Skepsis Revived

I appear to be in recycling mode this week, so I thought I’d carry on with a rehash of an old post about skepticism.  The excuse for this was an item in one of the Guardian science blogs about the distinction between Skeptic and sceptic. I must say I always thought they were simply alternative spellings, the “k” being closer to the original Greek and “c” being Latinised (via French). The Oxford English dictionary merely states that “sceptic” is more widespread in the UK and Commonwealth whereas “skeptic” prevails in North America. Somehow, however, this distinction has morphed into one variant meaning a person who has a questioning attitude to or is simply unconvinced by what claims to be knowledge in a particular area, and another meaning a “denier”, the latter being an “anti-sceptic” who believes wholeheartedly and often without evidence in whatever is contrary to received wisdom. A scientists should, I think, be the former, but the latter represents a distinctly unscientific attitude.

Anyway, yesterday I blogged a little bit about dark energy as, according to the standard model, this accounts for about 75% of the energy budget of the Universe. It’s also something we don’t understand very well at all. To make a point, take a look at the following picture (credit to the High-z supernova search team).

 What is plotted is the redshift of each supernova (along the x-axis), which relates to the factor by which the universe has expanded since light set out from it. A redshift of 0.5 means the universe was compressed by a factor 1.5 in all dimensions at the time when that particular supernova went bang. The y-axis shows the really hard bit to get right. It’s the estimated distance (in terms of distance modulus) of the supernovae. In effect, this is a measure of how faint the sources are. The theoretical curves show the faintness expected of a standard source observed at a given redshift in various cosmological models. The bottom panel shows these plotted with a reference curve taken out so the trend is easier to see. Actually, this is quite an old plot and there are many more points now but this is the version that convinced most cosmologists when it came out about a decade ago, which is why I show it here.

The argument drawn from these data is that the high redshift supernovae are fainter than one would expect in models without dark energy (represented by the \Omega_{\Lambda}  in the diagram. If this is true then it means the luminosity distance of these sources is greater than it would be in a decelerating universe. Their observed properties can be accounted for, however, if the universe’s expansion rate has been accelerating since light set out from the supernovae. In the bog standard cosmological models we all like to work with, acceleration requires that \rho + 3p/c^2 be negative. The “vacuum” equation of state p=-\rho c^2 provides a simple way of achieving this but there are many other forms of energy that could do it also, and we don’t know which one is present or why…

This plot contains the principal evidence that has led to most cosmologists accepting that the Universe is accelerating.  However, when I show it to first-year undergraduates (or even to members of the public at popular talks), they tend to stare in disbelief. The errors are huge, they say, and there are so  few data points. It just doesn’t look all that convincing. Moreover, there are other possible explanations. Maybe supernovae were different beasties back when the universe was young. Maybe something has absorbed their light making them look fainter rather than being further away. Maybe we’ve got the cosmological models wrong.

The reason I have shown this diagram is precisely because it isn’t superficially convincing. When they see it, students probably form the opinion that all cosmologists are gullible idiots. I’m actually pleased by that.  In fact, it’s the responsibility of scientists to be skeptical about new discoveries. However, it’s not good enough just to say “it’s not convincing so I think it’s rubbish”. What you have to do is test it, combine it with other evidence, seek alternative explanations and test those. In short you subject it to rigorous scrutiny and debate. It’s called the scientific method.

Some of my colleagues express doubts about me talking as I do about dark energy in first-year lectures when the students haven’t learned general relativity. But I stick to my guns. Too many people think science has to be taught as great stacks of received wisdom, of theories that are unquestionably “right”. Frontier sciences such as cosmology give us the chance to demonstrate the process by which we find out about the answers to big questions, not by believing everything we’re told but by questioning it.

My attitude to dark energy is that, given our limited understanding of the constituents of the universe and the laws of matter, it’s the best explanation we have of what’s going on. There is corroborating evidence of missing energy, from the cosmic microwave background and measurements of galaxy clustering, so it does have explanatory power. I’d say it was quite reasonable to believe in dark energy on the basis of what we know (or think we know) about the Universe.  In other words, as a good Bayesian, I’d say it was the most probable explanation. However, just because it’s the best explanation we have now doesn’t mean it’s a fact. It’s a credible hypothesis that deserves further work, but I wouldn’t bet much against it turning out to be wrong when we learn more.

I have to say that too many cosmologists seem to accept the reality of dark energy  with the unquestioning fervour of a religious zealot.  Influential gurus have turned the dark energy business into an industrial-sized bandwagon that sometimes makes it difficult, especially for younger scientists, to develop independent theories. On the other hand, it is clearly a question of fundamental importance to physics, so I’m not arguing that such projects should be axed. I just wish the culture of skepticism ran a little deeper.

Another context in which the word “skeptic” crops up frequently nowadays is  in connection with climate change although it has come to mean “denier” rather than “doubter”. I’m not an expert on climate change, so I’m not going to pretend that I understand all the details. However, there is an interesting point to be made in comparing climate change with cosmology. To make the point, here’s another figure.

There’s obviously a lot of noise and it’s only the relatively few points at the far right that show a clear increase (just as in the first Figure, in fact). However, looking at the graph I’d say that, assuming the historical data points are accurate,  it looks very convincing that the global mean temperature is rising with alarming rapidity. Modelling the Earth’s climate is very difficult and we have to leave it to the experts to assess the effects of human activity on this curve. There is a strong consensus from scientific experts, as monitored by the Intergovernmental Panel on Climate Change, that it is “very likely” that the increasing temperatures are due to increased atmospheric concentrations of greenhouse gas emissions.

There is, of course, a bandwagon effect going on in the field of climatology, just as there is in cosmology. This tends to stifle debate, make things difficult for dissenting views to be heard and evaluated rationally,  and generally hinders the proper progress of science. It also leads to accusations of – and no doubt temptations leading to – fiddling of the data to fit the prevailing paradigm. In both fields, though, the general consensus has been established by an honest and rational evaluation of data and theory.

I would say that any scientist worthy of the name should be skeptical about the human-based interpretation of these data and that, as in cosmology (or any scientific discipline), alternative theories should be developed and additional measurements made. However, this situation in climatology is very different to cosmology in one important respect. The Universe will still be here in 100 years time. We might not.

The big issue relating to climate change is not just whether we understand what’s going on in the Earth’s atmosphere, it’s the risk to our civilisation of not doing anything about it. This is a great example where the probability of being right isn’t the sole factor in making a decision. Sure, there’s a chance that humans aren’t responsible for global warming. But if we carry on as we are for decades until we prove conclusively that we are, then it will be too late. The penalty for being wrong will be unbearable. On the other hand, if we tackle climate change by adopting greener technologies, burning less fossil fuels, wasting less energy and so on, these changes may cost us a bit of money in the short term but  frankly we’ll be better off anyway whether we did it for the right reasons or not. Of course those whose personal livelihoods depend on the status quo are the ones who challenge the scientific consensus most vociferously. They would, wouldn’t they?

This is a good example of a decision that can be made on the basis of a  judgement of the probability of being right. In that respect , the issue of how likely it is that the scientists are correct on this one is almost irrelevant. Even if you’re a complete disbeliever in science you should know  how to respond to this issue, following the logic of Blaise Pascal. He argued that there’s no rational argument for the existence or non-existence of God but that the consequences of not believing if God does exist (eternal damnation) were much worse than those of behaving as if you believe in God when he doesn’t. For “God” read “climate change” and let Pascal’s wager be your guide….

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81 Responses to “Skepsis Revived”

  1. Anton Garrett Says:

    I don’t entirely agree with that OED. In the 1980s, ‘sceptic’ was the accepted UK spelling, and the UK branch of that movement which doubts the paranormal used the word ‘skeptic’ specifically to differentiate us from the general meaning of the word in the UK. (I don’t know whether the Skeptical movement in the USA had previously done the same thing in their country.)

