the temperature (Arctic) and oil (Greenland) lights just came on while your were driving his car.

    what does it mean? well it means that first you must stop the car.

    No, no. It means you crank up Rush Limbaugh louder, drown out the clattering, banging noises coming from under the hood. Twist the rearview mirror up so you can’t see the smoke clouds trailing behind.

    When you’re sitting by the road waiting for the tow truck, pull up Watts on the smartphone and read about how it never actually happened, that your engine is suffering from natural variability, not owner failure.

  5. 55
    michael sweet says:


    This was posted at Neven’s blog:

    For those wondering about the NIC estimates (as can be seen here:, NIC produces operational ice analyses, focused on using many data sources of varying quality and quantity to detect as much ice as possible, even small concentrations. NSIDC’s passive microwave data may miss some low concentrations (it uses a 15% concentration cutoff), particularly during melt. So it’s not unusual for NIC/MASIE to show more ice, though it’s more than in other years because the low concentration ice is scattered over a much larger area.

    An important point is that NIC/MASIE, while picking up more ice, is produced via manual analysis and the data quality and quantity varies. So the product is not necessarily consistent, particularly from year-to-year. NSIDC’s product is all automated and consistently processed throughout the record. So there may be some bias, but the bias is consistent throughout the timeseries. This means that comparison of different years, trend values, and interannual variability are more accurate using NSIDC.

    Hope this info helps.

    Walt Meier

    [Response:Thanks! -rasmus]

  6. 56
    Mike Roddy says:

    Kevin McKinney’s Skeptical Science summary of the global impacts of sea ice decline is a good one, but the public still has no idea. The reason is continued intimidation of mainstream media by the fossil fuel companies, especially since the largest single revenue stream for most media outlets comes from new car ads.

    We are hurtling toward a crisis, a fact well known by most Realclimate readers. Isn’t it time that formal approaches to television networks and major newspapers got under way? Framing this issue over whether one thinks polar bears are necessary is just what the oil companies would like to see happen.

    Letters to editorial boards and statements from scientific organizations have either been ignored or posted on page 16. A serious media strategy is needed, with input from scientists, and boots on the ground to insist on private audiences with the owners of our media companies.

    Editors and reporters are too scared for their jobs to act. We have to go straight to the top on this one, including handouts at shareholder meetings, as well as other strategies yet to be developed. For starters, media company owners need to be told that the notion of accelerated drilling in the Arctic is madness.
    Otherwise, those of us who pay attention to the science on this subject will continue to be just a geeky niche.

  7. 57
    Hank Roberts says:

    > ice area

    The decline in the ice area at _maximum_ is also interesting to look at over time.

  8. 58
    Scott says:

    Pete @ 42, Tamino @44,

    Thanks, this makes sense.

    It’s impressive that the sea ice can rebound so well given the minimum trend. I guess there’s a relationship between the rate of ice formation and the existence of “survival” ice. Maybe the surviving ice acts as an insulator making it easier for new ice to form.

  9. 59

    #41 Lenart Van De Linde,

    The pattern seems to be that the models that produce a more severe volume loss, which will imply increased area/extent loss due to increased open water formation efficiency, are assimilating models and have higher resolution than GCMs. Because the assimilating models (PIOMAS/NPS) use ‘observed’ atmospheric changes, it seems likely that atmospheric changes play a key role. By ‘observed’ I mean reanalysis and current weather forecast model data.

    Maslowski claims it’s higher resolution, but to quote from something I wrote on my blog:

    PIOMAS “has a horizontal resolution of 40 km X 40 km, 21 vertical ocean levels, and 12 thickness categories each for undeformed ice, ridged ice, ice enthalpy, and snow.” NPS “is configured using a horizontal, rotated spherical grid covering 1280×720 cells at a 1/12 degree (approximately 9km) resolution. It has 45 vertical layers” in the ocean. So whilst Maslwoski has asserted that resolution is a key factor it doesn’t seem to be the case when PIOMAS is considered, NPS is 9km square, PIOMAS 40km square.

    It seems to me that the common factor most likely to be the key is that assimilating models assimilate what the atmosphere is doing, including its response to the loss of sea ice. GCMs have this feedback, but for example they overestimate the strength of the winter inversion (Boe et al) so they would grow more ice than in reality, which would reduce volume loss and thence area/extent loss.

