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Sea ice minimum forecasts

Filed under: — gavin @ 17 July 2009

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

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

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

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

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

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

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

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

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

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

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

858 Responses to “Sea ice minimum forecasts”

  1. 151
  2. 152
    Mark says:

    “Mark @130, why question my scientific bonafides?”

    Because you should be able to consider a ball-park esti mate of that problem all yourself.

    That you didn’t shows you will not work well on your own outside your own comfort zone.

    “Thinking outside the box” it’s called.

    And you don’t have a worthwhile grasp on it.

    “Mark @132, again there’s the problem of 100 years…”

    What problem of 100 years? The power is one half of one millionth of a watt from your tidal average.

    Is that being sma ll a pro blem?

    “Okay…. Little is obvious to me, including this: how does that slow the Earth’s spin?”

    Strange. You knew so much yet stopped reading at some point.


    Read up yourself: it’s in the same place as the statement of the fact of the moon’s retreat from us.

    This partial knowledge is worrying. Are you running from a prompt somewhere? A blog post that said about it and you didn’t bother to read up on it, just decided to ask on here?

    Go read up on it.

    “The Moon creates tides and the friction slows the Earth, non?”


    Read up on the discussion where you found out that the moon is retreating. If it doesn’t say, then you’ve been sca mmed: it’s a false talking point.

    “but I don’t see why my weaknesses in this kind of thinking relative to climate scientists and physicists should invite ridicule.”

    The ridicule is because you have such very SPECI ALISED knowledge that oddly enough has some whopping great holes in it.

    Holes that would not exist if you were genuinely informed.

    And you have an over-sensitive skin. It wasn’t ridicule, it was shock at your lack of scientific ability displayed in that post.

    If you hadn’t known the earth-moon system was separating, it could be explained merely by assuming you hadn’t read up on the astronomy. But you do. Yet you don’t know the explanation of what is happening to make them separate.

    So you read somewhere something about it and then JUMPED to a conclusion. Forgetting to read up about it first.

    Not very scientific.

    Your plaintive, querulous query “can you tell me how to get a ballpark figure…” shows you won’t think outside the box and your lack of invention and ingenuity in doing this for yourself shows you will be unable to stretch the boundaries of science because you don’t know where to start.

    Not very scientific.

    And now you jump to a conclusion of ridicule?

  3. 153
    Mark says:

    “I think this latter approach is preferable, but of course I’m ignoring that the Sun’s gravity also plays a role in tides”

    Twice the force, in fact.

  4. 154
    Juola (Joe) A. Haga says:

    #140 “There is no ice on the bottom of the sea or lakes”, Bill DeMott. Permafrost thaws because a constituent is ice. Both land and continental shelf permafrtost is thawing. Rather an excessive amount of methane bubbling in the Laptev Sea was noted by Natalia Shakhova and Igor Semiletov. They attributed the bubbles to the possible emissions by clathrates, ice globules containing methane and trapped under pressure in the continental shelf by permafrost.

  5. 155
    truth says:

    Doug Bostram [82] and Martin Vermeer[90]
    I replied to each of your criticisms of me, including Doug Bostram’s sneer at my screen name—just a simple and truthful explanation— but for some reason, although you and all and sundry are allowed to attack me , I’m not allowed a civil reply. [moderator–you are, as long as it doesn’t violate our comment policy, which your comments typically do on multiple grounds, and as long as it is indeed ‘civil’]
    All of my replies were ditched.
    No dissent allowed, I guess.
    Anyway, I just want it on the record that I don’t accept your [edit]
    Marcus [ 67] , my reply to your more civil remarks was also binned, but I don’t believe your three points were correct, in particular, point1.
    How is albedo reduced if , as you claim, the soot is not visible to the naked eye on the ice ?

  6. 156
    Doug Bostrom says:

    tamino 20 Jul 2009 at 10:18 pm

    “I guess [J. Bob] decided that nobody was going to believe his ridiculous claims about the sea ice data, so he’d lay the groundwork (in #103) for questioning the data itself…

    He followed through in #138 with “Seems that before one can use statistics, effectively, one has to have an idea of the quality of the data. Statistics will not improve the smell of garbage coming in to garbage going out.”

    Whoops, I did not notice the earlier post. Only two data points but they do exhibit a trend if one draws a line between them.

    J.Bob, is this a sampling error we’re looking at? Inquiring minds need to know.

    It took me about 5 minutes to discover a document from the horse’s mouth including everything you need to address your worry; I’m amazed that you’d walk around needlessly haunted by your doubt for so long.

    Anyway, you asked twice, so here are the answers you say you’re looking for, –again–.

    As I mentioned, what likely errors do exist appear to be accounted for and presented in tabular form for you to scrutinize. More granular exploration of the instrumentation’s limitations can be pursued via the list of references. Perhaps you can find something there by reading; no idle speculation is necessary, only work.

  7. 157
    Hank Roberts says:

    > an oversensitive skin
    Ask any alligator, they’ll tell you the same ….

    I recommend Robert Grumbine’s blog for people willing to make beginner mistakes asking questions. He’s an ice/climate guy, who aims to be rather more welcoming to new people. (He filters all the nitwittery, allowing no faux ignorance or trolling — so his site offers much less fun for those who may go for the ankles when they see someone deserving of their pointed attention.)