    Pascal’s wager applied to climate change? It wasn’t applied when there was genuine concern among scientists that the first A-bomb or H-bomb would initiate a nuclear chain reaction that would consume the earth. Should it have been? And people don’t use it today to justify going indoors for risk of being struck by lightning by a distant thunderstorm, though lightning can occasionally travel anomalous distances horizontally through the atmosphere.

    • telescoper Says:

      Oops. Got it the wrong way round – hurried cut-and-paste. Now corrected.

      As for Pascal’s wager, the other examples you quote seem to have better defined (and extremely small) probabilities of a negative outcome.

  2. Monica Grady Says:

    Two comments:
    1) very disappointed to read about “this data” – I thought you were a purist on grammatical precision?

    2) Skepsis would have been a good title for the new open journal that you are piloting. Such a good title, though, that it has already been taken by a group of german philosophers. See http://www.academia-verlag.de/titel/66151.htm. The principles behind their journal, which is published annually, are:

    Skepsis is a journal for Philosophy and Inter-disciplinary Research. Its title denotes its principles: Critique and inquiry. Grounded on the constructive side of Scepticism, Skepsis provides an international forum for essays which, irrespective of their subject matter, manifest the impasse the mind reaches when it assents to dogmatism. Skepsis respects the intellectual tradition; however it grounds the truth on searching criticism and questions the principles of scientific discovery.

    • Anton Garrett Says:

      Consider it an abbreviation for “this dataset”…

      ‘Skepsis’ is unhappily close to “sepsis”!

      More seriously, I regard the comment, often repeated by scientists, that the scientific method is based on doubt and scepticism to be so one-sided as to be misleading. Science is guided by deep commitment to a certain set of principles, which are stated so seldom that they can get forgotten – even by scientists. Nullius in verba is just one of those. There is also the axiom that order in nature does genuinely exist and can be apprehended by our senses. Science is a passionate activity – it is conducted with passion by scientists, but with no prior commitment to the outcome which is settled by nature. (That’s why ‘creation scientists’ are bad scientists – the issue is agenda rather than about agenda rather than professional competence.)

    • Since I was referring to the obviously enumerable set of points on the graph, I agree that “these data” is correct and I have amended the text.

      I think “this data” is fine when referring to the non-count form which requires units (e.g. Gybte) – e.g. “have you reduced that data yet?”

  3. The temperature reconstructions are unfortunately not terribly reliable.

    For example, the headline IPCC reconstructions (looking at it, the plot you show appears to the one of these ) mine for a hockey stick shape.

    For example the Mann et al. classic study used a PCA algorithm which would have given a hockey stick to random noise. This has the effect of giving the one proxy which has a hockey stick a dominant weight and suppressing the rest. Interestingly the paper says that the reconstruction is robust to the use of a single proxy. This was shown to be false.

    Another source of bias is that analyses typically make a selection of a subset of proxy samples such that they match the 20th century rise.This sounds sensible. However, it is “double dipping” . If the data were just random noise (or noise + temp signal) it would give (or promote) a hockey stick by construction.

    The above are fundamental issues with this type of work. I certainly think its an interesting exploratory field. However, using the present results to inform public policy (and indeed to scare the public) is dishonest.

    Another concern is the response of the climate community to well reasoned criticism (as above). They have bunkered down and defended their methods, conceding nothing (in public though not in private as per their mails) and attacking the critics. This works for true believers although I’m disappointed by this.

    • Can you give references on those criticisms? I’m interested to learn more…

      • Anton Garrett Says:

        That’s your view of what it does, Philip. It’s just a blog on one side of the debate.

      • “It’s just a blog on one side of the debate.”

        Yes, but very detailed with many, many references.

        The question remains, and it is an important question: As long as there is more than one side, what is the criterion by which one can decide which side to believe? This is especially important for politicians, who obviously can’t be experts on all types of science but have the job to make decisions.

        The idea that climate researchers support AGW because they receive government money is absurd. This is “the Apollo landings were faked in the studio” level conspiracy theory. Note that no government had an agenda that AGW is a problem and funded people to justify it; rather, the idea that AGW is a problem came from basic research. You make it sound like the members of the cabinet own stakes in renewable-energy companies or something and are perpetrating a hoax in order to fill their own pockets.

        Also, if the researchers wanted more money, wouldn’t they say “we’re not sure; give us more money so we can refine our analysis” and not “we believe that GW exists and that it is AGW” which, if anything, could entice the government to say “OK, thanks; now you don’t need any more funding for this”?

        Some things are just obviously absurd, such as the claim that rock groups put subliminal messages on their records which cause people to commit suicide. As one rock musician remarked, if such things actually worked, wouldn’t the message be “buy more records” rather than one which caused their own customers to die?

        Say you are an adviser to a politician. You would tell him that AGW is not decided in the scientific community. What about the age of the Earth? Whether evolution existed? Whether the Earth goes round the Sun or vice versa? The debate exists in all of these issues, and many more as well. When should one “teach the controversy” and when should one recognize that a consensus exists which should at least be accepted as a tentative working hypothesis? I don’t mean your opinion but some objective criterion which a politician can use. Should it be who shouts the loudest? Who donates the most money? Remember, he can’t know enough about any such issue to make an informed decision based only on his own knowledge.

        Regardless of the by-laws of the RS or the interpretation of them, it would seem to me that something like the RS should indeed advise the government on scientific issues.

        Is there any AGW “sceptic” who is not very religious and/or politically conservative? (Another issue are people who say that AGW is real but that the state of humanity could be better improved by funding other things such as vaccinations, clean water etc and worry that the concern with AGW might siphon off funds which are needed more elsewhere.)

      • Hi Peter,
        my comments are restricted to the historical reconstructions. However, these have been used extensively by CAGW-proponents in the public sphere.

        The site below gives a good description of the criticisms of hockey sticks, in particular the data which featured on the front page of an IPCC report (and appeared in Gore’s film etc -I think its the one you showed) .

        http://climateaudit.org/multiproxy-pdfs/

        There was quite a battle between the crtics and the authors, leading to expert panels being called in. Both panels pretty much agreed with the criticism though one (with climate scientists involved) was a little more muted saying that the original conclusions were “plausible” even though the methods flawed (not sure what that means). The Wegman report (former president of the US NRS Stats Committee) was especially damning in his criticism. However, this being climate science, some critics noted that parts of his report (the standard boiler plate text supplied by his student, had been lifted from another source). This was therefore plagiarlsm and the report can be safely ignored etc.

        Many of the problems of the “classic” hockey stick also feature in other hockey sticks. Most notably poor statistics which artificially promote hockey sticks.

        The most prominent critic is a chap called Steve Mcintyre. Although lots of allegations have been levelled against him I’ve yet to see any have any substance (eg in the pay of the oil company). Many in the climate community would have done better to have addressed his criticisms rather than attacking him. They in fact would have done better to have come up with those criticisms themselves instead of allowing flawed results to be used for so long in public.

        It seems, however, as if things are changing albeit slowly. The hockey stick fever is (very slowly) abating with more recent reconstructions showing nothing exceptional about the 20th century.

        Regarding the “double dipping” fallacy i.e. selecting a subset of proxies which happen to be close to the recorded temperatures and then making the claim that your proxies show a good correlations, a recent paper (Karoly et al. – now withdrawn) used so-called detrending to mitigate against this effect. They then apparently got a hockey stick for the Southern Hemisphere. However, thanks to a bit of detective work and attempts at reproduction (that pesky Mcintyre and his readers again) it turned out that they had failed to detrend. They then had to withdraw the paper since the corrected analysis (i.e. no double dipping) didn’t provide enough data after selection. I think they may well be resubmitting and pretending it doesn’t matter anyway since everyone else double dips.

