RealClimate logo


Technical Note: Sorry for the recent unanticipated down-time, we had to perform some necessary updates. Please let us know if you have any problems.

Once more unto the bray

Filed under: — gavin @ 23 July 2008

We are a little late to the party, but it is worth adding a few words now that our favourite amateur contrarian is at it again. As many already know, the Forum on Physics and Society (an un-peer-reviewed newsletter published by the otherwise quite sensible American Physical Society), rather surprisingly published a new paper by Monckton that tries again to show using rigorous arithmetic that IPCC is all wrong and that climate sensitivity is negligible. His latest sally, like his previous attempt, is full of the usual obfuscating sleight of hand, but to save people the time in working it out themselves, here are a few highlights.

As Deltoid quickly noticed the most egregious error is a completely arbitrary reduction (by 66%) of the radiative forcing due to CO2. He amusingly justifies this with reference to tropical troposphere temperatures – neglecting of course that temperatures change in response to forcing and are not the forcing itself. And of course, he ignores the evidence that the temperature changes are in fact rather uncertain, and may well be much more in accord with the models than he thinks.

But back to his main error: Forcing due to CO2 can be calculated very accurately using line-by-line radiative transfer codes (see Myhre et al 2001; Collins et al 2006). It is normally done for a few standard atmospheric profiles and those results weighted to produce a global mean estimate of 3.7 W/m2 – given the variations in atmospheric composition (clouds, water vapour etc.) uncertainties are about 10% (or 0.4 W/m2) (the spatial pattern can be seen here). There is no way that it is appropriate to arbitrarily divide it by three.

There is a good analogy to gas mileage. The gallon of gasoline is equivalent to the forcing, the miles you can go on a gallon is the response (i.e. temperature), and thus the miles per gallon is analogous to the climate sensitivity. Thinking that forcing should be changed because of your perception of the temperature change is equivalent to deciding after the fact that you only put in third of a gallon because you ran out of gas earlier than you expected. The appropriate response would be to think about the miles per gallon – but you’d need to be sure that you measured the miles travelled accurately (a very big issue for the tropical troposphere).

But Monckton is not satisfied with just a factor of three reduction in sensitivity. So he makes another dodgy claim. Note that Monckton starts off using the IPCC definition of climate sensitivity as the forcing associated with a concentration of 2xCO2 – this is the classical “Charney Sensitivity” and does not include feedbacks associated with carbon cycle, vegetation or ice-sheet change. Think of it this way – if humans raise CO2 levels to 560 ppm from 280 ppm through our emissions, and then as the climate warms the carbon cycle starts adding even more CO2 to the atmosphere, then the final CO2 will be higher and the temperature will end up higher than standard sensitivity would predict, but you are no longer dealing with the sensitivity to 2xCO2. Thus the classical climate sensitivity does not include any carbon cycle feedback term. But Monckton puts one in anyway.

You might ask why he would do this. Why add another positive feedback to the mix when he is aiming to minimise the climate sensitivity? The answer lies in the backwards calculations he makes to derive the feedbacks. At this point, I was going to do a full analysis of that particular calculation – but I was scooped. So instead of repeating the work, I’ll refer you there. The short answer is that by increasing the feedbacks incorrectly, he makes the ‘no-feedback’ temperature smaller (since he is deriving it from the reported climate sensitivities divided by the feedbacks). This reverses the causality since the ‘no-feedback’ value is actually independent of the feedbacks, and is much better constrained.

There are many more errors in his piece – for instance he accuses the IPCC of not defining radiative forcing in the Summary for Policy Makers and not fixing this despite requests. Umm… except that the definition is on the bottom of page 2. He bizarrely compares the net anthropogenic forcing to date with the value due to CO2 alone and then extrapolates that difference to come up with a meaningless ‘total anthropogenic forcings Del F_2xCO2′. His derivations and discussions of the no-feedback sensitivity and feedbacks is extremely opaque (a much better description is given on the first couple of pages of Hansen et al, 1984)). His discussion of the forcings in that paper are wrong (it’s 4.0 W/m2 for 2xCO2 (p135), not 4.8 W/m2), and the no-feedback temperature change is 1.2 (Hansen et al, 1988, p9360), giving k=0.30 C/(W/m2) (not his incorrect 0.260 C/(W/m2) value). Etc… Needless to say, the multiple errors completely undermine the conclusions regarding climate sensitivity.