  10. 60


    The Arctic sea ice is floating on the ocean, so it displaces its own weight in water, its weight is distributed throughout the oceans – and is negligble compared to the weight of the oceans. It’s not like the Greenland or Antarctic ice sheets which sit on land. Its loss will have no tectonic effect, none at all.

  11. 61
    Perk Earl says:

    Reply to #38: Thanks for the link on fires in Europe. Funny you should post that because just the other day I was thinking it was odd that only the US seemed to be suffering heat waves and fires this Summer. Interesting how MSM reported Russia’s fires the year they occurred, but not the fires in Europe this year. Wonder if they got marching orders to avoid GW type related events. It would also explain why there seems to not be much of any reporting on the current record Arctic melt. This is definitely a case of ignoring a developing catastrophe will not make one ioda of difference in how bad things get, only how lacking we will have been in reducing our carbon footprint.

    Arson was mentioned as an ignition source for many of the fires, (although I’m sure the fires are worse due to dry, hot weather) and I wonder if that is a reflection of the frustration many people are having in Europe right now due to high unemployment.

  12. 62
    Brian Dodge says:

    My thoughts on the relationship between the melting ice/polar amplification and the Hadley cell/Rossby Waves/drought in the United States –

    Lets build a simple kitchen model. Take a 0.7m/24inch long food service pan with 0.1m/4inches of water in it. Put one end over a stove burner(the tropics), and tilt the pan so the other end(the pole) has a thinner layer of water(tropospheric thickness) over it. Turn the burner on low(solar+GHG forcing), put a few drops of food coloring in and watch the convective circulation(Hadley Cell) form. Note the position of the downward return flow of fluid(Hadley Cell dry zone). Tilt the pan so that the pole end has a thicker layer(increased tropospheric thickness due to polar amplification of GHG warming)[1]. I believe that the downward return flow(Hadley Cell dry zone) will move toward the pole(drought in SW united states and Europe) because the geometry of the flow changes. Now turn up the burner(increased GHG forcing); the convection (Hadley Cell) will expand even further.
    I’d bet one could take a large paella pan on a turntable with a burner at the edge, and play with the rotation speed, volume of water, and thermal input to generate a model with analogues to polar/Hadley/Ferrel cells and Walker circulation. If you floated a viscous layer of oil(stratosphere) on the water(troposphere), you could change the coupling between coriolis effects and thickness.
    Or competent climatologists could just model it – &;>) – for a mathematically rigorous starting point (WAAY beyond my math skills), see A Barotropic Model of the Interaction between the Hadley Cell and a Rossby Wave, Held and Pillips, Journal of the Atmospheric Sciences, Vol. 47, No 7, Oct 1989

    [1] Our simple model allows us to adjust the “troposphere thickness” independently of forcing/temperature gradient/AGW, but in the real world tropospheric thickness is an emergent property of two temperature gradients – tropical/polar and moist(ish) adiabatic lapse rate, both changed by AGW.

  13. 63
    Brian Dodge says:

    Is the figure dynamically updated?

    [Response:No – sorry. Rasmus]

  14. 64
    tokodave says:

    50 kristina: The overall implications for a changing climate are severe enough for a planet where the entire world’s infrastructure, forestry and agricultural practices are based on a historic climate that increasingly no longer exists, that we don’t need to try and link climate change to the tectonic forces that generate large earthquakes. Any geophysicists here?

  15. 65
    Toby Thaler says:

    Why is there so little analysis of barometric pressure trends and possible relationships to warming, Arctic ice loss, and other patterns? Am I missing it? My search of turns up “Variability and Trends of Air Temperature and Pressure in the Maritime Arctic, 1875–2000,” Polyakov et al. 2002, but not much else. Is it an irrelevant factor, and if so, why?

    [Response: There’s a lot out there on the winds in 2007, which dominated the loss. Look up Stroeve for example. That probably applies to this 2012 ice loss as well. –eric]

  16. 66
  17. 67

    Here’s a quick Popular Mechanics interview with Walt Meier on some of the details of how sea ice extent is measured, and some notes on extending the timeline earlier than 1979, when consistent satellite data began. Nothing startling for most people on this site, but could be useful. (Oh, written by me, by the way.)

