Karl Popper on ‘climate change’

In fact, Karl Popper said nothing at all about ‘climate change’ — what used to be called Anthropogenic Global Warming. The reason is straightforward. He died in 1994, aged 92, before the current fashion of AGW had reached its height. It is easy enough to suppose that he would have said, perhaps, that AGW is there to be falsified, and no one has falsified it yet — well emphatically anyway — so it can be accepted as the ruling theory. I have some sympathy with this approach, but it is I think too glib.

Popper wrote a great deal — 22 books and an unknown number of papers — and he wrote over a wide expanse of human knowledge. In the domain of ‘climate change’ he would be best known for his general perspective on the philosophy of science, in which he proposed that scientific theories could never be proven (proofs are for mathematics) but could be falsified, and that good science occupies itself in trying to falsify hypotheses through observation and experiment. In that way, he said, science advances. He was scathing at what he saw as attempt to postpone such tests, or avoid them, by protecting the original hypothesis. Other philosophers of science, especially Lakatos and Feyerabend, adapted his ideas to their own ends, and Popper’s perspective today is not as dominant in the field as it once was.

Nonetheless, I prefer his simple position about falsifiability to others. I heard him in a seminar in the late 1980s at the ANU, and he was most impressive, but I have not ventured very far into his work. But he is so eminently quotable. Here is a long passage from The Open Society and its Enemies, just an aside really, in a chapter on the sociology of knowledge; but it is so illuminating. I have done some editing, and separated some of the text into numbered paragraphs for the sake of the reader — the original comes in two  long paragraphs. The emphases are in the original.

1. Everyone who has an inkling of the history of the natural sciences is aware of  the passionate tenacity which characterises many of its quarrels. No amount of political partiality can influence political theories more strongly that the partiality shown by some natural scientists in favour of their intellectual offspring. If scientific objectivity were founded… upon the individual scientist’s impartiality or objectivity, we should have to say goodbye to it…

2. [T]here is no doubt that we are all suffering under own own system of prejudices… that we take many things as self-evident, that we accept them uncritically and even with the naive and cocksure belief that criticism is quite unnecessary; and many scientists are no exception to this rule, even though they may have superficially purged themselves from some of their prejudices in their particular field. [But however hard they try] they could not possibly attain to what we call ‘scientific objectivity’. No, what we usually mean by this term rests on different grounds. It is a matter of scientific method.

3. And, ironically enough, objectivity is closely bound up with the social aspect of scientific method, with the fact that science and scientific objectivity do not (and cannot) result from the attempts of an individual scientist to be ‘objective’ but from the co-operation of many scientists. Scientific objectivity can be described as … what I may term the ‘public character of scientific method’… [It has two important aspects.]

4. First, there is something approaching free criticism. A scientist may offer his theory with the full conviction that it is unassailable. But this will not impress his fellow-scientists and competitors; rather, it challenges them: they know that the scientific attitude means criticizing everything… Second, scientists try to avoid talking at cross-purposes… In order to avoid speaking at cross-purposes, scientists try to express their theories in such a form that they can be tested, i.e. refuted (or else corroborated) by such experience.

I find that section of his work clear and unambiguous, and I have encountered examples of his argument in my working life. If I were to summarise it in terms of my paragraphing, I would present it like this.

Paragraph 1 Once we have become committed to our hypothesis it is very difficult for us to accept criticism, even if we try to be objective about it. (If pushed hard we will build defences around our hypothesis — he says that elsewhere.)

Paragraph 2 We all do this sort of thing, and we will keep doing it, no matter how hard we try to be ‘objective’.

Paragraph 3 What saves us, and allows science to progress, is the co-operation of multitudes of scientists in exposing weaknesses in one’s hypothesis through the scientific method.

Paragraph 4 And that method consists of a hypothesis’s being exposed to experimental and/or observational data. If it survives that exposure, it can present as reliable, at least for the moment. If it doesn’t, it is rejected, however beautiful a hypothesis it is.

How does climate science stand up to all this? Not at all well, it would seem to me. The ruling hypothesis is that carbon dioxide is the control knob for the planet’s atmospheric temperature: the more of it, the hotter the atmosphere, and hotter atmospheres must lead to higher sea-levels, and all manner of other evils. Testing the hypothesis is bedevilled by problems of measurement: the globe is a big place, we don’t really know how much carbon dioxide there was in the air three hundred years ago, and we find it hard to agree on temperature measurements now, let alone those from one hundred years ago.

At the very least there are awkward problems with the ruling hypothesis. On the face of it, and accepting for the moment the reliability of temperature measurements over the last century or so, carbon dioxide has been increasing pretty steadily, but temperature has wobbled around, and there doesn’t appear to be a satisfying explanation for that disjunction.  Equilibrium Climate Sensitivity, which is supposed to exist and to multiply the effects of a doubling of CO2 to several degrees of extra warming, has not been found, after thirty years of assertion. The apparent ‘hiatus’ in the present century has been a problem for the hypothesis, for over the past 16 years we do have more or less reliable estimates of both CO2 and temperature. The defenders of the hypothesis have come up with a very large number of explanations, none of which is persuasive, and none of which can be easily tested.

My feeling is that Karl Popper would shake his head at all that, and say that too much effort is going into defending the ruling hypothesis and much too little into testing it properly. Noting that elected governments appear reluctant either to dismiss the hypothesis or to act on its recommendations, he might say that this whole area of science has become highly politicised.

Now I recognise that I might be over-keen to have the ruling hypothesis dismissed, no matter how ‘objective’ I might see myself as. No matter, I am prepared to wait until the hypothesis has been properly tested. I can only add that the longer it takes, the more likely it is that the CO2 control knob theory of climate will be rejected.

Footnote: Those who are interested in reading Popper may find it helpful to be guided by Rafe Champion, a student of the whole Popper oeuvre. You can see his readings and other advice here.