Generally speaking, these are the kinds of issues that get spotted by peer-reviewers: are the citations correctly interpreted? is the mathematics correct? is the reasoning sound? do the conclusions follow? etc. In this case, there really wouldn’t have been much left, and so it is fair to conclude that Monckton’s piece only saw the light of day because it wasn’t peer-reviewed, not because it was. Claims that the suggested edits from the editor of the newsletter constitute ‘peer-review’ are belied by the editor’s obvious unfamiliarity with the key concepts of forcing and feedback – and the multitude of basic errors still remaining. The even more egregious claims that this paper provides “Mathematical proof that there is no ‘climate crisis’ ” or is “a major, peer-reviewed paper in Physics and Society, a learned journal of the 10,000-strong American Physical Society” are just bunk (though amusing in their chutzpah).

The rational for the FPS publication of this note was to ‘open up the debate’ on climate change. The obvious ineptitude of this contribution underlines quite effectively how little debate there is on the fundamentals if this is the best counter-argument that can be offered.


536 Responses to “Once more unto the bray”

  1. 501
    David B. Benson says:

    ChuckG (486) — Thank you.

  2. 502
    manacker says:

    Message to Barton Paul Levenson,

    Re ur 494: Duh! Sure there were ice ages. Just like there was a LIA preceded by a MWP.

    Got nothing to do with the validity of Spencer’s physical observations showing a strong negative cloud feedback in today’s climate system.

    [edit - either be constructive, or don't bother]

    Regards,

    Max

    [Response: You are wrong though. If the climate system is so stable, how did it ever go into or come out of an ice age? Feedbacks during the last-interglacial were likely the same as today - so why was it so much more sensitive then? - gavin]

  3. 503
    Rod B says:

    Mark (500), I read Owen’s 442 post 17.5 times (e.g.). I can’t find “irrelevant” anywhere. But thanks anyway for proving my point.

    (…. I just can’t shake this tar-baby….damn… like a bad recurring dream…)

  4. 504
    Rod B says:

    Hank (498), you post seems interesting, but it’s a bit to cryptic for me. What are you asking or saying?

  5. 505
    Hank Roberts says:

    Hm. Spencer says Held reviewed his article.

    Held is publishing a method he says will:

    “… enable a climate feedback to be decomposed into two factors – one that depends on the radiative transfer algorithm and the unperturbed climate state and a second that arises from the climate response of the feedback variables. This factorization isolates the components of the feedback which are intrinsic to the
    radiative physics from those which arise from a particular pattern of climate response….The separation of the radiative and climate response components of the feedbacks enables a better understanding of the underlying physical processes which give rise to the feedbacks. This is readily apparent for water vapor and temperature feedbacks, whose vertical response patterns are tightly coupled …”
    http://www.gfdl.noaa.gov/~ih/papers/kernel_final.pdf

    Spencer says his article describes two methods (excerpt taken from the wattsupwithat blog description, which cites to Spencer’s speech) here: http://epw.senate.gov/public/index.cfm?FuseAction=Files.View&FileStore_id=e12b56cb-4c7b-4c21-bd4a-7afbc4ee72f3

    “… The first method separates the true signature of feedback, wherein radiative flux variations are highly correlated to the temperature changes which cause them, from internally-generated radiative forcings, which are uncorrelated to the temperature variations which result from them….

    Similar descriptions. No idea if the actual methods are similar. Held’s paper is at the link given. Spencer’s is just mentioned as soon to be published.

  6. 506
    Chris Colose says:

    Gavin’s last response to manacker raises an interesting question. It is not exactly intuitive to me that climate sensitivity should be the same given different boundary conditions. For example, once ice is gone, the ice-albedo feedback is zero if you turn up the temperature even further. I’d see no reason the ice-albedo feedback should be the same going from the LGM to the Holocene as it is going from Holocene into the future, given the same radiative forcing. Same with clouds.

    This is not an argument to support a low sensitivity of course!! Given the fact that paleo-hothouses were probably warmer than they would be with just the best estimates of CO2 rise and a 0.75 K/W/m**2 sensitivity one could argue the opposite– some other things going on probably. Using the 20th century as a tool for assessing climate sensitivity is hard due to the uncertainty in aerosols, and the fact we’re looking at transient effects and not equilibrium ones. The LGM is very useful, but has little resemblance to the Holocene.

