There’s virtue in reading the Comments

Judith Curry’s Climate etc website gets my top billing, as I’ve said before, and one of its great virtues lies in the Comments section that follows the essay. The reason is that the Comments section is a live and continuing debate, not just on the supposed topic of the day, but on aspects of it, or on something that comes in almost by accident, strikes a chord, and becomes itself a new argument.

As with all websites, hers has a retinue of regulars, plus some of the big names in climate science who drop in from time to time to disagree with the hostess or one of the commenters. Yes, there is a fair bit of name-calling, but you can scroll past that and watch for the real learning. And there are hundreds of comments, so reading them all requires dedication and time. Before I established my own website I wrote a few essays for her, and one of them attracted more than 700  comments. I’d love to say they were all complimentary. It wasn’t so.

I was prompted to write this essay because of a post of hers that I noted with a nod and at first let go. It was about the recruitment of a top Swedish climate scientist, Lennart Bengtsson, to the Academic Advisory Council of the Global Warming Policy Foundation in London. I passed the comments by, but a few days later, about to dismiss the post from my system, I had a quick look at them, which lasted for a couple of hours. It was well worth the time.

At one point the disputation began to centre around what was a theory. Was AGW a theory, a real theory, or just a hypothesis? How was a hypothesis different from a theory? Do all theories have to be tested against a body of observations? If so, what about the theory of evolution? I began wrestling with that stuff when I was an honours undergraduate student, and it was more or less familiar territory. Then out of the blue came the following crisp summary of the situation by Matthew R. Marler, a statistician. This is what he wrote.

There is a prima facie case, very simple, that human CO2 might warm the Earth. It has been presented many places, but for now I shall reference a relatively readable book: “Atmosphere, Clouds, and Climate” by David Randall, pp 45-49. Basically, an increase in atmospheric CO2 should lead to an increase in the absorption of upward long-wave infrared radiation from the Earth surface, so there could somewhere be an increase in heat accumulated in the Earth climate system, other things being equal. Whether you call that a hypothesis or a theory does not matter very much, and those words do not have exact enough definitions, but it certainly is at least a hypothesis.

However, there is almost no “body of evidence” that the accumulation of human-sourced CO2 is actually having any such effect. That the Earth has warmed since the end of the Little Ice Age has at least two different explanations, one of which says all of the increase is independent of human-sourced CO2, and the IPCC version which says that the increase up to 1945 or so is independent of human-sourced CO2. At least one theory says that the most prominent effect of the heat accumulation ought to be in the upper troposphere, but that effect has not been found in the most relevant (satellite) records of troposphere temperature.

At least one theory specifies “polar amplification”, a stronger warming at the poles than at the Equator and in mid-latitudes; if that is happening, it is only in the Arctic region not the Antarctic region. The computational models, known as GCMs (for global circulation models, or general climate models), incorporate a great deal of known physics over small regions, but their model runs produce modeled temperature increases greater than what has been observed since they were run, and miss the recent near 17-year “pause” aka the “hiatus” in surface and troposphere warming that has been observed. And so on: addressing the predictions of the diverse AGW theories point-by-point one finds little to no evidence that they have made any accurate predictions, where their predictions can even be calculated.

There it is, in a very few hundred words. Why couldn’t I have written that myself? Well, I didn’t, and Matthew Marler did. He is one of those whose comments I always read, in part because he is a statistician, and climate science is pretty weak when it comes to statistics. There are others there whose comments are also worth reading, and there are some whose very name causes me to scroll quickly by: I have read enough to know that they are there to be difficult, to hi-jack the post, to stop the flow of useful debate.

Yes, I know that is a value judgment, but you have to make them all the time, especially when you are reading the Comments sections!


Join the discussion 48 Comments

  • Judith Curry says:

    Hi Don, just checking in to make sure you are reading the comments 🙂

  • David says:

    “… and climate science is pretty weak when it comes to statistics.”

    Really? Statements like this would be a lot more compelling if you displayed some real statistical expertise. However, you tend to carefully avoid any technical discussion of
    statistical methods or analysis of climate data. I am not convinced that your personal knowledge of statistics and statistical methods qualifies you to make assertions like this.

