Julienne Stroeve’s New Paper

Julienne Stroeve from NSIDC sent her recent paper over, which she wrote in conjunction with Mark Serreze and others. Here is the abstract and link to the full document.


The sequence of extreme September sea ice extent minima over thepast decade suggests acceleration in the response of the Arctic sea ice cover to external forcing, hastening the ongoing transition towards a seasonally open Arctic Ocean. This reflects several mutually supporting processes. Because of the extensive open water in recent Septembers, ice cover in the following spring is increasingly dominated by thin, first-year ice (ice formed during the previous autumn and winter) that is  vulnerable to melting out in summer. Thinner ice in spring in turn fosters a stronger summer ice-albedo feedback through earlier formation of open water areas. A thin ice cover is also more vulnerable to strong summer retreat under anomalous atmospheric forcing. Finally, general warming of the Arctic has reduced the likelihood of cold years that could bring about temporary recovery of the ice cover. Events leading to the September ice extent minima of recent years exemplify these processes.


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28 Responses to Julienne Stroeve’s New Paper

  1. suyts says:

    Ok, I’m sure I’m reading this wrong, prob the drugs, but “Thinner ice in spring in turn fosters a stronger summer ice-albedo feedback through earlier formation of open water areas.”

    Thinner spring ice makes for a stronger albedo feedback? Eh?

  2. etudiant says:

    Leaves wiggle room at the very end:
    Natural variability such as seen in 07-09 may create temporary recoveries.
    Otherwise a well referenced paper. Will doubtless need close scrutiny to see if all the references check out, but the trends appear pretty clear.

  3. Scott says:

    I must say I was very happy to see this line:

    suggests acceleration in the response of the Arctic sea ice cover to external forcing

    [emphasis added]

    “External forcing” is exactly right. These could be natural (cycles or changes in currents, etc), from GHG gases, from aerosols, from outside the planet, etc. The term “external forcing” is much preferred over global warming or its synonyms.

    This is an important distinction. For instance, say that the warming in the 20th century was conclusively shown NOT to be significantly manmade (which I doubt is true, but that’s not the point). That would not mean that preparations for increased warming would be unjustified, particularly if the identified cause indicated increased warming through the 21st century.

    Also, congats to Dr. Stroeve on getting this published.


    • Julienne Stroeve says:

      James, I agree…external forcing is a good word to use because it incorporates natural and GHG-forcing. Certainly in the data we see warming in all seasons in the Arctic, which is partly externally forced and partly being generated from within the Arctic itself (i.e. autumn warming). This paper attempted to synthesize recent studies on factors behind the declines this past decade, and this will include of course references to studies that discuss GHG-forcing (from climate models) as well as papers that discuss changes in atmospheric and oceanic circulation that are impacting the ice cover. Of course this is a vastly evolving field, so some of it is already out of date (i.e. the changing role of the Beaufort Gyre to ice loss is not discussed).

      • suyts says:

        Thanks Doc, but Scott isn’t one of my pseudonyms. But I will echo his congratulations on the publishing. I’ll have a more specific comment/question on the GHG’s attribution in a comment as soon as I finish up a thing or two.

  4. Julienne Stroeve says:

    an update to the ice age discussed in my paper (in press in GRL)

    from the abstract:
    Analysis of a satellite-derived record of sea ice age for 1980 through March 2011 shows continued net decrease in multiyear ice coverage in the Arctic Ocean, with particularly extensive loss of the oldest ice types. The fraction of total ice extent made up of multiyear sea ice in March decreased from about 75% in the mid 1980s to 45% in 2011, while the proportion of the oldest ice declined from 50% of the multiyear ice pack to 10%. These losses in the oldest ice now extend into the central Arctic Ocean and adjacent to the Canadian Archipelago; areas where the ice cover was relatively stable prior to 2007 and where long-term survival of sea ice through summer is considered to be most likely. Following record-minimum multiyear ice coverage in summer 2008, the total multiyear ice extent has increased to amounts consistent with the negative trend from 2001–2006, with an increasing proportion of older ice types. This implies some ability for the ice pack to recover from extreme conditions. This recovery has been weakest in the Beaufort Sea and Canada Basin though, with multiyear ice coverage decreasing by 83% from 2002 to 2009 in the Canada Basin, and with more multiyear ice extent now lost in the Pacific sector than elsewhere in the Arctic Ocean.

