Tropical trends

The issue of reconciling tropical temperature trends at the sfc and in the troposphere rumbles on, although in a not very serious way: its a good subject for research, but it doesn’t seem to be a major septic playing point, probably because the issue is too complex to get much traction.

A brief recap: once upon a time the satellites said the trop, globally, wasn’t warming. That disappeared ages ago. We’re now looking only at the tropics, which are warming too, and the remaining issue is whether the trop warming is compatible with the surface warming. Models and (we believe) basic physics says the trop T mid-height should warm about 1.4 times as much as the surface. Everyone agrees that for changes like the seasonal cycle, this is true. The issue is whether its true for the long-term trend.

Enter “A comparison of tropical temperature trends with model predictions” by David H. Douglass John R. Christy Benjamin D. Pearsona and S. Fred Singer” in press in IJC; and “Tropical vertical temperature trends: A real discrepancy?” by P. W. Thorne, D. E. Parker, B. D. Santer, M. P. McCarthy, D. M. H. Sexton, M. J. Webb, J. M. Murphy, M. Collins, H. A. Titchner,1 and G. S. Jones; GRL VOL. 34, L16702, doi:10.1029/2007GL029875, 2007.

You don’t have to go far to see that Thorne et al is a higher quality paper. The basic conclusion is that the uncertainty in the trends from the satellites is large enough that there is no inconsistency.

Weirdly enough, Singer et al come to the opposite conclusion: that they are inconsistent. I doubt very much whether their error analysis is good enough to conclude this. One problem is that they lump all the IPCC runs together, without noticing that some are rubbish (though to be fair the IPCC does this too). There are clearly errors in the review copy: model 17 has a trend, in unspecified units, of 219 at the sfc at -1275 at 1000 hPa; they should be very nearly the same (model 2 has a simlar problem. Curious. Singer et al very late on remove these “outliers”). The uncertainty in the modelled trends is taken to be the inter-model SD/sqrt(n-1), which I think is dodgy. And table III invites us to believe that the obs have no uncertainty, which is tricky, since they disagree amongst themselves.Table III also has what I assume is a typo of “MSU” for “UAH”. UAH and RSS disagree by nearly 0.1 oC/decade; if that is a meaningful measure of obs uncertainty then RSS and models agree. Singer et al also take this ~0.1 value, but then come up with the blatant falsehood that “In all cases UAH and RSS satellite trends are inconsistent with model trends” which I can’t see as anything other than nonsense, unless they are arbitrarily lowering their error tolerance somewhere else. I haven’t talked about the sondes, which are also interesting. But I think everyone agreed that the satellites were far better?

[Updates:

(1) RC has now done this very nicely: see here.

(2) One thing RC don't pull out, but mention in passing, is that the tropical amplification is a common feature of *all* forcings - solar, GHG, whatever. Thus the wackos lose the plot when they say things like "The observed pattern of warming, comparing surface and atmospheric temperature trends, does not show the characteristic fingerprint associated with greenhouse warming. The inescapable conclusion is that the human contribution is not significant and that observed increases in carbon dioxide and other greenhouse gases make only a negligible contribution to climate warming." Because you *can't* conclude that even if you believe this paper entirely. What you could conclude is that the models are wrong - but their purported belief in the obs provides no reason to believe in solar forcing at all

-W]

Comments

  1. #1 Martin Lewitt
    2007/12/10

    NOAA surveys show that tropical stratospheric charateristics (ozone and temperature) have already expanded poleward faster than predicted by the models for the year 2100. Could the same model weaknesses be responsible for all these?

    http://sciencenow.sciencemag.org/cgi/content/full/2007/1203/3?etoc

  2. #2 LuboŇ° Motl
    2007/12/11

    One doesn’t really need a PhD to see that the models disagree with reality – just look at the graphs

    http://motls.blogspot.com/2007/12/douglass-christy-pearson-singer.html

    I guess that most people who read this blog don’t actually need to see the paper under discussion, just to be assured by an amateur that “alarmism is always of higher quality”. The rest, however, can look at my page where all the relevant materials are linked.

    [I await with interest your discussion of the error analysis of Thorne et al; and your reconciliation of "In all cases UAH and RSS satellite trends are inconsistent with model trends" with reality -W]

  3. #3 Jason Coleman
    2007/12/11

    Just reading Dr. Connolley‘s bio, something tells me he ranks considerably above “amateur.” I, too, would like a little more substance. However, this rush to disregard the author is not only hasty, but incorrect.