    [Response: Let me rephrase your concern. Is climate sensitivity for negative forcing (i.e. a cooling) the same as the sensitivity to a positive forcing? Now for small enough changes, the answer will be yes (since you can always linearise), but what is small enough? Obvious as well is that this will break down at some point (on the way to Snowball Earth or Venus). As far as we can tell, the LGM fits with our notions of climate sensitivity for today's climate, but there is some evidence that things change as it gets warmer - some very long GCM runs have a long term effective sensitivity larger than they started with (i.e. as it warms the sensitivity increases). But there is no obvious evidence that sensitivity to the LGM is very different from current climate. There are some subtleties - the efficacies of the LGM forcings (ice sheets, dust as well as GHGs) might well be different from CO2, and that could make a small difference. - gavin]

  7. 507
    Mark says:

    Rod B #503.

    I see you still have problems with maths.

    You can’t read something 17.5 times. 17 times and halfway through again before giving up, yes. 17.5 no.

    I’ve rolled a dice. It got 5. This his higher than the average dice roll on a d6, so this dice is loaded.

    Is this accurate?

    Well, average for a d6 is 3.5, this is 5, so since we know 5!=3.5 this is true.

    However, the statement is not innacurate.

    And you know this in your question because from your post in #386

    ‘it’s meaningless’, or ‘it’s statistically insignificant or misleading’. I knows dat;

    insignificant

    i know that

    your words.

  8. 508
    Mark says:

    “However the statement is not inaccurate” => “However the statement is innacurate”

  9. 509
    Owen Phelps says:

    Rod B: “Owen, my question is eminently understandable to anyone who reads with their eyes open.”

    Oh play fair, sir. I’ve not been having a go, and I asked my question in good faith. That response just isn’t helpful, and is practically designed to raise one’s hackles.

    I’ve read and re-read many of your comments and their replies, with a view to becoming better informed. I don’t have a particular axe to grind. With that in mind, you look like you’re asking: “out of curiosity, are we saying that Monckton applied the techniques of linear regression without making a simple calculation error?”. The answer to that appears to be “yes, he managed to not make a simple calculation error”. But the question doesn’t appear to be particularly relevant, as applying a technique without making a calculation error is not particularly useful when you’ve either chosen the wrong technique or the wrong data to use it on. Which is what seems to be the case here.

    So, with no maliciousness intended, or any motive other than to become better informed, I would like to ask explicitly: what other point did your question have, if not simply to satisfy your curiosity? I freely accept I may have missed it, perhaps even by letting other commenters colour my view. If you could set me straight, it would be greatly appreciated.

    Rod B: “Oddly, Jürgen didn’t bat an eye.”

    That’s true. But did you miss his follow up when he was questioned on it?

    Jurgen: “OK, ‘regression coefficient’ – sorry about that. English is not my native language, and while I do work in a scientific field, I don’t use all that much statistics in it and so wasn’t sure of the precise word.”

    He had made essentially the same mistake you had, mixing up informal and formal meanings.

  10. 510
    Owen Phelps says:

    Mark @500: 2) Owen has given cuts of your comments saying you did say it

    I don’t think my comment supports that statement, Mark.

    There’s a difference between:

    a) Rod B said X, and
    b) Rod B said things that imply X.

    I argue that Rod implied X, or at least, left that conclusion easily inferable. But he didn’t actually say X. Granted, that sounds like pedantic hair-splitting — and in informal discussions it probably wouldn’t matter — but since that’s exactly what we’re doing on the whole “trend” thing, it’s incumbent on us to play by the same rules here.

  11. 511
    Rod B says:

    Owen (509), Hooray! That is EXACTLY what I asked. Jürgen, during the storm, gave me the answer with no fuss, muss, or embellishment. As I recall he actually calculated, using the same data, a slightly different linear regression trend line from Monckton (in addition to his refutation of Monckton’s analysis) — I’m not sure what that means and didn’t think it worthwhile to pursue further.

    This entire discourse required four to six posts at best, not the forty-eleven that occurred. I think it was relevant, though not earth shaking. Given that Monckton analysis certainly seemed misleading, and was attacked here as such, I was simply curious if, while maybe wrong in his analysis, he can none-the-less at least do the math correctly. (I’m not very good at it, my degree in Mathematics aside.) It got out of control, IMO, because of a trait shown by many (most? certainly not all) AGW proponents: that is if a person attacks any part of AGW, that person is presumed 100% wrong in every thing he does or says in his life. Somehow, it seems to me, if they agree that the antagonist knows how to tie his shoes, that will somehow dilute their AGW position, and (seems like) they will fight it at all costs and reason, including sinking their teeth like a pit bull into a blind, precise, and exclusionary definition of words.

