NSIDC’s Dr. Walt Meier – part 2

Yesterday, Dr. Meier commented on PIPS -VS- PIOMAS, here is Part 2

Southern hemisphere sea ice continues to be well above normal - click for larger image

Here are some thoughts on three other sea ice issues addressed in recent posts: (1) concentration vs. extent, (2) the causes of the 2007 record minimum, and (3) whether it is possible for the Arctic to lose all its sea ice during summer. Again, I’m speaking only for myself and not as a representative of the National Snow and Ice Data Center or the University of Colorado at Boulder.

Concentration vs. Extent as a measure of the summer ice cover

Sea ice concentration fields are difficult to interpret during summer because of the significant melt that occurs. Areas of low concentration may include open water or ice with surface melt or some combination of both.

Atmospheric moisture, which is higher in the summer, can also affect the observed concentration (e.g., concentration values can change with passing storms). Extent is a more consistent and stable measure of the amount of surface covered by ice and is more legitimate in comparing the data from different years, which is why NSIDC uses extent. Because of the melt and atmospheric effects on concentration, it can be particularly misleading to Steve’s comparison of two single days of concentration data. If one wants to compare concentration, it is better to compare monthly averages, which smoothes out at least some of the ephemeral atmospheric and surface effects. Looking at anomalies for June from 1990 and 2010, there isn’t much difference in the middle of the Arctic (the 2010 anomaly is a bit lower) with lower anomalies in 2010 in coastal areas. Again though, in the central Arctic this may indicate more open water or simply more intensive surface melt. Comparisons with other years can be made at NSIDC’s Sea Ice Index.

Monthly concentration anomaly (in percent) for June 2010 (left) and June 1990 (right). Positive anomalies (higher than average concentration) are in red, negative anomalies (lower than average concentration) are in blue. Anomalies are relative to a 1979-2000 average.

Reasons behind the record low minimum 2007 ice extent

Ice motion has been discussed as a major reason for the record 2007 minimum. While ice motion was important, it was far from the only contributor. For example, Zhang et al. (2008) attribute ~30% of the ice volume loss to ice motion, with the remaining 70% due to pre-conditioning (i.e., thinner ice cover) and more solar heating. Kwok (2008) attributes 15% of the extent loss to motion of ice from the Pacific side across the pole toward the Atlantic. Ogi et al., (2008) calculated a 37% contribution of unusual winds (and resulting ice motion) to the September extent.

So, what else played a role? Kay et al. (2008) suggest that below normal cloud cover and enhanced solar energy played a role (though another study, Schweiger et al. [2008] suggest the role may have been limited). Steele et al. (2008) found anomously high sea surface temperatures during 2007, which enhanced melt. Lindsay et al. (2009) showed that by 2007, the ice cover had thinned enough to reach a threshold where a dramatic loss in extent was possible under conditions experienced during the summer of 2007. Furthermore, the thinner ice cover allows the ice cover to be blown by winds more easily (Haas et al., 2008) – i.e., the winds contributed to the low extent, but the thin ice enhanced the effect of the winds.

In other words, the 2007 minimum was not simply the result of unusual ice motion. It was the result of ice motion, enhanced melt, warmer ocean temperatures, and a long-term thinning trend seen in a variety of observations (Maslanik et al., 2007; Nghiem et al., 2007; Kwok and Rothrock, 2009). The same atmospheric conditions would not have led to such a low extent in earlier years when the ice pack was thicker. As Ogi et al. (2008) say (with clarifying comments by me italicized in brackets): “… the precipitous decline in September SIE [sea ice extent] in recent years is mainly due to the cumulative loss of multi-year ice: summertime SLP [sea level pressure] anomalies [which control the strength and direction of the wind anomalies] have played an important role in setting the timing of record lows, but the long term trend is mainly due to preconditioning [the thinning of the ice cover].”

Can the Arctic really become sea ice-free during summer?

It has been suggested that the Arctic really can’t lose all its sea ice during summer because there isn’t enough energy to melt all of the ice in the short summer. There are a couple of reasons why this thinking is faulty.

First, we know the Arctic can potentially lose all its sea ice during summer because it has done so in the past. Examination of several proxy records (e.g., sediment cores) of sea ice indicate ice-free or near ice-free summer conditions for at least some time during the period of 15,000 to 5,000 years ago (Polyak et al., 2010) when Arctic temperatures were not much warmer than today.

Second, the primary evidence provided for the implausibility of ice-free summers is the plot of daily temperature for regions poleward of 80 degrees N from the Danish Meteorological Institute. It shows that temperatures rise only a couple degrees above freezing for a period of about 75 days throughout the entire record since 1958. So there is no warming trend of the surface air temperatures in the high Arctic. So how could one possibly melt ice near the pole with summer temperatures at most a couple degrees above freezing with no increasing trend?

North of 80 degrees, the Arctic has been continuously covered by ice, even during summer, throughout the entire record (except for a small area briefly during summer 2007). As a result, any heat energy in the vicinity will be used to melt ice and will not raise temperatures. Only after the ice melts can the ocean absorb the energy allowing the ocean surface and the air above it to warm significantly. So the summer near-freezing temperatures don’t say anything much about the energy available to melt ice, only that ice is melting. (I’ll note that it is possible to have higher air temperatures locally, for example due to a weather system bringing in warm air from the south, but the average over the entire region will stay near freezing).

However, there are still only ~75 days of melt, which isn’t much time. But one needs to think about the overall process of what happens in the Arctic, not simply the direct solar energy. As temperatures increase, summer extent decreases, which allows more absorption of solar energy. This melts more ice, decreasing the extent and thinning the ice. Heat absorbed in the ocean away from the ice edge will warm the ocean waters, which will delay freeze-up in the fall. This leads to less ice growth further thinning of the ice. With warmer temperatures, melt will begin earlier in the spring and freeze-up will start later in the fall (as has been observed, e.g., Markus et al. [2009], Serreze et al. [2009], Stroeve et al. [2006]). This is a positive feedback (the sea ice-albedo feedback). Under this feedback, the ice will eventually become thin enough to melt completely most everywhere in the Arctic during a single summer.