  18. 68
    Petter says:

    Could someone explain the difference between the main NSDC analysis and NSIDC IMS graph which is not at a minimum? I guess they meassure the ice extent differently, but what is the difference?

  19. 69
    BillS says:

    Received this today and send it along “as is” and hope it is appropriate to do so:

    Cc: “”
    Subject: [CRYOLIST] Arctic sea ice data set inter-comparison and new resource available

    Dear colleagues,

    With all
    of the attention on Arctic sea ice, the resource that we’ve been putting
    together on the Climate Data Guide,, may be of

    Here is
    one figure comparing 2003-2007 September mean sea ice concentrations across 10
    data sets:

    particularly surprising that there have been so few systematic comparisons of
    sea ice climatologies and trends among the many data sets. Currently, records
    are being broken across most if not all of the major satellite and algorithm
    combinations, but I think the differences (esp. for sea ice concentration and
    area) are important in the context of comparing observed sea to coupled models,
    calculating surface fluxes, and prescribing boundary conditions for atmospheric

    Climate Data Guide aims to gather knowledge on the strengths and limitations of
    numerous climate data sets, including sea ice concentration. We post well
    informed and substantiated expert commentaries. Each page also has a comments
    section at the bottom for more informal tidbits. Please consider making a
    contribution; it is a relatively painless process. It is described more at Sea ice is just one of
    many topics. For instance, there is a lot of interest at NCAR in the
    performance of various renalyses in the polar regions. Surely there is
    knowledge out there that could be given a little more daylight?

    A side
    benefit of gathering these data sets has been the development of one of the
    more searchable (IMHO) data sites. See specific sea ice
    information, or a more generic
    representation of data set attributes.

    for your interest.



  20. 70
    Jim Larsen says:

    This close to what could be the end of September ice, the usual rule of thumb, that adding one more data point adds little value, weakens. Even a partial data point, such as 2012 so far, becomes quite helpful.

    The first Key Point of is:
    “CMIP5 models continue to underestimate rate of sea ice loss”

    It’s possible that “reality” isn’t an average run. Otherwise, we’re in a race of sorts to see if a model can “predict” the event before it happens.

    So, we’ve got a complex tool which isn’t quite(?) ready to do the job, and we’ve got “the perils of extrapolation”.

    But then, there really isn’t any action plan, other than to ensure that as much oil can be extracted as soon as possible.

    54 Mike R said, “the largest single revenue stream for most media outlets comes from new car ads.”

    I just saw a jay Leno’s garage episode showing GM’s BIG truck and SUV versions of the Volt. Leno was impressed. They quoted 100 to 1000s of MPG. Eyeroll. Anyway, converting the fleet to series-hybrid, which is what GM seems to want to do, would require lots of ads. I think Owner/Executive agenda counts for more. Ads happen based on circulation. And, owning a media company is becoming more and more about exercising your right to personal free speech.

  21. 71
    Sean says:

    by Carlos Duarte
    Director, Oceans Institute at University of Western Australia

    Groundhog Day: The ice extent in the Arctic Ocean reaches a new minimum

    I received a phone call from a journalist this week interested in my thoughts on the new minimum of Arctic ice sheet, since I published a paper earlier this year, arguing that the dynamics of the Arctic ice sheet is signaling at the proximity of a tipping point.

    In our conversation he asked whether I was prepared to speculate on the possible causes of this new minimum. I found the question a little perplexing and conveying an intense sense of deja-vú, as this is a recurrent experience every month of August for at least the past 6 years.

    In the 1993 movie Groundhog Day), Bill Murray is a TV weather reporter who finds himself locked onto the same day, waking up to same sequence of events repeating themselves over an over on a loop.

    With so much evidence there, how can we continue to ponder on the possible ultimate causes of Arctic ice loss?

    The noise on the climate change debate has reached such level that my colleagues in the US, particularly scientists within Federal agencies, tell me that they avoid taking a position on climate change in public conversations and news releases.

    The reluctance of the US public to agree with the wealth of scientific information pointing to an on-going and future warming of the climate due to anthropogenic green-house gas emissions seems to be curving now with the severe heat, drought and crop failure in the US this year.

    rest of short article here:

    It is way overdue imho, that scientists all over the world begin to speak in a language that people can understand, and stop dithering. iow be BLUNT, and gain attention through BIG OPINIONS – and use those tools spoken of in the book Language Intelligence recently mentioned.