    • GenghisCunn says:

      David, if you had been following the debate closely over several years, you would be well aware of many sound critiques of the statistics capacity of the leading climate scientists. Steve McIntyre first drew attention to this about 15 years ago. Former ABS head Ian Castles and former OECD Chief Economist demolished the basis of the IPCC’s scenario projections around 2001. The Climategate e-mails show the sloppiness of procedures used, and include serious concerns expressed by the poor non-climate scientists who had to try to make sense of the data. Etc, etc, time and again leading climate scientists who do not have a statistical background and have not liaised with professional statisticians have been found wanting.

      Don doesn’t run a technical blog. Go to, e.g,. Climate Audit and Climate Etc, and links from those sites, if you want a more technical appraisal.

      • David says:

        It would be one thing to argue that the “interpretation” of the statistics is weak; it is quite another thing all together to claim that the statistics per se are weak. Perhaps if Don had authored a couple of textbooks on statistics, then I might take notice.

        If Don is relying on their expertise, as opposed to his own quite limited knowledge of the statistics, then he should make that clear. As it is I am quite within my rights to ask him to provide some evidence for his claim.

        Sighting just three critiques of climate science HARDLY justifies the sweeping claim that “climate science is pretty weak when it comes to statistics.”


        And if you had read the literature as closely as you purport to,
        you will see that Ian Castles’s main criticism of the IPCC are with the interpretation of the economic data rather the climate science!

        Exhibit A:

        Castles and Henderson (2003) publish a critique of IPCC’s Special Report on Emissions Scenarios (SRES), in Energy and Environment called “The IPCC emission scenarios: An economic-statistical critique”

        In their abstract they argue

        “… they convert national GDP data to a common measure using market exchange rates.

        And conclude

        “More broadly, the IPCC should try to ensure a more balanced, informed and professional treatment of the economic and
        statistical aspects of its work. In particular, there should be a greater involvement of economic ministries and statistical agencies.”

        Link here

        So the focus is on the economic interpretation rather than the climate science. Nothing they wrote remotely supports the claim that “climate science is pretty weak it comes to statistics.”

        Exhibit B:

        In “IPCC Issues: A Swag of Documents” Castle and Henderson again focus their criticism on the economic analysis of the data

        “These focus on the main single ground of our criticism—namely, the use in the SRES of nominal exchange rates, rather than
        purchasing power parity rates, for expressing the GDP of different countries in a common unit of measurement.”

        Again your argument does not hold water, I’m afraid.

        • Don Aitkin says:


          I know yours is a reply to Genghis Cunn, but I re-enter to say that I have a post in preparation on Ian Castles, in celebration of his work both as Statistician and as ‘climate sceptic’. And I’ll make it clear in future if I am relying on the work of others.

          • David says:


            I look forward to it.


          • John Morland says:


            From your postings on this blog, it appears from your perspective its going to be 22 years and 3 months years of doomsayer CAGW (40 years last pause (1900-1940) minus 17 years 9 months current pause) outlook, before we (perhaps) know one one way or the other. Whereas the climate rationalists who have a more positive view (you may think deluded) can enjoy our remaining limited life (or 22 year 3 months) free from this green CAGW guilt madness.

            (This reminds of the medieval ages catholic church, how they held their power over the various countries (kingdoms) throughout Europe – through guilt)

            There are more and more scientists coming out of the woodwork who publicly annoucetheir are skepticm about the IPCC’s CAGW position. You may consider this irrelevant and I would agree. However, I have said before, and say it again, in REAL science skepticism is what its all about – it is essential for scientific progress and never ever advocate “the science is settled”. Any science discipline advocating this position merely confirms their precarious position.

          • David says:


            I do not see myself as a CAGW “doomsayer”. I do however believe that the benefits of a response to AGW outweigh the costs.

            I would suggest to you that your retreat from referring to human induced global warming as AGW to CAGW, suggests that you are slowly relenting on this issue.

          • Don Aitkin says:

            But what are the benefits of such a response? All the arithmetic suggests that nothing we do will have much effect on global temperature — Flannery said we wouldn’t notice a difference for a thousand years. What is this great benefit you see in the carbon tax and the other measures that have been put in place?

          • David says:

            If you are going too quote someone you should put a link so we can get a sense of (I) the accuracy and (b) the context of the quote.