There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise.

References

Haas , C., A. Pfaffling, S. Hendricks, L. Rabenstein, J.‐L. Etienne, and I. Rigor, 2008. Reduced ice thickness in Arctic Transpolar Drift favors rapid ice retreat, Geophys. Res. Lett., 35, L17501, doi:10.1029/2008GL034457.

Kay, J.E., T. L’Ecuyer, A. Gettelman, G. Stephens, and C. O’Dell, 2008. The contribution of cloud and radiation anomalies to the 2007 Arctic sea ice extent minimum, Geophys. Res. Lett., 35, L08503, doi:10.1029/2008GL033451.

Kwok, R., 2008. Summer sea ice motion from the 18 GHz channel of AMSR-E and the exchange of sea ice between the Pacific and Atlantic sectors. Geophys. Res. Lett., 35, L03504, doi:10.1029/2007GL032692.

Kwok , R. and D.A. Rothrock, 2009. Decline in Arctic sea ice thickness from submarine and ICESat records: 1958–2008, Geophys. Res. Lett., 36, L15501, doi:10.1029/2009GL039035.

Lindsay, R.W., J. Zhang, A. Schweiger, M. Steele, and H. Stern, 2009. Arctic sea ice retreat in 2007 follows thinning trend, J. Climate, 22, 165-176.

Markus , T., J. C. Stroeve, and J. Miller (2009), Recent changes in Arctic sea ice melt onset, freezeup, and melt season length, J. Geophys. Res., 114, C12024, doi:10.1029/2009JC005436.

Maslanik, J.A., C. Fowler, J. Stroeve, S. Drobot, J. Zwally, D. Yi, and W. Emery, 2007. A younger, thinner Arctic ice cover: Increased potential for extensive sea-ice loss, Geophys. Res. Lett., 34, L24501, doi:10.1029/2007GL032043.

Meier, W.N., 2005. Comparison of passive microwave ice concentration algorithm retrievals with AVHRR data in Arctic peripheral seas, IEEE Trans. Geosci. Remote Sens., 43(6), 1324-1337.

Nghiem, S.V., I.G. Rigor, D.K. Perovich, P. Clemente-Colon, J.W. Weatherly, and G. Neumann, 2007. Rapid reduction of Arctic perennial sea ice, Geophys. Res. Lett., 34, L19504, doi:10.1029/2007GL031138.

Ogi , M., I.G. Rigor, M.G. McPhee, and J.M. Wallace, 2008. Summer retreat of Arctic sea ice: Role of summer winds, Geophys. Res. Lett., 35, L24701, doi:10.1029/2008GL035672.

Polyak, L., and 17 others, 2010. History of sea ice in the Arctic, Quaternary Science Rev., 29, 1757-1778, doi:10.1016/j.quascirev.2010.02.010.

Schweiger , A.J., J. Zhang, R.W. Lindsay, and M. Steele, 2008. Did unusually sunny skies help drive the record sea ice minimum of 2007?, Geophys. Res. Lett., 35, L10503, doi:10.1029/2008GL033463.

Serreze, M.C., A.P. Barrett, J.C. Stroeve, D.N. Kindig, and M.M. Holland. 2009. The emergence of surface-based Arctic amplification, The Cryosphere, 3, 11–19.

Steele, M., W. Ermold, and J. Zhang, 2008. Arctic Ocean surface warming trends over the past 100 years, Geophys. Res. Lett., 35, L02614, doi:10.1029/2007GL031651.

Stroeve, J., T. Markus, W.N. Meier, and J. Miller, 2006. Recent changes in the Arctic melt season, Ann. Glaciol., 44, 367-374.

Zhang, J., R. Lindsay, M. Steele, A. Schweiger, 2008. What drove the dramatic retreat of arctic sea ice during summer 2007?, Geophys. Res. Lett., 35, L11505, doi:10.1029/2008GL034005.

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81 Responses to NSIDC’s Dr. Walt Meier – part 2

  1. Henry chance says:

    From a carefull look at the graphic:

    “The urgent need to act can’t be overstated” (climateprogress)

    I am concerned, very concerned about my grand children.

  2. Luis Dias says:

    [snip - ad hom, insulting, and juvenile - you've been warned - permanent troll bin for you now Luis]

  3. Jay Currie says:

    Thank you for this. The science of Arctic ice is fascinating.

  4. Tom_R says:

    >> Henry chance says:
    July 14, 2010 at 11:18 am
    From carefull look at the graphic:

    “The urgent need to act can’t be overstated” (climateprogress)

    I am concerned, very concerned about my grand children. <<

    I'm leaving a message for my grandchildren to stay off the Arctic ice.

  5. Richard says:

    I don’t know. I quit reading after “proxy”. That’s even worse than a Godwin.

  6. nc says:

    How come the German overflight seems to be ignored by everyone?

  7. Martin Brumby says:

    Still no evidence it is anything to do with CO2.

    Still no evidence that it is anything to do with Anthropogenic CO2

    Still no evidence that no arctic ice would be a bad thing.

    Still no evidence that building tens of thousands of wind turbines will do diddly squat about melting ice, global “average temperatures” or anything else except transferring huge amounts of loot from the average little man to the politicians, city slickers and “climate scientists” and denying the third world poor any prospect of hope or progress.

  8. John Peter says:

    The final paragraph: “There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise.”
    In my opinion, if Dr Meier had been smart he would have stated “ice-free IF temperatures continue to rise”. He clearly seems to believe in AGW and the fact that summer Arctic sea ice has increased since 2007 and atmospheric temperatures have remained more or less constant since 1998 does not affect his judgement. He is probably right in what he is writing except his emphasis on the unquestionable forecast (I would say belief) that global temperatures will continue to rise cause by AGW. On the other hand he may not secretly include himself in the “sea ice community” or they are all (in that community) desperate to appear “on message” with Obama and company. If he said otherwise he might be out of a job. Dangerous times for those in official jobs who would like to express their own thoughts.