    • Jimbo says:

      Hi Julienne,
      What per centage of the loss of Arctic sea ice is attributable to soot? I ask because I have seen previous papers pointing at soot and giving a figure for this forcing.
      Soot climate forcing via snow and ice albedos

      • Julienne Stroeve says:

        Jimbo, no doubt that soot is playing a role. But to be able to determine how much it has contributed to sea ice decline, would require basin-wide estimates of soot. That is something we do not have, there are actually very few in situ measurements of soot content over sea ice areas. Remote sensing in the visible wavelengths is sensitive to soot content, so it could be possible to get some information from visible measurements, but the problem is that different ice types have different reflectances, so separating out the soot contribution from differences in ice type for example is difficult if not impossible using optical imagery. Another way to try to get at it would be to do some atmospheric modeling of transport and deposition of soot from its source.

  5. NikFromNYC says:

    Because it has such a huge roundly symmetrical land mass centered exactly on the planet’s rotational axis, circular ocean and wind currents combine in a circular pattern around Antarctica that isolate it from black carbon soot but not from impotent CO2, so only the Arctic is melting due to dirty snow.

  6. Julienne Stroeve says:

    oops, sorry James.

    • suyts says:

      lol, No problem……as to my comments questions……

      Dr. Strove,

      Once again, congrats, and thank you for sharing this with us.

      I’m making the assumption that you’ve made it a point to bring this to our attention for the purposes of feedback…….so…..

      I enjoyed the paper. It mostly stuck to the facts, the verbiage was clear(except for us slow ones), the paper wasn’t muddled with incomprehensive graphs, and was reasonable………except….(now, you knew that was coming….:-) )

      “The downward trend in September ice extent is best explained from a combination
      of natural variability in air temperature, atmospheric and ocean circulation, and
      forcing from rising concentrations of atmospheric greenhouse gases (GHGs; e.g.
      Serreze et al. 2007a, b).”

      Ok, I can’t say that I’ve read Serreze07, so maybe I’m off base, and I understand that it is accepted that GHGs cause an increase in temps, but how much isn’t easily defined and is a contentious subject, so much so, I don’t believe there is an accepted amount that one can attribute to GHG’s. Wouldn’t it be better (and easier to model) and more accurate to simply state “air and sea temperature”? Or, is the paper claiming a different mechanism altogether just by the mere presence of GHG’s themselves?

      I did also see where the warmer water from the oceans caused the delay of ice formation. This could probably be the impetus of another paper rather than covering it in this one. But couldn’t one view this as a “heat shedding” mechanism? Has there been any energy budget analysis done? That is to say, are the oceans giving up more energy than receiving by having this open area of sea?

      Lastly, and the statement that bothered me the most, ….

      “Consider two sea ice regimes, one in a cool pre-industrial age and
      another in a warmer climate regime. Compared to the cool regime, the spring ice
      cover in the warm regime will consist of less old, thick ice and more thin, first-year ice,
      as well as a lower winter ice extent. It follows that there will be less ice in the warm
      regime in September—the thin ice melts out easily, the summer ice-albedo feedback
      is stronger, and it is simply warmer. We can broadly view what is being observed
      in the real world since about 2002 in the context of a warmer regime. Compared to
      30 years ago, when the ice was still in the cooler regime, today there is more thin ice
      in spring, enhanced shortwave radiation absorption and a warmer climate.”

      I’m sure this has little to do with the content, thrust and meaning of the paper, still………
      uhmm…. by implication, the industrial age started in 1981? It must have, because that’s when we were in a cool regime and the cool regime is apparently “pre-industrial”.

      Now, mind you that was a rushed read, so I may have more comments and questions later. I can only imagine the horrific labor and effort it took to write this, so please understand that the comments and critiques are made with the best of intentions.

      To know that this is all that a died-in-the-wool skeptic that paints all govt scientists with the same broad liberal conspiratorial George Soros paintbrush, Reagan loving creationist can come up with……… well, that’s high praise indeed.

      Congrats to your whole team.

      • Julienne Stroeve says:

        Not surprised by your questions….I sent this paper to Steve, mostly for information, but feedback is always welcome.

        On your first question, the link between GHGs and sea ice loss is purely based on the temperature increase. In climate models, both the temperature increase and the summer sea ice loss are robust signals when they run the models with the observed record of GHGs. Atmospheric circulation on the other hand is not a robust signal, which is one of the reasons why predictions of variables such as precipitation between models is all over the place (no consistent signal, except for a drying of the American Southwest). So in other studies, sea ice loss is linked to the te mperature rise from the observed record of GHGs. In our 2007 study, we suggested that 45-50% of the observed decline is a result of GHGs, whereas the rest is from natural climate variability. This number came from averaging all the climate model runs from the IPCC AR4 and assuming that the mean averages out the natural variability signal so that the remainder is the models GHG forcing. This of course is based on how well the models simulate both the GHG and the natural variability. In my opinion there is a lot of uncertainty, so the jury is still out.