          • Don Aitkin says:

            Where were you in 2011? This is one of the best reported Flannerisms, and I’ll give it more or less in full. Flannery is talking to Andrew Bolt on his morning radio program on March 25th, 2011:

            Bolt: ‘On our own, by cutting our emissions, because it’s a heavy price to pay, by 5 per cent by 2020, what will the world’s temperatures fall by as a consequence?

            Flannery: Look, it will be a very, very small increment.

            Bolt: Have you got a number? I mean, there must be some numbers.

            Flannery: I just need to clarfy in terms of the climate context for you. If we cut emissions today, global temperatures are not likely to drop for about a thousand years.

            Bolt: Right, but I just want to get to this very basic fact, because I’m finding it really curious that no one has got (this) fact. If I buy a car … I want to know how much it costs and whether it is going to do the job.

            Flannery: Sure.

            Bolt: In this case I want to know the cost of cutting our emissions by 5 per cent by 2020 and will it do the job: how much will the world’s temperatures fall by if Australia cuts its emissions by this much.

            Flannery: Look, as I said it will be a very, very small increment.

            Bolt: Can you give us a rough figure? A rough figure.

            Flannery: Sorry, I can’t because it’s a very complex system and we’re dealing with probabilities here.

            Bolt: …I’m just trying to get the facts in front of the public so we know what we’re doing. Just unbiased. Is it about, I don’t know, are you talking about a thousandth of a degree? A hundredth of a degree? What sort of rough figure?

            Flannery: Just let me finish and say this. If the world as a whole cut all emissions tomorrow the average temperature of the planet is not going to drop in several hundred years, perhaps as much as a thousand years because the system is overburdened with CO2 that has to be absorbed and that only happens slowly.

            If you want to see the rest of it for context, or see whether or not i reported it accurately, you look it up! It’s not that hard.

          • David says:

            Don thank you for the link.

            1. It never occurred to me to read Andrew Bolt.

            2. Flannery may be correct when he says it may take
            1000 to restore CO2 to current levels. But it does not follow that no action should be taken. The relevant benefit of any intervention will be the difference between the actual temperature, and counterfactual, (i.e. if no intervention had
            taken place). NOT the difference between today’s temperature and the realised temperature in the future. That is just a cost!

            I’m not sure where you spent 2011, but you might recall that the often stated aims of these interventions (ETS, tax, direct
            action, etc) is to LIMIT the global temperature rise to only 2 degrees.

          • Don Aitkin says:

            I don’t read Andrew Bolt, but you wanted the link. Yes, I understand the point you are making, but neither Flannery nor anyone else has been able to give a clear statement of what the counterfactual would produce, for the same reason: there is just so much uncertainty about just about everything.

            Even the radiative transfer physics statement that a doubling of carbon dioxide would produce an increase of around 1.1 degrees C, comes with ‘other things being equal’. As we know, other things are not equal, especially in climate.

          • David says:

            “ALL the arithmetic suggests that nothing we do will have much effect on global temperature”
            Your are funny Don. Never let it be said that you past up an opportunity to make a sweeping statement. 🙂
            John chose to characterise my position on AGW as a “doomsayer”. I simply make the point that not everyone who believes some action AGW should be undertaken is necessarily predicting doom.
            I know taking a position of moderation on an issue is an anathema to the way you like to run this blog but there is such a thing as a middle ground.

    • Don Aitkin says:


      I’m surprised that you think so. I have commented on the statistics of climate science on many occasions. I am not a trained statistician, but my major work in political science, Stability and Change in Australian Politics, is based on a wide understanding and employment of statistical methods — and that was in the 1960s and 1970s. And as Genghis Cunn says elsewhere, that climate science is really weak at statistics is common ground. The IAC said so, and so did Wegman, not to mention Steve McIntyre et al.

      Perhaps I’ll do a dissection of something one day just for you, so you can find the weaknesses in it.

      • David says:


        You are the artful dodger, when it comes to this issue.

        “And as Genghis Cunn says elsewhere, that climate science is really weak at statistics is common ground. The IAC said so, and so did Wegman, not to mention Steve McIntyre et al.”

        Where do the IAC say that? IN this executive summary of a report they published on IPCC in 2010.