    Americans (the #1 indulgent polluters in the world by size) are the slowest dim witted people on the planet – that’s why media orgs like FOX NEWS even exists. Time to fight fire with fire isn’t it?

    [Response: Let’s be fair now. The U.S., Australia and Canada are together the worst polluters on a per capita basis. Last time I checked, Canada was worst. As for dim-wittedness, well, fingers can be pointed at just about everyone, everywhere. –eric]

  22. 72
    Harmsy says:

    It’s a shame the graphic says “Januay” not “January”! Can someone please change the spelling? It loses some of its authenticity!

    [Response:Fixed. Thanks! –eric]

  23. 73
    dhogaza says:

    Interesting how MSM reported Russia’s fires the year they occurred, but not the fires in Europe this year. Wonder if they got marching orders to avoid GW type related events.

    I’ve seen coverage of fires in Spain, in particular one island where firefighting aircraft were returned to the mainland when they thought the fire was controlled, only to see the fire blow up and the aircraft unavailable for over 24 hrs.

    Perhaps there’s less coverage than for the Russian fires because a) the Russian fires were horrendously extreme b) it’s a Presidential election year in the US and the incumbent is at much greater risk than normal c) events in the middle east (particularly syria) are claiming a lot of the column inches available for international coverage by the US press.

    Conspiracy-thinking light “maybe they’ve been told not to cover GW events” is a bit too tinfoil-hattish for my taste.

  24. 74
    owl905 says:

    There’s nothing happening. Tony T. Watt has produced (discovered/uncovered/stumbled upon) a graph that shows less than a rock-bottom minimum record. Walt Meier even contributed to try and clarify the issue, but it already had the numb in the number.

    No rock is left unthrown … but for a parallel, Tony guided me to the ‘non-record-setting’ graph once before: the Danish 30% threshold group. He didn’t use it, or reference it, this time around:

  25. 75
    Steve Fish says:

    Re- Comment by dhogaza — 27 Aug 2012 @ 6:49 PM:

    In my not so limited experience, with the exception of commentators and news agencies with obvious biases, much of the mainstream news focus is due to incompetence, gullibility, and a sort of big buzz profit motive.

    News be entertainment. Steve

  26. 76
    Gerry Beauregard says:

    Since the summer minimum is getting so close to zero, the graph would be clearer if the scale on the vertical axis started at zero rather than 4M km^2. At the rate things are going, by mid-September this year the sea ice extent will likely be below 4M km^2 anyway.

  27. 77
    WhiteBeard says:

    50, Allen W., 27 Aug, 6:47 AM

    Alaska is a large state when compared to other in the US, but the affected area is quite small. It’s about like extrapolating weather on Cape Cod and Mass bay to all of New England and the Mid-Atlantic States.

    As well, Kivalina is some distance north of the Bering Straits on the east coast of the southern Chukchi Sea. The Chukchi is a named portion of the Arctic Ocean. Kivalina’s the village that needs to relocate due to increased erosion from fall storms, as it no longer has a sea ice buffer formed before their onset and gets much media attention as a climate change affected “poster child”. Here’s the latest.

  28. 78
    MalcolmT says:

    Steve Fish @74: You left out the fact that the major media outlets all borrow endlessly from each other so that a great percentage is edited and subbed, if not written, by people a long way from the action, i.e. people who don’t know much about it. That adds ignorance to incompetence and gullibility.

  29. 79

    Cudos to Mr Tamino on his web site about WUWT author and followers falling into even greater ignoramus fame. By the way I am encouraged to expose their accomplishments more because of the way they responded to Mr Meier

    Now lets process WUWT ability with prediction the scientific way

    June Extent Outlook
    WUWT and Neven photo bucket
    2012 4.9 million km square 4.0 /Watts off by more than 0.9 million km2
    2011 5.5 4.5 /Watts off by 1 million

    How revealing, a perfect record of failure!… Mr Watts your ultimate peer is not only found in academia and science institutes, but in the future, by which you have failed. Review your understanding of the science or continue failing.