  8. 158
    J. Bob says:

    #149 Doug- Thank You Doug, the following is from the NIDC ref.
    Confidence Level/Accuracy Judgment

    Estimates of the accuracy of the NASA Team algorithm vary depending on sea ice conditions, methods, and locations used in individual studies. Cavalieri et al. (1992) summarizes several of these studies. In general, accuracy of total sea ice concentration is within +/- 5% of the actual sea ice concentration in winter, and +/- 15% in the Arctic during summer when melt ponds are present on the sea ice. Accuracy tends to be best within the consolidated ice pack when the sea ice is relatively thick (greater than 20 cm) and ice concentration is high. Accuracy decreases as the proportion of thin ice increases. See Cavalieri et al. (1992), Steffen et al. (1992), and other listed references for an overview of the algorithm performance.

    So if I read this right, it looks like a error, or uncertainty range of 5 to 15 %. Assuming a 10% error, that would be about 2 mill. sq. km. error/uncertainty. So for the anomaly data, it’s rather hard to argue one way or another, as to the degree of change. Much less, what is causing it. Seems a satellite measuring ice went out about some time ago, only it deteriorated rather fast, so the problem was more noticeable. The worst ones are the slow moving ones that escape notice, and data is accepted as fact. That’s why re-calibrations are helpful.

    Unfortunately with all those digits in a reading, some might get the impression that it’s accurate to that level. Depending on the circumstances, we used to have to “pad” the uncertainty digits with zeros to highlight error/uncertainty, especially to a Marketing Director.

    #144 Tamino – So if you have a long term error “drift” in the sensor, how do you use statistics to help you separate real temperature “drift” or sensor “drift”? Unless you re-cal a unit to a known standard, or compare it to other sensors you know (hopefully) are good, statistics will not help. That’s the purpose of comparing results with other methods. That is why I cross checked my Fourier Analysis of the 1659-2008 Central English temp data, with a different method ( 4-pole Cheb. recursive filter). Both methods showed the recent flattening/downward trend in global temperature over the last decade, that MAY indicate it being part of a 40-50 year cycle.

    One of the best ways to tell if people are on “thin ice” with their arguments, is the their use of condescending remarks.

  9. 159
    Steve L says:

    Acknowledgements: Kevin & Thomas & Hank
    Disacknowledgements: Mark
    The problem of 100 years is that you use 100 years in an example to show how wrong I am, but the change I started writing about occurred over several billion years, thus magnifying even a small effect I presume. The problem of unscientific conclusion jumping is exemplified by your conjecture that I’m getting this stuff from some sort of scamming talking points based on the fact that there are holes in my knowledge. And that I don’t know how to do science because I didn’t read up on every aspect or figure everything out first before commenting on an idea. (The simple answer is that I’m busy doing my own science; others know this stuff much better so I came here looking to gain from their expertise.) Shall I question your ability to do science or to teach? The moderators should correct me if I’m wrong, but I thought it was perfectly acceptable behaviour (not shocking behaviour) to visit this blog and ask about an idea because others might share links to something directly relevant or be capable of quickly figuring something out, and sharing that. I didn’t realize I had to “stretch the boundaries of the science” myself before commenting.

  10. 160

    Truth : “the black carbon that’s clearly visible in all photographs of Arctic”:

    “as you claim, the soot is not visible to the naked eye on the ice ?”

    NO, none whatsoever especially by Arctic ice dwellers present for decades… Place that idea in the bin….

    #140, The Multidecadal melt periods suggested have nothing in common with the current vast shrinkage of old ice. Back in the 80’s there was such things as ice 10 meters thick. Often sought by “bush” pilots in support for Arctic ocean expeditions, they were vast and easy to find. Not so, now a days. Data from 30’s and 40’s are scarce, but I must suggest access to International Ice patrol data, with respect to Iceberg seasons. If there were great melts during that period, iceberg seasons would have been greatly affected.

  11. 161
    Aaron Lewis says:

    When sea water freezes slowly, low salt ice is formed and a very cold brine is rejected. Such low salt ice floats. The high density brine sinks, and under some conditions can rapidly freeze sea water forming a frozen solid that is denser than sea water and called “anchor ice.” Sometimes “ice” does not float.

  12. 162
    Mark says:

    “The problem of 100 years is that you use 100 years in an example to show how wrong I am, but the change I started writing about occurred over several billion years,”

    But it’s the CHANGE that forces the current warming, since the change in forcing will cause change until the system catches up with the forcing.

    That billion year old forcing was part of the stable temperature 999,990,990 years ago. So only changes over the 100 years could be considered as requiring a change in temperature.

    So there is no 100 year problem as you put it. Except being a problem in the idea that tidal forces could cause global warming.

  13. 163
    Mark says:

    “I recommend Robert Grumbine’s blog for people willing to make beginner mistakes asking questions.

    Comment by Hank Roberts ”

    And if it hadn’t been on something pretty darn esoteric (the moon moving away), I could have accepted a beginners’ mistake.

    But the moon moving away I’ve only ever seen said where it explains where that move is coming from: the rotation of the earth.

    So if it had been “Does the dissipation of the tides cause warming?” I would have explained.

    Then asking “how would I do the ballpark guess?” kind of demanded a “Hope you’re not a scientist”. Because the idea of being able to come up with such a rough calculation is the first level of defence for weeding out wasteful ideas in science.