  4. #4 QrazyQat
    2007/12/12

    If Motl really thinks dueling CVs at twenty paces is an appropriate way to judge this subject, I’d put my money on an experienced climate modeller being much less of an amateur on this subject than a physicist. (Advice to folks using ad hominems: don’t use one that works against you rather than in your favor. :)

  5. #5 Miguelito
    2007/12/12

    It’s taken down nicely at RealClimate. Not sure if William was involved or not even though he’s “retired” from there.

    http://www.realclimate.org/index.php/archives/2007/12/tropical-troposphere-trends/

    The “discrepancy” fits between the error bars (which were conveniently left out by Douglass et al) and a newer dataset is available, which was also purposely not used.

    Why am I not surprised?

  6. #6 JamesG
    2007/12/13

    The fact that you can fit a bus in the error bars is not really a robust defense of the models. It’s just another reason not to be 90% confident of them.

    [Good to hear you saying that the error bars are large - you realise thats a denuncuiation of Singer et al, of course? I think its a good reason to agree with Thorne et al - the error bars are large enough that models and obs are consistent. Separately, we know that the errors aren't large enough to allow no-warming as a possibiity, if you're interested -W]

  7. #7 Martin Lewitt
    2007/12/13

    I seem to recall that physicists were “amateurs” at calorimetry and electrochemistry, yet were still able to point out the flaws in Pons and Fleischman methodology despite their calorimetry being solidly within a peer review tradition. Performing calorimetry on the earth, well enough to attribute and project a circa 0.8W/m^2 energy imbalance being stored into oceans within the system is a difficult task, based on far more parameterizations and assumptions and with documented errors several times larger than the skill needed. In a complex nonlinear system, modelers may find enough confusion amidst masses of data from simulations and the climate and amidst regional “noise” to CLAIM with “confidence” that errors will cancel out, but will they be able to PROVE it.

    But to claim skill, the modelers will not only have to overcome the insights of “amateurs” such as physicists, accountants and other “deniers”, they will also have to explain away a wealth of diagnostic results of fellow climatologists and true believers.

    [Not clear what we need to explain away. You could give an example, if you liked -W]

  8. #8 JamesG
    2007/12/14

    “Separately, we know that the errors aren’t large enough to allow no-warming as a possibiity, if you’re interested”
    As the minimal acceptable result for a model run is that it produces a warming trend then that result is guaranteed. Try increasing the Aerosol parameter to it’s max error bar and see how much cooling you get.

    [You misunderstand. I mean, the errors on the obs -W]

  9. #9 Lab Lemming
    2007/12/15

    Isn’t the relationship between surface and mid trop going to depend on weather, and specifically the ratio of convecting vs stratified areas in the tropics?

    [I'm told that the amplification is a matter of basic physics, but I'm afraid I don't know the exact details. Since this is climate it shouldn't depend on the days weather, but it works on all longer timescales I gather -W]

  10. #10 Martin Williams
    2007/12/28

    I found this info after – in letter to Hong Kong paper – Viscount Monckton made much of the supposed tropical trophosphere results show the minor warming that ceased in 2001 wasn’t caused by greenhouse gases.
    I aim to write letter refuting his bunkum; post here helps.

  11. #11 Eli Rabett
    2007/12/28

    Martin Lewitt neglects to mention that the flaws in what Pons and Fleischman published pointed out by the physicists were flaws in their nuclear physics, not calorimetry and that to this day people are claiming net power generation from calorimeters.

    Once you snip off the fluff, his plaint comes down to two points: First, you can;t possibly measure net energy/enthalpy content of the oceans accurately enough to say anything. He might want to have a conversation on this with Roger Pielke Sr., although the latter is not talking these days. Second that the measurements of radiation flux from the Earth are not accurate enough to make any claim about a net energy imbalance of 0.85 W/m2. He might want to talk to Spencer and Christy about that one.

  12. #12 JamesG
    2007/12/28

    “the error bars are large enough that models and obs are consistent” is quite an odd conclusion. The error bars are so large that they can’t be trusted at all is a more appropriate conclusion. That the models produce warming at all is even a prerequisite assumption used to calculate the aerosol forcing. Then realclimate.org tells us the obs cannot be relied on. So we have useless models and useless obs whose error bars are so large that they slightly overlap despite their mean curves being far apart. And we are supposed to base policy on this? No wonder the consensus of scientists is so important: There’s nothing else!

  13. #13 Hank Roberts
    2008/02/24

    Chuckle. The spin that can be accomplished with mere placement of punctuation is sometimes amazing:

    QUOTE
    … to hear someone speak with such certainty and such confidence about what the climate is going to do is — well, I suppose I could be kind and say, it’s annoying to me.
    -John Christy of the U.N.’s Intergovernmental Panel on Climate Change (co-recipient of the 2007 Nobel Peace Prize)….
    END QUOTE

    Found at dubyadubyadubya.freerepublic.com/~theraven/

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