    But I digress. Your 491 post was fair; you just happened to get in the crossfire of Mark’s and my p**sin’ contest. Sorry.

    This really, really, really ought to conclude it. It’s way over age, and there’s barely any interest anymore.

  12. 512
    Martin Vermeer says:

    But Rod, we only have your best interest at heart! You’re such a lousy judge of character — trusting Singer, Lindzen, GWB — you’re just asking to be suckered again.

    You were obviously fishing for an excuse to trust the good viscount; friends don’t let friends do that.

    So, yes, Monckton can tie his own shoelaces. Probably. Or perhaps Anthony Watts ties them for him.

    Forget I ever spoke.

  13. 513
    dhogaza says:

    It got out of control, IMO, because of a trait shown by many (most? certainly not all) AGW proponents: that is if a person attacks any part of AGW, that person is presumed 100% wrong in every thing he does or says in his life.

    it got out of control because – being as charitable as I can – you misspoke when you asked the question in the first place.

    We answered the question you asked. Not the question you claim that you meant to ask. Responsibility lies in your court. Our sin is to take you at face value, a sin few of us are likely to repeat given your insistence that our doing so is evidence of this unpleasant trait you describe above. Which is bullshit, pure and simple.

  14. 514
    Mark says:

    Roc B #511. Maybe we ought to name you after Ives’ “The unanswered question”.

    Do you disagree that the average throw of a six-sided dice is 3.5?

    So therefore all dice are crooked because NONE OF THEM will throw 3.5.

    You never answered that.

    You never answered Owen’s query either.

    You missed your own quote which I supplied you where you said you knew that it was statistically insignificant and misleading.

    If you take a linear regression, you have one value. The line with the lowest error.

    You want to make “lowest error” equal to “no error”. Therefore, even mathematically speaking, the answer was wrong. Since linear regression is the line with the LEAST error. So the result of a linear regression is something like:

    A gradient of -0.003 +/- 0.04.

    If you ask “does that mean the gradient is negative”, the answer is no. It is nearly as likely the gradient is positive. Therefore the answer to “is the gradient negative” is “no”. There can be no conclusion about the sign of the gradient.

    You, however, didn’t believe that PURELY because you didn’t want to work out your error bars and you want Monkton to be right because he gives the answers you want.

    [edit - this conversation is getting extremely tiresome - please move on]

  15. 515
    Rod B says:

    dhogaza (513), a close overt real-time example from #260:

    “….if the answer is “yes,” it could be put to use in constructing misleading rhetoric. I can easily imagine someone copying a yes response to your question, and pasting it out of context somewhere else, while proclaiming “see?!?….”

    Owen, see what I mean?

    Martin, if you recall, I said the good viscount was misleading, seemed dishonest, and looked goofy. Not to worry much. Though, like your other examples, he does have some good bona fides. But, hmmmm, maybe he really can’t tie his own shoes! Shoots that theory… ;-)

  16. 516
    Ray Ladbury says:

    Rod B. et al., I don’t think that further fileting this horse is particularly profitable. For what it is worth, I do not attribute any ulterior motives to you. I do think that your language was imprecise and that you did not fully appreciate the imprecision of your language or the potential consequences of that imprecision. I think that perhaps you do not appreciate them even now.

    What you meant to ask was whether his numerical result was correct. Perhaps you didn’t understand that when you use terms like “trend” there is a reasoning that goes along with the numerical analysis. Even if you get the right numerical answer for the wrong reasons, you are still wrong.

    What people here need to understand is that you do not share our gloomy assessment of the morals of those committed denialists like Monckton. What you need to understand is that denialists do take quotations out of context–just ask Carl Wunsch. As a result, scientists are rather sensitive to precision in language and are rather reluctant to relaxing that precision even when it would seem to be “irrelevant” to do so.

    The oracle of ReCAPTCHA: resent Quality

  17. 517
    Mark says:

    Owen, #510.

    you’re not a politician, are you?

    Sorry :-)

    However, they do use words like “the right honorable gentleman is in error” rather than actually SAY “you lying little bugger!” and hence get around the rules against calling someone a liar in the houses of parliament.