 

Join the discussion 71 Comments

  • Alister McFarquhar says:

    I used to think I was Popperian

    Now I know I am

    appreciate your precis

  • whyisitso says:

    It’s interesting that your newish blog platform doesn’t appear to support hyperlinks or even clickable links.

    • Don Aitkin says:

      Whyisitso:

      I’ve changed the text reference at the end to a link. I agree that the word ‘here’ at the end of the sentence is not as blue as I would like it. But it produced the proper website for me. Let me know if it doesn’t work for you.

  • JimboR says:

    Did you try running those four paragraphs past your own position? Simply state your position as a hypothesis and give it a go. Some possible examples of the skeptics position, stated as a hypothesis might be:

    “The Earth is not warming.”
    “An increase in greenhouse gasses does not lead to more warming.”
    “A warming Earth is good for insert-fav-pastime-here”
    “A warming Earth is good for humanity”

    The better skeptics tend to pick one and argue it. In a belts-and-braces fashion, some skeptics embrace them all. Given they’re not self-conflicting, even that’s a reasonable position to take provided it doesn’t lead to complacency, For example:

    I don’t need to be too rigorous in my testing that the earth isn’t warming because even if it is, I have another hypothesis that claims it’s not caused by greenhouse gasses. And I don’t need to be too rigorous with that one, because even if it is, it’s helping Tasmanian winemakers produce better wine.

    • Don Aitkin says:

      Jimbo, I did examine my own position (I always do). But what you put forward is not a position that any sceptic I know would adopt. A better set might go like this, using your examples but making them more sensible:

      ‘Given the published temperature data, the warming of the planet since 1900 does not appear to be unusual.’

      ‘Increases in warming are unlikely to be due solely to human additions to CO2 levels in the atmosphere.’

      ‘On the evidence a slow warming of the planet is likely to be good for plants and animals, for a long time to come.’

      ‘On the evidence, increases in carbon dioxide in the atmosphere are likely to produce a greener planet, and more food.’

      Since Tasmanian winemakers think they have the best conditions already for cool-climate
      wine production, they are unlikely to agree with you that a warmer Tasmania would be good for them. But given Tasmania’s cold winters, a lot of other Tasmanians would be most happy with a warmer climate, as would virtually all Canadians.

      • JimboR says:

        Hopefully they’ll be able to adapt and fill the huge demand for the varieties that can no longer be grown on the mainland.

      • margaret says:

        I’m not sure where to insert this link but reading the four paragraphs that describe the sociology of knowledge, here might be the spot for what is an interesting article.
        “arguments, data, publications, or even the official policies of scientific organizations that give every impression of being perfectly reasonable — of being well-supported by the highest quality of evidence, and so forth — but which don’t hold up when you scrutinize the details. Bullshit has the veneer of truth-like plausibility. It looks good. It sounds right. But when you get right down to it, it stinks.”
        http://quillette.com/2016/02/15/the-unbearable-asymmetry-of-bullshit/

  • David says:

    Don,

    Popper might ask you what mean by “properly tested”. The AGW hypothesis is tested every time a climate scientist reports a p-value.

    • David says:

      I know the scientific evidence support the hypothesis that the world is round. But I don’t think this hypothesis has been “properly” tested, yet.

      • David I am not sure that the IPCC reports give calculated p values, they give subjective estimates of certainty regarding things that the most robust skeptic would not dispute, like there has been some warming and it could conceivably be related to CO2. Much the same applies to the “consensus” reported by Cook et al.
        As for the hypothesis that CO2 is the primary driver, that has been refuted every year since the pause in warming while CO2 continued to accumulate.
        Look at the widening credibility gap between the predictions of 90 or so computer models the actual trajectory of the global temperature,
        The current uptick in temperature due to the El Nino does not support the hypothesis of human-induced warming.

        • bobo says:

          Hi Rafe,

          “they give subjective estimates of certainty regarding things that the most robust skeptic would not dispute”
          They use Monte Carlo simulations to determine uncertainties which is pretty objective. At what level are you claiming subjectivity?

          What predictions are you referring to? Projections are never “correct”, what’s important is the “degree of wrongness” is sufficiently small to ensure that the models are useful. Do you know what the margins of error are for the projections and the temperature you refer to?

          As for the pause, what pause are you referring to specifically? If you’re referring to a pause in global warming you’re mistaken:
          http://www.climatechange2013.org/images/figures/WGI_AR5_FigBox3.1-1.jp g

          “As for the hypothesis that CO2 is the primary driver, that has been refuted every year since the pause in warming while CO2 continued to accumulate.”
          How specifically is the hypothesis refuted? How does this assertion imply that global warming is not occurring? Why is it necessary that global temperatures increase from one year to the next? What if the underlying warming signal of the global surface air temperature was occurring at 0.015C per year – don’t you think natural variability is going to play an important role in global temperatures from year to year?

    • JimboR says:

      Indeed. And the counter-hypothesis is often tested with little more rigor than “common sense” or by passing a “reasonable eye” over the dataset. For me at least, Popper’s take home message is go with the guys doing the rigorous testing, and on this issue they seem to be far better represented on one side of the hypothesis than on the other counter side.

  • michael says:

    It would appear the hypothesis is at, or close to, a tipping point. I have been warning some of the politicians of my views but they have not responded to the burning question – will you still be on the AGW train leaves the station will you still be on board. I look forward to the unseemly crush at the exits.

  • bobo says:

    Hi Don,

    “No matter, I am prepared to wait until the hypothesis has been properly tested. I can only add that the longer it takes, the more likely it is that the CO2 control knob theory of climate will be rejected.”

    What is a “proper test”?

    “Equilibrium Climate Sensitivity, which is supposed to exist and to multiply the effects of a doubling of CO2 to several degrees of extra warming, has not been found, after thirty years of assertion. ”

    In what form should ECS exist? You do realise that climate sensitivity is dependent on the type of forcing and the stage of earth’s glaciation, i.e. it’s not a precise constant, don’t you?