  14. 164
    Martin Vermeer says:

    “truth” #155:

    I’m not allowed a civil reply. [moderator–you are, as long as it doesn’t violate our comment policy, which your comments typically do on multiple grounds, and as long as it is indeed ‘civil’]

    I can confirm what moderator wrote. My comments have been snipped at times too, usually for intemperate language (did I say that I’m allergic to lies?). The moderation rules are simple, a fairly legalistic application of comment policy by apparently not climatologically trained operators. And like cops they have no sense of humour. It really isn’t that hard.

    BTW my remarks required no reply. There really isn’t much to reply to someone observing the serial repetition of long-debunked untruths. Shame would be the apt response.

  15. 165
    Hank Roberts says:

    “truth” asks above:
    > How is albedo reduced if , as you claim, the soot is
    > not visible to the naked eye on the ice ?

    Note: he said it happens; now you’re asking _how_.
    That’s a different question.
    Do you accept that it does happen even when you can’t see it?
    That’s easy to check — you can look this up.

    I pasted your question into the Search box for Google Scholar and found this within the first few dozen hits, in less than a minute:

    “… Impurities, such as soot or dust, within the snow absorb radiation more efficiently than the ice in the snow grains, thus lowering the albedo of the snow cover. Warren and Clarke (1990) found that very small concentrations of soot that are invisible to the naked eye decrease the albedo of snow….”

    The cite there is to:
    Warren, S.G. and A.D. Clarke, 1990. Soot in the atmosphere and snow surface of Antarctica, J. Geophys. Res., 95, 1811-1816

    So yes, there’s evidence for the statement made.
    Now, you want to ask _how_ this happens?
    You realize it’s a different question, a real one?

    Because given your history, “truth” — I’d guess you were just making a rhetorical expression of disbelief in the fact.

  16. 166
    Mark says:

    “One of the best ways to tell if people are on “thin ice” with their arguments, is the their use of condescending remarks.

    Comment by J. Bob”

    Of course, a terrible and incorrect argument could also result in condescention.

    You know, like “Have the IPCC considered it may be the SUN that is doing all this?”.

    A query inviting condescention.

    Of course, most of Jim-Bob’s points of of that quality, so he’s come to the conclusion that it must be “thin ice” rather than he “has nothing” since he knows he’s right, it’s just that the science is being suppressed…

  17. 167
    Mark says:

    PS to Hank’s 158 post. Filtering out the nitwittery also makes it less necessary to treat the nitwits with undeserved respect.

    After all, if the nitwit posts are pruned, there’s no false “discussion” where someone will use their unearned respect to “prove” the debate is still on (see Plimer/Monkton et al).

    And the point of putting the debate on continuous repeat is so that there is always a “reasonable” request to say “we don’t know yet if we have to, and it will cost, so we’d best wait until it IS sorted out”.

    What the denialists want by the back door.

  18. 168

    Two points:

    1) The melt season is at an interesting point right now; it appears that the 2009 plot is likely–based mostly on the trajectory of past seasons–to dip below that of 2006 sometime within the next week, thereby becoming (for a time at least) the second-lowest extent. (This assumes no drastic change in the current melt rate, which is admittedly a sizable assumption.)

    2) A question regarding the physics of glacial cracks & meltwater, proceeding from the previous post, where there was a bit of a thread going. The question there was, how does meltwater behave in a glacial crack? Gavin pointed out that the densities involved imply 10% more pressure within the crack than within the surrounding ice. A poster stated that he thought the meltwater might freeze, creating a lateral pressure.

    My intuitive take: the crack is surrounded by many thousands of tons of (relatively inelastic) ice. It *can’t* expand, so becomes supercooled. But, I wondered, was this plausible given such a small pressure differential? The following discussion seemed to say, “no.” (Ie., since it takes 135 atmospheres to lower the freezing point 1 degree C, a 10% pressure differential will result in a negligible lowering of the freezing point.)

    So, what happens? Presumably the pressure can preferentially act in two ways: to lift liquid water in the melt pond, or to propagate the crack downward. (This might be a good place to mention another post, which seemed to state that pressure in a water column was largely independent of depth. This made no sense to me, and appears to be wrong, according to this discussion. But perhaps I misunderstood what that poster was trying to say.)

    If a crack gets deep enough, the pressures will become such as to lower the freezing point significantly (and presumably that 10% differential will obtain throughout the column.) Here’s a discussion of supercooled liquid water flow in glaciers that I found (2003):

    Don’t know if I’m on the right track (or, indeed, any particular track!) with these musings, but feedback, elaboration, or comment would be warmly appreciated.

  19. 169
    silvia says:

    you are sik! [sic]

    [edit] like you are dreaming of a green christmas…dream on and be quiet, your time will be over soon!

  20. 170
    Rod B says:

    Mark (153), did you say the Sun’s tidal force on the Earth is twice that of the Moon??

  21. 171

    #155 truth

    hmm… truth doth protest too much.

    The moderators here are in my opinion extremely intelligent and very fair. They are also cool headed in their assessments, more-so than I.

    You’ve been around here awhile, so you ‘should’ know. I myself have been edited plenty of times. That’s because I get frustrated with silliness that does not have a foundation in holistic reasoning (but is rather based on myopic out of context arguments and unfounded or rhetorical bias).

    My guess is that you are posting drivel or ad hominem remarks, and thus are edited. If entire posts are being ignored, then I would venture to say that you are adding nothing intelligent to the conversation.