        The word “statistics” in not mentioned once, much less any broad criticism of the statistical methods employed within climate science. If you search on the term “statistics” it does not appear once. They mainly seem to focus on institutional processes within the IPCC.

        And as for Genghis Cunn, please read my comments comments below.

        • Don Aitkin says:


          I was astonished by your remark, and worried about my memory, but having gone back to the IAC Report, suggest you read Chapter Three in its entirety. Not only does the report politely discredit the whole notion of expert judgment being couched as though it represented real probabilities, it made formal recommendations about the need to improve the IPCC’s treatment of risk and uncertainty… ‘The IPCC uncertainty guidance provides a good starting point for characterizing uncertainty in the assessment reports. However, the guidance was not consistently followed in the fourth assessment, leading to unnecessary errors. For example, authors reported high confidence in statements for which there is little evidence, such as the widely quoted statement that agricultural yields in Africa might decline by up to 50 percent by 2020. Moreover, the guidance was often applied to statements that are so vague they cannot be disputed.’ And so on.

          Did the IPCC take any notice? I can’t find evidence that it did. Probability, risk and uncertainty are all core elements in statistics.

          • David says:

            Thanks Don

            I will have a read

          • David says:


            I have now had a chance to read Chapter 3. It is hardly a damming criticism of the Climate Science. The AR4 is simply one 5 year old summary of the Climate Science. The nub of the IAC’s complaint is that the AR4 report does not communicate risk and uncertainty as well as it could
            have. These may be valid criticisms, but they hardly support your claim that the Climate Science is weak on statistics. The fact that these criticism did not make it to the executive summary should tell you something about their gravity.

            Go to Chapter 9 in IPCC report version 5. The reference list extends for 25 pages, 50 per page, 1250 in total. That reference list would choke a stray dog. Your statement implies that a significant proportion of the statistical analysis presented in these articles is weak. For me to
            accept your statement I would need to see a systematic review of say 10 % of these articles demonstrating serious flaw in the statistical analysis of approximately 15% to 30% of the of the published articles.


          • Don Aitkin says:


            We will have to agree to disagree. The whole IAC report is polite, and I regard Ch 3 as highly critical, since uncertainty itself is the nub of the problem with AGW. You don’t. So be it.

            I don’t have the time to do what you propose, nor do I think it is necessary. It doesn’t matter how many peer-reviewed article the IPCC report offers. The question is, are the methods used to deal with uncertainty adequate? I don’t think they are. The temperature data are so rubbery that it is hard to take them seriously as real measurements, and yet the whole AGW issue is based on them.

            Perhaps I should ask you why, given the problems with them, you think they are fine. Richard Muller’s BEST data are better than the what we had before, but there is nothing like a representative global sample to work from, and the SST data are awful. But you think they are valid. Why?

        • Peter Kemmis says:


          It seems that you and I draw conclusions on different bases. When examining some disputed issue in a field wherein I have received no special training and can claim no expertise, I consider the information and arguments presented by each side (and there may be more than two sides). I don’t find I need to have special expertise in that area in order to evaluate that information and the associated arguments, for I assess the validity and comprehensiveness of the data, and review the logic and reasonableness of the arguments. I suggest to you that many people draw conclusions in the same way. For my part, I would otherwise never be able to form an opinion of my own; I would always have to rely on some authority.

          This doesn’t mean that I never accept authorities. As do we all, I rely greatly on them: as an example, for my survival I rely on others to ensure that the plane I am boarding won’t crash. For matters that are not in dispute, I’ll generally accept the position of the authority concerned.

          Your objection to Don’s assessment of the quality of the statistics associated with the currently orthodox position on climate science, appears to be based on the fact that he’s not a statistician. Well, if you are not prepared to assess the analyses of statisticians sceptical of the orthodox position and of IPCC reports (some references have been suggested by GhengisCunn and others), would you care to offer your grounds for thinking that the statistical work is of good quality, other than by appealing to authority?

          • David says:


            As I have stated I don’t object to Don or anyone else arguing that the climate models need to consider other factors or arguing on how the statistics are to be interpreted but I do draw the line at blanket assertions that one side of the argument is “weak on the statistics”

            In this case GhengisCunn’s references do not support his arguments (see my responses). But I do appreciate his contributions to this blog.

            As have mentioned before I am impressed with Professor Muller’s statistical analysis because of the large sample size.