    “The apparent ‘hiatus’ in the present century has been a problem for the hypothesis”
    Hiatus in what? Not surface air temperature, not UAH 5.6 TLT satellite data, not ocean temp data, not in sea level, not in total thermal energy of climate system etc etc etc.

    • Don Aitkin says:

      I think this is cocktail party stuff, but talking it seriously, for a moment, I reply as follows.

      Proper test. I think that the AGW hypothesis is being tested all the time. It is not doing well, and is propped up by subsidiary defences (missing heat in deep ocean etc).

      ECS. There have been many peer-reviewed papers on this subject. It requires lots of assumptions to start with, but the most recent half a dozen papers all suggest that if there is a real ECS it will be at the lower bound of the IPCC’s proposed range.

      Hiatus. Even the UK Met Office says there has been a hiatus, and the current el Nino, which has produced a warming spurt, is not the result of greenhouse gas emissions.

      These are what Popper would call tests of a kind. AGW is still there, but tattered, in my opinion. Steven Mosher says that it is the only game in town, and that sceptics need a well-supported rival theory. He’s right, given the power distribution, but intellectually quite wrong. Anyone can provide a critique of the AGW hypothesis without having a rival theory, and they do it all the time. That the critiques don’t have the right effect, from the critiquers’ points of view, is most often the function of politics, not science.

      • bobo says:

        AGW hypothesis not doing well? You need to extend your horizons beyond cherry-picking the unverified record that Spencer uses.

        An ECS occurring at a lower bound (in the case of IPCC that is 1.5) is mathematically impossible. You ought to be quoting an interval. Moreover, based on physical evidence it is a non-constant function.

        During the so-called hiatus, something highly improbable – if there was no global warming – has happened. 15 of the sixteen hottest years have occurred since 2000 and the remaining year was 1998. Think about that for a second. Given that there are 140 odd years of records, the probability of any one year being the hottest on record is roughly 1/140 (depending on the year). To have a cluster of hottest years like this is highly improbable unless warming is occurring. Sure El Nino years are more likely to break records, but 2014 was not an El Nino year and was the most likely previous candidate for hottest year (surface temp). Even if the El Nino warming signal (~0.1C) is subtracted off the 2015 temperature, it is still significantly hotter than 2014. From a rational, probabilistic perspective your argument has no ground if we restrict ourselves purely to surface temperature, but it’s already known that the climate system has strongly accumulated heat energy during the period of the so-called hiatus, ie global warming has occurred unabated during that period.

        “Anyone can provide a critique of the AGW hypothesis without having a rival theory, and they do it all the time. ”
        Every person and their dog seems to be providing critiques, but I’m yet to see a critique that stands up to scrutiny. It’s like people providing religiously motivated advice – easy to do, many people do it, but it’s worthless. The reason AGW is still around as a theory is because nobody – no one within those armies of industrious climate sceptics – has managed to come up with a punch that connects, a counterexample.

        • Don Aitkin says:

          Bobo,

          You do hop around a lot. Who is arguing that there has been no warming since the middle of the 19th century? While that occurs, as it has been doing in an irregular fashion, some ‘hottest’ records will be broken from time to time. There’s nothing improbable about it, and the margins of some of those ‘records’ are tiny.

          On ECS, the Cato Institute (don’t shriek) has listed 14 peer-reviewed papers that have estimated a low ECS. You can see them here (I hope). If that doesn’t work just Google the central title.

          /Users/donaitkin/Library/Containers/com.apple.mail/Data/Library/Mail Downloads/FEEDEA39-B7AD-426C-AD59-C4CCBEEAA3A5/Cato Institute Lists 14 Low Climate Sensitivity Papers.webarchive

          • bobo says:

            Don,
            From time to time hottest records will be broken, but what is the probability of the cluster of 15 hottest years occurring since 2000 occurring? Pretty small. Here’s an abstract from a study that investigated the probability of such clustering:
            http://www.nature.com/articles/srep19831

            “2014 was nominally the warmest year on record for both the globe and northern hemisphere based on historical records spanning the past one and a half centuries1,2. It was the latest in a recent run of record temperatures spanning the past decade and a half. Press accounts reported odds as low as one-in-650 million that the observed run of global temperature records would be expected to occur in the absence of human-caused global warming. Press reports notwithstanding, the question of how likely observed temperature records may have have been both with and without human influence is interesting in its own right. Here we attempt to address that question using a semi-empirical approach that combines the latest (CMIP53) climate model simulations with observations of global and hemispheric mean temperature. We find that individual record years and the observed runs of record-setting temperatures were extremely unlikely to have occurred in the absence of human-caused climate change, though not nearly as unlikely as press reports have suggested. These same record temperatures were, by contrast, quite likely to have occurred in the presence of anthropogenic climate forcing.”

            Regarding ECS, all that seems possible to determine is a probability distribution function. That’s why you can’t pick a single number, say 1.5, because the support of a single number has measure zero, so the probability of that number occurring is 0/something=0. You need to specify a range, like 1-1.5 etc. We’ve been there before. You seem to be referring to ECS in response to CO2 emissions, which is extremely difficult to determine without the use of GCMs. You should try calculating it by hand to get some appreciation for how difficult it is to determine.

      • bobo says:

        Also, you say “AGW is tattered as a theory”. How does this fit in with a Popper’s thoughts on falsification? Not at all. According to Popper, until a theory has been disproved, it survives as a theory. I don’t think Popper says anything about changing confidence in a theory; the qualificaiton that a theory is “tattered” is a statement of your confidence in the theory.

        From Popper’s perspective all that matters is that it hasn’t been disproved.