    Now about this very strong early August cyclone, there is a great disparity between a melt influenced by High pressures (2007) and a cloud covered super cyclone (2012 Anticyclones push the ice outwards, cyclones consolidate ice inwardly. Which was the case in 2012. However the mega cyclone in question did some mixing of warmer sea water and already existing very weak thin sea ice. A “hot” super anticyclone would have probably done more melting and flushing. Again
    emphasis must be placed that there was lack of sunshine in summer of 2012 yet 2012 melt was greater than 2007. The decline of Arctic sea ice may be permanent, possibly delayed but by ideal future summer weather conditions, a possible long shot would be delaying melting by a very cloudy spring early summer, and a cool late August September Anticyclonic influence either scenarios twinned with a very strong La-Nina in the middle of winter during the long night. ….. Otherwise welcome to the new warmer world not quite the same as the old world.

  30. 80
    Lawrence Coleman says:

    71 Sean. I’ve being saying exactly that for years mate!, it seems as though scientists haven’t got the foggiest clue how to connect to the layman. But Gavin made the point earlier about creating your own personal blog, if you happen to be articulate either orally or with penmanship (keypadmanship) and if you can actually grasp the true gravity and significance of what is happening in front of our very eyes as opposed to wishing it away(the cowardly american approach) then for christsake create a blog with your ideas (as long as they are grounded in good science) and go selling it on facebook or twitter etc. I agree..Time to fight fire with fire! As it stands now, the best we can probably do is keep life..or what vaugely resembles life teetering along in a living hell for thousand of years. Whether humans actually make it is by the by. Don’t forget the oceans will be inhospitable to life for an epoch. Still I refuse to give up fighting until the last bullet takes me to the ground, that’s just my nature.

  31. 81
    Allen W. says:

    77 WhiteBeard 28 Aug 2012 at 1:07 AM

    I might have put up the wrong link, the story I was referring too was about torrential rain in Nome, AK, where the mouth of the Yukon river discharges into the sea. Rain that falls north of the continental divide naturally ends up back in the Arctic ocean, but the stuff that falls south of the divide ends up in the Yukon or its tributaries and ends up in the Bering Sea.

  32. 82
    Jaime Frontero says:

    Lawrence Coleman@80

    “(the cowardly american approach)”


    Michael Mann is an American (as are many of the RC core). So is James Hansen. Al Gore. And the myriad of American activists who work on the Climate Change issue all over the world – many of whom have been killed.

    Explain to me (and to everyone, if you would be so kind), please, A.) how these both famous and uncounted men and women are cowards; and B.) how your comment has a place on this site – devoted to the science of Climate Change and its spread.

    That was completely uncalled for.

    [Response:I’m not aware of anyone having been “killed” for climate change activism. I would hope it doesn’t come to that. –eric]

  33. 83
    Douglas McClean says:

    What happens to these datasets when the assumption that the area around the pole that is above the inclination of the satellite(s) is fully covered in ice no longer holds? Do we have any alternative ways to collect information about that part of the ocean, maybe from aircraft?

  34. 84
    Henry says:

    Typo: “the annual sea-ice minima usually is observed”
    either “minima … are observed” or “minimum … is observed”
    (It just bugs me seeing this right at the top of the article.)

  35. 85
    Unsettled Scientist says:

    owl905, it appears that Anthony Watts hasn’t read the manual for MASIE at NSIDC. It specifically says that this is a bad product to for analyzing longterm trends due to climate change.

    “While operational analyses are usually the most accurate and timely representation of sea ice, they have errors and biases that change over time. If one is interested in long-term trends in sea ice or how it responds to changing climate forcing, generally, it is best not to use an operational product, but rather one that is consistently produced and retroactively quality controlled. The NSIDC Sea Ice Index monthly ice extent, and the satellite passive microwave data sets upon which it is based, is one example. The Sea Ice Index gives a daily image of extent as well as monthly products. However, these daily images are not meant to be used for climate studies or for inferring anything longer than seasonal trends. Satellite data are not quality controlled quickly enough; and for reasons explained in the Sea Ice Index documentation, the daily ice edge position can be off by tens of kilometers or more from the ice edge that an analyst would draw. Reasons include known errors in thin ice detection, bias in summertime concentration estimates, and the relative compactness of the marginal ice zone. See Partington et al. (2003) for an assessment of operational versus satellite-derived ice concentration.”