        • DaveW says:

          Hi David – Here’s an easy and entertaining introduction into the mathematical/statistical problems with climate models:

          • David says:

            Thank yuo

            I went for 10 minutes but then lost interest. I will try again later to night.

          • DaveW says:

            Really David, if you are going to criticize others for their comments on statistics you can’t just nod off when someone goes into a detailed summary of the problems. Are you really interested in climate science or just a bloviator?

          • David says:

            Geeze, its a 52 minute presentation. But as promised I will give it a look. I hope its worthwhile 🙂

          • David says:


            Thanks, interesting presentation by Dr Don Easterbrook.

            There is no discussion about statistical methods, as such. But that’s fine. He argues that climate Science not an empirical problem but a problem of fundamental research. I would have thought there are challenges in both the theory and the evaluation of the empirical evidence.

            He goes on to chat about different aspects of climate

            The term “Greenhouse” is a euphemism for the real underlying processes. Correct

            Modelling fluid dynamics is challenging. I am sure it is.

            The error term is not random. Agree.

            At the 32 minute mark Easterbrook verbals a climate
            scientist that he/she with the claim of having found a “perfect solution”. A humorous anecdote but I doubt its authenticity.

            Prediction outside the sample range can be problematic. Agree a lot.

            An alternative view can be found here.


            Thanks for the clip it was interesting. But nothing in it to lead me to believe that “the climate science is pretty weak when it comes to statistics”.

          • DaveW says:

            Hi David – the video I linked is a talk given by Professor Chris Essex – he’s a Canadian mathematician / physicist / modeller. Don Easterbrook is a US geologist. Essex has worked on climate models and knows what he is talking about. He points out several problems including using the basic equations (some aren’t solved yet), the errors that are introduced when computer approximations to the equations are used, and the lack of reality associated with other aspects of the models. The IPCC has said ‘we will never be able to forecast climate’. He’s not that negative, he just demonstrates that we can’t do it yet and the models are not reliable – they don’t compute. Sounds like ‘pretty weak when it comes to statistics [i.e. collecting and analyzing numbers]’ to me. His other points on the confusion resulting from calling it the ‘greenhouse effect’ or talking about carbon instead of carbon dioxide are bonus, but relevant for understanding why false assumptions lead to wrong conclusions. The anecdote about the Russian seems questionable because who would turn down a million dollar award?

          • David says:


            Yes point taken. I did have Essex confused
            with Easterbrook .

            ‘we will never be able to forecast climate’ (IPCC)

            If you are going to quote someone at least supply a link so we can see the context. I am sure there is some interesting context to this quote. If we understood the future
            perfectly we would not need statistics. Statistics is a way of modelling uncertainty.

            You need to differentiate between the role of a theoretical climatic modeler like Essex with a that of a statistician.
            Essex is arguing that we need more sophisticated models of climate. Fair enough. The statistician will then test Essex’s model by collecting data for all the variables that he suggests might be important. The statistical model will attempt to identify which of those explanatory variables have the strongest ability to explain variation in temperature. Currently CO2 is consistently identified as a
            major cause contributor to climate, hence the AGW concern.

            So if Essex comes up with a new approach to modelling climate, it is going to be evaluated using the same sorts of
            statistical techniques as are currently used to evaluate the contemporary climate models. And who knows he may blow AGW out of the water.

            If you go back to the link you sent me, you will see that Essex argues “that climate Science not an empirical problem but a problem of fundamental research.” In effect what he is saying is it is not the statistical techniques that are the issue but that in his view the climate models do not have the correct explanatory variables. He could be correct.

            But he gives NO evidence to suggest that Climate Science uses retrograde statistical techniques or is “weak at statistics” I am sure for example that someone like Judith Curry, a climate scientist who expresses a somewhat sanguine view on AGW, has an excellent understanding of

            In my view what differentiates Climate Scientists who are believers of AGW from a non-believers of AGW is not their ability to model Risk (aka statistics), but is more a reflection of the way they deal with Uncertainty.

          • DaveW says:

            Hi David,

            As I understand it, statistics as a field is essentially applied mathematics – the study of the acquisition and analysis of data. It isn’t just estimating probablilities or risks, as you seem to mean it. I’m not certain what Don means.