        I’ll answer the next questions in a few…need to attend to something else first.

  7. PJB says:

    Dr. Stroeve’s sharing is appreciated. Skeptics and dissidents are an integral part of science. It is only human to include expectations and habituations in an article written by real people (as opposed to spin-meisters, apologists or advocates). That we can comment upon such things in a reasonable and polite manner is key. The truth will out, as long as we don’t shut it out.

  8. Julienne Stroeve says:

    James, yes as the ocean refreezes in autumn, it has to release the heat it gained during summer back to the atmosphere. Heat budget analysis shows that most of the heat is released back to the atmosphere (what you call heat shedding). But it appears that some is being retained in the Ocean. The exact amount is still uncertain, mostly because of large error bars in the measurements.

  9. Julienne Stroeve says:

    James, Ok…so on your final question…yes, I can see how that statement would bother you. And in fact, it was more for illustrative purposes rather than an exact time-period. The thrust of the meaning is that at the moment it appears the sea ice is in a warmer regime than it was 30 years ago. And it was more to the effect, that while we will expect less September sea ice this summer than back in the 1980s, based on large part because of the thinner ice cover and overall warmer temperatures in all seasons, we cannot predict if September 2011 will be greater or lower than say 2010. Predictability remains difficult at this point because we still cannot predict the weather. If you run sea ice models with observed thickness and concentration say in Spring, and use the actually observed summer circulation patterns, the models do a good job. Some of the groups that contribute to the SEARCH outlook do forecasts using this approach, but force the model with say an average SLP/temperature pattern based on the last decade.

    Global climate models cannot be used for short-term predictions because the model will be in its own phase of natural variability that you cannot expect to match what is happening today. GCMs are more useful for long-term predictions, though as I’m sure you have noticed there remains a lot of uncertainty.

    • suyts says:

      Dr. Stroeve,

      Thanks for responding to all three of my questions. Obviously, my second was simply a theoretical observation that would go something like, “Wouldn’t it be nice if we knew the ingoing and outgoing energy budget from the arctic oceans.?” Obviously, that is something we are a long way away from knowing.

      My first, has more to do with wondering why an extra level of complexity was added when even without it, it wouldn’t be possible to know the exact equation?

      If I am confusing, I apologize, having thoughts and articulating them are always the hardest for me. But, if we trying to discern the causes of the diminishing ice cap, and if GHG’s are only applicable to temps, why include them at all before understanding how the temps effect the icecap?

      In simple math form…… sea temps from lower lats. = st…….. temps in the arctic = at …..natural occurrences such as the AO, wind currents, PDO, etc = no so, …….. st(x)+at(y)+no(z)= arctic ice extent…x,y, and z being the various weights assigned… with me? This, even simplified down as such has so many complex intricacies and interactions, it is impossible to know today. But, you didn’t stop there, you guys added GHGs which are parts of both x and y……… so it would look something like

      (ghg*solar input*other no)(x) +ghg*solar input*yet more no) +no(z) = arctic ice extent…..

      In my opinion, and I realize it is just mine, wouldn’t it be easier to ascertain first, the effect of temps on our ice and then try to ascertain the effects of GHG’s on temps? Perhaps a cart/horse analogy. At any rate, that’s how I’d approach it, but I’m not the one that wrote it……… its easier to be a critic than a person that actually does something. 🙂

      On my last question/observation. I get the illustrative purpose. And, obviously there was a regime change. Sadly, it coincided with the time we were able to make satellite observations. Did the industrial revolution have any thing to do with it? Perhaps, probably not, seeing that event preceded the regime change by about 150 years, and there’s anecdotal evidence that there had been other regime changes prior to this one.

      And, perhaps it may be that I’m a bit hypersensitive to the issues, but going hand in hand with my first, this seem to be a gratuitous hat tip to warmists. If this is the thing one must do, then so be it.

      Dr. Stroeve, thanks for responding, and congrats again. I deeply appreciate the attention you’ve given.

      James Sexton

      • Julienne Stroeve says:

        Hi James, the reason why I said GHGs impact the air temperature and that is the driver for sea ice loss in climate models is because in the model simulations, the temperature rise from GHG loading correlates most strongly to the modeled sea ice decline. Sea level pressure pattern variations are not robust among the climate models, whereas the temperature rise and the sea ice loss are. So in the models at least, it is the air temperature rise that is the primary driver for the sea ice loss.
        Of course we know that changes in circulation patterns play a large role as well, which you can even see in the climate models as short-term variability superimposed on the downward trend line. And many papers that discussed for example the 2007 minimum focused on the circulation pattern of that summer and its impact on the sea ice loss, not GHGs. But it is widely agreed that the 26% drop in September ice extent between 2006 and 2007 would not have been as large if the ice cover had been thicker, so then you need to ask the question what is causing the ice cover to thin? Part of that is circulation driven, part from warming air and ocean temperatures.