        None of the above means that AGW isn’t happening. In fact the historical stuff is used largely as PR fluff – attribution studies are typically made with the models alone. However, I find it difficult to assign too much trust to a AGW interpretation of recent warming given that reconstructions of the past are so uncertain (we don’t know enough to exclude natural variations).

      • Anton Garrett Says:

        Philip: how government should proceed when there is no informed unanimity over a technical issue can be seen to be a difficult issue regarding matters of economics.

        “The idea that climate researchers support AGW because they receive government money is absurd.”

        Although your side of this debate shamelessly uses that argument in relation to the far smaller amounts of money that one or two oil companies put into research (before they saw much more money available by diversifying to get green subsidies), you are in fact building up your own straw man beyond what I said or anything it implied. The effect of money is more subtle, more insidious. It includes selective funding for grant applications and scientists who do research predicated on dangerous anthropic global warming, and partisan journal editors. for more detail, see:

        http://jonova.s3.amazonaws.com/sh2/the_skeptics_handbook_IIj-sml.pdf

        “Is there any AGW “sceptic” who is not very religious and/or politically conservative?”

        Last time you asked whether there was any skeptic of DAGW (don’t forget the ‘dangerous’) who was not a religious fundamentalist. I gave you one. Now you ask whether there are any who are not religious and/or politically conservative. And your side suggests that *my* side puts out smears! That question is of course unanswerable, as political affiliations are not stated among the scientists who have publicly signed statements of scepticism. There are so many that I expect you will find all shades of political opinion represented, not that it matters to the science.

        Your rhetoric is that of someone who has read only one side of the argument, and/or the other side only in your own side’s words, in caricature.

        PS Peter: From memory, it was Steve McIntyre who showed that random data gave a hockey stick 9 times out of 10 according to Mann’s protocol.

        The scientific issue is this: for a dry atmosphere it is today an undergraduate exercise (first done by Arrhenius) to determine the amount of heating caused by a given amount of CO2. But the amount of warming due to incremental CO2 is to be multiplied by a certain factor due to water vapour in the atmosphere, and the value of that factor is what is under fierce contention, both theoretically and experimentally. The IPCC says it is about 3 (and shouts alarm). Skeptics say it is close to one and perhaps less than it, ie between 0 and 1.

      • The Mann results are broadly consisent with others in the literature. For example, see the summary of http://books.nap.edu/openbook.php?record_id=11676&page=R1 which provides an overview of the field as of 2006.

        McIntyre and McKitrick criticisms of Mann are discussed and debunked at http://www.realclimate.org/index.php?p=121

      • Michael
        Yes, some other reconstructions give hockey sticks. If you compare with those then of course the Mann et al. result looks fine. If you pick the ones that don’t (eg eg Jan Esper et al, Global and Planetary Change 88–89 (2012) 1–9) then the picture changes. The problem is you’re not allowed to cherry pick in science. Presenting a tidy picture when the data don’t allow it is not permitted. Its poor scientific practice of the type which leads to data points being removed from graphs because they go in the wrong direction (the famous “hide the decline” of reconstructed temps in the late 20th century in a recent IPCC report). I don’t do that type of thing. Nobody I know in my field does that type of thing. Its not allowed. Adverse data usually tell you something. The historical reconstructions are problematic and shouldn’t be used (even if some of them look striking and are great PR figures).

        Regarding the “debunking” source you gave, its hardly suprising that a website run by Mann and colleagues will be hostile to the criticism. The independent committees (North and Wegman) which were set up to review the criticism found them valid.

        I’ve never understood why admitting to criticism is so hard in this field. Science is very rarely definitive. In most fields the practitioners try to break paradigms and not defend them. This is how paradigms are strengthened.

      • RW
        First I regurgitate blindly things on blogs (even though I’ve read the papers) and now you accuse me of inventing things.

        Regarding my “invention”, my words on attribution were very clear – I referred to “quantitative attribution”. Quantitative IPCC statements which purport to determine the extent to which man has influenced the temperature are not determined by the hockey sticks. The IPCC quantitative statement on attribution is that, with a 90% confidence, mankind is driving recent climate change. This quantitative attribution statement is made with models and instrumental data. You should be grateful that this is the case since the reliability of the hockey sticks are problematic. In addition to the statistics problems, some of them actually go down in the late twentieth century. I know the IPCC reports just remove these “inconvenient” data points to present a tidy picture but that’s appalling scientific practice. Or do you think its perfectly ok to trim the distributions to show the shape you want ? Furthermore, you write that removing the one dominant proxy doesn’t kill the hockey stick shape. This is shown in the M&M work which I referenced. If they are wrong then please show the graph i.e. Mann et al. without the dominant proxy ? Why is it ok to have an algorithm which would give a hockey stick shape with noise ? What do you think would happen in the real life world of signal+noise (i.e. not 100% signal nor 100% noise) ? Do you think it could cause a bias towards a hockey stick ? If not, why not ?

        Regarding the rest of your post I’m afraid this really is becoming tiring. The majority of reconstructions are locally based (Mann’s was – in effect it was very locally based given the weighting of one proxy). If you dislike my example then you’ll end of rejecting a whole load of studies you do like. Cherry picking is not a sensible approach.

      • “Why is it ok to have an algorithm which would give a hockey stick shape with noise”

        For heaven’s sake, Dave, will you just understand this simple point? The algorithm reveals patterns that are present in noisy data. If a hockey stick pattern is not present, the algorithm will not find one.

      • RW
        The algorithm finds a hockey stick when none is present at generation (red noise). What I don’t understand is why you think this is acceptable for a study for which finding a real hockey stick (as opposed to another shape) and measuring the properties of that stick provide central conclusions of the work.

        To put in the context of my own field, if we used algorithms to look for and measure a Higgs signal (peak of a certain width on a background) which made the random background mimick the signal we’d be laughed at (and rightly so) even if the “background Higgs” was slightly different (eg width a bit bigger). We certainly wouldn’t be defending it loudly and insulting anyone who objected to it.

        Regarding the deletion of adverse data which deviates from the instrumental record, what is your view here ? Do you think it misleading ? I do.

        Also, I’m missing the graphs showing what happens if the dominant proxy is removed from the Mann et al. study. Please show us that the hockey still is still presented there. I provided references to the peer reviewed literature in which it is no longer present. You said this is untrue. This is your chance to show I’m wrong rather than saying I’m wrong. Please take it rather than throwing an insult.

      • “The algorithm finds a hockey stick when none is present at generation”

        Same old, same old. It does not. This is a lie, spread by professional disinformers, and you’ve obviously fallen for it much too enthusiastically to ever be able to let go.

    • Roger Wesson Says:

      You start with falsehood, which you seem to have picked up from a blog run by an ex-mining consultant. The principal components analysis which first revealed the “hockey stick” shape of global temperature trends would have found a hockey stick in random noise, if a hockey stick shape was present by chance. It did not and could not turn no trend into a statistically significant trend. The hockey stick is revealed by the analysis because it is present in the data.

      Using the best results available to inform public policy is common sense. How you can think of it as dishonest, I can’t imagine.

      Who is trying to scare the public? Are the public getting scared? Should those who realise there is a potential disaster ahead somehow take it upon themselves to avoid scaring the public?

      • Roger
        You illustrate my point (about attacking people) very well. The fact someone is an ex-mining consultant is neither here nor there. I have lots of letters after my name but I don’t think it implies anything about the quality of any argument I may put forward.

        Both the North report and the Wegman reports independently found that the ex mining consultant’s criticisms were valid. These committees were explicitly set up to try to settle the dispute. One nevertheless found the Mann et al. study’s conclusions “plausible” even though the wrong methods were used and the other was simply damning. This hardly represents either a ringing vindication of the paper or a condemnation of the stupidity of an ex mining consultant.