  • Don Aitkin says:

    Popper would say ‘hmm’ to all that. There are few experiments that can be set up to test the AGW hypothesis. Its basis is a series of propositions familiar to us all. Each has a certain plausibility. Time alone can test most of them ‘properly’. I don’t think enough time has elapsed to be sure, or decently sure but, as I argued in the essay, AGW is not looking good — too many discrepancies, and too much defence-building. Good hypotheses don’t need that sort of protection. If AGW was beyond question we wouldn’t even be talking about it, and no one would have to say that the science is settled (or now that jobs are at stake, to say that there is still work to do).

  • Steven Mosher says:

    “How does climate science stand up to all this? Not at all well, it would seem to me. The ruling hypothesis is that carbon dioxide is the control knob for the planet’s atmospheric temperature: the more of it, the hotter the atmosphere, and hotter atmospheres must lead to higher sea-levels, and all manner of other evils.”

    Err No. That is not the hypothesis.

    C02 is ONE OF the knobs
    IF, you hold all other knobs constant, and DOUBLE the c02 knob, the planet will warm by between 1.5C and 4.5C
    OVER TIME. THAT is the hypothesis.

    problem: We cant hold hold the other knobs constant, so while the theory is testable IN PRINCIPLE ( all that Popper’s
    falsification requires) testing it in PRACTICE is difficult.

    • Don Aitkin says:

      Steven,

      You are correct, though few others are as careful as you to use the ceteris paribus caveat. But the danger you face, and I can see David and others pouncing on you, is that you aren’t saying what all those other things are. Surely you’re not introducing the notion of ‘unknown unknowns’!

    • Aynsley Kellow says:

      ‘IF, you hold all other knobs constant, and DOUBLE the c02 knob, the planet will warm by between 1.5C and 4.5C
      OVER TIME. THAT is the hypothesis.’
      This is NOT the hypothesis – there is another stage:
      If you DOUBLE the c02 knob, the planet will exhibit an increase in water vapour that will amplify the additional climate forcing of about 1°C caused by CO2 to between 1.5°C and 4.5°C.
      That intermediate hypothesis must withstand repeated attempts at falsification before we can place much faith in it – and therefore the subsequent proposition.
      Thus far, the evidence in support of it is weak. Recall:
      Paltridge, G., Arking, A., & Pook, M. (2009). Trends in middle-and upper-level tropospheric humidity from NCEP reanalysis data. Theoretical and Applied Climatology, 98(3-4), 351-359.
      Recall also the extent to which climate science strays form Popperian science, when the referee at Journal of Climate Reviewer stated: “the only object I can see for this paper is for the authors to get something in the peer-reviewed literature which the ignorant can cite as supporting lower climate sensitivity than the standard IPCC range”.
      Climate science would benefit from a good dose of Popper. Instead, it tends to take Feyerabend’ description as a prescription. Unfortunately, the philosophy of science is not a required subject for scientists.

  • colin davidson says:

    (Don, my apologies, I mistakenly posted this on your previous thread, meant it to go on this one…)
    The CAGW hypothesis is based on projections made by climate models. Those models incorporate the “settled science” of radiative imbalance caused by increased concentration of CO2, transfer of that imbalance to the surface, and positive water vapour feedback.
    The average projections of the very many models consistently overestimate the actual temperature increase by a factor of nearly 3 times. This is not a “near miss”. It is proof that there is something wrong with the “settled science”. (The radiative imbalance part of the science is generally accepted. Where the error seems to lie is in either the transfer mechanism to the surface, or in the positive water vapour feedback. My guess is the latter, based on recent work on what happens to atmospheric water vapour in massive thunderclouds, but it could well be in both.)
    The data is not lying, but the models are. (Some of the climate clergy are claiming the data is wrong! Perhaps also Galileo was wrong to rely on data rather than the certainty provided by the Church view?)
    It follows logically that if the models are consistently unable to “project” (they mean “predict”) correctly, then they are in error, and any CAGW hypothesis based upon them is necessarily falsified.
    The theory is wrong – it does not produce answers which are consistent with observed (measured) behaviour. It is incorrect to claim that ”the science is settled”, and unforgivable to base public policy on such flawed models and disproven theory.

  • David says:

    “Some of the climate clergy are claiming the data is wrong!”

    Colin that’s on of Don’s go-to arguments. He is forever disparaging this data set or that.

  • colin davidson says:

    David,
    The allegation that “Skeptics don’t do data pre-1998” is quite untrue. I based my comments on data extending back as far as satellite records go, 1975.
    But, if you object to that, because it doesn’t go back to, say, 1750, then I am happy to go back further, to 900AD. The evidence, and there is a great deal of it, well documented on the excellent website CO2science.org, is that the medieval period, worldwide, was most likely warmer than now.
    Have climate “scientists”, the ones who run the models, included this in the models? No.
    Have they countenanced a periodic climate variation with a period of about 1000 years, which on the archaeological evidence is well established (Minoan warm period, roman warm period, medieval warm period) ? No.
    Have they an explanation for the Little Ice Age of the 1600s-1850? No.
    Starting at 1750 is cherry picking of the very worst sort.
    And denying that the models are grossly in error, cannot correctly explain the last 50 years (let alone the last 8000), and must therefore contain erroneous physics, is unscientific, bordering on fraudulent.
    If you are a real scientist, an honest one, the DATA is paramount. Theories are subordinate to the DATA. If the theory does not agree with the observations, it is not the observations but the theory which is in error.
    If you are not a scientist but a clergyman, the theory is more important, and the data can be discarded.
    The spectacle of publicly prominent climate priests denying that the theory could possibly be in error, castigating and traducing honest scientists who have pointed out that there is something grossly wrong with the theory is a scandal. Science is not about belief. It is about generating possibilities which fit the data. And the present theory does not do that, cannot be tweaked to do that because there is a fundamental flaw in our story of how things work – at least one flaw, probably many more.
    If you don’t think that the climate hypothesis as it stands is disproven then I invite you to look at the data and tell me why the models which cannot replicate the recent history from 1975 with any accuracy should be accepted as the gospel. In any other field of science, and particularly in physics or astronomy this non agreement would be laughed out of court.
    And will be, in the court of history. A 20th century Phlogiston, a Piltdown Man of a theory pushed by a climate priesthood who will brook no debate, and in many cases who will not release their data or methods.