        Cause and effect are very difficult to ascertain however. Warming can come from increases in GHGs, circulation changes, land-surface changes, feedback effects, etc. Trying to separate out GHG induced changes in air temperature and corresponding circulation changes from natural variability is difficult if not impossible using observational data. This of course is a reason why folks develop models, so they can run controlled experiments to try to isolate responses of the climate system to different forcings.

        My view is that both natural variability and anthropogenic warming (from not just GHG increases, but also land cover changes, air pollution, etc), together with the ice-albedo feedback, are combining to keep the summer ice cover low. It is of course entirely possible for natural variability to slow the ice loss for a few years, but if the background warming continues, eventually the natural variability will again be in phase with that background forcing and ice loss will continue.

      • suyts says:

        Dr. Stoeve, thanks for the clarification. Given the context, I see how it could be reasonable to include GHG’s as opposed to just temps, but it would still seem more prone to additional complexities. I also agree with the other anthropogenic issues being a causation. I dunno, maybe it could be useful for a chicken/egg paper, x causes thinner ice, y causes more significant ? winds/currents/temps?

        At any rate, I thank you again……BTW, I just read this, you were cited a couple of times…..

        Click to access tcd-5-1311-2011.pdf

  10. Latitude says:

    Well I have a model too.
    Who in this world was stupid enough to put that “0” line at the top?

    Where temperatures are the most unstable…………………

    If the atmosphere is what’s buffering the planets temperature, and keeping us all from freezing to death.
    If CO2 does everything it’s claimed to do, then it’s part of that buffering system.
    We all know that the less buffer the more unstable, the more buffer, the more stable………….

    and every CO2 and temperature reconstruction shows that the planet wants to be cold and have less CO2 buffering….

    In a sane world, wouldn’t we want to increase the buffer?
    If we could just lower CO2 levels to what they were during the MWP and LIA and Dust Bowl,
    The climate would be much more stable………

    • suyts says:

      You mean a mean of 10 degrees below today may not be preferable???? Why, that’s just crazy talk!! If Eskimos can do it, we all should!!!!

      And, are you stating that the the MWP, LIA, and even the 30s aren’t indicative of the well known stable climate period known as “pre-350ppm”?

      • Latitude says:

        LOL this whole idiotic science, every bit of it, is all based on “something’s wrong”…..

        But then look at how “wrong” is defined…….

        Who in their right mind would look at that graph and pick the very top, obviously most unstable….
        …and slap “normal” on it?

        If CO2 did 1/10th or even 1/100th of what is claimed, we should be cranking it out like there’s no tomorrow…….

      • suyts says:

        Yes, we should. I have no idea where warm got the valuation of “bad” from. I think it was either J.H. or MM that as children were slow learners and burnt themselves on momma’s cook stove so often that maybe they now associate warmth as aberrant behavior…..IDK, maybe its a secret club of slow learners that includes big Al. He certainly has the academics to prove he is a slow learner. I don’t know how we got to the point of associating cold with good. Could be that the group of slow learners did it so often that the ice packs given to them made them feel relief, so…….

        Or how someone came to believe past climate was more stable than current. I mean, sure we have more reported hurricanes and tornadoes than in the 1800’s but any imbecile can see that our satellites had an errant component in them back then. Heck, I don’t know when it became newsworthy to note that Australia had a flood or drought. I think it would be newsworthy if they weren’t in one stage or another. But then, I don’t get how people believe others when they say they know the PH balance of the oceans……….Which one? What part? How deep? And, as that study you showed pointed out, it could either be good or bad……. but only in the most extreme of cases. How do they know what is was back when? OF course, tree rings and ice cores are my favs. By this ring, I can tell that 1000 years ago the earth’s temp was 53.675 degrees….. F. And they say it with such certitude. And people believe them. This ice, this H2O, after immediately being evaporated, it went in the sky obtained the necessary isotopes, formed a cloud, fell to the ground as snow, in this particular spot, was frozen here and suspended in time and place ever since trapping gases there too, that is somehow indicative of the entire earth’s atmosphere specific to the time we absolutely know they obtained the specific isotopic attributes………. And seemingly rational people believe this stuff.

        It is all supposition based on and heaped upon illogical hysteria that people have taken for truth.

      • Latitude says:

        Can you just imagine how nuts they would all be…..
        …if the climate stopped changing

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