    My guess is that Watts doesn’t care that he is using a product that has errors and biases built-in to long-term trends because those errors and biases currently support his point. He is likely willfully ignoring the fact that this is a bad product to use to determine climate responses, and doesn’t care that the data sources and analysts NIC uses may have changed over the course of just a couple weeks.

    [Response: Whatever credibility Watts might have had has now been completely erased by his abuse of FOIA (publishing personal family details about people is not the intent of FOIA). –eric]

  36. 86
    Hank Roberts says:

    Eric, that may be a reference to this recent report:

    [Response: Fair enough, but this is rather different. There is a big difference between first-world climate change activists and third worlders just trying to defend their lands. I’m not saying that any of this isn’t serious and alarming, but it is best not to conflate these things.–eric]

  37. 87

    #65 Toby and Eric,

    You’ll find a list of papers about 2007 at the end of this post. You can also find posts at my blog under the tag ‘Arctic Dipole’.
    There are links to papers under each of those posts, you can then use the references of those papers to explore the issue further.

    Unless you have unpublished information I don’t have, I really don’t see this year as at all analagous to 2007. In block quotes is how I understand 2007, to save you having to wade through that to get to my point.

    As with 2007 2010 and 2011, this year, as soon as the sea ice edge entered the Arctic, the anomalies (Cryosphere Today area) fell through the floor.
    2010 later recovered somewhat, but 2011 and 2012 were at least as low as 2007.

    NCEP/NCAR doesn’t show 2007 like synoptic patterns in 2012 and 2011, nor does it show anything atypical of the 2000s IMO. So I see 2007 as due to the specific process outlined in below (block quote). What happened in 2011 and 2012 is different. Both years show record loss from Jun 1st to July 31st, 2008 to 2010 was around 5.4M km^2, 2011 & 2012 over 5.8M, 2007 under 5.8M.

    I am becoming more convinced that the last two years are as a result of a massive volume loss in Spring 2010. Here’s a graphic of the PIOMAS volume series (blue) and interannual changes (red), in 1000km^3.
    This was done for a different purpose so it’s for Oct – Nov average. But it shows that the volume loss of 2010 is of the same order as that for 2007, a result that stands for earlier periods during summer. This volume loss is from ice over 2m thick – from analysis of PIOMAS grid box data.

    What I think is happening is that after the clear-out of summer thick ice from PIOMAS in 2010, which also happened 2011, and (due to the same change in seasonal cycle) very probably happened in 2012, the Artic Basin sea-ice has thinned such that open water formation efficiency has increased. This happened in 2010, so the process was ongoing throughout the melt season. But by 2011 and 2012 it was complete and in the CT area anomalies and early summer melt rates, we see the consequences of increased OWFE: record areal melt seasons without anomalous weather driving them.

    No need to reply, sorry to dump all this detail on you but I’m in the process of revising my previously conservative stance on when we’ll see a virtually sea ice free state. So I have all this stuff to hand. FWIW I’m now wondering if Dr Wadhams is correct in saying we’ll see further crashes in the next few years. Up to this summer, and until I saw the detailed PIOMAS data, I had argued against the ‘early transition’ camp.

    Schweiger et al, Zhang et al (a & b) and Perovitch et al support the following broad picture of the processes leading to the losses of 2007: An influx of warm waters through the Bering Strait, driven by the extreme positive Arctic Dipole delivered enough heat to melt 0.5m of ice over the Chucki Sea. That influx of warm waters can itself be attributed to the Arctic Dipole, as the meridional wind anomalies that characterise it are able to draw water in through the Bering Strait (+ve phase) or the Atlantic (-ve phase). The Arctic Dipole also hastened the transpolar drift, transporting large amounts of ice over the Arctic and increasing build up off Canada and transport through the Fram Strait, this lead to the formation of open water in the Pacific sector of the Arctic. This resultant open water, under clear skies, allowed the ice albedo effect to increase absorbed solar radiation by 500%. Schweiger et al find that insolation during June and July did not drive the sea-ice recession at that time, although it did cause thinning of the ice, Perovitch’s study of mass balance buoys finds that insolation (the 500% figure) did cause subsequent warming from August onwards due to open water. As Schweiger et al note “local heating in response to the removal of sea ice is the more likely reason for the increase in temperature” [south of the ice edge].