  22. 172
    Ike Solem says:

    BobF is talking about the Pielke Sr. & ICECAP promotion of a slanted view of a paper on Arctic temperature trends and postulated global climate modes:

    Not having the paper, it’s hard to say what they actually did. From the abstract:

    (a) the Arctic amplification (ratio of the Arctic to global temperature trends) is not a constant but varies in time on a multi-decadal time scale,

    (b) the Arctic warming from 1910–1940 proceeded at a significantly faster rate than the current 1970–2008 warming, and

    (c) the Arctic temperature changes are highly correlated with the Atlantic Multi-decadal Oscillation (AMO) suggesting the Atlantic Ocean thermohaline circulation is linked to the Arctic temperature variability on a multi-decadal time scale.

    Poor historical data is a serious problem in analyzing 20th century changes as well as in forecasting future rates of decline. Dynamically, there is a circulation and flow of Arctic sea ice, linked to ocean currents and atmospheric wind patterns. Energy-wise, heat and momentum budgets are complicated by large polewards energy transfer from tropical regions.

    The single largest global influence on the Arctic is has previously been though to be the tropical Pacific, with the main source of natural variability being El Nino & La Nina. For a paper on this interesting phenomenon (AO links to ENSO)

    Moore & Grinsted “Influence of the Arctic Oscillation and El Nino-Southern Oscillation
    (ENSO) on ice conditions in the Baltic Sea: The wavelet approach

    “These results are consistent with GCM simulations showing dynamical connections between high-latitude surface conditions, tropical sea surface temperatures mediated by tropical wave propagation, the wintertime polar vortex, and the AO and with models of sea ice and oceanic feedbacks at decadal periods.”

    The fundamental scientific issue is the nature of such ‘oscillations’. Some phenomena (like the tides) have an obvious periodicity driven by orbital dynamics, with a small but significant irregularity.

    Others have a quasi-periodicity that is linked to gravity waves – see the QBO wiki blurb Such gravity waves may also play a role in timing the 22-year solar cycle – something solar physicists picked up from atmospheric physicists, interestingly enough:

    Mayr et al. 2001In the Earth’s atmosphere, a zonal flow oscillation is observed with periods between 20 and 32 months, the Quasi Biennial Oscillation. This oscillation does not require an external time dependent source but is maintained by non-linear wave momentum forcing. We propose that such a mechanism also drives long-period oscillations in planetary and stellar interiors, and we apply it here to generate a flow oscillation for the 22-year solar cycle.

    Others may appear periodic, but actually be chaotic. What that means is that very small differences between two initial states result in wildly different outcomes at some later time, characteristic of the system in question. For example, consider the moons of Saturn. If we take two measurements of their locations that differ slightly, and plug those numbers into a planetary orbital model, we expect no major difference when it comes to predicting the moon’s future locations.

    With ENSO, two sets of very similar values of ocean temperature, wind speed, air pressure, etc. would indeed result in very different predictions and outcomes. This appears similar to the situation in the atmosphere, but with a longer time period before divergence. It seems probable that other postulated fluctuations behave similarly, and it is also clear that, in particular, the regional effects of ENSO etc will change as the oceans and atmosphere warm.

    For example, the main factor in the susceptibility of sea ice extent to these fluctuations has been the thinning – 1-meter thick ice can be pushed around by the wind, which was a major factor in the most recent record low extent. However, more open water means more ocean-air temperature exchange, leading to lingering warmth in the Arctic fall and warmer Arctic winters.

    This predicted warming of the Arctic winter has also been observed:
    Comiso 2006 Abrupt Decline in the Arctic Winter Sea Ice Cover

  23. 173
    Doug Bostrom says:

    truth 21 Jul 2009 at 9:31 am

    “I replied to each of your criticisms of me, including Doug Bostram’s sneer at my screen name—just a simple and truthful explanation— but for some reason, although you and all and sundry are allowed to attack me , I’m not allowed a civil reply.”

    Here’s a teachable moment. How did did “truth” comport himself/herself/itself (sorry, the moniker allows no more precise pronoun) when he/she/it parachuted into this thread?

    “Why are Real Climate and the rest of the AGW proponents completely ignoring the research of NASA’s Drew Shindell—and NASA’s own reports on the role of black carbon in Arctic warming?

    Why is the AGW side so desperate to have all the focus on CO2?”

    The underlying assertion is flat wrong, which if it were coming from a complete neophyte and presented as a sincere question on this site would certainly be acceptable. However, “truth” introduced this silly fiction in a way that was arguably rude and obnoxious, while being well acquainted with the exhausted patience of regulars on the site. Translated, “truth” entered the conversation saying that climate scientists are either incompetent or pursuing a non-scientific hidden agenda.

    Being carelessly loose with truth while simultaneously adopting the conceited pseudonym “truth” and at the same time displaying a really poor attitude is an almost irresistible invitation for a withering response.

    Now “truth” is whining about being sneered at, treated in turn rudely and obnoxiously, even though nobody chose the absurdly conflicted costume he/she/it volunteered to wear in a public appearance where the outcome should be no mystery.

    Rude and obnoxious replies are not particularly unusual here when RC regulars are confronted with stale talking points coupled with pugnacious presentation. Repeated exposure to expired canards elicits a positively allergic response. If you can’t stand heat, don’t turn up the thermostat.

