Oh dear, now we have Does The 2007 IPCC Statement For Policymakers Accurately Present The Observations Of Recent Global Temperature Trends? [2014 update: dead URL. Here's a wayback machine link] on the grounds of a lack of trend over the last 5 years (actually “statistically significant”, though its not clear how the stat sig was calculated – probably once you are emeritus you can do them in your head).

But the first commenter makes the obvious point very well (and has actually gone to the trouble of doing the work): I did the exercise of looking at all overlapping 5-year periods in the figure you reference, and there’s a statistically significant trend in only about 7 out of 24 5-year periods, despite the clear overall long-term trend. Indeed: if you pick a short time period, then natural variability makes it quite likely you’ll see no sig trend *despite* the overall sig trend.

RP has no answer to this, other than to agree, which makes all that post pointless.

Comments

  1. #1 Thom
    2007/05/11

    Wondering if you did not clarify that this is RP Sr. and not Jr., because you forgot. Or is it because both Pielkes have this habit of falling on their swords, so what the point of making a distinction.

    [Readers with long memories will recognise this as a Sr thing -W]

  2. #2 Lubos Motl
    2007/05/11

    If you pick short enough time interval, there’s no trend. If you pick long enough interval, you inevitably have to find *some* trend. Whoever thinks otherwise – that all climate should be constant at arbitrarily long timescales – is mentally ill.

    The fact that there is not even a detectable signal at realistic timescales relevant economically – which means that we’re orders of magnitudes from “dangerous” signals at this timescale – is a main reason why we (all sane people in the world) say that the global warming orthodoxy is a big stupidity.

    [Hi Lubos - if you're falling back to the econ stuff, you're welcome to it. But all you are saying about the science is wrong: there is a stat sig trend over decades or the century, and no - of course there is nothing a priori that says you would have to find it. This mantra that climate is always changing is meaningless -W]

  3. #3 guthrie
    2007/05/11

    Lubos, have you ever heard about the frog in the pan of water?

    [But apparently its not true -W]

  4. #4 Mark Hadfield
    2007/05/11

    Pity you didn’t stop after the first paragraph, Lubos. You were making sense.

  5. #5 Thom
    2007/05/12

    [Incivility deleted - please be nice folks]

  6. #6 Hank Roberts
    2007/05/12

    William, RP says he wants you to show him the Joules because he doesn’t believe there are any.
    Or something.

  7. #7 Mico
    2007/05/12

    Hank, At least PR is completle right to challenge the IPCC report which is very superficial, and you comment even more.

    [If IPCC was so bad, don't you think RP could come up with something better than this? -W]

  8. #8 Hank Roberts
    2007/05/12

    Hey, I’m just reading and trying to understand. Of course my comments are superficial, taxpayers are like that (wry grin). But we think the science is important, and appreciate those who take the time to try to explain things.

    Question here seems to be — since both RP and WC and the first commenter in the referenced thread agree that five years isn’t adequate to demonstrate a trend; and since the cited page shows definite trend lines, and points out the El Nino peaks and the trends are still there — where is the question?

    The people who keep saying, but, since the last El Nino there hasn’t been another El Nino as big, are right, but that doesn’t say anything about the longterm trend on the page everyone’s looking at. Trend line’s there.

    So what’s the question? Is it that the trend line somehow doesn’t show “joules” accumulating?

    [Where is the question? Hard to say. We all agreee that 5 years is too short to draw trend lines, in which case we all agree that RPs original post was nonsense - in which case it reduces to his familiar "lets use joules as our metric, using this highly reliable paper about ocean warming... ah, oh, it wasn't so reliable after all, oops..." (only he omits the bits after metric) -W]

  9. #9 Thom
    2007/05/12

    William, thank you for deleting my comment and providing your expert opinion on what is/is not incivility. You’ve just lightened my daily reading list.