  18. 518
    kevin says:

    Hey hey hey. That quote from 260 did not illustrate that “that person is presumed 100% wrong in every thing he does or says in his life.” That quote from #260 was about people ripping innocuous things out of context and using them to tell lies. I was pointing out that people in this forum probably wanted to avoid making that type of maneuver easy for those who use such dirty tricks. I was *not* saying that I presumed you or Monckton to be “100% wrong in every thing he does or says in his life.” Not even close.

  19. 519
    kevin says:

    Heh. I don’t think Rod’s a troll, but any troll would be glowing with pride over a thread like this :)

  20. 520
    Rod B says:

    Ray (516), the profitability of this discourse went negative eons ago :-) ! Gavin, with clearly the patience of Job, is himself now putting an end to it.

    I firmly believe my own assessment of the process here, but I would not at all attribute it to “ulterior motives”. None-the-less, I probably should be more restrained in my psychoanalyzing

  21. 521
    Rod B says:

    kevin (518, 519), I knew your example was not perfect; why I fudged a bit by calling it a near example. It wasn’t worth digging out a better example — though they can be found in RC — and dragging out a long post..

    “Glowing with pride” is not exactly my current situation. (In case my irony is missed — not anywhere near it! I’m almost as tired of it as Gavin and all but a couple of posters.)

  22. 522
    dhogaza says:

    I firmly believe my own assessment of the process here…

    And your own assessment of climate science, and of evolutaionary biology …

    Sorry, I don’t have much faith in your own assessment.

  23. 523
    Owen Phelps says:

    Mark @517: Owen, you’re not a politician, are you?

    Ha! No, far from it :-). Since you don’t know how much effort it takes for me to stay civil (I’ve got a quick temper, and I tend to overreact), I’m going to take your comment as an unqualified compliment :-).

  24. 524
    Ike Solem says:

    It helps, when talking about “the” climate sensitivity”, to incude latitudinal and regional (i.e. ocean, coast, or continental interior) information. The climate sensitivity in Alaska, for example, is different from the climate sensitivity in Hawaii. The response to the main forcing (anthropogenic infrared-absorbing gases in the troposphere) is location-dependent. Also, keep in mind that the transient climate response (TCR) is the well defined estimate here.

    The TCR is the expected change in surface temperature at the time CO2 doubles relative to pre-industrial levels, assuming a 1% steady increase per year in CO2 emissions.

    The equilibrium climate sensitivity is highly theoretical, as it does not include carbon-cycle feedback estimates. The equilibrium situation (for 2X CO2) appears to be something similar to the period 3.5+ million years ago, when there were no glacial cycles and sea levels were tens of meters higher than now, but it will take centuries to reach such an equilibrium.

    As far as manacker – whoever that is is just recycling the same tired garbage that was promoted by Douglas et al – their “low climate sensitivity” nonsense that was regurgitated by Monckton, mostly verbatim – direct plagiarism, picked up and repeated by Roger Pielke Sr. and Steve McIntyre. What they do is take one or two pieces of information that are uncertain, focus all their attention on that, ignore everything else, and call it science – which it isn’t.

    You can try to repackage this till you are blue in the face, but the bottom line is that Douglas et al claim that the oceans are not warming, and that the surface temperature increase is the only climate response to the CO2 forcing. Essentially, that’s their argument, which they dress up in a long-winded equation-sprinkled garment. That’s what manacker is recycling, that’s what Monckton is recycling, that’s why Pielke Sr. went hog-wild over the Lyman et al report on cooling of the surface ocean, and so on.

    If Triana, the Deep Space Climate Observatory, has been launched in the 90s, you’d have a decade long-record of the exact Earth energy balance. If there is a difference between energy emitted and energy absorbed, then the Earth as a whole is either cooling or warming. Since the data for surface temperatures are pretty extensive (in the Northern Hemisphere, at least), and the ocean temperature data are pretty limited (especially in the Southern Hemisphere), you can point to the ocean and claim that the uncertainty means there could be a low climate sensitivity.

    The argument is complete B.S., but that doesn’t keep the broken records from repeating themselves endlessly.

    That’s the case with every single “scientific issue” raised on threads by denialists. Let’s see – “CO2 is already saturated with respect to absorption” – refuted in the 1950s, but that didn’t keep fossil fuel PR types from posting hundreds of comments about it.