            Essex is a modeller and like other modellers he must study how the data he uses is acquired and analyzed. Otherwise he would just be a computer technician cranking in data and out projections with no thought (a possible explanation for IPCC models).

            As I understand Essex, he has concluded that climate models cannot do what they are asked to do. They can’t hind cast properly and can’t forecast with any reliably because they cannot analyze the data properly due to fundamental flaws that are not overcome by parameterization. This is a pretty big statistical analysis problem: he says climate models are not dealing with the real world, but are down the rabbit hole.

            Another major statistical problem is GIGO – e.g. land temperature statistics. Weather stations were established to measure local weather, not follow changes in climate. A number of statistical analysis techniques have been developed to try to use this data to make claims about average temperatures (or usually deviations from some average period). These are meant to address data collection problems (missing data, changes in location, instrumentation and urban development) and also adjustment and grid analysis problems similar to what Essex talks about. For example, do large grid averages actually have any meaning in the real world or are they only relevant to the computer simulations? The land temperature data base has numerous statistical problems.

            The shonkyest AGW statistics that I know of are the probabilities assigned various IPCC statements. Apparently these are made up out of whole cloth. I’m >90% certain this is true.

          • David says:


            Here is a definition of the American Statistical Association. A statistician can potentially liaise with a wide range of professionals.


            “The best thing about being a statistician is that you get to play in everyone else’s backyard.” (John Tukey, Bell Labs, Princeton University)

            Its not like the good quality statisticians only work with people who are climate skeptics and the poor quality statisticians work with proponents of AGW.

            I’m a 100% certain of that.

          • DaveW says:

            Is that the Tukey after which the correction factor for multiple comparisons was named?

            May be you are right, but I bet statisticians who are natural skeptics do better work on average.

          • David says:

            yes agree!

    • GenghisCunn says:

      David, I’d recommend you read the article by Robert Brown of Duke University at

      Brown concludes: But until the people doing “statistics” on the output of the
      GCMs come to their senses and stop treating each GCM as if it is an independent
      and identically distributed sample drawn from a distribution of perfectly
      written GCM codes plus unknown but unbiased internal errors — which is
      precisely what AR5 does, as is explicitly acknowledged in section 9.2 in precisely
      two paragraphs hidden neatly in the middle that more or less add up to “all of
      the `confidence’ given the estimates listed at the beginning of chapter 9 is
      basically human opinion bullshit, not something that can be backed up by any
      sort of axiomatically correct statistical analysis” — the public will be safely
      protected from any “dangerous” knowledge of the ongoing failure of the GCMs to
      actually predict or hindcast anything at all particularly accurately outside of
      the reference interval.

      • David says:

        It’s a garden variety “group think” argument. To summarise

        A. The climate models well documented.
        B. The science is complex.
        C. He wants a grant.
        D. The models are complex
        E. Climate models contain assumptions
        F. Concludes climate models can’t

        “.. predict or hindcast anything at all particularly accurately outside of the reference interval”

        But offers no evidence to support this claims nor does he define “particularly accurately”.

  • John Morland says:

    Perhaps one of the reasons why the alarmist climate science models are pretty weak when it comes to statistics and accurate predictions is the physical property of CO2 being a very weak “greenhouse gas” (I do not like this term , a more accurate term – a low temperature radiation absorber) together with the still yet unknown alleged positive feedback on atmospheric water vapour concentration and climate sensitivity which is falling as more research is done in this area. Anyway let’s look at CO2.

    The 19th century physicist, John Tyndell discovered the infrared (IR) absorption lines of many common gases. A gas’ IR absorption lines is the gas’ physical
    property that causes the so-called greenhouse effect by absorbing a
    particular IR wavelength, causing the molecule to vibrate a certain way (depending on the IR wavelength absorbed) and either re-emitting that IR wavelength (as “back radiation”) or colliding with another gas molecule hence transferring its vibrational energy into the other molecule’s kinetic energy which could, prima facie, end up as extra heat in the atmosphere.

    John Tyndell noted from all the IR absorbing gases which he experimented on, CO2 was by far the weakest. The strongest IR atmospheric absorbing gas (hence the strongest ‘greenhouse’ gas) he discovered was…water vapour! And there is at least 20 times more water vapour in the atmosphere than the current CO2 concentration.