    However it is not quite as simple as this because the Arctic Dipole itself was both cause and effect. Bluthgen et al use a model forced with observed sea surface temperatures and ice concentrations to study the atmospheric situation in 2007. They find that the initial atmospheric pattern leading to ice loss is reinforced both regionally and due to ice-export acting to intensify the ice loss. So this pattern, the Arctic Dipole, was itself intensified by the sea-ice loss it caused.

    Bluthgen et al, 2011, “Atmospheric response to the extreme Arctic sea ice conditions in 2007.”

    Perovitch et al, 2008, “Sunlight, water, and ice: Extreme Arctic sea ice melt during the summer of 2007.”

    Schweiger et al, 2008, “Did unusually sunny skies help drive the record sea ice minimum of 2007?”

    Zhang et al a, 2008, “The role of Pacific water in the dramatic retreat of arctic sea ice during summer 2007.”

    Zhang et al b, 2008, “What drove the dramatic retreat of arctic sea ice during summer 2007?”

  38. 88

    #83 Douglas McClean,

    During the summer MODIS can be used by analysts to fill the gap in – it has no data hole. It’s not a problem. During the winter the ice will refreeze.

  39. 89
    Jaime Frontero says:

    [edit: off topic]

  40. 90
    Wyoming says:

    [edit: off topic]

  41. 91
    Douglas McClean says:

    Thanks for the info Chris @88.

  42. 92
    Unsettled Scientist says:

    Eric [edit: off topic] I wanted to point out here that the MASIE product is specifically bad for trend analysis and that is made clear by the NSIDC. People trying to use it for information on the sea ice’s response to climate change need to RTFM.

  43. 93
    michael Sweet says:

    NSIDC applies a correction to their area data for the polar hole. It was described last year, but I don’t have a link. AIR they use the ice concentration of the last 1 degree below the hole for the entire hole. I imagine that NSIDC will implement a correction for extent when that becomes necessary (they might already and I have not heard). They are professional in their data analysis.

    What does it matter anyway? When the hole makes a difference the Arctic is ice free.

  44. 94
    Douglas McClean says:

    It doesn’t matter, for exactly the reason you mention.

    I didn’t mean to imply that this hadn’t been considered or that anyone was unprofessional; I was just curious.

  45. 95
    Norman says:

    At Skeptical Science Daniel Bailey posted an interesting graph of 1938 arctic ice extent in August to compare with 2012.

    1938 shows lots of arctic ice. I checked some other dates. In 1954 August they show a lot of close drift ice. I am not sure how that compares to the modern version of determining sea ice extent so that there can be a good apples to apples match up.

    I read that the current method of filling in grid locations in the arctic is if the ice amount is greater than 15% a grid is considered to be 100% ice. Less than 15% and the area is considered ice free.

    The question is how would the current large area of ice free arctic ocean look compared to the 1954 area?

  46. 96

    For the “what does it matter folks”, Dr Jennifer Francis has a number of talks available online, including the YouTube:

    Her C.V.:

  47. 97
    Jim Larsen says:

    93 Michael said, “What does it matter anyway? When the hole makes a difference the Arctic is ice free.”

    The refuge for ice is the Canadian and Greenland coast, which isn’t terribly close to the pole. Will September 2012 area measurements be affected by the hole? Dunno. Do you?

  48. 98
    WhiteBeard says:

    #81, Allen W., 28 Aug, 8:35 AM

    The mouth of the Yukon is ~90 mi south across Norton Sound and another 30 or so miles further south along the coast from Nome. Nowhere is the Yukon’s drainage closer to Nome than around its mouth.

    You are reading about localized phenomena of a week to ten days duration occurring at locations that are exotic to you. To have the effect you seem to want to be possible, they would need to be something like continent spanning and season long.

  49. 99
    Edward Greisch says:

    I just sent letters to my local newspapers announcing this RC article. I recommend you send letters to your local newspapers making the same announcement to get around MSMs reticence. Do not put more than 1 URL per letter and stick to their word limit, probably 200 words. A record ice melt is too visible to be ignored.

  50. 100
    SqueakyRat says:

    The shape of 2012 curve is disquieting. It has not even begun to flatten out. The minimum in 2007 was later than usual, and this year looks to be later yet.