    The whole episode with Douglass et al is similar to that of Idso et al in the 1980s, Lindzen et al in the 1990s – bad science promoted by public relations firms in order to influence public opinion and government policy. This should not really surprise anyone – look how much time and money the tobacco industry spent on fighting the link between cancer and smoking – and fossil fuels are a much bigger industry than tobacco products are. There are many examples – S. Fred Singer is a “scientist” who worked for both the tobacco and fossil fuel PR industry, and there are many like him.

  25. 525
    Hank Roberts says:

    > The TCR is the expected change in surface temperature
    > at the time CO2 doubles relative to pre-industrial
    > levels, assuming

    _at__the_time_? No committed warming included at all in the TCR?

    ______________
    ReCaptcha: “Binge department”

    [Response: Well there is committed warming (which is why TCR is less than the equilibrium sensitivity). But TCR is just the realised warming at a specific time. It's slightly less uncertain in the models than the full equilibrium value - not least because most of the coupled models have not been run out to full equilibrium. - gavin]

  26. 526
    William Astley says:

    In reply to:

    “[Response: Thanks for helping complicate a very simple issue! Stratospheric cooling is predicted from increasing CO2 (and was so predicted decades ago), this is the opposite behaviour than with solar forcing. It’s basic radiative physics - and while there is a lot of interesting research on dynamical couplings between the stratosphere and troposphere, the radiative effects are completely uncontroversial. (And, in case you hadn’t noticed, the stratosphere is indeed cooling)"

    Stratospheric cooling is the opposite behaviour that would be expected from an increase in TSI (Solar forcing.) - Yes. I agree, however:

    Stratospheric cooling is what would be expected if there was a reduction in planetary cloud cover in response to solar initiated electroscavenging which removes cloud forming ions. (Electroscavenging is the name for a process where sharp changes in the solar flux at the earth, creates space charge in the ionosphere which is hypothesized to remove cloud forming ions.)

    Based on the data and research I have seen, the two mechanisms by which solar magnetic cycle changes are hypothesized to modulate planetary cloud cover are still valid.

    Comment:
    TSI has very recently been dropping, it is assumed due the recent slow down in the solar magnetic cycle. There are still sharp increases in the solar wind, however, so the temperature effect on the earth of a reduction in the TSI is mitigated by hypothesized electroscavenging effect.

    [Response: And there I was thinking that the GCR-climate hypothesis was the least supported idea out there.... Might you have even one study that supports any one of these ideas? - gavin]

  27. 527
    David Rogers says:

    This is a climate change question unrelated to recent posts.

    Some of the cold water in the Arctic sinks and flows Southward into the Atlantic, and is replaced by warmer surface water. The Gulf stream helps to warm the Northward-flowing surface water.

    I have come across the hypothesis that if the Arctic warms enough to prevent or significantly reduce the sinking of cold water, the result could be that the Gulf Stream would be stopped.

    Are there numbers to support this hypothesis? Surely the Gulf stream is driven primarily by the rotation of the Earth (the Coriolis effect, which causes the overall clockwise circulation of the North Atlantic)? My intuition is that the circulation of water to and from the Arctic fits into the Coriolis-driven circulation rather than driving or even significantly enhancing it.

  28. 528
    Hank Roberts says:

    David, where did you come across that hypothesis?
    Pointer to your source would help answer your question.
    The first link under Science (right side of page) is to a history of the research; you’ll find the early models of circulation (literally physical models — rotating spheres with fluid) correspond to your intuition.

    The “Start Here” link at the top of the page is a good place to begin.
    That will lead you in a few clicks to this FAQ that should help.

    http://ipcc-wg1.ucar.edu/wg1/FAQ/wg1_faq-10.2.html

    The Gulf Stream is only part of the process, described more in the FAQ.
    From that you can pull search terms like this to look for research.

    Just as an example:

    http://scholar.google.com/scholar?num=50&hl=en&lr=&newwindow=1&safe=off&scoring=r&q=meridional+overturning+circulation+&as_ylo=2005

    Vary the starting year; note which papers have been often cited by subsequent papers.

    You can follow the development of the ideas. You’ll find good summary papers in the recent years.

    I’m an amateur reader here; I try to give pointers as I’m the kind of person who reads the fine manual, the readme file, and the FAQs and that’s the extent of the help I can offer. Better answers will follow from people who really know something.

    Oh, using the Search box at the top of each page here will also turn up many previous threads appropriate to your question.