    If you’re a thin-skinned “skeptic” and imagine you’ve got a beef to pick with any particular facet of climate science, why not first make sure of your facts, then present your “finding” with a neutral affect?

  24. 174

    #101 J. Bob

    Understand that the atmospheric lifetime of CO2 and forcing, combined with oceanic thermal inertial paints a pretty reasonable picture of what is actually happening.

    All things considered we are on a new path and that path is warming.

    A reasoning mind does not need history to understand basic Newtonian physics. If you drop an apple while you are standing on the earth, it will drop toward the earth. In this sense, climate is very easy to understand.

    Think of it like a 230 car locomotive loaded with steel on a downhill slope. Inertia. In this case the C02 is the steel and it is in the atmosphere (the downhill slope). It will not be easy to slow and reverse to return to previous state climate range.

  25. 175

    # 103 J. Bob

    From a lay perspective, it is probably a good idea not to worry as much about the error bars but rather recognize the basic trend based on the forcing component. The error bars will remain on various data sets and get smaller over time.

    The trend is clear.

  26. 176
    Doug Bostrom says:

    J. Bob 21 Jul 2009 at 10:25 am

    “So if I read this right, it looks like a error, or uncertainty range of 5 to 15 %. Assuming a 10% error, that would be about 2 mill. sq. km. error/uncertainty. So for the anomaly data, it’s rather hard to argue one way or another, as to the degree of change.”

    I disagree. In order to dismiss the downward trend in the data, you need to posit and then identify a mechanism producing a previously unidentified bias in the data product that will explain the downward trend.

    I don’t think you can do that, based on what I read of the instrumentation’s function. If you look here

    you’ll an extremely detailed accounting of how these measurements are obtained, including calibration philosophy and methods, how orbital mechanics interact with the RF observations, etc. It all seems pretty airtight.

    Again, if you’re questioning the validity of the data, you need to identify an error source that will explain the downward trend in ice coverage as observed by the instrumentation. Comprehensive information on the instrumentation is available for you to do the work required for such finding.

  27. 177

    #158 J. Bob

    Are you disagreeing with the general trend because of the error bars?

    If so, why?

    Additionally, do you realize that in post #85 you stated

    “Global sea ice still running about normal, no mass meltdown:”

    and then pointed everyone to a graph that showed a downtrend.

    Do you realize that the visual of the graph to the untrained eye would look like there is no downtrend but that in fact there is a significant trend?

    I added the chart you showed to this page (scroll down to global ice) specifically because that was one of Moncktons arguments. Read it and let me know if you still think nothing is melting?

    Then take a look at this glacier chart

    Take a look at glacial retreat

    Of course, study over at NSIDC

    Last but certainly not least:

  28. 178
    Steve L says:

    Good golly, Mark, read what I’ve written! I’m not blaming tidal forcing for global warming! I’m blaming the Moon moving away from the Earth for global COOLING (only warming if going backward through time, until the Moon was much closer to the Earth, potentially having a significant impact on the Earth’s temperature). Mis-reading what someone writes and assuming they are politically motivated is bad pedagogy, not to mention unscientific.
    PS. You seem to be overly concerned with who I am and my motivations and not with the questions I’ve actually tried to ask. Would it be more scientific to search up comments by Steve L on climate blogs than to assume that I’m an AGW-denier? (I wanted to keep this about the issues, but if you read through your comments, they’re largely of a personal nature — how scientific is that?)

  29. 179
    Brian Brademeyer says:

    Re: 168, Kevin McKinney:

    I believe the statement was made that the gradient was constant in a water column, not that the pressure was constant. (Admittedly a rather clumsy phrasing, but that was my take on it).

  30. 180
    Stephen says:

    To Mark, comment # 118 (in response to my earlier comment):

    I gather that, by your post back to me, you think using “extinct” is good science writing, and not a form of hyperbole?

    But your post, cryptic as it was, doesn’t support your position, unless your suggest that your use of ‘extinct” with reference to arctic ice maps to:

    “3: of a fire; being out or having grown cold; “threw his
    extinct cigarette into the stream”; “faint smoke from the
    extinguished candle”; “the fire is out”; “the quenched
    flames” [syn: extinguished, out, quenched]

    Clearly, in a science-based discussion analyzing the global impact of warming, someone using the word “extinction” should be understood to be referring to “the permanent disappearance of a species (or some other permanent disappearance)from the Earth.”

  31. 181
    Doug Bostrom says:

    Steve L 21 Jul 2009 at 3:20 pm
    “Good golly, Mark, read what I’ve written!”

    I think maybe you’re seeing the RC equivalent of anaphylaxis.

  32. 182
    Doug Bostrom says:

    Steve L 21 Jul 2009 at 3:20 pm
    “Good golly, Mark, read what I’ve written!”

    I think maybe you’re seeing the RC equivalent of anaphylaxis. You’re not a nut, but the even a coincidental and perfectly innocent resemblance to being a nut triggers a hyperimmune response…

  33. 183

    #178 Steve L

    Okay, I’ll bite. What are your motivations here?

    And while we are at it, what relevance does a discussion of the moon have on current global warming?

    Shouldn’t you start your own thread or blog on the subject. This thread largely revolves around understanding climate science with a special regard to recent changes in the climate environment that are causing additional forcing to be imposed on the earth climate system.