  9. tallbloke says:

    “There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as if temperatures continue to resume a rise.”

    There you go Walt, fixed.

  10. Gary says:

    Instead of an overall area extent, why not report it by sectors of, say, 45 degree wedges radiating from the geographic north pole? That might iron out some of the variability due to wind effects?

  11. MattN says:

    “Still no evidence it is anything to do with CO2.”

    I think this can’t be emphasized enough….

  12. jakers says:

    nc says:
    July 14, 2010 at 11:44 am
    How come the German overflight seems to be ignored by everyone?

    Link, please?

  13. Just The Facts says:

    Walt

    A couple tangentially related questions:

    There appear to be mechanisms that help to balance Global Sea Ice such that when when one pole is above average;

    the other pole is often below average;

    and Global Sea Ice remains reasonably stable:

    Here is a good overlay showing the relationship between Arctic and Antarctic Sea Ice Area:

    Why are there no Global Sea Ice Extent charts on the NSIDC website?

    On the right side of this page;

    http://nsidc.org/data/seaice_index/

    in the drop down, it would seem a logical to add Global. Can this be done? Is there a reason why NSIDC does not offer this information?

    Also, we’ve already tread over this ground, but NSIDC’s choice to exclude data after 2000 from their standard deviation calculations makes the “normal” range misleadingly narrow, such that both the Arctic;

    and Antarctic;

    are currently outside this range. Why does NSIDC exclude data after 2000 from their calculation? Can the data through 2008 be added to help dispel the perception that NSIDC excludes this data in order to make the current Arctic Sea Ice Extent look misleadingly anomalous?

  14. Jim Cripwell says:

    An excellent paper. Hpwever, I have one major quibble. Walt writes “There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free AS temperatures continue to rise.” (My capitals)

    This implies that global temperatures are going to go on rising. I think it is much more scientific to replace “as” with “if”. i.e. ” will become ice-free IF temperatures continue to rise”

    But then comes the important question. How long might it be before we see an ice free summer in the Arctic?

  15. Smokey says:

    I agree with Martin Brumby.

    I would condense his statements to: ‘So what?’ Unlike the alarmist crowd, we all know that the climate always changes, and that the planet has been naturally warming since the LIA.

    The alarmist conjecture claims that the warming is caused by human activity. But the hypothesis that the observed temperature changes are a consequence of natural variability has never been falsified.

    All this arm-waving over what is a natural, regional event happens because out of all the climate scares pronounced by co-opted scientists, the only one that hasn’t been completely debunked is the Arctic ice trend.

    But unless the Antarctic begins to trend the same way, then what is occurring in the Arctic must be seen as regional climate variability. The burden of showing that CO2 is the cause is entirely on the alarmist scientists. So far, they have shown us models, opinions, assumptions, conjectures, and everything else — except for empirical, testable evidence.

  16. jakers says:

    John Peter says:
    July 14, 2010 at 11:57 am
    …they are all (in that community) desperate to appear “on message” with Obama and company. If he said otherwise he might be out of a job. Dangerous times for those in official jobs who would like to express their own thoughts.

    Silly. Whenever I see comments like this, my first thought is “gee, then how did they all survive Bush/Cheney for 8 years, as they expressed the same, and at that time very unpopular in the Executive Branch, scientific opinions?”
    Maybe, just maybe, it really is the prevailing view…

  17. jakers says:

    Smokey,
    So just what is this “natural variability”? Just how does it work? By what means is it doing this? What mechanism is in play? How do we scientifically explore this “natural variability”? Or is it, as Dr. Spencer says, just what happens, and there is no reason or possibility of explaining it?

  18. Paul says:

    A precondition that contributed to the 2007 melt was further wind-driven loss of thick ice in 2006. Meier should be a bit more upfront about that point.

  19. peterhodges says:

    so the arctic has had ice free summers in the recent past, and may see them again if it keeps warming.

    meanwhile, it’s snowing in july in canada-

    http://www.theweathernetwork.com/news/storm_watch_stories3&stormfile=jaspersnow_13_07_2010?ref=ccbox_weather_bottom_title

  20. PeterB in Indianapolis says:

    Jakers,

    As Walt pointed out in his paper, there is pretty strong evidence that the arctic may have indeed been ice-free during some times in the period of 15,000 to 5000 years ago. He also says at that time it was NOT MUCH WARMER THAN NOW (which means it WAS INDEED warmer than now.

    Since there was no man-made CO2 15,000 to 5000 years ago, this ice-free condition in the Arctic only be attributed to… wait for it… NATURAL VARIABILITY.

    The term “natural variability” is not mystical in any way, shape or form. Climate CHANGES. It always HAS changed, and it always WILL change, and this will happen regardless of what human beings do. We MAY have some influence on the direction and/or magnitude of climate change, but that has yet to be conclusively proven. So far all climate change from 1850-present is well within the previous range of documented climate changes. For example, Walt does acknowledge that it was indeed warmer (albeit not much warmer) at least at some period or periods of time from 15,000 to 5000 years ago compared to now.

  21. PJB says:

    So, by the same token, antarctic ice is increasing because of the continued warming?

    “Again, I’m speaking only for myself and not as a representative of the National Snow and Ice Data Center or the University of Colorado at Boulder.”

    Hopefully the two “versions” would be identical, as we are paying for the official one. The good Doctor’s presentation is much appreciated both for its tone as well as its content. His “AGW” tendency is understandable but needs factual verification if it is to be chosen over the influence of natural variation.