    • David says:

      “Starting at 1750 is cherry picking of the very worst sort.” No its not. There is a good theoretical reason to consider the beginning of a structural break @ 1750. Its called the Industrial Revolution. You can google it.

      Asking increases in CO2 which have occurred over the last 300 yeas to explain temperature variations which occurred 8000 years ago is silly, obviously.

      .

      • Don Aitkin says:

        When the Industrial Revolution started is a matter for debate (http://www.history.com/topics/industrial-revolution).
        I would have said about 1780, but it doesn’t really matter. The real question is, what were CO2 levels like then? We don’t know. I have read a paper in which an attempt was made to estimate them from trying to quantify trees burned, coal mined, and so on. Tricky stuff. Error? Uncertainty? Yes, well …

        Nonetheless you can see graphs where the ‘structural break’ is indicated, as though there is no doubt at all. I don’t pay too much reverence to them. We’re safer in the contemporary period — yes, from 1979 for atmosphere and about 2005 for Argo.

        But of course that doesn’t give us much room for establishing trends. I’m doing my best with those in the next episode of my ‘climate change’ summary, next week.

        • David says:

          We’re safer in the contemporary period — yes, from 1979 for atmosphere and about 2005 for Argo.”

          Not at all. When testing for structural breaks in time series, the first thing that is required is a theoretical rationale. Then you run the test.

          The AGW protagonists ave an increase in CO2 caused by the advent of the Industrial revolution. Skeptics on the other hand must rely on their “unknown natural causes”, which just happen to coincide with a large El Nino.

          In my view “much safer” to rely on a theoretical rationale that I can find in a book. I reckon “unknown natural causes” sounds more Karl Jung than Karl Popper.

    • bobo says:

      Colin,
      You mention the
      “Minoan warm period, roman warm period, medieval warm period”
      Could you explain how you’re so certain that these periods of warming are due to global warming, and are not a regional dipolar phenomenon? And moreover, how this is relevant to the current period of global warming?

  • colin davidson says:

    David posted: “Asking increases in CO2 which have occurred over the last 300 yeas to explain temperature variations which occurred 8000 years ago is silly, obviously. ”
    To which my response is:
    Any theory which ignores the natural variation in climate which is clearly shown in the archaeological record of the last 8000 years, in the measurements from the 1600s to the present, and in the repeated temperature increasing phase followed by temperature-static or decreasing phase of the last century is silly, obviously.
    That silliness is exposed by the inability of the current models to conform with observations. As predictive tools the models are useless. And it’s because there is something grossly wrong with them. That’s the settled science.
    Basically David is arguing that the models are correct, even though they fail in the period 1975 to the present, the period when we have the very best measurements, the satellite period.
    How unscientific is that?
    Very.

  • colin davidson says:

    Bobo asked:
    “You mention the
    “Minoan warm period, roman warm period, medieval warm period”
    Could you explain how you’re so certain that these periods of warming are due to global warming, and are not a regional dipolar phenomenon? And moreover, how this is relevant to the current period of global warming?”

    The evidence contained in the database at http://www.co2science.org that the MWP was a global event is now very strong. Unless you think that the Incas farmed in the North Atlantic basin, or that evidence from Australia and New Zealand is also from the North Atlantic basin.

    The reason these periods are relevant to the present warming is that these were natural climate changes, unaffected as far as we know by CO2 levels. On the basis that the Minoan period was around 1200BC, the Roman warm period was around 0BC, and the Medieval warm period was around 1000AD we would expect some sort of natural warming event to be occurring right now- in fact on the basis of these events we would expect the temperature right now to be warmer than it is, as they were all most likely warmer than now.
    Not to include a natural warming signal in the models is an error. I understand the problem – we don’t know why these alternating warmer-colder phases occurred, therefore we can’t reliably model them. The same is true of the variations in the temperature of the last century – we don’t know what causes the trajectory to change from relatively rapid warming to stasis/cooling and then back again, with a period of 30-40 years.
    But what we do know is that the climate models are wrong. They do not predict temperatures which are within cooee of the measurements, thus the physics of CO2 induced warming are not properly understood, not settled.
    It’s about time the “scientists” looked critically at the theory. What, for example, is the reason the Russian climate model predicts the measurements so accurately, while the CSIRO and the rest of the clergy are off in la-la land?

    • bobo says:

      Colin,

      “The evidence contained in the database at http://www.co2science.org that the MWP was a global event is now very strong.”

      Was there simultaneous warming globally? Or was there just a warm spot somewhere with a coinciding cool region elsewhere, these regions moving around? If the warming was simultaneous I’d like to see a link to the specific research, the URL of a website homepage doesn’t fly.

      “But what we do know is that the climate models are wrong. They do not predict temperatures which are within cooee of the measurements”

      Do you have a reference for this claim? Again, a link to a specific study would be great, please.

  • colin davidson says:

    David mentioned the BOM data set in one of his recent posts.
    “they whinge temperatures measured at sea and complain about data collected by the BoM. ”
    There is a distinction in science between theory (what someone thinks might be the truth) and measurement (I recorded this on that date at that time with this instrument). The raw temperature measurements are DATA. But the BOM data is an adjusted form of the measurements. That would be OK provided the detail of the method used in adjustment was available for scrutiny. But it has not been released, and therefore the BOM data falls into the category of THEORY, not data. The BOM data is what someone thinks was the case.
    The BOM claims it has a really god, high quality process. But no-one is allowed to know what that is.
    Given the absolutely correct criticism that undocumented manipulation of the data has led to complete nonsense at many sites, you’d think the BOM would be falling over itself to release the detail of its adjustment methodology.
    But no, it’s circle-the-wagons-time.
    This naturally prompts the question: “What have they got to hide?”
    My question would be different:
    “Call yourselves scientists?”