  10. #10 Bob
    2007/05/13

    Ok, I have to jump in here! I keep hearing the true believers of the IPCC spot that 8 of the last 10 yrs have been the warmest on record and that this is proof of the validity of AGW and man’s evil ways. But if the true believers buy this, then why is the lack of warming shown in a true believers study pointed out by RP Sr any less meaningful. I think you doth protest to much is 10 yrs more significant that 5? While it may not be statistically significant it is still evidence that should be noted as NOT in agreement with the faith (or dare I say it Science???)…..

    [Hi Bob - good comment, and rather better than RP managed. First off, we know there is natural variability frm year to year so we don't expect an steadily increasing trned - there will be jumps. Second, we know there is an upward trend over the last 30 years - its obvious by eye and can be confirmed by the stats. But as the first comment to RP said, if you pick 5-year sub-samples out of that 30 year period, *most* of them don't show a stat sig trend. So that gives us good reason to believe that 5 years is not good - on the basis of experience.

    8-of-the-last-10-are-warmest is a different statistic, and without having done the analysis I don't know how good it is at detecting trends. Maybe it is just eye candy - its not what I'm going on -W]

  11. #11 Steve Bloom
    2007/05/13

    Bob, if you read the IPCC WG1 SPM (and please do) you’ll get a more accurate sense of the evidence. The fact that global surface temperatures reflect a fairly consistent warming trend over the last ten years is not in and of itself a central part of the argument simply because it is indeed too short of a period. OTOH, people do mention it a lot since the odds are rather slim of something like that happening in the context of a long-term trend that was either flat or cooling (plus of course people do like to talk about the weather). What RP Sr. has done is much worse than that, though, as you’ll see if you keep following the discussion there.

    I should point out for those without sufficiently sharp eyes (no doubt it’s the Vitamin D in the carrots) that the first commenter William quoted is also a co-author on RP Sr.’s brand-new magnum opus (cited in the post). Being thus predisposed to be nice to RP Sr., the commenter rather delicately gave him an opportunity to volunteer that point #2 was just as defective as point #1, but RP Sr. failed to avail himself of it. I suspect the commenter was well aware that point #2 actually has larger problems than #1.

    [Well spotted, I'd missed that -W]

  12. #12 Mico
    2007/05/13

    RE Hank Roberts | May 12, 2007 04:14 PM;
    Whether taxpayer or scientist, accumulating financial data, or temperature data and putting them in graphs, or not, is simple accounting requiring little skills, whether for short or long period. But I agree that accumulating JOULES may sound interesting, but will hardly be of much help either for better understanding climate relevant question.

  13. #13 Steve Bloom
    2007/05/13

    Mico, it’s worth pointing out that since joules (total ocean-atmosphere heat content) can only be calculated by reference to the very data sets that RP Sr. attacks as unreliable, the whole exercise is a contradiction.

  14. #14 Bob
    2007/05/13

    Ok, I have re-read the subject post and the succeeding comments. I have one point to make. Your comment above and your quote of the comment by John Nielsen-Gammon, was some what selective. I will give you credit that you provided the link so that anyone could following it and read the entire commentary but it was selective. The first commenter only found issue with one of RP sr points but he did say

    “I’m not aware of a theory that predicts whether a model’s underestimate of natural variability should be expected to coincide with an overestimate (or underestimate) of CO2 sensitivity, although it is certainly one reason to treat models with caution.”

    I take this to mean that while he points out the problem with time span of 5 years being too short to have strong statistical significance it is meaningful enough so as to warrant attention. As I read the post RP sr is doing what any good Scientist should do and that is to critically review material in his field and comment. This is no different that you would do I am sure. I thought your lead in comment was guilty of what you are accusing “SNARKING”. It is your blog so it your rules, I just wanted to make the observation.