  22. Robert says:

    jakers ,
    there’s a paper out (Chylek et al. 2010) which seems to consider the mechanism which explains arctic versus antarctic trends to be associated with the AMO. The paper does indicate though that the positive phase of the AMO will soon come to an end.

  23. jakers says:

    OK, so it’s “natural variation” then. Well, if you can’t identify the mechanism, the ‘how’ of its workings, then how is it not mystical?

  24. Frederick Michael says:

    This blog is blessed by Dr. Meiers obvious love of teaching.

  25. So if something other than AGW caused an ice free arctic summer a few thousand years ago, could Walt Meier explain why he is convinced it is AGW this time and not the same mechanism as the last time?

    Also, as it appears that Antarctic ice is rising above average about the same amount as the Arctic is below average, the net anomaly for humanity to worry about is……zero?

  26. Michael Penny says:

    So if “Examination of several proxy records (e.g., sediment cores) of sea ice indicate ice-free or near ice-free summer conditions for at least some time during the period of 15,000 to 5,000 years ago”? How come we still have polar bears?

  27. Milwaukee Bob says:

    Wow! Great analysis. But Dr. Meier, in your last 2 paragraph’s wherein you say:
    As temperatures increase, summer (ice)extent decreases, which allows more absorption of solar energy.
    And: With warmer temperatures, melt will begin earlier …..
    And again: There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise.
    Could you clarify WHAT temperatures you are specifically talking about? And site, as you did so well in both this and the previous contribution (be it ocean or atmosphere), the studies/data that show the temperatures that “continue to rise”.

  28. Michael Penny

    Fantastic question!

  29. carol clapham says:

    The post is interesting. Whilst the Mid Holocene warm period did see an ice free Arctic for possibly a couple of thousand years (Norwegian research) the actual cause of that warming is a mystery – and so are what are supposed to be ‘natural’ ups and downs in the climate. Something must cause them to happen. As C02 was not involved it is equally just as likely that C02 is not involved in modern warming – and it is simply the Sun being more active (or some other factor). What cannot be denied however is that mountain glaciers in the Alps and the Andes show evidence of shrink – sometimes quite dramatic shrink. Now, the altitude of mountains might suggest that as they are closer to the Sun and less inhibited by cloud that once again the Sun has been in a more active mode over the last 100 years. However, what bothers me is the fact that one of the Andes glaciers has melted to such a degree that plants frozen over 5000 years ago have only just emerged from a frozen state. That smacks of a warming that is greater than anything in the last 5000 years – otherwise the plants would have died off. There is also a hint that at around 3000BC one section of the Andes, at least, was suddenly uplifted – taking those plants from a lower altitude position where they normally grow into a high altitude position where they were quickly frozen and preserved. That means the warming is even greater – as it has climbed through that altitude hike. Any explanations?
    Likewise, archaeologists in Canada are now seeking out thawing ice patches and finding human artifacts, mainly associated with hunting, that were dropped or left behind thousands of years ago. This suggests once again that in spite of the Roman Warm Period and the Medieval Warm Period and the Little Medieval Warm Period (Tudors) that ice kept those artifacts preserved – until now. These ice patches may also be located in high places – but as far as I know are not associated with mountain tops.

  30. Casper says:

    Hi Anthony,
    There is an interesting article (in German) about the ice melting phenomena observed this spring. Astonishing is a correlation between ice melting in the Arctic and the de Vries/Suess solar cycle. Of course other cycles have been discussed there.

    http://translate.google.de/translate?js=y&prev=_t&hl=de&ie=UTF-8&layout=1&eotf=1&u=http%3A%2F%2Fwww.eike-klima-energie.eu%2Fnews-anzeige%2Farktische-sommereisschmelze-ein-menetekel-fuer-eine-bevorstehende-anthropogene-klimaerwaermung%2F&sl=de&tl=en

  31. tallbloke says:

    jakers says:
    July 14, 2010 at 12:52 pm (Edit)

    OK, so it’s “natural variation” then. Well, if you can’t identify the mechanism, the ‘how’ of its workings, then how is it not mystical?

    Here, have a look at this:
    Arctic insolation Vs Arctic temperature and Co2 Vs Arctic temperature

  32. latitude says:

    I’m sorry Dr. Meier, there are entirely too many “will” “can” and other predictions of the future to suit me.

    The facts are, you guys are good about hindcasting, and pretty good at figuring out what has already happened.

    But you all have the worst record of predicting the future any group of people could have.

    When you guys start getting lotto numbers right, let me know.
    There’s a reason there are no weather or climate pools, like football pools.

  33. richard telford says:

    carol clapham says:
    July 14, 2010 at 1:23 pm

    “Whilst the Mid Holocene warm period did see an ice free Arctic for possibly a couple of thousand years (Norwegian research) the actual cause of that warming is a mystery”

    The cause of that warming is fairly clear. The Earth’s orbit was slightly different in the early Holocene, with greater summer insolation at high latitudes. This extra solar heating, together with feedbacks (such as reduced albedo) caused the Arctic to warm in the Early-Mid Holocene. We can be absolutely sure the same process is not happening today.

    “and so are what are supposed to be ‘natural’ ups and downs in the climate. Something must cause them to happen. ”

    Not necessarily. A certain amount of unforced, internal variability is expected. You can get an idea how by running a climate model without any external forcing.

  34. Kevin Kilty says:

    I would suggest that Dr. Meier’s statement …“There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise.” Is also true because the Arctic has been ice-free in the recent past — about 8,000 ybp — and will probably pass though a similar state in the future.

  35. rbateman says:

    There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise.

    And conversely, the Antarctic will continue to exceed all previous ice extents due to temperatures that continue to rise!
    If that doesn’t makes sense, Dr. Meier, it’s because the assumption of warming is not consistent with reality.
    I see no warming trend north of 80L.
    If you have some ideas about why the North warms while the South cools, now would be a good time.