    • David says:

      Colin this is a silly argument too. The unhomogenised temperature data are available. And I know this because;

      1. Dr Jennifer Marahasy (a professional BoM botherer) analyses them ad nauseam. On any rainy Sunday afternoon she can be seen comparing unhomogenised and homogenised BoM datasets; before breathlessly reporting her findings. http://jennifermarohasy.com/about/

      2. Professor Muller has analysed 14 million unhomogenised temperature records (enough data to choke a stray dog) to report that homogenisation makes no difference to the reported relationship between CO2 and temperature.

  • colin davidson says:

    David posted: “Colin this is a silly argument too. The unhomogenised temperature data are available.”
    The point is that the BOM homogenised set was created by a method which has not been disclosed – it cannot be verified or criticised. The homogenised set is someone’s untestable opinion, and is not data. An argument based on someone’s opinion is not a scientific argument. Scientifically the BOM homogenised set is worthless. For the Clergy, however, opinion is everything (this is a test of whether someone is religiously committed to the cause, or whether one has an open mind. The religious will be happy to take unsubstantiated opinion as Gospel. The open minded will reject the untestable.)
    Professor Muller says the same thing more politely (I haven’t checked what he actually said, in the absence of a quotation I’ve taken what David reported as truth). He said it doesn’t matter if you don’t use the homogenised set.
    A good thing too. One should always use best evidence, and the BOM homogenised set is very far from being best evidence – it is unable to be tested in any sense.
    As I said in my previous post, what on earth are the BOM thinking?

    • David says:

      It probably wont surprise you to know, that I don’t agree with this either. I am a fan of the BoM. As far as I am concerned they provide great data.

      • colin davidson says:

        David,
        You are entitled to your belief. As I pointed out above, the BOM homogenised set is not testable, not able to be replicated. It is therefore someone’s opinion. What you are saying is that you are happy to base your arguments on someone else’s undocumented, unreplicable and untestable opinion.
        That is a religious but not a scientific approach. But I’ll respect it for what it is worth.

    • JimboR says:

      Colin, have you read

      Techniques involved in developing the Australian
      Climate Observations Reference Network – Surface Air
      Temperature (ACORN-SAT) dataset
      CAWCR Technical Report No. 049
      CTR_049.pdf

      Section 7 “Development of homogenised data sets” is fairly detailed. And according to the BOM site, they’ll even supply you with the source code:

      “Python computer source code implementing the percentile-matching algorithm is available by request to: helpdesk.climate@bom.gov.au

      • JimboR says:

        Reading it, you certainly don’t get the impression the work is done by a bunch of amateurs (which is the usual impression I get when reading findings from all the BOM botherers). I was particularly drawn to “7.9 Corrections for data precision” only because it’s a topic I’m very familiar with in my own totally unrelated field.

        Early AWSs apparently only reported temperature to the nearest degree. They state that this “will have no
        systematic effect on mean temperatures”; a concept that the show-us-your-error-bars botherers continue to struggle with. But they go on to point out it does add a bias to statistics like “number of days below 15C”. I was encouraged to see they use a very similar technique to what I use in my field… they add white noise to the signal and rely on the oversampling to tease out the extra resolution that’s hiding in that data…. i.e. they dither the signal.

        • David says:

          Interesting

        • JimboR says:

          In classical signal processing theory, oversampling and decimation lets you trade off bandwidth for resolution (or signal-to-noise ratio). When you’re measuring something as slow moving as temperature you’ve typically got bandwidth to spare, so you might as well put it to use. Even if your sensor is only good to the nearest degree, you can achieve way better than that, simply by oversampling (all in software). But it only works if there’s sufficient noise in the signal.

          “This is an interesting counter-intuitive example where adding some dithering noise to the input signal can improve (rather than degrade) the final result because the dither noise allows oversampling to work to improve resolution (or dynamic range).” https://en.wikipedia.org/wiki/Oversampling

          That’s not exactly what they’re doing, but it’s the same principle.

      • colin davidson says:

        Jim,
        The BOM Technical Advisory Forum reported in June 2015 as follows:
        “The Forum noted that the extent to which the development of the ACORN-SAT dataset from the raw data could be automated was likely to be limited, and that the process might better be described as a supervised process in which the roles of metadata and other information required some level of expertise and operator intervention. The Forum investigated the nature of the operator intervention required and the bases on which such decisions are made and concluded that very detailed instructions from the Bureau are likely to be necessary for an end-user who wishes to reproduce the ACORN-SAT findings. Some such details are provided in Centre for Australian Weather and Climate Research (CAWCR) technical reports (e.g. use of 40 best correlated sites for adjustments, thresholds for adjustment, and so on); however, the Forum concluded that it is likely to remain the case that several choices within the adjustment process remain a matter of expert judgment and appropriate disciplinary knowledge.”
        In other words, although the BOM follows a procedure, that procedure is subject to undocumented fiddling.

    • bobo says:

      Colin,

      Let me juxtapose two statements you’ve made on this thread:

      “The data is not lying, but the models are. (Some of the climate clergy are claiming the data is wrong! Perhaps also Galileo was wrong to rely on data rather than the certainty provided by the Church view?)”

      and

      “Scientifically the BOM homogenised set is worthless.”

      Coherence is not your strong point Colin.

      • colin davidson says:

        Bobo, taking 2 quotations out of context is an appalling method of argument!
        But for the record:
        1. The use of unreplicable data, such as the BOM homogenised set is a nono, simply because no-one can be sure why they adjusted the data. The homogenised set is someone’s untestable opinion, it is not data. It is therefore worthless as a scientific tool, and should never be used as part of a scientific argument.
        2. The data which is compared to the models is also adjusted data (radiosonde and satellite measurements). These adjustments are reclicable, and therefore the data sets can be used in a scientific argument.