    Bear in mind, there are many that use red herrings to distract the conversation away from contextually relevant information regarding paleo climate and our current global warming event, and I myself am wondering how could the faint young sun or moon orbit be relevant in this context? But if you have something relevant between this, the moon and anthropogenic global warming, what is it?

    More specifically, how is the amount of forcing change that may or may not be imposed on the climate system by the moon moving away relevant to our current event. Can you express this in forcing of W/m2?

    Context is key.

  34. 184

    #158 J. Bob,

    Here is that Global Sea Ice graph on a non-stretched x-axis with the OLS trend and uncertainty intervals:

    The decline in global sea ice is both clear and significant.

    For more background, read:


  35. 185
    Mark says:

    “Good golly, Mark, read what I’ve written! I’m not blaming tidal forcing for global warming!”

    I’ve told Hank of for bad arguments, Steve.

    What makes you think you’d get a by on making more bad ones just because it isn’t proving AGW false?

    My problem isn’t the arguments denialists make against AGW. It’s the ***bad*** arguments denialists make against AGW.

    And pro-AGW people can make just as bad an argument.

    Now, you still haven’t given where you got the partial informtaion that told you that the moon was getting further away but didn’t explain why.

    And it doesn’t matter what side of a fence you sit, if you want to consider yourself a capable scientist, you will have to think of several ways of getting a ball-park estimate. Not just ask others.

    After the ballpark, you can see if it’s worth asking anyone about it.

    But you didn’t do that [edit]

    But when did I say you were a denialist? I said if you’d read something somewhere and got part of the picture but didn’t care enough to read up, read up but “edited out” the reasons or just had a brain-fart, doesn’t matter.

    You’d either scammed yourself, been scammed or other activity that isn’t really worthy of someone who wants to be considered “scientific” in their field.

    And that’s the same if you were arguing that AGW is right over that half-baked (if that) theory, trying to prove it was “something else” or just trolling for attention.

  36. 186
    Mark says:

    “Mark (153), did you say the Sun’s tidal force on the Earth is twice that of the Moon??

    Comment by Rod B”

    No it was someone else [edit–lets be civil]

  37. 187
    Mark says:

    [edit–lets be civil]

    Well tell that barnstack that.

    “Oh, I thought that the ratio was X:Y …gives link..” would work better rather than the prissy “did you just say…?”

    No, it was some other person.

    So sod off.

  38. 188
    J. Bob says:

    #176 Doug

    I’ll stick with what the document says;
    Cavalieri et al. (1992) summarizes several of these studies. In general, accuracy of total sea ice concentration is within +/- 5% of the actual sea ice concentration in winter, and +/- 15% in the Arctic during summer when melt ponds are present on the sea ice.

    That’s a standard way of specifying instrumentation. That means you have about a +/- 2 million sq. km. error/uncertainty in the presented data, and the real data it somewhere in there. So don’t get to excited about the least significant digits.
    From your reference:

    Bootstrap Algorithm Error Analysis
    Under ideal winter situations when only thick ice and open water are present, ice concentration can be derived with the Bootstrap technique at an accuracy of about five to 10 percent, based on standard deviations of emissivities as used in the formulation. Errors are higher in the seasonal sea ice region than in the central Arctic region because of higher standard deviations of consolidated sea ice in the 19 vs 37 GHz plots. This is partly because of spatial changes in surface temperature that are not as effectively accounted for by this set of data.

    farther on:
    Despite this adjustment, the error is still substantial and can be larger than 20 percent due to spatial variations in melt and affects of meltponding.

    If I read this right, instead of +/- 10%, should I now look at a +/- 20% error/uncertainty, and increase the error band to 4 million sq. km.?

    #177 – John, what I am saying, is that one should not get to excited about a 3% error, when the over all error/uncertainty can be as high as 20%. One may not know if there is a instrumentation problem or a sea ice problem in a fine grain analysis. It doesn’t mean you don’t watch it, just be aware of what your dealing with.

  39. 189
    BobFJ says:

    Ike Solem Reur 172
    You wrote concerning my 140:

    BobF is talking about the Pielke Sr. & ICECAP promotion of a slanted view of a paper on Arctic temperature trends and postulated global climate modes:

    Not so Ike. Here is the link again:
    It is to the AGU, (American Geophysical Union) and their respected Journal; GRL (Geophysical research letters).

    You seem to want to denigrate this paper, but please note the diverse and impressive authorship, which BTW includes Chris Folland of the Hadley Centre! Note too, GRL’s peer review process timing.

    Petr Chylek
    Space and Remote Sensing, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
    Chris K. Folland
    Met Office Hadley Centre for Climate Change, Exeter, UK
    Glen Lesins
    Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
    Manvendra K. Dubey
    Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
    Muyin Wang
    Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle, Washington, USA

    Received 19 April 2009; accepted 9 June 2009; published 16 July 2009.

  40. 190
    Steve L says:

    JPR @183, I’ve tried to lay out my motivations @137; faint young Sun was discussed on Realclimate previously and I link to that @89, so presumably it’s fair game to comment/ask about very ancient climate stuff. I wouldn’t have belaboured the point I tried to make, or defend it, if I thought it was being received properly. I suspect that if I’d tried to be more complete when I first brought it up (rather than be overly cursory — I knew it was a bit off topic) some of the misunderstandings might not have occurred and you would have had to read less of this personal stuff. Sorry about that. But now I’m going to take Mark’s bait….