  29. 529

    In reply to: #98 [Response: "… The paleo-climate picture is a terrible cartoon of what happened. You are much better off with the more up-to-date fig 6.1 in AR4 (p441)… "

    Hardly "much" better off: it's only three years. AR4's cut-off date for new papers was the end of 2005; Geocraft's CO2 reference is 2001; temperature is 2002—not too shabby. IPCC reference Royer, 2006, for CO2 data references. I wish I could see his paper (I can't locate it online), but Dana Royer was analysing previous data, they weren't brand new; was there some revelation in those three years? IPCC reference even earlier papers for the temperature data: 1991 and '92. Geocraft's are more recent than that.

    Anyway, the Geocraft graph compared atmospheric CO2 with "average global temperature"; in other words, air temperature. Figure 6.1 in AR4 compares atmospheric CO2 with deep ocean temperature—and shows, to my eye, a fairly good correlation.

    But atmospheric and deep ocean temperatures are not at first sight comparable, the one changing hourly, the other on centennial or longer scales and there's no fast thermal path between them, that's for sure. How would the atmosphere heat the ocean more than the sun? Why do you say Steve would be "much better off" looking at deep ocean temperatures? After all, the discussion concerns the effect of CO2 on atmospheric temperature at decadal scales or less. If CO2 affects the deep ocean, surely it is with some enormous lag, which is probably invisible in Figure 6.1, since the time resolution is only ±1 Myr. What would be the mechanism? How do deep ocean temps help our understanding of the AGW theory/process?

    AR4 does mention atmospheric temperature reconstructions without reservation, but are the proxies in fact doubtful, or at least less certain than the deep ocean reconstructions? Is that why you reference no graph of ancient atmospheric temperature? Or is there another reason?

    Cheers,
    Richard Treadgold,
    Convenor,
    Climate Conversation Group.

    [Response: There are no clean proxies for global surface air temperature over these timescales. But the fact that it is impossible to say where that reconstruction came from or what information was used should immediately raise your suspicions that it is either based on some heuristic qualitative feelings or that instead it is using an implicit connection between ocean temperatures and surface air temperature instead. Either way, the connection to reality is tenuous. IPCC did a much better job of tracking these factors back in time - with the attendant uncertainties and with actual references (!) - why bother trying to defend some hand-drawn graph which obviously doesn't have either? - gavin]

  30. 530

    why bother trying to defend some hand-drawn graph which obviously doesn’t have either [uncertainties or references]?

    Defend?! That was unexpected—you are certainly mistaken. Actually, you recommended to Steve more recent data and I questioned your reference to the AR4, since that isn’t much more recent. I defended nothing.

    But the fact that it is impossible to say where that reconstruction came from or what information was used should immediately raise your suspicions that it is either based on some heuristic qualitative feelings or that instead it is using an implicit connection between ocean temperatures and surface air temperature instead.

    What?! The graph doesn’t show ocean temperature, it shows atmospheric CO2 levels and air temperature! Still, I agree with you on the lack of uncertainty and references. Hence my interest in your response to Steve. I wanted to know what best to replace it with.

    IPCC did a much better job of tracking these factors back in time—with the attendant uncertainties and with actual references

    No, they did not—not here, anyway. That is to say, they might have done a good job, but not on surface air temperatures; these are deep ocean temperatures. I’m surprised to be pointing this out—it’s your reference.

    Indeed, how could they track air temperatures, since you say “there are no clean proxies for global surface air temperatures over these timescales?”

    I’m interested to know, as my questions reflect, about the correlation between CO2 and deep ocean temperatures (not, surprisingly, air temps) and what that might tell us about AGW.

    Gavin, you’ve mistaken me on one trivial point, misread the two graphs we are discussing and neither answered any of my questions nor responded to any substantive remarks. Would you care to start again? I still want to know why you made that reply to Steve and how on earth deep ocean temperatures respond to CO2—apparently.

    Cheers,
    Richard.

  31. 531
    Marcus says:

    Richard:

    1: “not too shabby” was what you said about Geocraft’s references. And you seemed to be trying to claim that AR4 Figure 6.1 was “hardly ‘much’ better” than the Geocraft hand-drawn figure. That sounds like defending the Geocraft hand-drawn figure to me.

    2: Gavin stated that either a) Geocraft was hand drawing their figures based on qualitative feelings, or b) that they were using an implicit ocean-air temp connection. That “b” option does not state that the Geocraft figure is using ocean temperatures, it is stating that, assuming charitably that their temperatures are not just pulled out of their rears, that they are assuming global temperatures are correlated with something we have proxies for, such as ocean temperatures.