  36. frank says:

    Due to orbital mechanics, the Arctic was warmer than present about 7,000 years ago, allowing trees to grow to the edge of the Arctic Ocean and possibly producing brief periods in the late summer when the Arctic was ice-free. I’m not sure if any humans lived in the area, but the polar bears and other species obviously survived this experience. The Greenland Ice Cap didn’t melt. Methane may have bubbled from melting permafrost, but not enough produce a spike in methane levels in ice cores. Why should anyone – the alarmists or the skeptics – care?

  37. I’m always glad to see posts like this from those in “the other camp” (so to speak). Generally the AGW crowd issues a series of flat statements to the media ending with “and it’s worse than we thought,” with few details of the science behind them — the science being all too complicated for our little minds to grasp. (Okay, so in my case that’s true — but still.) Then I come here where I read what seem to me to be excellent attacks on these flat statements, complete with scientific backing. However, I know that this site has a particular view-point and bias, but I also know that the people on this site can be remarkably vigilant in trying to balance that viewpoint.

    So what I end up with is the AGWs on one side treating me like an idiot who must listen to whatever they say or risk being categorised as a flat-earther, and reasonable, intelligent discussions of the science by the anti-AGW crowd. (And as the AGWs moan about the problems they’re having with “communication” they might just look at that particular dynamic.)

    Thank you, Dr. Meier, for coming here and talking about the science. I’ll let those with more knowledge hash out how “robust” it is, but for me, at least it’s nice to see answers from the other side that don’t involve ad hominem attacks and broad statements about the end of the world. (Seriously — that endless doomsday scenario, of which we’ve had so many over the decades, and throughout history, doesn’t inspire intelligent people to pay much attention.)

    And as for whether any possible ice retreat is caused by human activity, that’s not the issue in Dr. Meier’s essay. The issue is whether or not his science is good.

  38. Stephan says:

    I am daringly predicting a NORMAL minimum NH ice this year
    Just check this out ladies and gentlemen LOL

    http://ocean.dmi.dk/arctic/icecover.uk.php

    The next 6 months mark the end of even the concept of AGW

  39. noiv says:

    After reading the article and the comments I’m wondering what the AGW skeptics would accept as a prove, that CO2 is connected to disappearing ice?

    Just in case somebody thinks falsification is a good thing.

  40. MikeD says:

    Dr. Meier continues to prove a very valuable asset to this website. It is my opinion that we can derive much integrity and strength as a community by attracting more “cross aisle” communication. This is one trend in climate science I’d like to see continue ;P. If we can’t enter their domain for open communication we CAN encourage and be receptive to them entering ours. Preaching to the choir tends to only go so far as compared to dissenting dialogue. And that applies to both sides of the AGW coin.

  41. TomRude says:

    In other words, the 2007 minimum was not simply the result of unusual ice motion. It was the result of ice motion, enhanced melt, warmer ocean temperatures, and a long-term thinning trend seen in a variety of observations (Maslanik et al., 2007; Nghiem et al., 2007; Kwok and Rothrock, 2009). The same atmospheric conditions would not have led to such a low extent in earlier years when the ice pack was thicker. As Ogi et al. (2008) say (with clarifying comments by me italicized in brackets): “… the precipitous decline in September SIE [sea ice extent] in recent years is mainly due to the cumulative loss of multi-year ice: summertime SLP [sea level pressure] anomalies [which control the strength and direction of the wind anomalies] have played an important role in setting the timing of record lows, but the long term trend is mainly due to preconditioning [the thinning of the ice cover].”
    ====

    Let’s compare this with what Walt Meier said then (published on Yahoo):

    “This year’s record was caused by a “perfect storm” of interacting factors, Meier , said by telephone. These included a long-running high pressure system that kept skies cloudless over the Arctic, along with a circulation pattern that pushed ice out of the Arctic towards Greenland, instead of letting it circle around the Beaufort Sea north of Alaska as it usually does.”

    Also quite misleading is Fig. 1 Part1 of ice age distribution: 1985 jumping to 2008, 2009 and 2010. Over the past 3 years the variability of distribution is quite significant. Therefore juxtaposing a snapshot at 1985 out of context, without showing the variability then simply occult the processes that lead to yearly transformation of the Arctic ice.

    Let’s notice also that the multiyear ice on these images is considered 5y + and not 20y or 50y. Therefore, if Arctic ice was so stable in the past, where has 50y ice gone Dr. Meier? It is likely it has been melted and recycled in an ever dynamic Arctic. Thus presenting 1985 as a supposed representation of the Arctic Ice of the past -i.e. stable- and the evolution since as a abnormal situation -i.e. AGW induced changes- is misleading at best.

  42. Douglas DC says:

    Very good to see this on this website, this is why I come here as a mere layman.
    They cannot accuse Anthony of not presenting the other side-in a reasonable fashion.
    BTW- I suspect Luis the troll has been thrown into that place before. Style and all that…

  43. jakers says:

    richard telford says:
    July 14, 2010 at 1:45 pm
    “and so are what are supposed to be ‘natural’ ups and downs in the climate. Something must cause them to happen. ”
    Not necessarily. A certain amount of unforced, internal variability is expected. You can get an idea how by running a climate model without any external forcing.

    But if, as has been argued here often, climate sensitivity is low, this variability with no forcing would be very very small. You can’t have it both ways.

  44. Green Sand says:

    Many thanks Dr. Walt Meier I have found both articles very interesting with a great deal of food for thought. I am trying not to get indigestion, so will keep chewing awhile.

    Just one comment, at present, after the “Hockey Team”, I think references to a “Sea Ice Community” could be counterproductive. This subject is far too polarised as it is. (is that a pun?).

    The “we know better than you” meme that I find attached to AGW policy could account for some of the lack of “cross fertilisation”? It typifies the “consensus science” stance, a stance that politicians may take. However if scientists call a consensus are they not actually saying “I must be correct, my community says so”? Therefore where is the motive and opportunity to look further, deeper?