        If the data were purely noise then this wouldn’t pass the selection on significance. However, should one use any algorithm which delivers a hockey stick shape from noise then one is highly sensitive to bias in a real life signal+noise situation which would artificially inflate a hockey stick blade. In short, its best to avoid algorithms which have a bias to deliver a predefined shape especially if getting that particular shape is a message of your paper. The central conclusion of the Mann et al. work was that recent times have shown unprecedented warming even smallish shifts are going to change this conclusion.

        Still on Mann et al., they argued in the paper that their work was insensitive to the composition of proxies. This simply isn’t true. It depends critically on one out of many proxies (the rest being weighted down). Take that one proxy away and the hockey stick vanishes (see the links I posted earlier). The algorithm mined for a hockey stick.

        You write that we need to use the best results to inform public policy. If this is one of the best results then the field is in trouble.

      • Anton Garrett Says:

        McIntyre has put plenty of critiques of the hockey stick analysis into mainstream peer-reviewed journals:

        http://en.wikipedia.org/wiki/Stephen_McIntyre#Selected_publications

      • Anton

        The ex mining consultant (and a reader of his blog) also killed a flawed paper which had received a lot of publicity showing an apparent hockey stick in the Southern Hemisphere.

        They couldn’t reproduce the work and discovered a mistake. The paper has now been withdrawn. Funnily enough the authors claimed they independently found the mistake (after peer review in proofs stage and at the same time – within the hour – of the mistake being discussed on the ex mining engineer’s blog).

        The ex mining consultant is rather competent considering he’s only an ex mining consultant.

        The ex mining consultant is btw not even what is termed a “climate denier”. He just seems to dislike sloppy statistical analysis. He also campaigns for open access to data used for public policy development.

      • Of course someone’s expertise is highly relevant. I wouldn’t trust an ex-mining consultant to inform my views on the accelerating expansion of the universe, and nor do I trust an ex-mining consultant to inform my views on the attribution of recent climate change. If the letters after your name don’t give your views in the relevant areas any greater weight at all then I can’t imagine why you got them.

        A publication based largely on the Wegman report was subsequently retracted due to plagiarism. Mann’s original work has been extended and reconfirmed by himself and several other groups. There is no doubt about the basic result.

        The PCA in Mann’s analysis did not generate hockey sticks from noise, nor artificially inflate any. Noise sometimes contains hockey stick shapes, by chance, and the algorithm would find those. It would find them whether they turned up or down, and it would find other shapes too, if they were present in the data. The hockey stick shape of the global temperature reconstruction was present in the data, which is why the algorithm found it. It is real.

      • RW

        Expertise is highly relevant, credentials less so. The ex mining consultant has demonstrated via peer reviewed works that he has this expertise. Why do people still feel the need to write that he’s an ex mining consultant ? I’m more interested in the quality of an argument than credentials.

        The “plagiarism” in the Wegman report was boiler plate text from a student. I think you probably know this. However, in the highly charged “climate war” any weapon will do to attack someone who comes with a disagreeable message.

        I don’t know how you can maintain that the hockey stick in Mann’s paper is real given that (a) random noise gives a stick and (b) it relies on one out of (from memory) 56 proxies to produce it. The hockey stick may well be real but Mann’s work can’t be used to show it. Furthermore, you may or may not be aware more recent reconstructions seem to be abandoning the hockey stick.

        This is complicated stuff. Its quite ok to say we don’t simply know if today’s temperatures are higher than they were 500 years ago.

      • “random noise gives a stick”

        You’re not understanding. Principal components analysis will reveal a hockey stick shape in data, if the hockey stick shape is in the data. If you generate enough random noise, you will generate some that by chance contains a hockey stick. If you apply PCA to that noise, it will reveal the hockey stick. It is not correct to claim that “random noise gives a stick”.

        ” it relies on one out of (from memory) 56 proxies to produce it”

        Not true. See the many studies which use different proxies and different analysis techniques, and come to the same conclusion. A few are plotted here:

        “recent reconstructions seem to be abandoning the hockey stick.”

        Also not true.

        “This is complicated stuff. Its quite ok to say we don’t simply know if today’s temperatures are higher than they were 500 years ago.”

        It’s not ok to say that if the data tell us the opposite.

      • Anton Garrett Says:

        RW,

        Nobody is disputing that if a hockey stick is present in randomly generated data then Mann’s protocol would find it. But if a hockey stick is NOT present then will this protocol indicate one?

      • “if a hockey stick is NOT present then will this protocol indicate one?”

        No. Principal components analysis is used in many fields of science and if it had some kind of inherent bias that extracted hockey sticks from data where they were not present, you can be sure it would not be widely used at all.

      • RW
        As Anton wrote, nobody disputes that the Mann analysis would give a hockey stick if a hockey stick was there. The problem is that it is biased towards giving a hockey stick.

        Regarding the multiproxy study you haven’t understood the posts. I’m referring to Mann’s multiproxy study. It is stated in the paper that the results are insensitive to the use of different proxies. That is untrue. If one proxy is removed the hockey stick vanishes. That result is weak science and should never have been used to influence public opinion. I’m surprised that people still defend it now. Much better to admit is was poor and move on.

        Regarding the other studies, yes of course some come up with hockey sticks. Others don’t. Some reconstructions even go down in the late twentieth century. The point is that one can’t cherry pick. Science doesn’t work like that. The data at present don’t allow us to say that the 20th century warming is exceptional. This doesn’t falsify the AGW hypothesis but does dent it, not least since so many AGW proponents were so enthusiastic about waving around plots from a very flawed paper and defending to the hilt that which can’t reasonably be defended.

      • Anton Garrett Says:

        RW,

        I’m aware what PCA is. I don’t know exactly how it was applied by Mann and that’s why I ask whether *in his protocol* it would see hockey sticks where there aren’t any.

      • Anton
        Mann’s study selectively picked up one proxy which had a hockey stick shape and gave it a dominant weight in the PCA. (From memory) I think there were over 50 proxies. The rest weren’t hockey stick shaped. In the paper it was stated that the results were *not* sensitive to one proxy. This was untrue and was shown to be untrue (even by Mann’s own former student in an attempted replication if my memory is correct here).

        In answer to your question, in a multiproxy setting, Mann’s algorithm was excellent at finding hockey stick when there isn’t one present (for most of the proxies).

        BTW the one proxy which is hockey stick shaped is not recommended as a temperature proxy (I think this was a consequence of the North report) since it is thought to have responded to the CO2 and not temperature.

        In science conceding a flawed study should be trivial. Nobody holds grudges, we just learn and move on.

      • “Dave”, you are just regurgitating nonsense that you’ve picked up on anti-science blogs now.

        “As Anton wrote, nobody disputes that the Mann analysis would give a hockey stick if a hockey stick was there. The problem is that it is biased towards giving a hockey stick.”

        No, it isn’t. You’ve been duped by misinformers. Shame on you for that.

        “If one proxy is removed the hockey stick vanishes. That result is weak science and should never have been used to influence public opinion. I’m surprised that people still defend it now. Much better to admit is was poor and move on.”

        Not true. The result has been confirmed by numerous subsequent studies. It was not poor, it was a landmark in paleoclimatology. You’re surprised that people defend it only because you’ve been duped by misinformers into believing things about it that aren’t true.

        “Regarding the other studies, yes of course some come up with hockey sticks. Others don’t. Some reconstructions even go down in the late twentieth century.”

        Why “of course”? And which studies do you have in mind which have temperatures going down? Ground and satellite temperature records show a sharp rise during the late 20th century.

        “The data at present don’t allow us to say that the 20th century warming is exceptional.”

        Define “exceptional”.