    Mark @185 thinks my argument is crap. I can’t find out why from him because he’s [self-edit] and focused on personal stuff, but I’m trying to obtain Bruce Bill’s Nature Geoscience article (recommended by Hank @109) and may learn something there. I don’t think Mark knows what my argument is — he thinks I’m saying the Moon has caused global warming over the last 100 years or something. And he thinks I may be seeking attention (projection) or that, to prove authenticity, I must spend more time and space here describing where I got the partial ideas I have. Very well: I’m a fish geneticist so I like evolution and I’ve watched Thunderf00t on youtube (one video mentions the Moon getting farther away); also as I’m a fish geneticist who works with a temperature sensitive creature, I’m interested in tides and temperature; finally I’m not a physicist so I don’t understand how the Moon gets farther away by slowing the Earth without tidal breaking. You’d think someone who based several of his own comments on a poor reading/understanding of something (I’m not asking Mark to prove his 100 year fetish is authentic — I don’t care) would understand how partial ideas get formed!
    I hope this satisfies you, JPR. This is gladly(!) my last comment on this topic unless I learn more (hopefully from the Nature Geoscience article when I can access it) and can provide something useful on W/m2. Thomas @146 has dampened my optimism that this is possible because very little is known about actual conditions that existed so long ago when whatever effect the Moon had would have been strongest.

  41. 191
    Doug Bostrom says:

    J. Bob 21 Jul 2009 at 5:45 pm

    [handwaving about scattered errors omitted]

    So you concede that you cannot identify any systematic source of error that will reproduce the trend of declining ice identified by the instruments.


    Then you should stop emitting unsupported statements such as:

    “So for the anomaly data, it’s rather hard to argue one way or another, as to the degree of change.”

    Let me repeat:

    “…if you’re questioning the validity of the data, you need to identify an error source that will explain the downward trend in ice coverage as observed by the instrumentation.”

    You did not do that. Other errors are irrelevant. The instrumentation indicates a downward trend in ice coverage that you have failed to explain via defects in the data.

    Sorry to be so repetitious but it seems to be unavoidable.

  42. 192
    Doug Bostrom says:

    Lest anybody be misdirected, let me emphasize that J.Bob in his 21 Jul 2009 at 5:45 pm post is attempting to explain an observed downward trend in ice coverage by resorting to errors of a type that while significant are not capable of producing a systematic trend of erroneous underestimation of ice coverage.

    The errors J.Bob refers to are seasonally consistent and end up producing measurements with shorter error bars in winter, taller error bars in summer.

    The errors he is referring to do not grow year-by-year, nor do they produce a skew or trend in measured area over the course of years.

  43. 193
    Doug Bostrom says:

    re Steve L 21 Jul 2009 at 6:30 pm

    Further to your posts and even more solidly off-topic, but I understand some of the cognoscenti believe terrestrial life would not have emerged but for the lunar tide. So we would have been stuck at the fish stage, which I suppose would have precluded our current combustion-related problems.

    Speaking of evolution, here are some ideas found mixed in association together at a hapless congressman’s recent town hall meeting on health care. He found himself confronted with more than medical bills:

    ““It’s still a theory, so is Darwin’s theory of evolution! And yet we have the audacity to say global warming is accurate, it’s more than a theory? How about how cold it’s been this spring. Personal data, data shows that since 1998 average temperatures have been cooling!””

    ““The virus was built and created in Fort Dix, a small bioweapons plant outside of Fort Dix. This was engineered. This thing didn’t just crop up in a cave or a swine farm. This thing was engineered, the virus. Pasteur International, one of the big vaccine companies in Chicago, has been caught sending AIDS-infected vaccines to Africa. Do you think I trust — I don’t trust you with anything. You think I’m going to trust you to put a needle full of dead baby juice and monkey kidneys? Cause that’s what this stuff is grown on, dead babies!””

    ““Do you have any idea what that cap and trade tax thing, bill that you passed is going to do to the Suffolk County poultry industry? That’s how chicken houses are heated, with propane. It outputs CO2. I mean, I’m outputting CO2 right now as I speak. Trees need CO2 to make oxygen! You can’t tax that!””

  44. 194

    #173 Doug Bostrom

    Thank you for your assessment of the ironically misnamed ‘truth’.

    Personally I think he/she/it has more in common with a shill, or a troll.

    The improperly named ‘truth’ seems to have an agenda: that of avoidance, or neurosis, on the science of climate. ‘truth’ also seems to be one of those that wants to wear the badge of being able to say ‘the RC posters don’t like me and my truth’, so obviously the science regarding AGW must be wrong.

    To hide anonymously behind the moniker of ‘truth’ and babble incoherently about how the petabytes of data and innumerable hours of analysis are wrong is simply mind boggling. But easy to understand when it comes from an anonymous source so ineptly named ‘truth’.

    But you see, what I am writing is exactly what the foolishly named ‘truth’ wants; I have been suckered into his expertly woven web so that he can now say that I am a mean person and don’t care about science, therefore anything I say about global warming must be wrong.

    If only he/she/it would bestow upon us a real name associated with the actual poster, that we may herald such wisdom and understanding and possibly elect he/she/it into an office of our great land that such person/entity may then bless the nation, nay, the world with profound elucidations about how all those crazy scientists are wrong.