    Right or wrong Steve Goddard, makes his stance on his own, backs his thoughts with his predictions for all to see, somehow I don’t think he is part of the “Sea Ice Community” or is he?

    For an issue as critical as AGW, having “teams and communities” held together by consensus is far too warm slipper and cosy.

    In a lighter vein, like the England football team, I can’t help thinking that most teams and communities benefit from the infusion of new, young, hungry blood?

    Once again many thanks for your insight, it is greatly appreciated.

  45. rbateman says:

    Speaking of the dipole anomaly:

    Heads or tails?

  46. NicL says:

    “There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise.”

    Which temperatures ? Where ? Could anyone clarify ?

    Does he mean seasonal – The temperature will continue to rise until September ?
    Does he mean -As we climb out of the Little Ice Age and revert to normality ?
    Does he mean – As this ball of rock which was once molten solidifies ? (Whoops that is cooling)

    Aside from my rather vulgar mocking tone – Can I seriously, humbly and genuinely ask what he means by ” as temperatures continue to rise.”

  47. kwik says:

    “There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise.”

    I have problems with this statement too.

    Is Walt getting this from “The Models”? From the super-duper computers?

    There are real world indications that says the temperature will decrease, not increase.
    So…..

  48. Dave says:

    Jakers>

    You seem to be making a very good case for solar-activity driven climate change. Is that your intention?

    Just a note: it’s not ‘mystical’ to say that the climate must vary naturally, because we know that it *has* varied naturally. You’re right that any posited explanation without good proof is a touch ‘mystical’ by the definition you appear to be using.

  49. Gareth says:

    Does the truncated basis period exaggerate the sea ice trends at both ends of the world?

  50. richcar 1225 says:

    DRr Meier,
    Are you aware of the 2007 JGR arcticle that looked at arctic sea ice volume trends for the twentieth century and determined there was none.

    http://www.agu.org/pubs/crossref/2007/2006JC003616.shtml

  51. Deanster says:

    Until proven otherwise, I will continue to believe that the ice melt extent etc is related to the higher solar output that existed from throughout the last half of the 20th Century. While “models”, created by people with practicly no knowledge of the complete impact of the Sun on Climate, make ignorant claims about the contribution of the sun, it stands as fact, that we do not know the extent to which the sun impacts climate.

    As noted by Dr Mier, the arctic has been ice free before, .. and it froze back up. We know that the arctic must have been quite warm as recently as 1000 years ago, when the Vikings settled Greenland, and yet, “Greenland” turned to Iceland in a relatively short period of time. Another fact that remains, is that NO modern climate research has been done during a prolonged period of solar minimum. Taking into account all the proposed lag times and the dynamics that exists regarding climate, most of which is poorly understood, the next 10 years could turn ALL of the accepted theories on their heads.

  52. geo says:

    Ah, “pre-conditioning” re 2007. Yes, I shall use that term in the future. I’ve always agreed that the 2007 situation was multiple reasons, and that “pre-conditioning” (which isn’t what I’d been calling it before right now) is certainly an important one.

    Dr. Meier, I must say I’ve noticed a tendency towards “worse than we thought” reporting tendencies from NSIDC. One of the things I’d like your organization to consider is to the degree you get ahead of yourselves you do no one any favors.

    “As bad as we thought in 2006″ should be bad enough. You are now potentially faced, if Steve is right (and I predicted even higher than he did, tho I was silly enough to do it two months earlier unnecessarily, tho I largely agree with his analysis and have said so repeatedly), with a situation where as of minimum extent for 2010 you may have in fact more-or-less “returned” to the Pre-2007 trend.

    But because there was some excited overanalyzing of 2007, and predictions of imminent doom based thereon, now you are going to find it much harder to get a “it’s as bad as we thought it was in 2006, which is plenty bad enough” message across to the public if 2010 returns the trend line to pre-2007 historic decline rate. And the only fault for that will be NSIDCs. I don’t know about you, but I think that is really unfortunate.

  53. dscott says:

    Anthony, has anyone done a study to compare Earth’s Aphelion distances on July 6 each year to that of ice extent on Antarctic ice during the Southern Hemisphere’s winter?

    2010-Jul-06 11-hour Earth at aphelion 1.016702 AU (94,528,559 miles or 152,096,452 km)

    How about Earth’s perihelion distance on Arctic ice extent during the Northern Hemisphere’s summer?

    2010-Jan-03 00-hour Earth at perihelion 0.983290 AU (91,422,023 miles or 147,098,036 km)

  54. jakers says:

    Dave says:
    July 14, 2010 at 4:00 pm …

    Why does it have to be solar? What I’m pointing out is that nothing “just happens” in the natural world, with no cause. Maybe the mechanism is subtle, hard to discover, difficult to pin down scientifically, but there is always a cause. Natural variability, however, is never it – though it may be a useful term to group together a collection of common, oft occurring processes for simplified reporting.
    So, to just exclaim “Natural Variability!” is as unreasonable as the old “God did it!”.

  55. Richard M says:

    I’m a little confused by Jakers claims. It seems he believes gravity (among many other phenomena) simply doesn’t exist. Hmmmmmmmmmmm.

  56. Tommy says:

    This is a positive feedback (the sea ice-albedo feedback). Under this feedback, the ice will eventually become thin enough to melt completely most everywhere in the Arctic during a single summer.

    This albedo feedback makes sense, but there is something that makes me wonder.

    There is something else that doesn’t happen under ice, but does once the ice is melted: The exposed water is able to begin evaporating. Isn’t this true? If so, wouldn’t that be a negative feedback towards sea temperature?

    Living in Texas, I don’t really know how big that feedback would be in the arctic. It certainly makes a huge difference here. Here in July, a dark wet cotton shirt is more comfortable than the whitest waterproof jacket because it allows sweat to evaporate.