    3: Since there are no good air surface temp proxies on the time scales of the graphs, therefore ocean temps are the best way to track global temperatures on the million year scale. So, therefore yes, the IPCC did do a much better job.

    Other notes: on a decadal timescale, it is possible for ocean and air surface temps to diverge, but on a several thousand year time scale the ocean _does_ mix, and therefore the energy imbalance at the top of the atmosphere does propagate through the system, and therefore ocean temps _do_ give you some idea of what is happening with surface temperatures. (also, given that the original post is citing a Geocraft figure showing a 600 million year timescale, why do you claim that the discussion is about “decadal time scales”?)

    And, unlike Gavin, you do indeed misread graphs, as well as responses: the IPCC references the 1991 and 1992 papers about ice volume. The temperature references are the 2001 to 2004 papers. And AR4 references to atmospheric temperature reconstructions are likely for the past 600,000 years, not the past tens of millions.

    Would you care to start again?

    [Response: Let's slow down a bit. I went back to the Scotese site to see if I could find a real reference for the temperature curve. I couldn't (but maybe someone else can have a look). However, it does appear that he is trying to reconstruct temperatures on a qualitative basis (using the kinds of soils and rocks and whether glacial ice is present) rather than any quantitative geochemical proxy. This means that any curve he draws (by hand) is fundamentally schematic and of very poor resolution - basically one or two data points per geologic era. It is wholly inadequate therefore for trying to quantify CO2/temperature relationships (as in the geocraft picture). The results highlighted in the IPCC report are completely different - they are based on geochemical proxies (chiefly oxygen isotope ratios in deep ocean carbonate) which have known relationships to both temperature and global ice volume, have much higher resolution and can detect events like the PETM which you will note is absent on the Scotese curve. Now the PETM has been known about since the early 1990s, and it's absence on a curve that Richard claims is up-to-date is a little troubling, no? - gavin]

  32. 532
    Hank Roberts says:

    > Scotese site
    I tried email to the info contact address there, pointing to this thread
    –after recent discussion of the general idea, addressed here: http://tamino.wordpress.com/2008/09/17/open-thread-6/#comment-22617

  33. 533

    In reply to #531:

    1. Three years is little better, but it wasn’t about more recent data. Gavin wanted to recommend a different graph; he just gave the wrong reason. His main point was what he called the “terrible cartoon”. I was nit-picking. Let it go.

    2. Ah, now I understand, thank you. However, “their temperatures are not just pulled out of their rears” is disgusting. ‘Not just invented’ would have been sufficient. Wash your filthy mouth out.

    3. I agree.

    why do you claim that the discussion is about “decadal time scales”? Because the main thread, commenting on Lord Monckton’s work, concerns AGW in this day and age.

    Yes, I misread the references to ice volume as temperature; thank you for pointing that out.

    Gavin:

    Your suggestions about the source of the Scotese data are far better informed than mine could be; still, without a reference we’re just guessing. If the graph was drawn by hand, it wouldn’t be the first time a good scientist did that. You point out the absence of the PETM; that invites suspicion. But thanks for trying; let’s hope there’s a response to the email from Hank (and well done, him).

    You say the data in the AR4 “have much higher resolution”. Yet it’s only ±1 My; is the resolution better elsewhere? I’m wondering how such coarse resolution can help us understand AGW. At least, in time for it to matter; otherwise we’re waiting generations for equilibrium—hardly a practical course.

    The Geocraft graph was presented by Steve to show lack of correlation between CO2 and temperature over a long time scale. You discount that graph because it lacks references (though it might yet contain goodness?) and prefer to replace it with the IPCC effort.

    Now we have a longer period and a larger temporal granularity and by equilibrium, correlation might be evident. It’s difficult to tell, since I wonder how to read those huge ranges of CO2. But all hint of causation is surely lost. Now the question is: what causes atmospheric temperature to change? I have in mind that temperature, rising, can cause outgassing of oceanic CO2. Yet CO2 can cause temp to rise, and there are other influences on temperature. Figure 6.1 doesn’t seem to help us with this. So, what’s the evidence?

    Cheers,
    Richard.

  34. 534

    Hmmm, a week now without response. Are you all on holiday? Was it something I said?

  35. 535
    Ray Ladbury says:

    Richard Treadgold,
    Ever heard of physics?

  36. 536

    Ah, sorry, what’s your point?


Switch to our mobile site