    I mentioned “low temperature radiation absorber”; how low a temperature? Let’s me describe this from a human (Homo Sapien) perspective..

    Just imagine a 40° C day – hot, sweaty, searing heat from the sun and in your face heat radiating from the ground or pavement, you quickly become thirsty, heat stressed and head for shade and water. If you were lost in the bush/desert without water you would die from dehydration if help did not come soon.

    Then consider a -20° C night, freezing cold deep crisp snow everywhere, every breath of air seems to hamper your lungs, your face feels like its freezing solid, you need thick warm clothing, scarf, beanie, thick gloves, goggles; you look for
    shelter, a hot fire and piping hot soup to warm you up. If you were lost in the snow you would quickly of exposure.

    Think of the difference between these 2 scenarios, it is 60° C difference.
    Then think of another 60°C colder still! What?! Ma ma mia, that’s right …-80° C.

    At that temperature many common gases such as propane, ammonia, chlorine,
    sulphur dioxide have long since liquefied at 1 atmospheric pressure(-42°C, -34°C, -35° C, -10° C) even CO2 has frozenas dry ice (at -79° C). There is only one settlement in the world where it sometimes reaches this frigid temperature; Vostok,
    Antarctica at the height of its winter. If you were lost outside, no matter what clothes you are wearing, you would quickly die and be frozen solid shortly after, it would be impossible to breath normally as the delicate tissue in your lungs would be instantly frozen. The only colder place, where you could stand, near Earth would be on the moon during the lunar night.

    Now the crunch, -80° C is the temperature of CO2’s greenhouse effect “back
    radiation” that allegedly will warm the lower atmosphere to dangerous, even
    catastrophic (even apocalyptic temperatures)! Huh!! CO2’s absorption radiation line is at 15 microns IR wavelength (IR ranges from 0.8 to 100 microns wavelength – visible light is 0.4 to 0.8 microns) equates to the peak IR wavelength emission of a black body radiator (think off a lump of black iron or charcoal) at a temperature of -80° C under Wien’s Displacement Law (this law unifies electromagnetic radiation (light) with temperature). Just Google – Wien’s Displacement Law calculator to confirm this.

    It gets better, a black body radiator at -80C has a broad band IR radiation whereas CO2’s 15 micron emission is relatively narrow band (13.5 to 16.5 microns), therefore it’s energy (or heat) is less – think of a 100-watt incandescent bulb vs. a 20-watt fluorescent bulb – similar visible light output but the incandescent bulb is much hotter to touch because its light emission (hence energy which in this instance we feel as heat) has a broader range.

    It gets even better, the other 2 CO2 absorption lines are 2.8 and 4.2
    microns (which equate to around 720° C and 470° C respectively). These 2 absorption lines partially shade us from those 2 IR wavelengths which are beaming out from the sun – hence a slight cooling effect.

    So does CO2’s cooling effect counter its ever so slight warming effect? Good question! At this stage, I would go along with the prima facie hypothesis i.e. no.

    • dlb says:

      John, your comment has really made me have a think.
      After much consideration I don’t think the wavelength or the theoretical temperature of emission of CO2 is the issue. The thing is CO2 is back radiating a certain number of Watts of energy, far much more than the background of outer space. This will slow down the loss the loss of solar derived heat from the earth’s surface.
      The way I am thinking, may be similar to the following. If you place an electrical resistor connected to a current in a well insulated thermos of water, the resistor may be at a temperature of around 37c but as energy can not escape from the thermos the water will not stop warming when it reaches 37c. The temperature of the water will keep increasing till the water boils.

    • Mike O'Ceirin says:

      Sorry John I object to the statistics comment. My understanding is that statistics is “the practice or science of collecting and analysing numerical data
      in large quantities, especially for the purpose of inferring
      proportions in a whole from those in a representative sample” now that is just the problem. What do you mean by “climate science models”? Wegman presented a convincing argument that the MBH hockey stick is statistically flawed. This reinstated the MWP and the LIA. So is this the sort of model you mean?