    In the winter, I feel a lot warmer wearing a pure white dry jacket over a darker wet one.

    Another thing: if I put a pitcher of tea in the fridge (not freezer) with the cover on, the tea stays liquid, no matter how long it is left there. If I put the pitcher in uncovered, the tea ices over on the same day.

    Evaporation just seems like a pretty powerful negative feedback to me. It is something we experience commonly. And it seems strange that such a thing would not be mentioned along with the albedo feedback.

  57. Rhoda R says:

    Jakers – the whole problem is that we humans do not have perfect insight into what makes weather, let alone climate. This whole AGW nonsense started with Phil Jones saying, in effect, that CO2 must cause the temperature to increase because we can’t explain it any other way. What he should have said is that we don’t know why temperatures were rising because climate science is still in its infancy. Money that could have been used to explore the relationship of, say for example, magnetic magma movements or solar fluctuations, has been wasted on the kind of doggeral that Mann et. al. have been shoving out.

  58. Tommy says:

    I thought of something else about evaporation. The albedo feedback is only applicable during sunshine. Evaporation feedback is applicable when the sky is clear, cloudy, and even at night.

    So if one can say (in theory) that the albedo feedback melts more ice, requiring more time for the winter to refreeze it, resulting in an earlier spring melt…
    can one also say (in theory) that the evaporation feedback cools more water, requiring less time for the winter to refreeze it, resulting in a later spring melt?

  59. rbateman says:

    dscott says:
    July 14, 2010 at 4:49 pm

    I argued that the South Pole was colder due to being farther away in winter than the North Pole in 8th grade General Science.
    The teacher laughed, and said that was not possible due to the South Pole being closer in the summer.

  60. rbateman says:

    Rhoda R says:
    July 14, 2010 at 5:58 pm

    How many billions have been wasted chasing a ghost cause?
    I agree. There is so much more that could have been spent on other research.
    What a terrible waste.

  61. Robert in Phoenix says:

    Thank you Dr. Meier.

  62. Oakden Wolf says:

    What a lot of the commenters apparently fail to realize is that for a very large portion of the broad sector of the scientific endeavour that can be called “climate science”, the current indications of climatic warming due to increasing atmospheric greenhouse gases are a “given” — or a starting proposition, or a boundary condition, if you will.

    For them to abandon this starting proposition, they would have to be shown universally that there are eminently plausible reasons NOT to take this expectation as a given. For Dr. Meier to say “There is little doubt in the sea ice community that during summer the Arctic can become ice-free and will become ice-free as temperatures continue to rise” is as natural as his breathing reflex. There’s no rational way for them to think any other way.

  63. Cassandra King says:

    A thoroughly enjoyable read and a window into the mind of a very educated person, thanks Dr Meier.

    One point does stand out though, if as Walt suggests the Arctic was warmer and ice free in the past then why does he believe that this time the warming is anthropogenic in nature and not natural?
    If a natural cycle managed to warm the planet beyond what we are seeing right now then I fail to see just how a CO2 signal can be detected over and above a natural rise.
    These questions aside, Its great to see guest posts such as this as it adds to my knowledge base to give me a fuller picture of wahts going on.

  64. The south pole is colder primarily because it is at high elevation.

  65. kwik says:

    jakers says:
    July 14, 2010 at 3:16 pm

    “But if, as has been argued here often, climate sensitivity is low, this variability with no forcing would be very very small. You can’t have it both ways.”

    Here;

    http://www.drroyspencer.com/2010/06/millennial-climate-cycles-driven-by-random-cloud-variations/#comment-134

  66. gilbert says:

    Michael Penny says:
    July 14, 2010 at 1:04 pm

    So if “Examination of several proxy records (e.g., sediment cores) of sea ice indicate ice-free or near ice-free summer conditions for at least some time during the period of 15,000 to 5,000 years ago”? How come we still have polar bears?

    Polar bears are smart. They can tell the difference between natural warming and CAGW. CAGW scares the crap out of them.

  67. redetin says:

    It seems that we have 30+ years of good satellite data of both area and extent for both poles. However, there does not seem to be a comprehensive description of the year to year causes of the annual maxima, minima and rates of change in each year. This will require a major effort to collect together the regional meteorological and oceanographic data, which is sparse in places, and to match this to the ice patterns. But if we can’t explain the 30 years for which we have good ice data then there is little hope of predicting future positions.

  68. johnh says:

    So if “Examination of several proxy records (e.g., sediment cores) of sea ice indicate ice-free or near ice-free summer conditions for at least some time during the period of 15,000 to 5,000 years ago”? How come we still have polar bears?

    Because they adapted to ice free conditions, and adapted back the way once the ice reformed. And if they did it once they can do it again.

  69. Hoppy says:

    Dr Meier states “First, we know the Arctic can potentially lose all its sea ice during summer because it has done so in the past. Examination of several proxy records (e.g., sediment cores) of sea ice indicate ice-free or near ice-free summer conditions for at least some time during the period of 15,000 to 5,000 years ago (Polyak et al., 2010) when Arctic temperatures were not much warmer than today. ”

    So what is all the fuss about?

  70. PeterB in Indianapolis says:

    Jakers,

    There are many MANY factors involved in natural variation. One of the reasons that “climate science” is in such an awful state right now is that even the “climate scientists” do not fully understand all of the perfectly natural variables involved, nor do they understand how all of these variables interact. This is precisely why the vast majority of models are hopelessly wrong.

    In order to have a “good” model, you should know what a vast majority of the variables are and you should have a pretty darn good idea of how all of the variables interact with each other. Right now, most climate models can be characterized as educated guesses at best.

    If you actually follow this site at all, you already know that SOME of the variables involved are insolation, cloud formation, oceanic cycles, solar activity (or lack thereof), orbital variations, precession, and many many others. You should already know at least that much if you do actually read the articles on this site. You should also know that we have barely even begun to scratch the surface on how all of these things interract, although there are certainly scientists attempting to ascertain the interractions between all of these forces and how they influence climate and on what time-scale.