        Very simple really. Undocumented fiddling with the data to the point where no-one can replicate it means that the resultant set is worthless, whatever the Clergy say.

        • bobo says:

          Any reconstruction of temperature that is built from more than one data set is homogenised. That’s statistics for you. What you need to demonstrate is why/how the particular homogenisation process you refer to is not sound – detail and numbers are required for that.

          • colin davidson says:

            The quotation supplied above is very relevant. Part of it says: ” The Forum investigated the nature of the operator intervention required and the bases on which such decisions are made and concluded that very detailed instructions from the Bureau are likely to be necessary for an end-user who wishes to reproduce the ACORN-SAT findings. Some such details are provided in Centre for Australian Weather and Climate Research (CAWCR) technical reports (e.g. use of 40 best correlated sites for adjustments, thresholds for adjustment, and so on); however, the Forum concluded that it is likely to remain the case that several choices within the adjustment process remain a matter of expert judgment and appropriate disciplinary knowledge.”
            In other words, adjustments are made on the fly, to someone’s opinion. Those decisions are NOT RECORDED. Which means that the whole is NOT REPLICABLE.
            You don’t need any numbers, the process is not scientific, it is not possible to replicate it.
            Basically, the BOM has adopted a non-quality process, one which cannot be audited in any sense. A non-scientific process.
            Quite an achievement for a scientific organisation.

  • colin davidson says:

    Bobo asked if a more detailed link to the data on the Medieval Warm Period could be provided: http://www.co2science.org/data/mwp/mwpp.php
    And here is a link to a chart showing how warm it was then: http://www.co2science.org/data/mwp/quantitative.php
    This very high quality site also provides the summary of scientific papers on CO2 fertilisation of many plant species here: http://www.co2science.org/data/plant_growth/plantgrowth.php
    It is wonderful that for all the major crop species, the fertilisation effect is greater than 25% increased yield for a doubling of atmospheric CO2, and for wheat and rice much more than that.

    • bobo says:

      Global warming may or may not have occurred during MWP. You haven’t presented evidence which suggests with a high degree of confidence that global warming occurred in the MWP. To be fair, that’s not to say it didn’t happen though.

      But you’re criticising models for not picking up on the MWP. Indications by several studies suggest that the MWP was caused by changes to the Gulf stream current, and if this indeed is the case, there is no reason why MWP should appear in the GCM hindcasting. You don’t have enough justification to support your claim.

      re comments in moderation, moderation seems automatic for links to php, pdf and perhaps other file extensions. Try inserting a space between the last and second last letters of the url in your comment, this will ensure it won’t be held up in moderation.

      • colin davidson says:

        The evidence cited is what there is. It is based on all the scientific papers which have made an estimate, and the statistical indication from those papers is that the medieval warming period was about 0.25 DegC warmer than now.
        You are entitled to deny that, of course, but the weight of evidence is against you.

        The several studies which reckon the MWP was confined to the Atlantic basin are ignoring the rest of the evidence from outside that basin. Once again I refer you to the detailed evidence contained in the links. My particular favourite is the evidence from high civilisations in South America.
        Once again, you are entitled to ignore all the evidence of a world-wide phenomenon, but the evidence still exists. The consensus position is that the MWP was warmer, and was global, based on the evidence, but I accept that the CAGW religion requires that this not be so.

        Finally, your denial of the evidence has led you to the conclusion that the previous warm periods are irrelevant to climate modelling. That is, you don’t believe that natural variation is a strong influence on climate. So we should perhaps ignore the unexplained variations in temperature over the past 150 years – the cold snap of the 1890s, the cold snap of the 1970s, the stasis (if not yet cold snap) this century, and deny that these are natural variation. And ignore the evidence (eg skeletons at the tops of mountain passes) of previous warm periods, evidence which is strong. Perhaps we should also ignore the ice ages, because we don’t really know what caused them.

        A I have pointed out, the present models are worthless. They ignore things which are known (at least 3 major climate cycles – ice ages, warm periods, cooler-warmer variations) and ascribe all the warming to CO2 and tweakage for volcanos and aerosols. The predictions made by the models are so unrealistic, so far from the measurements, that we know that there are serious errors in the physics incorporated within them. The world has demonstrated that it does not work in the way the models think it ought to.

        • bobo says:

          Given that the Atlantic ocean lies off South America the evidence you mention could be linked to that. Anyway, I’m still waiting for you to provide a study that unequivocally shows that MWP was caused by global warming. The uncertainties associated are large enough that global warming could have occurred, or it may not have occurred at all.

          AGW doesn’t require that the MWP was not caused by global warming. Why would it? Let’s suppose that the MWP was indeed caused by global warming – and there is no evidence to suggest that it did with a high degree of confidence – then there is a missing forcing from the models. Once that forcing is added to the models, then there ought to be agreement with reconstructed temp records. But suppose there was some forcing that occurred then such as unusual solar activity. There is no reason to believe that such a forcing could occur again today undetected. In addition, AGHGs provide the right amount of forcing for the observed GW, so a counter effect to that would be required as well, complicating the picture.

          But until the MWP can be demonstrably shown to be caused by GW, there is no point going down that path of hunting for a missing forcing.

          • colin davidson says:

            1. Peru is not near the Atlantic.
            2. “…the MWP was not caused by global warming…” First, let us define Global Warming. It means a period when the mean surface temperature of planet Earth is rising.
            Global Warming cannot cause anything. it is a state of existence, a description of what is happening, not why. (Unless it has some other (religious) meaning, a degenerate definition of a perfectly accurate descriptive English phrase.)

            Obviously, as you point out, these repetitive 1000year periodic Global Warmings followed by Global Coolings must be caused by something. As the IPCC acknowledged until the dreadful work by Mann et al. That work of course is now completely discredited – only a very few scientists think it of any use, and most believe that it has badly damaged the standing of all scientists.