      I don’t think statistics is of importance when “in climate research and modeling we should recognize that we are dealing with a coupled non-linear chaotic system, and therefore that long-term prediction of future climate states is not possible”. Anyone care to nominate the source of that quote? GSM’s are a computer representation of a hypothesis which uses CO2 as the evil gas which will by forcing heat the earth to unbearable levels. They do not analyse data, they create it. These virtual models of the earths atmosphere must produce results that reality agrees with. Our planet by refusing to agree with them and raise it’s temperature for the last 17 years has joined the climate skeptics.

  • Don Aitkin says:

    I came across this paragraph from Judith Curry, and felt that it was relevant to the discussion here:

    ‘With regards to climate science, the biggest concern that I have is the insistence on ‘the facts.’ This came up during my recent ‘debate’ with Kevin Trenberth. I argued that there are very few facts in all this, and that most of what passes for facts in the public debate on climate change is: inference from incomplete, inadequate and ambiguous observations; climate models that have been demonstrated not to be useful for most of the applications that they are used for; and theories and hypotheses that are competing with alternative theories and hypotheses.’

    • David says:


      I have just been having a look at an article written by Judith Curry and Webster called “Climate Science and the Uncertainty Monster”.
      I get the sense she is someone you respect with regards to her views on climate change. It’s a very well written and balanced article, in my view. It considers both sides of the debate. And she makes some useful suggestions on how to the IPCC could improve their reporting in the future, without denigrating or belittling them. I can highly recommend it to you.

      • Don Aitkin says:


        Yes, I know the article well, and have been an admirer of Judith’s work and her position since I came across her website shortly after she founded it in 2010. As you might have seen in a recent thread, I have written for her, and she is a friend. If you don’t know her website, it’s in my view the best place to go to learn about the whole issue — and as you imply, especially about uncertainty.

        • David says:

          Thanks Don

        • David says:

          I was going to mention earlier, when you distinguished
          between Risk and Uncertainty, that I thought it was a very useful point for youto make.
          The idea being that Risk can readily be expressed as a mathematical probability while Uncertainty cannot. I think one of the first people to discuss this was Frank Knight in his PhD, He then went on to establish the Chicago
          School of Economics. But the person who I also think makes quite a profound contribution to this field was the US Secretary of Defence Donald Rumsfeld. When asked how the war in Iraq was going he responded with

          “Reports that say there’s — that something hasn’t happened are always interesting to me, because as we know, there are known knowns; there are things that we know that we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns, the ones we don’t know we don’t know.”

          I love this quote. He copped a lot of flak for it, because
          of course if you have a relative in a war zone you just want to be told everything is going to be alright. However, I think it is a really useful guide to approach any problem which involves Risks and Uncertainties. Its the last group, the unknown unknowns, that can be quite problematic and their possible existence should keep us all humble.

  • PeterE says:

    Thanks for drawing attention to this summary; it is cogent and persuasive.

  • Gus says:

    “there is almost no “body of evidence” that the accumulation of human-sourced CO2 is actually having any such effect.”
    I would say, there isn’t even much evidence that it is human-sourced CO2 that is being accumulated. Sure, humans pump CO2 into the atmosphere, but so does the ocean, the soils, rivers, lakes, tropical jungles, volcanoes and so on. How much of this atmospheric CO2 is really human, versus how much is natural? Although various accounts have been cooked to answer this question, the emphasis should be on “cooked” and “accounts.” This is not the same as the actual observation and measurement that can be carried out from space only. The US satellite that was meant to do so blew up at launch in February 2009. Luckily the Japanese GOSAT launch was successful and the mission continues to this day–yielding most surprising and unexpected results. NASA is planning to launch Orbiting Carbon Observatory-2 (OCO-2) in July this year. The idea that a single measurement on Mauna Kea, an active stratovolcano in the middle of warm, tropical ocean, is representative of the atmospheric CO2 level everywhere is preposterous. CO2 concentrations and fluxes vary widely across the globe, from place to place, from day to day, from year to year even.
    Frankly, until we have satellite data that tells us clearly where CO2 comes from and where it goes, over at least a decade or more, statements blaming humanity for CO2 increase in the atmosphere are groundless allegations. The ocean is the most likely culprit, in response to increased solar activity throughout the whole of the 20th century. It is also most likely to re-absorb the CO2 excess and pretty quickly, should solar activity abate for decades to follow. We’ll see. It’s really hard to predict what our sun is going to do.

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