        “Mann’s study selectively picked up one proxy which had a hockey stick shape and gave it a dominant weight in the PCA.”

        Untrue.

        “In the paper it was stated that the results were *not* sensitive to one proxy. This was untrue and was shown to be untrue (even by Mann’s own former student in an attempted replication if my memory is correct here).”

        Your memory is not correct.

        “In answer to your question, in a multiproxy setting, Mann’s algorithm was excellent at finding hockey stick when there isn’t one present (for most of the proxies).”

        It did not, and could not, find a hockey stick shape in the data unless one were present.

        “In science conceding a flawed study should be trivial. Nobody holds grudges, we just learn and move on.”

        A study whose results have been widely replicated and confirmed is not a flawed study. Indeed, we move on, and no actual scientists are still fighting the battles that you’re engaged in.

      • RW
        Please don’t assume you know what I’ve read. I make no assumption about you. I’ve read the blogs, the papers, the critiques, the replies and the reports. Writing I’m wrong doesn’t make me so nor does writing that I’m duped. I dislike the belief that many physicists have in, eg, TeV-scale supersymmetry. I find the arguments rather weak. However, I don’t tell SUSY-proponents that they’re duped and get their info from misleading blogs. This isn’t how science works.

        The peer reviewed literature I described plus the reports commissioned to look into the dispute support me on the conclusions I made on the Mann et al study. It shouldn’t be a controversial viewpoint.

        The Mann study does promote hockey sticks and it does consequently rely on one proxy. This is all in the peer reviewed literature. Furthermore, that one proxy is now thought to to be CO2-sensitive rather than temperature sensitive – North report, from memory). It is a matter of legitimate concern to those of us outside the climate community that a paper which was flawed in these ways is still defended and promoted (loudly) when it should have been quietly shelved and forgotten.

        As I mentioned, yes of course other studies give hockey sticks. However, others don’t (eg Jan Esper et al, Global and Planetary Change 88–89 (2012) 1–9). You are not allowed to cherry pick those which support your viewpoint. Science doesn’t work that way even if politics does.

        Temperature reconstructions are messy. The likelihood is that they can’t be used to help in any attribution argument regarding 20th century warming. Indeed the quantitative attribution arguments made by IPCC don’t use them at all.

        One final point – the world has changed. Just as the peer reviewed literature contains it fair share of scientifically worthless journals the internet contains its fair share of scientifically worthwhile blogs. It doesn’t work to dismiss an argument since it might first have appeared on a “blog” run by an “ex mining consultant” (who happens to have a good grasp of statistics). Climate scientists have discovered this to their cost (eg Karoly et al., withdrawn after the blog hosted a discussion the reproducibility of the study, Mann et al. for obvious reasons) .

      • “Please don’t assume you know what I’ve read.”

        Your dogged repetition of specific false claims makes it very clear where you are getting your information from. It’s not even an assumption.

        “The peer reviewed literature I described plus the reports commissioned to look into the dispute support me on the conclusions I made on the Mann et al study. It shouldn’t be a controversial viewpoint.”

        You’re clearly not familiar with the peer reviewed literature. Mann et al’s work has been validated, confirmed, extended and built upon in the peer reviewed literature.

        “The Mann study does promote hockey sticks and it does consequently rely on one proxy.”

        Their methodology did not and could not “promote” hockey sticks. Their conclusions did not rely on one proxy. See the numerous similar results in the subsequent literature.

        “It is a matter of legitimate concern to those of us outside the climate community that a paper which was flawed in these ways is still defended and promoted (loudly) when it should have been quietly shelved and forgotten.”

        You’ve been duped into believing the study was flawed. Good science should not be “shelved and forgotten”. Results that have been widely replicated and confirmed should not be “shelved and forgotten”. The Mann results stand, and it’s really time you accepted that. It’s been almost 15 years since they were first published.

        “As I mentioned, yes of course other studies give hockey sticks. However, others don’t (eg Jan Esper et al, Global and Planetary Change 88–89 (2012) 1–9). You are not allowed to cherry pick those which support your viewpoint. Science doesn’t work that way even if politics does.”

        You never explained why you say “of course”. And it’s a little difficult to see why you think the Esper et al reconstruction of summertime temperatures in northern Scandinavia can be directly compared to global or hemispheric reconstructions.

        “Temperature reconstructions are messy. The likelihood is that they can’t be used to help in any attribution argument regarding 20th century warming. Indeed the quantitative attribution arguments made by IPCC don’t use them at all.”

        If you are going to make simple factual claims that are easily checked, you should try to make them accurate. There is a chapter in the IPCC 2007 report entitled “Understanding and attributing climate change”. There is a section in that chapter entitled “What can be learned from the past 1,000 years?”. And what do you suppose they discuss in that section? Why invent stuff, Dave? There is no longer a sensible discussion to be had if that’s your style.

      • Anton Garrett Says:

        RW,

        You have read Mann and the ensuing discussion in more detail than me, in which case you should be able to support your arguments with better references than the IPCC. It is run by a railway engineer (not even a mining consultant) and is almost wholly political, as one of its senior members Ottmar Edenhofer admitted in an interview with the Neue Zuercher Zeitung (14/11/2010): “We redistribute de facto the world’s wealth by climate policy… one has to free oneself from the illusion that international climate policy is environmental policy. This has almost nothing to do with environmental policy any more”.

      • Dave, you still don’t understand that PCA does not and cannot find patterns that are not there. Nor will it imply that the patterns revealed are statistically significant if they are not. Even if it could, why would it find hockey sticks that turn up and not hockey sticks that turn down? This doesn’t seem to have occurred to you.

        Anton Garrett – if you don’t like the IPCC reports, you could read some of the thousands of scientific papers referenced therein. Forgive me if I continue to accept them as excellent summaries of the state of climate science and do not reject them in their entirety on the basis of a single out of context quote.

      • Anton Garrett Says:

        I forgive you.

      • “Ottmar Edenhofer admitted in an interview with the Neue Zuercher Zeitung “

        This seems to be the source:

        http://www.nzz.ch/aktuell/startseite/klimapolitik-verteilt-das-weltvermoegen-neu-1.8373227

        It is an interview. There are no quotation marks to indicate who said what. The short (1- or 2-sentence) paragraphs are the questions (some of which have some interpretation by the interviewer) of the previous answer and the longer ones are the answers.

        As someone fluent in German, he seems to be stating the reality that climate-political decisions have economic consequences and vice versa. Your use of the word “admitted” makes it sound like he owned up on the fact that AGW is a hoax. This is not what he meant, by any stretch of the imagination. Maybe some aspects (like what is from the interviewer and what is from the interviewee) were lost in translation but of course the original is definitive.

        It is quote-mining like this which gives the AGW “sceptics” a bad name, but apparently they have no choice but to resort to such tactics.

        Yes, the article could have been clearer about who said what, what are (implied) questions and what answers, but this is not difficult. Before quoting a source, one should understand it. Maybe something was lost in translation, but that is no excuse.

      • Anton Garrett Says:

        Phillip: Yes, that’s the source. I checked out the German original myself a while ago. With occasional recourse to a dictionary, my German is good enough to verify the accuracy of the sentences I reproduced in English, and I note that you haven’t challenged the accuracy of the translation.

        As to who said it, which of a senior member of the IPCC and a newspaper reporter is going to say ““We [wir] redistribute de facto the world’s wealth by climate policy…” Last time I looked the Neue Zuercher Zeitung was not a major climate lobbyist.

        The interview was certainly wide-ranging, but how does context alter the meaning of that passage?

      • Quite simply, context is everything. This is a classic example of quote mining. It’s almost as bad as extracting “there is no God” from “The fool hath said in his heart, There is no God” (Psalm 14:1) and saying “There, even the Bible says that there is no God”.