    [I'm sorry but you still appear not to have understood the main point: 5 years *is* too short to do anything meaningfull with, and the first comment demonstrates that clearly. Did you understand his point? That if you go back over the record and clac the 5-y trends, few are sig, yet the overall pattern clearly is. To make this more obvious perhaps, consider an articifial pattern of (0,0,0,0,0,1,1,1,1,1,2,2,2,2,2,...) and take 5-year trends starting at 0,5,10,15,... steps in. All are zero, yet the overall trend is up. RP is not doing what a good scientist should do, which is to take on board valid criticism and chnage his opinion based on people pointing out flaws -W]

    Now I am not going to get in a battle with Steve B. on credentials but I have worked on large statistical scientific models as well as engineering models and know the difference. My experince is that scientific models are research tools that are used for developing better understanding of scientific research, and as such they (as any good engineer who has worked with research scientist will tell you) should always be treated with a large helping of skepticism. It is this skepticism that will keep the scientific model from drifting into trouble. So while I fully agree that the world is warming, I am having some problems with the claimed efficiency/accuracy and use (out side of research) of scientific models.

    As a last point before venturing in to the blog world on CLIMATE I have spent a lot of time reading and researching the material at RealClimate and Climate Science and I have read much of the last two IPCC reports (and yes Steve I have read the SPM). So, I have learned much, I still question much and I am still in the process of learning (as we all should be). So I thank you for your time.

    Also so as to goad Steve B. on, based on my reading here and at Climate Science I still don’t buy your comment

    “I suspect the commenter was well aware that point #2 actually has larger problems than #1.”

    So far it looks like SNARKING on your part. I am not going to engage you in literary fisticuffs as I judge you my superior. I would just like to see more evidence as I am always open to convincing.

    [There are problems almost everywhere, I agree, but the judgement is on what is good enough to be worth using. If you're still reading and learning, you're very welcome -W]

  15. #15 Steve Bloom
    2007/05/14

    And so in the end RP Sr. is reduced to arguing that the models aren’t very good at doing step changes even though they have the overall trend nailed pretty well. Well, duh, as a modeler might say.

    Yes, Bob, it’s snarking, but you have to understand that it’s snarking in the aftermath of RP Sr.’s baseless championing of the idea that the Lyman et al paper presented a fundamental challenge to AGW theory (which he went on about for months; see the final comeuppance here). Now he seems to be scrambling around looking for similar angles. That’s fine, but each time he gets sloppy like this he can expect to be called on it since otherwise members of the public may take his claims at face value. You would think that being publicly corrected by a co-author and then by an amateur like me would cause him to change his approach, and maybe eventually enough such events will do the job. I have a feeling it won’t be soon, though.

  16. #16 Steve Bloom
    2007/05/16

    The agony continues. In the latest comments RP Sr. makes it clear that he admitted no error in response to comment #1.

    Now he has a new post attacking the recent Lynn et al paper on future southeastern U.S. warming. Is it just me, or are these attacks getting both more frequent and sloppier?

  17. #17 Roger Pielke Sr
    2007/05/20

    All – I am quite disappointed that Stoat has embedded the science disagreement that you have with the weblog on Climate Science within general ridicule. While individuals can disagree with each other, professional courtesy should be a requirement. My recommendation is that if you want to be seriously discussing climate science that you refrain from personal degradation.

    Nonetheless, despite these personal attacks on Stoat, I will write here one last time the essence of the Climate Science weblog

    http://climatesci.colorado.edu/2007/05/10/does-the-ipcc-statement-for-policymakers-accurately-present-the-observations-of-recent-global-temperature-trends/

    which is as follows;

    The assessments of longer term (decadal) trends in any climate metric are made more complicated by shorter term variations. We agree on that.

    However, the use of heat in units of Joules is a particularly effective way to assess global warming or cooling even on shorter time periods since, unlike a global average surface temperature trend, Joules provide a mass integrated value. As long as it is sampled with sufficient spatial resolution at two selected time and globally, it provides a snapshot of the radiative imbalance between these two time periods.