    Nay, we mere mortals must bow down to the anonymity of the splendor of masked diatribes, non sequitur arguments, straw-men, false dichotomies and red herrings and wallow in our foolish consideration of the works of scientists who are guilty of examining evidence using such device as the relatively unestablished scientific method…. because everyone knows that the climate has been around much longer that the scientific method…, at least on this planet.

  45. 195
    Nick Barnes says:

    J.Bob @158 and 188, no, sea ice doesn’t work like that.
    Here, look at the current sea ice concentration map from Cryosphere Today.

    The key fact which you are missing, and which you can see from that map, is this: almost all of the ocean is either ice-free (much less than 5% ice) or has very high ice concentration (over 95%). This is fundamental to an understanding of sea ice: you’ve either got ice, or you haven’t. Check MODIS for direct visual confirmation. Here’s a picture from today. Even now, in the middle of a ferocious melt season, when the ice at 90 East and 83 or even 85 degrees North is all chopped up like a frappuccino – a daunting sight to the keen amateur ice watcher – it still covers well over 90% of the sea surface. During the winter, it’s even more cut and dried.

    This bimodal behaviour is why we can even talk about an “ice edge”. So when ice scientists say they have a 5% or a 15% or even a 20% error bar on their concentration numbers, they *aren’t* talking about the areas which read 100%, or 0%. The error bars there are very much smaller. They are talking about the ice edge, that fringe around the ice pack which has 80% or 50% or 25% ice. Determining whether a given point in this fringe has a 40% concentration or a 50% concentration is very hard: there’s a large error bar, but it makes no difference at all to the total extent number. In fact this ice edge is especially narrow in winter. Consider this tool at CT, which lets you see concentration maps from many different dates.

    Observe also that most of the ice fringe has high ice concentrations (above 50%). This all counts as 100% towards the “ice extent” number (which counts all areas with over 15% ice concentration). The only uncertainty is over the size of the very narrow fringe with less than 15% concentration. It is difficult to pick out even a single pixel from a concentration map which counts towards this uncertainty. On a MODIS shot you can trace a low-concentration fringe, but it’s very narrow – a few tens of kilometres at most, often well under a kilometre. As the perimeter of the late-summer ice pack is maybe ten thousand kilometres (paradoxically it is much less in winter), the extent uncertainty is not going to be millions of square kilometres. It’s just not, and you can’t advance a single study which says that it is.

    So no, there isn’t anything like a 20% error bar on the ice extent number.

  46. 196

    #188 J. Bob

    I’m trying to understand your context. Are you arguing the finer points of climate science or are you arguing the validity of the AGW science?

    As I understand it, the further you get out to the edge of the error bars the less likely the accuracy based on the overall analysis or the specific data point. So why get excited about the possibility of a 20% error/uncertainty?

    I’m all for reducing error bars ;) but context will get you relevance every time. So I want to understand your argument point. Is it AGW is partly, or largely false, in concept; or merely that the planet is warming, the ice is melting and we need to be more precise….

    But, as indicated in your previous post #85 “Global sea ice still running about normal, no mass meltdown” so I’m confused? Your statements seem to be contradictory. Maybe you can help me understand better what precisely you are saying?

  47. 197

    #190 Steve L

    Thank you for the context. I looked at the original RC article, faint sun, and also looked up the departure rate of the moon.

    3.8cm per year and steady.

    Consider the potential of influence on the time scales of seasonal vs. eons and periods. I would add the context of actual forcing as illustrated by the GCM’s into this context. You seem to be considering the possibility of major, or substantial, climate influence on shorter time scales, even seasonal, but how much (W/m2)? Also consider that any influence on short time scales would likely prove to be statistically insignificant in this context (that of forcing changes that are human caused).

    I would never say don’t examine something, but thar be dragons where context is less understood, as you have noticed. Sometimes things out of context can smell a bit fishy (no pun intended… okay, pun intended, sometimes I get a chuckle out of how silly I can be).

    For further context, consider the GHG change rate estimated by a study from a University in the UK indicating a change rate of 15,000 times the natural rate of change (for a typical glacial/interglacial shift).

    So while off topic and out of context in consideration of AGW, it may be interesting study.

    I saw a documentary on the lunar orbits relationship to the earth rotation and other interesting points once, but don’t recall the relationships. I would guess that the relationship is gyroscopic. The closer an ice skaters arms are drawn in in a spin the faster the spin and vice versa, the further the arms are outstretched the slower the rotation.

    All in all, the lunar departure is a long slow process and I can’t think of any good reason it would have a significant impact on climate on shorter time scales such as that being examined in relation to AGW.

    For my own understanding: If you were to say the global warming event was human caused, what % value or range would you assign it to human causes?

  48. 198
    BobFJ says:

    Kevin McKinney Reur 168, item 2)
    “…The question there was, how does meltwater behave in a glacial crack?…”
    Perhaps this experiment will help:

    Anne van der Bom, Brian Dodge, Doug Bostrom, & Sidd:
    Please also study

  49. 199
    Steve L says:

    JPR @197, I suppose I would subscribe to the estimates provided by detection & attribution by the IPCC. I have no reason (or ability) to come up with my own. I note that climate sensitivity estimates haven’t changed much over the last twenty years — seems to me like things have been worked out quite thoroughly.

  50. 200

    #195 Nick Barnes

    Excellent post! I learned a few new contexts there myself.