        I don’t question your translation and it is clear that Edenhofer said this. Nevertheless, the context is important. The interview is not about AGW at all. (My guess is that both interviewer and interviewee don’t question its existence.) It is about the economic consequences of climate politics. Edenhofer is not “admitting” to anything here. Yes, Edenhofer said that climate policy redistributes wealth. Whatever one thinks of AGW, it is clear that change is possible only with economic incentives. This is almost a tautology.

        Context is everything.

        Stradivari puts up a sign “Best violins in the world”. Down the street, Guarneri puts up a sign “Best violins in town”. Context is everything.

      • Anton Garrett Says:

        I get your message that context is everything, but if that were true then the meaning of words would be entirely determined by context, which would imply that they have no intrinsic meaning, which is false. Context is certainly significant, but you have not explained how the plain meaning of that quote is negated by context.

      • OK, “context is everything” was hyperbole, particularly in the context of the joke. (This is the only hyperbole from me in this thread.) As to explaining it, one has to read the context. The original source is online. People are free to read it (and get it translated if necessary), read your quotation from it and determine whether it creates a misleading impression.

  4. “This is a good example of a decision that can be made on the basis of a judgement of the probability of being right. In that respect , the issue of how likely it is that the scientists are correct on this one is almost irrelevant.”

    But there are an infinite number of judgements we could make about all sorts of events that, however improbable, could possibly occur and that we would wish to avoid.

    The God analogy is useful here. Which God should we believe in? And I don’t mean which God among the Gods of Christianity, Islam, Hinduism etc. I mean all possible Gods that may possibly exist (and send us to hell if we don’t believe in them). To be on the safe side, according to Pascal’s wager, we should believe in all of them, adhering to all possible doctrines in order to avoid the worst possible fate. We would have to believe in an infinite number of propositions, all of which would inevitably be contradictory to other beliefs that you’re supposed to hold!

    I think even faced with the worst possible future scenarios, people will want to convince themselves through evidence that action is worth taking or else Pascal’s wager would have us forever worrying about an infinite number of things that might happen and expending all of our energy trying to avoid those things.

    • This is very similar to the suggestion put forward by the Quirmian philosopher Ventre, who said, “Possibly the gods exist, and possibly they do not. So why not believe in them in any case? If it’s all true you’ll go to a lovely place when you die, and if it isn’t then you’ve lost nothing, right?” When he died he woke up in a circle of gods holding nasty-looking sticks and one of them said, “We’re going to show you what we think of Mr Clever Dick in these parts…”.

      —Terry Pratchett, in HOGFATHER

  5. “Moreover, there are other possible explanations. Maybe supernovae were different beasties back when the universe was young. Maybe something has absorbed their light making them look fainter rather than being further away.”

    Most of the effort of the two groups who did the work for the Nobel Prize went into answering these types of questions, not for understanding 1950s cosmology and making a plot. This tends to get overlooked. Yes, we should be sceptical, yes we should be open to new possibilities and yes a false consensus can be a problem (like when most people believed in the Einstein-de Sitter model). However, at least the consensus now is based on data and has been independently verified. Moreover, it was not the conclusion the people involved expected. Science doesn’t get any better than that. I’ve often heard these criticisms of the SNIa work, which unfortunately makes it look like that someone who works in a completely different field within 30 seconds was able to come up with a “but have you considered…?” remark which shatters the conclusions which were years in the making. It ain’t so, Guv’nor. :-)

    I think the positive cosmological constant is in the same status today as Omega < 1 was a few years ago. At first, many people said that it just can't be so, but some people (you and George Ellis, among others) argued that this is what the data show and now it is, probably correctly, consensus.

  6. IMO the SN1a diagram isn’t just not superficially convincing – it’s also deeply not convincing. Even with proper binning [which seems to be anathema to SN people] the statistics weren’t good enough at that point to be *convincing* – though they were certainly pretty intriguing as evidence. And, of course, there were the many possible systematic issues, which had to be investigated and checked one by one.

    What does seem to have been convincing is the combination of the SN data with many other pieces of evidence that had already been around for some time and turned out to fit together well. The dL-z diagram on its own isn’t that informative…

    • I agree. To put it another way, I’d say that if we *only* had the Supernova data and nothing else (especially no CMB and no LSS clustering) then nobody would believe in dark energy….

  7. Anton Garrett Says:

    The Bayesian approach to hypothesis testing requires those hypotheses as input. Consequently, the same data that prefer Hypothesis ‘A’ when tested against ‘B’ may actually discriminate *against* ‘A’ when a new hypothesis ‘C’ is tossed into the ring. Example: the datapoints lie close to a straight line of gradient 2. ‘A’ is a physical theory predicting gradient 1.5, ‘B’ predicts gradient 1, and the newcomer ‘C’ predicts gradient 2.

    All hypothesis testing is comparative.

    • Yes, and in the case of the SN data the curves are obtained from Friedman models with different parameters; the “best” one is selected from this subset. But it’s perfectly possible that an alternative model will eventually be found that provides an even better fit.

      • Can you quantify this? If the selected FLRW model fits the data with an acceptable goodness of fit, then there is no motivation to introduce a new model, especially if it fits too well. One can always find an arbitrarily complicated model which fits arbitrary data arbitrarily well.

  8. Peter,

    That’s a great post.

    in regard to the comments that follow the post:

    I would encourage those who are interested, irrespective of ones thoughts on the matter, to actually become informed about the science and debate rather than just repeat things read from the web. For full disclosure, much of my research has a direct link to climate, and I have read and learned the science (try reading Physics of Climate by Peixoto and Oort, the new book by Pierrehumbert, the actual IPCC reports), and I do read information from BOTH sides (I read Nova’s blog as well as Tamino’s and RealClimate and WattsUpWithThat and TheBlackboard etc.). I encourage people not to just accept the information they read from either side, but to actually research BOTH sides of the argument and think about them rather than parrot paragraphs. Also, FOLLOW UP on what you read, look for rebuttals etc. — you will often find that statements continue to be made long after they have been shown to be false.

    In response to Anton’s comments about Tamino’s blog, it is indeed “just a blog”, however peer-reviewed papers have come out of this “just a blog”, and what is more, Tamino is an equal-opportunity debunker and has critiqued recent papers by Hansen on his “just a blog”.

    I would strongly suggest that people also read the link that Anton provided to Jo Nova’s work. I suggest that they also follow up the sources cited in that work (I wonder if anyone can find the British peer). Also look for critiques of her representation of the science. Also, look at the tables in her presentation (they are in the Appendix) and notice that the header in columns 2 is “Climate Science”, not Anthropogenic Global Warming — this is rather like saying that the whole astronomy budget is being spent on cosmology!

    As for funding, climate research is expensive; seeding doubt is cheap. I also doubt that there is a significant bias in funding towards projects in favor of global warming. Having sat on funding panels, I can truthfully say that this has most definitely NOT been my experience.

    For the more technical stuff (Peter asked for references, and I’ll try and supply some), the original Mann et al paper (Nature, 392, 779, 1998) used a principal components analysis as a means of data reduction to obtain past temperature records. This was among the first attempts to do this globally. Their PCA procedure was criticized by several (including McIntyre et al. http://www.agu.org/journals/gl/gl0503/2004GL021750/2004GL021750.pdf), and Mann et al agree that it was not the most sophisticated analysis that could be done. However, this aforementioned paper also is flawed (see e.g. Wahl and Ammann (Climate Change, 85:33-69, 2007). The general consensus appears to be (and one can perform these analysis oneself using the data and R or Matlab) that the original analysis was not the best, but no matter how you do the analysis, the hockey stick shape is there and doesn’t go away. Oh, and McIntyre and McKitrick did NOT reproduce the methodology of Mann et al., they used a different methodology.