    This use of Joules is analogous to the accumulation or removal of bricks. With global warming, bricks (Joules) are accumulated while they are lost with global cooling. The latest assessment of Lyman et al with their correction is that the bricks (Joules) have not been accumulating the last few years. You can (correctly) question if the bricks (Joules) are being sampled with sufficient spatial resolution and/or have biases in the counting of the amount, but the concept is scientifically sound.

    The weblog on Climate Science on May 10 2007 presents evidence that the measurement of two components that contribute to the Joules in the climate system (part of the tropospheric and of the stratosphere) do not have recent trends which conform with the prediction of the multi-decadal global climate models for these layers. The scientific reply (if you are defending the IPCC perspective) would be, for example, to describe where heat within the troposphere, sampled by the RSS MSU data, has gone to elsewhere in the climate system, or present evidence of cold biases in this data set.

    [Roger - I'm not sure what you mean about personal degredation. If its the bit about working out trends in you head, then that was only intended as a light-hearted way of pointing out that you had mere asserted a lack of stat sig without in any way demonstrating it.

    If you want to discuss this seriously, I think you need to properly withdraw your points 1 & 2 (ie the lack of 5-y trends), rather than what you seem to be doing, which is no longer talking about them.

    The use of joules has obvious problems, as the problems with the ocean heat measurements has shown. At the moment, the sfc record is clearly better. Its no good relying on Lyman et al. which is cleary in a state of flux -W]

  18. #18 Steve Bloom
    2007/05/20

    Roger, two quick points:

    The people disagreeing with you aren’t idiots, and many are colleagues of yours with arguably better qualifications. It is both insulting and a waste of your time to think that you can improve your arguments by putting them in terms appropriate for a bright sixth-grader.

    When you use terms like “absurd” to refer to IPCC conclusions, you invite similar ridicule of your own views.

  19. #19 Eli Rabett
    2007/05/21

    Another point is that heat is work, and work is heat and together they are energy which is what is conserved. You don’t want to just monitor heat, you have to also monitor energy as in wind and currents. The first law appears to have passed Climate Science bye. Which brings us to another Flanders and Swann moment (yeah, Eli knows, obsessions are not good things, but Roger has his and Eli has mine) link to mp3

    The First law of Thermodynamics.
    Heat is work and work is heat
    Heat is work and work is heat
    Very Good.
    The Second law of thermodynamics.
    Heat cannot of itself pass from one body to a hotter body
    Heat cannot of itself pass from one body to a hotter body
    Heat won’t pass from a cooler to a hotter
    Heat won’t pass from a cooler to a hotter
    You can try it if you like but you’d far better not-a
    You can try it if you like but you’d far better not-a
    ‘Cos the cold in the cooler will get hotter as a rule-a
    ‘Cos the cold in the cooler will get hotter as a rule-a
    ‘Cos the hotter body’s heat will pass to the cooler
    ‘Cos the hotter body’s heat will pass to the cooler
    Heat is work and work is heat and work is heat and heat is work
    Heat will pass by conduction and
    Heat will pass by conduction and
    Heat will pass by convection and
    Heat will pass by convection and
    Heat will pass by radiation
    Heat will pass by radiation
    And that’s a physical law

    Heat is work and work’s a curse
    And all the heat in the universe
    Is gonna cool down,
    ‘Cos it can’t increase
    Then there’ll be no more work
    And there’ll be perfect peace
    Really?
    Yeah, that’s entropy, Man.
    And all because of the second law of thermodynamics which lays down:
    That you can’t pass heat from a cooler to a hotter
    Try it if you like but you’d far better not-a
    ‘Cos the cold in the cooler will get hotter as a rule-a
    ‘Cos the hotter body’s heat will pass to the cooler

    Oh, you can’t pass heat from a cooler to a hotter
    Try it if you like but you’ll only look a fool-a
    ‘Cos the cold in the cooler will get hotter as a rule-a
    And that’s a physical law
    Oh, I’m hot
    That’s because you’ve been working!
    Oh, Beatles, nothing!
    That’s the first and second laws of thermodynamics.