            I doubt that you have read anything of the hypothesis by Svensmark. You might try reading “The Chilling Stars” by Henrick Svensmark and Nigel Calder, published in 2007. That may well provide a pointer to the mechanism.

            How do you account for the apparent correlation of sunspot numbers with cooling and warming phases? The solar scientists are quite hot on that.

            And how about David Evans’s reworking of the models and his predictions for the next 5 years?

          • bobo says:

            “Peru is not near the Atlantic.”

            You do realise that changes in currents in the Indian ocean affect weather on the east coast of Australia, for instance?

            Here is a hypothesis for MWP that holds broad support: a hot spot alternated between Europe and South America, in response to an ocean current configuration in the Atlantic. Because the hotspot was countered by cooling elsewhere, Earth’s climate system was in radiative balance, i.e. no global warming was occurring.

            As for the cosmic ray hypothesis, there isn’t evidence to support it.

          • colin davidson says:

            (This is a reply to Bobo’s post two posts down – I couldn’t find a reply button there)
            I guess that the Western side of South America has the same climate as the Eastern side then? And the evidence from Australia and New Zealand, why that is actually support for the Atlantic/South America hypothesis. How silly of me, of course they are in the Atlantic basin.

            1. The majority opinion is that the MWP was worldwide, and hotter than now.

            2. The Clergy don’t like that. First the fallacious papers by Mann tried to get rid of it. The Climate Clergy cheered…until it was shown that the Mann stuff was a complete load of cobblers.

            3. So they moved on and regrouped. They need the MWP and all the other WPs to disappear, otherwise the CO2 catechism is dangerously weakened, particularly the bits which say that this is the hottest its ever been, and that natural variation is weak. They can’t refute the evidence so they invent ever more tortuous claims, for which there is little support outside the Climate Church.

            4. I invite BoBo to refute the data detailed in the cited website. Preferably with papers by archaeologists and not dendrochronologists. That crowd have a long task ahead of them to restore a shred of credibility to their profession.

  • Neville says:

    Colin you are wasting your time trying to change their religious beliefs. These people care zip for data, but love their dogma. The mitigation of their CAGW is probably the greatest con and fraud in recent history. Even Dr Hansen called Paris COP21 ” just BS and a fraud,” because he knows it will not change anything at all. Very simple maths proves the case.
    Lomborg’s PR study showed that even if every country carried out their part to the letter it would only change temp by about an unmeasurable 0.05 C by 2100. How many 100s of trillions $ would be flushed down the drain for this guaranteed zero result is anyone’s guess. These people are barking mad fanatics, but I’ll still give a few references showing the previous NATURAL WARMER periods from the PR studies.

    The Calvo et al study showed that the southern OZ temp has been dropping for at least 6,000 years and so has rainfall. This is for both SST and onshore temps. Prof De Deckker on Catalyst ABC was part of this long study. The southern ocean SST have been dropping recently as well.

    http://onlinelibrary.wiley.com/wol1/doi/10.1029/2007GL029937/full#grl23139-bib-0027

    The PAGES 2K study also backs up the last 1800 years of the Calvo study using Antarctic ice core proxies that show warmer temps from 149 AD ( Roman WP) to 1250 AD ( med WP) and a spike from 1671 to 1700. All warmer than today.
    And the Wilson et al study found evidence for the Med WP in NZ.

    http://www.co2science.org/articles/V3/N34/C2.php
    Also there many studies showing a Med WP in Antarctica. Here’s a number of PR studies.

    http://www.co2science.org/subject/a/antarcticmwp.php

    • David says:

      The take away message fro this paper is not an anti AGW one. Calvo et al. describe a slow long term cooling trend that has occurred over the past 8000 years. AGW describes a rapid warming trend over a few hundred years. The two processes are not mutually exclusive. Here are some quotes from some other publications written by Eva Calvo the lead author from the paper who’s results you have mis-interpreted.

      Paleo-perspectives on ocean acidification

      “The anthropogenic rise in atmospheric CO2 is driving fundamental and unprecedented changes in the chemistry of the oceans. …. We argue that ocean conditions are already more extreme than those experienced by marine organisms and ecosystems for millions of years, emphasising the urgent need to adopt policies that drastically reduce CO2 emissions.

      Effects of climate change on Mediterranean marine ecosystems: the case of the Catalan Sea

      “The Catalan Sea, located between the eastern Iberian coast and the Balearic Islands, is a representative portion of the western Mediterranean basin and provides a valuable case study for climate change effects on Mediterranean ecosystems. Global warming is reflected regionally by a rise in sea level over the last century, an increase in surface temperature of around 1.1°C in the last 35 yr, a progressive salinisation of intermediate and deep waters and a strengthening of the stratification.”

      Calvo accepts the evidence for AGW, and you should too.

      • Neville says:

        David you are desperately clutching at straws. SLs down our east OZ coast were 1.5 metres higher only 4,000 years ago and today Sydney is about 0.65mm year and Brisbane is 0.09mm a year. That’s a little over 2 inches at Sydney and about a third of an inch at Brisbane by 2100. A lot less than the previous 100 years. So where’s the co2 impact since 1950?
        But please tell us how to mitigate your so called CAGW fantasy. Remember China, India etc will emit at least 90% of new co2 emissions until 2040, while the OECD countries will nearly flat-line.

        • David says:

          Neville, what I am saying if that the author of the paper you cite (Calvo et. al ) would not agree with your interpretation of their results.

          Try and focus.

  • Neville says:

    My last comment ended up in moderation, I don’t know why? But here’s another new study backing up recent work from the CSIRO showing the planet is greening. All because of increased co2 levels. Just an extra bonus.
    http://wattsupwiththat.com/2016/02/16/study-increased-carbon-dioxide-is-greening-deserts-globally/

    • Don Aitkin says:

      Neville,

      I’m sorry your comment sat in a queue for a while. I’m getting a hell of a lot of spam, and the system now catches everybody who isn’t a frequent contributor. You almost are! It’s now here.

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