    One of the things that has convinced me that Anthropogenic Global Warming is real is that, over time, all the objections (the hockey stick is wrong, temperature records are biased by heat island effects, etc. etc. etc.) have all been shown to be incorrect. Do we know everything about it? No. Do we know enough to know it is happening? Yes. Should we be concerned? If society does not take action soon, then yes (though I will not be here to see the consequences of our action or inaction).

    Adrian

    • Adrian
      The Wahl and Amman paper is based on a statistical quantity never seen before or after in the literature to claim a significance in their results (in order to support the Mann et al. work). Science doesn’t work that way. We decide on our criteria before looking at the data. We certainly don’t invent quantities because the standard ones don’t work for whatever argument we wish to put forward. I think the ex mining consultant is right to question the validity of hockey stick results based on poor use of statistics and application of the scientific method.

      Wahl and Amman was also discussed in the Wegman report which came down heavily in favour of the critics.

      There is a good argument for acting to reduce CO2 emissions – its just that the hockey sticks shouldn’t be used to support it.

  9. The problem with man caused global warming, now re-branded as simply climate change, is that there is no repeatable science going on here, and no way to invalidate it. Cold, hot, wet, dry all are proof of climate change (caused by man). This is not science. As far as the graph shown, where is the mid-evil warming period and the little ice age. Those events were common knowledge via peer reviewed studies in the past, but are suppressed now, like they never happened. This one stupid graph from Mann does not invalidate all the work before it. Where are the error bars? How were they measuring temperature in the year 1200? If we have hockey stick type warming going on, why did the warming stop in 1998 immediately after the graph was released? All great questions that will never be answered by the climate change crowd.

    • Assuming you’re the same Kevin, note that doubting the reality of the big bang doesn’t make your pronouncements on AGW more believable. Quite the opposite, in fact.

      • telescoper Says:

        To go back to the topic of the post, doubting the Big Bang is fair enough. I doubt it’s true in all respects. But that’s not the same as ignoring all the evidence in its favour and making false statements about its physical coherence. It’s clearly the best description we have of the structure and evolution of the Universe, and I’m sure many elements of it will survive into the distant future.

    • Of course, one needs to define “big bang”. There is very good evidence that the universe is expanding from a hot, dense state when primordial nucleosynthesis occurred, that the universe is described by FLRW etc. I wouldn’t include, say, inflation in the big bang as such. Many people tend to throw the baby out with the bathwater. If inflation is shown to be wrong, this does not mean that the universe is not expanding, that big-bang nucleosynthesis is wrong, that GR doesn’t describe the universe etc.

      • According to my Congressional representative, the Big Bang theory is just a “lie from the pit of Hell” (do a quick Google search for Paul Broun to see what other topics this esteemed gentleman and medical practitioner consigns to the fiery pits). So there, that’s evidence enough for me!!!!! After all, this man must be trustworthy and wise, he’s both a Christian and sits on the House Science and Technology Committee, so he must know all about these things. I’m convinced.

      • Anton Garrett Says:

        You want to give this guy a shock Adrian? Tell him that he is talking like a theological dualist, ie God runs heaven, Satan runs hell. According to the Bible by which Rep Broun presumably claims to navigate, Satan is not in hell yet, and when he gets there he too will suffer helplessly (Matt 25:41, Rev 20:10). Broun is, without realising it, basing his comments on late mediaeval imagery, but while the paintings are superb the theology is far from the Bible.

        That’ll get his attention as no scientific comment could. THEN you can tell him that before the Big Bang was proposed science was silent on the origin of the universe – so that the verdict of science, when it came after some 200 years, is that there was a beginning. Then ask him to quote the first sentence in the Bible (In the beginning God created the heavens…) Then ask him why he is anti-Big Bang.

        If you really want to open his mind then tell him that, since space began at the Big Bang, and Einstein showed that time and space are deeply interrelated, time also began at the Big Bang, and that asking what happened before the Big Bang is (very!) like asking what is north of the North Pole. Translated into theological language that he will like: as the Bible says that there is only God and his creation, and as time is not God, then time itself is created by God, and the Big Bang is the locus of that creation. Tell him that this solves the “who created God” regress problem, which frankly has not been well dealt with in other ways but which implicitly involves a time-ordering.

        You’ll have his full attention after that!

  10. Most of us here are not climate scientists (I did work a bit in climate modelling back in the mid-1990s). Most of us are experts in one field, if that. Nevertheless, we feel confident that we know what is right and what is wrong in many scientific fields. What is this based on? Usually, a consensus of experts and, if there is no consensus, a check to see if there are any obvious axes to grind.

    With respect to AGW, it is clear that oil companies have an axe to grind. It is not clear to me why any government has a vested interested in believing AGW exists (unless you believe that the leftist politicians just want an excuse to make you feel bad about driving your SUV). Also, since most research is state funded, then one should doubt essentially all consensus in science, not just AGW.

    As long as all AGW “sceptics” are religious fundamentalists (God, not man, decides what happens to the Earth), politically conservative and seeing bogus leftist agenda everywhere, doubters of the big-bang, sceptical about AGW for some stated reasons but not sceptical about other stuff where the same reasons should apply or say that the other side is just an opinion but don’t like the same said about them, any rational person would believe, without very good evidence to the contrary, that the consensus about AGW is correct. Stuff like “climategate” where an obvious attempted hatchet job was exposed (i.e. the accusations of the “sceptics” were shown to be false) increases the suspicion that the AGW “sceptics” will stop at nothing to try to convince the world that there is some huge hoax, conspiracy etc going on—and without any valid motivation on the part of the hoaxers and conspiracists. This reminds me of Fred Hoyle doubting archeopteryx.

    • Anton Garrett Says:

      “With respect to AGW, it is clear that oil companies have an axe to grind. It is not clear to me why any government has a vested interested in believing AGW exists”

      Here is why: It’s a great excuse to tax us more. As for oil companies, they expanded into green some time ago in order to harvest government subsidies to that sector.

      Your final paragraph is one of the finest rants I have seen for a long time. Too bad it is almost wholly inaccurate in its portrayal of the DAGW skeptics. And your side grumbles about smear!

      • “It’s a great excuse to tax us more.”

        Taxing the population is an end in itself? You really believe this? It might have some credibility if the taxes went to benefit (illegally, of course) those voting for higher taxes, but AGW is a hoax perpetrated for the purpose of raising taxes for their own sake? Really? Is this the best you can do?

        Oh, I get it—you’re a fifth-column agent posting satirical stuff in order to discredit the AGW “sceptics” by exaggerating their claims. I wish I could believe this. When honest supporters of a cause are indistinguishable from their caricatures, something is wrong.

        Why not come clean and say that all state expenditures are bogus because they are just a ruse to tax the population?

        Have cosmologists suppressed the theory of everything discovered in the 1950s by some chap in his garage and invented all the interesting puzzles in cosmology in an elabourate hoax to get government funding, which ultimately derives from taxes paid by oppressed entrepreneurs?

        As to which side correctly characterizes the other, time will tell.

      • Anton Garrett Says:

        “Taxing the population is an end in itself?”

        The higher the taxes are, the more money the politicians who set the taxes have to play with – and consequently the more power they have. Don’t tell me that politicians don’t enjoy wielding power.

        Nobody is saying tax should be zero. You might prefer to argue against what I did say, rather than what I didn’t.

        I too look forward to the verdict of history.

      • You still fail to provide any objective criterion by which to judge whether a political decision is driven by a hidden agenda or has been honestly made.

      • Some politicians enjoy wielding power, sure. Not all. Some go into politics (where they earn much less than they would, or in some cases did or will, elsewhere) out of a sense of duty.

        The idea that politicians raise taxes primarily to increase their power is absurd.