  71. Anu says:

    There are a couple of reasons why this thinking is faulty.
    That’s a nice way of putting it… “faulty thinking”.

    “I believe your faulty knowledge and faulty concentration have led you to some faulty thinking, good sir”.
    I bet Internet comments would have been much more polite if the Internet were invented back in the 1880’s – too bad Charles Babbage couldn’t get the funding he needed.

    http://en.wikipedia.org/wiki/Charles_Babbage

  72. Jimbo says:

    Dr. Meier,
    is this the fly in your ointment?

    From NASA – Arctic Reflector
    “Although sea ice and snow cover had noticeably declined in the Arctic from 2000 to 2004, there had been no detectable change in the albedo measured at the top of the atmosphere: the proportion of light the Arctic reflected hadn’t changed. In other words, the ice albedo feedback that most climate models predict will ultimately amplify global warming apparently hadn’t yet kicked in.”

    From Columbia University, McGil University – Published paper 19 July 2007 [pdf]
    “The predicted substantial decrease in Arctic summer sea ice concentrations during the twenty-first century may favor cloud formation, which should diminish or even cancel the ice-albedo feedback by shielding the surface.”

  73. Tim Clark says:

    First, we know the Arctic can potentially lose all its sea ice during summer because it has done so in the past.

    Apparently without the aid of CO2, eh? But generous of you to admit it.

  74. Tim Clark says:

    jakers says:July 14, 2010 at 4:53 pm
    Why does it have to be solar? What I’m pointing out is that nothing “just happens” in the natural world, with no cause. Maybe the mechanism is subtle, hard to discover, difficult to pin down scientifically, but there is always a cause. Natural variability, however, is never it – though it may be a useful term to group together a collection of common, oft occurring processes for simplified reporting.
    So, to just exclaim “Natural Variability!” is as unreasonable as the old “God did it!”.

    Now there’s some logic. It fits right in with the rest of the AGW mantra:

    We can’t find any other causative mechanism, so it has to be CO2. After all we have a correlation.

    Yeh, that’s the ticket.

  75. rbateman says:

    stevengoddard says:
    July 14, 2010 at 10:01 pm
    The south pole is colder primarily because it is at high elevation.

    I figured that out much later. Back in the 60’s, we didn’t have instant data access, just what was in our textbooks.
    Now, we only need to figure out why one pole’s ice grows while the other shrinks.
    At one time, the Arctic was doing the same thing that the Antarctic now does..make more ice.

  76. jakers says:

    RE: Richard M says:
    July 14, 2010 at 5:47 pm
    I’m a little confused by Jakers claims. It seems he believes gravity (among many other phenomena) simply doesn’t exist.

    What, you think gravity is just “natural variation”, and has no cause?

    kwik says:
    July 15, 2010 at 12:03 am
    About Spencer…

    I thought Dr. Spencer’s post on wuwt where he said “…the climate system to cause its own climate change. Climate change is simply what the system does” was very unscientific. Btw (see next) Dr. Spencer says CO2 does and will increase temperature, but not that much cause sensitivity is low. So, the climate system changes, on a whim, from small internal chaotic variations, yet put an external forcing to it and it won’t hardly do nothin. hm

    Tim Clark says:
    July 15, 2010 at 1:37 pm
    We can’t find any other causative mechanism, so it has to be CO2. After all we have a correlation.

    Never said that Tim, did I – no mention of CO2. So you think things “just happen, can’t say why…”? Gee, who needs science anyway, right…

    PeterB in Indianapolis says:
    July 15, 2010 at 6:37 am
    About natural variables.

    Well, correct Peter, there are lots of variables. Talking about actual variables (like GHGs too!) is quite different from say “natural variation”. All those items you list are causative agents, they can be quantified, they can be used as an explanation for some observation. Quite the opposite of “natural variation/variability”

  77. R. Gates says:

    Stephan says:
    July 14, 2010 at 2:32 pm
    I am daringly predicting a NORMAL minimum NH ice this year

    ________

    Define “normal”…

  78. Smokey says:

    jakers says @3:16 pm:

    “A certain amount of unforced, internal variability is expected. You can get an idea how by running a climate model without any external forcing. But if, as has been argued here often, climate sensitivity is low, this variability with no forcing would be very very small. You can’t have it both ways.”

    It is you who tries to have it both ways.

    Your second sentence is based on nothing more than always inaccurate climate models. If the climate’s sensitivity to CO2 was high, then an increase in CO2 would have a direct and very noticeable effect on temperature. Since it doesn’t, CO2 must have little effect on temperature. And as we know, rises in CO2 follow rises in temperature on all time scales.

    Although CO2 probably has a small effect on temperature, the effect is so insignificant that it can be completely disregarded; most of the small 0.6° rise in temperature from the mid-1700’s until 2010 was due to the retreat of the Little Ice Age, and the 35% rise in CO2 contributed only a tiny part of that modest increase.

    A one-third increase in CO2 has had a very small effect on temperature. Ergo, CO2 can be disregarded. It is a very small player among many more important climate factors, like the clouds and the ocean.

    Finally, the null hypothesis of natural climate variability has never been falsified, while the CO2=CAGW hypothesis is falsified every day by planet Earth.

  79. David Gould says:

    Smokey,

    Graph ln CO2 v temperature for that same period. The correlation between those two variables is actually very good indeed.

  80. David Gould says:

    (r^2 value approx. .82 – does not take autocorrelation into account, however, so true value will be lower)

  81. Bruce Cobb says:

    Jakers, you seem to have your knickers in a twist over the use of the phrase “natural variation”, which is an accepted phrase (USGS uses it) meaning “non-anthropogenic”. The exact causes are a separate matter altogether, are complex, and certainly not understood or agreed upon. But, you knew that.
    Pick your battles.

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