      • Anton Garrett Says:

        Phillip: Whether you find it absurd or not, I believe this is a major driver of tax policy. “Look, with more tax revenue we can do this, this and this!” “Great idea, let’s.” Just how disinterested are such decisions? We all know that power corrupts. Please tell me what you mean by an objective criterion.

        “Some go into politics (where they earn much less than they would, or in some cases did or will, elsewhere) out of a sense of duty.”

        That might have been the case when politicians were poorly paid – too poorly to allow non-rich people to enter politics, which was a problem. But today we have a different problem: professional politicians who have never held a proper wealth-creating job in their lives, would probably be incompetent in one, and who make rather too good a living off the taxpayers whom they tell what to do.

      • I doubt it is a major driver of tax policy. This sounds like typical neoconservative propaganda. Someone who has a pathological desire to wield power over others probably has more efficient outlets than politics.

        Objective criterion? You think AGW is bogus but, say, research on the CMB is OK (at least you haven’t claimed here that it is a scam). Who built those satellites? Was there an independent audit? Aren’t the scientists dependent on government money? Can’t one find articles, even in refereed journals, which question standard cosmology? Where is the difference, other than your subjective feeling that one is bogus and one is not?

        There are many examples of politicians who did something else before or after their time as politicians. Some earned much more doing something else. Yes, some might earn more as politicians, someone who worked as, say, a taxi driver then became foreign minister. But I think that’s OK.

        Regardless of what they earn, it is the responsibility of the voters to get rid of the bad ones. No democracy can, in the long term, be better than the population.

        You seem to imply that politicians are of necessity corrupt just because they have power and that in order to maintain that power they will increase taxes for no reason. If anything, I hear more often that politicians want to cut taxes too much (in my opinion) in order to become popular.

      • Anton Garrett Says:

        No idea Phillip, I’ve not educated myself on the CMB. Can we stick to the point? You are the one who talked about objective criteria.

        “This sounds like typical neoconservative propaganda”

        And that sounds like a pretty weak argument.

      • OK, easy question: What other scientific consensuses do you doubt, and why do you doubt them and not others?

      • Anton Garrett Says:

        “What other scientific consensuses do you doubt”

        I dispute your premise that there is scientific consensus that global warming due to manmade CO2 emissions is dangerous.

      • Which other, if any, conclusions held by a majority, but not 100%, of scientists in the field do you doubt? Why do you doubt these (if there are any) and AGW but not the others? Since you are not an expert in all of these fields, what criterion do you use, other than gut feeling, to decide which to believe and which to doubt?

      • Anton Garrett Says:

        Where I find no unanimity among experts, I don’t always make a firm decision; sometimes I keep the question open in my mind. Sometimes I back myself to hold a minority view, eg hidden variables underneath quantum mechanics. What is your answer to your own question, please?

      • Not sure why I need to answer my own question, but I suppose the best description is similar to Carl Sagan’s baloney detector.

  11. Anton Garrett Says:

    Well Peter, if you want to rack up 70 comments in 36 hours you know what topic to blog on.

    • Dang, you beat me to it Anton!

    • Anton, in reply to your earlier advice on Rep. Broun (I cannot seem to reply within that thread), I’m afraid that you are far too optimistic. Such tactics have bee tried many times by folk far more patient and better than myself. All to no avail. If anything, they have made matters worse!

      Having lived in the deep south for more than half my adult life (which is a sobering thought!), I have become quite good at identifying those whose minds are shut tight, and nary a crow-bar (metaphorical, of course) or any other form of argument will open them. They believe what they believe and that’s the end of it, period, no argument, done, finished. Discussing different opinions with these people is like watching a three-year old cover their ears and repeatedly shout “I can’t hear you!” in an effort to drown you out. I think this is definitely a case where the US of A is “bigger and better” than most other countries; I hope you never have to confront one of these individuals.

      So, I’ve learned to choose carefully where I put my effort, and the aforementioned representative is, I’m sad to say, a very, very, very lost cause. But your optimism and advice is appreciated.

      • Anton Garrett Says:

        “Discussing different opinions with these people is like watching a three-year old cover their ears and repeatedly shout “I can’t hear you!” ”

        The solution to that is to ask questions rather than make statements. But I agree it can be difficult with some mindsets.

    • telescoper Says:

      Yes, indeed. It’s all been bubbling up nicely while I’ve been busy (and, more recently, travelling)…

  12. Dr Sceptic Says:

    Apologies for not reading all the comments, this point may have been made already, but it is interesting that while for the cosmology example you quote the source of the data, for the climate graph you don’t. But it looks very much like the discredited 1998 ‘hockey stick graph’.

    “assuming the historical data points are accurate”
    Not a good assumption. Read the paper by McShane & Wyner (2011) in Annals of Applied Statistics,
    “A Statistical Analysis of Multiple Temperature Proxies: Are Reconstructions of Surface Temperatures Over the Last 1000 Years Reliable?”

    It is a bit worrying that someone who is clearly very knowledgeable about astrophysics should have so little understanding about this field, but be quite happy to paste in a graph lifted off the internet and blog about it.

    • telescoper Says:

      I wasn’t claiming knowledge of climate change. Actually I know very little about climate physics. It’s a field far removed from my own speciality. That wasn’t the purpose of the post. Perhaps if you read it you would realise that. And also the previous comments.

  13. Its unfortunate that this topic also degenerates into a “they’re wrong”, “no they’re right!” type of discussion. I did try to emphasise that my own criticisms were limited to historical reconstructions. However, the true believers won’t accept any criticism of their faith.

    Anyway, here are some documents relevant to the iconic hockey stick. To keep it simple, here is a rough description of the complaints followed by the independent reports which were commissioned following the criticisms.

    Complaints:
    (1) Mann’s algorithm makes a hockey stick reconstruction out of red noise. It is argued that this is due to, amongst other things,an inappropriate use of PCAs.
    (2) The hockey stick itself is not robust to the use of different proxies (as claimed in the paper). It depends on using one type: bristlecone pines. These proxies show a burst of growth in the 20th century which the researchers who took the data do not think can be attributed to temperature i.e. it isn’t a temperature proxy in the 20th century.

    Wegman report. Wegman was the Chair of the National Research Council’s Committee on Applied Statistics.

    http://www.uoguelph.ca/~rmckitri/research/WegmanReport.pdf

    North report. North is a professor at Texas A&M and a distinguished
    figure in climate world.

    http://books.nap.edu/openbook.php?isbn=0309102251

    In brief, Wegman came down very hard on the hockey stick. North was softer but pretty much agreed. A quote from North to a Senate Committee on this: “We had much the same misgivings about his work that was documented at much greater length by Dr. Wegman.”
    Source: http://www.gpo.gov/fdsys/pkg/CHRG109hhrg31362/html/CHRG-109hhrg31362.htm

    North’s report mentioned that the use of bristlecones (which drive the hockey stick shape) should be avoided:
    “While “strip-bark” samples should be avoided for temperature reconstructions, attention should also be paid to the confounding effects of anthropogenic nitrogen deposition (Vitousek et al. 1997), since the nutrient conditions of the soil determine wood growth response to increased atmospheric CO2 (Kostiainen et al. 2004). (STR Preprint, 50)”.

    Given the above, I’m staggered that this plot is still shown and that CAGW proponents are shouting “move along, nothing to see here”. Indeed it is the refusal of the climate community to concede this that makes me sceptical of the results coming from the whole historical reconstruction field. There are also other issues of concern in the other studies such as (a) “double dipping” (also giving rise to a hockey stick from noise) (b) removing adverse data in order to show a tidy picture and (c) cherry picking i.e. promoting only those results with a nice hockey stick and ignoring others.

    Nothing I’ve seen convinces me that temperature reconstruction results are yet ready to inform public policy.

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