Credit where it’s due

March 17th, 2007 by Ben Goldacre in bad science, climate change | 185 Comments »

It had been so slaughtered by the time Friday came around that there was no way I could write about the Global Warming documentary with any poise, since it had all been done to death. Steve Connor in the Independent was truly exemplary, and in case you missed it, here it is. Go sister.

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185 Responses

  1. GMcP said,

    March 23, 2007 at 5:01 pm

    Durkin’s solar graph is very similar to one published by Danish physicists Friis-Christensen and Lassen in 1991. Some of the data was subsequently corrected, but it looks like Durkin uses the uncorrected data.

    Here’s a criticism of the original paper.

    Here’s graph 1(c) from that report overlayed on Durkin’s graph – he appears to have clipped off the bothersome flat bit at the end.

    Hat tip:

  2. mikep said,

    March 23, 2007 at 5:36 pm

    Some unfinished business. I have quoted the Wegman report extensively and it in no way supports either Liverpool Miss’s or Deano’s account. The NAS panel report is more equivocal and failed to address the issue of the deficiencies of the original Mann at al studies head on. That part of its conclusion which gives most comfort to the Deanos of this world reads as follows.

    “Based on the analyses presented in the original
    papers by Mann et al. and this newer supporting
    evidence, the committee finds it plausible that the
    Northern Hemisphere was warmer during the last
    few decades of the 20th century than during any
    comparable period over the preceding millennium.
    The substantial uncertainties currently present in
    the quantitative assessment of large-scale surface
    temperature changes prior to about A.D. 1600 lower
    our confidence in this conclusion compared to the
    high level of confidence we place in the Little Ice
    Age cooling and 20th century warming. Even less
    confidence can be placed in the original conclusions
    by Mann et al. (1999) that “the 1990s are likely the
    warmest decade, and 1998 the warmest year, in at
    least a millennium” because the uncertainties inherent
    in temperature reconstructions for individual
    years and decades are larger than those for longer
    time periods, and because not all of the available
    proxies record temperature information on such
    short timescales.”

    The newer evidence is

    “that includes both additional large-scale surface
    temperature reconstructions and pronounced
    changes in a variety of local proxy indicators, such
    as melting on icecaps and the retreat of glaciers
    around the world, which in many cases appear to be
    unprecedented during at least the last 2,000 years.
    Not all individual proxy records indicate that the
    recent warmth is unprecedented, although a larger
    fraction of geographically diverse sites experienced
    exceptional warmth during the late 20th century
    than during any other extended period from A.D.
    900 onward.”

    Nevertheless the Mann conclusion was only described as plausible rather than likely and the firm conclusion was only that it is now warmer than it has been for 400 years which none of the major participants in this debate had ever denied. Moreover the report appears to accept (as plausible?) a Medieval Warm period.

    Moreover the report did not examine the new reconstructions in any detail. As I will show in a subsequent post many of these new studies re-use the old proxies which have already been shown to be at best dubious, some of them re-use discredited methods. We cannot say for sure that this is true of all of them, but that may be because it is not possible to work out exactly what they have done from the work that has been published.

    Finally I have tried to pick the bits of teh NAS report which are most favourable to Mann et al. If you dig down into Chapters 9 and 11 you will find plenty of specific criticism of Mann and no rebuttal of MacIntyre and Mckitrick.

  3. GMcP said,

    March 23, 2007 at 6:04 pm


    I thought that Wahl and Amman repeated the MBH analysis, taking on board the MM criticisms, and got pretty much identically the same results for the last 600 years at least.

    Do you dispute this?

  4. Deano said,

    March 23, 2007 at 6:19 pm

    Since mikep is keen to cite NAS as an authourotative voice perhaps he doesn’t realise that they, along with every other major science academy in the world have signed a joint position statement on Global Warming:

    We urge all nations, in the line with the UNFCCC
    principles4, to take prompt action to reduce the causes of
    climate change, adapt to its impacts and ensure that the
    issue is included in all relevant national and international
    strategies. As national science academies, we commit to
    working with governments to help develop and implement
    the national and international response to the challenge of
    climate change.
    G8 nations have been responsible for much of the past
    greenhouse gas emissions. As parties to the UNFCCC, G8
    nations are committed to showing leadership in addressing
    climate change and assisting developing nations to meet
    the challenges of adaptation and mitigation.
    We call on world leaders, including those meeting at the
    Gleneagles G8 Summit in July 2005, to:
    · Acknowledge that the threat of climate change is clear
    and increasing.
    · Launch an international study5 to explore scientificallyinformed
    targets for atmospheric greenhouse gas
    concentrations, and their associated emissions scenarios,
    that will enable nations to avoid impacts deemed
    · Identify cost-effective steps that can be taken now to
    contribute to substantial and long-term reduction in net
    global greenhouse gas emissions. Recognise that delayed
    action will increase the risk of adverse environmental
    effects and will likely incur a greater cost.
    · Work with developing nations to build a scientific and
    technological capacity best suited to their circumstances,
    enabling them to develop innovative solutions to mitigate
    and adapt to the adverse effects of climate change, while
    explicitly recognising their legitimate development rights.
    · Show leadership in developing and deploying clean
    energy technologies and approaches to energy efficiency,
    and share this knowledge with all other nations.
    · Mobilise the science and technology community to
    enhance research and development efforts, which can
    better inform climate change decisions.”

  5. mikep said,

    March 23, 2007 at 6:45 pm

    re 175. Yes. See for example

    Here are a few highlights. First eh summary

    “Ammann and Wahl (AW herein) build their entire comment on two methodological
    arguments (principal components using the correlation matrix and rescaling impact on RE benchmarking), which repeat almost verbatim two arguments previously made by Huybers [2005], neither adding new justification, nor discussing, much less rebutting, anything in our Reply [McIntyre and McKitrick 2005c; “MM05c” herein]. Nor do they address the subsequent discussion in Bürger and Cubasch [2005]. Additionally, AW not only repeat results that we had previously published, but claim them as their own and then accuse us of having failed to report them. In their abstract and summary, AW make claims that are unsupported in their text, then assert our results are “unfounded,” despite the fact that results from their own code yields validation statistics (unreported by AW) that strikingly confirm claims in McIntyre and McKitrick [2005a] (MM05a) concerning spurious significance in the Mann et al. [1998] (MBH98) reconstruction.”

    And in particular

    “1. AW falsely asserted that a hockey stick shape appears in “all the summaries… of
    the ITRDB [North American] network” (emphasis added). As we pointed out in
    MM05b and in our Reply to Huybers, there is no hockey-stick pattern in any
    North American PCs in the summary in the BACKTO_1400-CENSORED
    directory at Mann’s FTP site – a summary excluding a small group of bristlecone
    sites. The hockey stick pattern is characteristic of bristlecone growth and does not
    appear in summaries in which bristlecones are not present.
    2. AW accused us of not reporting the presence of a hockey stick pattern in lower
    order PCs. In MM05a para. 12 (MM05b – p. 75), we expressly reported that the
    bristlecone hockey stick appeared in the covariance PC4, further pointing out
    (unlike AW) that it only accounted for 8% of total variance. In MM05b (p. 76),
    we expressly reported that the bristlecone hockey stick appeared in the PC2 using
    correlation PCs. Remarkably, AW presented the same observations as novel (see
    their Figures 1b and 1c) and reproached us over it.
    3. AW falsely accused us of retaining only two PCs in our analyses using covariance
    PCs, ignoring a specific discussion in MM05b (p. 76) of the impact of retaining
    up to 5 covariance PCs.
    4. AW say we failed to consider the effect of “proper” standardization on
    temperature reconstructions, while completely ignoring results presented in
    MM05b (p. 76) using correlation PCs – an equivalent methodology. AW then
    claimed – without any supporting calculations or discussion of our different
    findings – that the differences between MBH98 and a reconstruction using 2
    correlation PCs are less than “five hundreds of a degree”. However, for Case 5b
    of Wahl and Ammann (under review), which also uses 2 correlation PCs, the
    reported RE statistic (0.18) is 0.30 lower than the RE statistic for the
    corresponding MBH98 emulation (0.48) – a result which is inconsistent with the
    claim of a negligible difference.”

  6. mikep said,

    March 23, 2007 at 6:58 pm

    Or perhaps even better here

    Again one quote

    “Robustness to Presence/Absence of Dendroclimatic Indicators

    One of the fundamental representations of MBH98 (and Mann et al [2000]) was its “robustness”, including robustness to presence/absence of dendroclimatic indicators. One of the central criticisms of MM05b was that (a) this MBH claim was simply untrue and (b) that MBH98 withheld adverse information about the lack of robustness to presence/absence of bristlecone pines; (c) that the bristlecone pines were flawed proxies.

    WA fail to report or rebut the first MM criticism.

    On the second point, WA failed to report or rebut the MM criticism that MBH98 had both withheld adverse information about the lack of robustness to presence/absence of bristlecone pines and had made misrepresentations about robustness to dendroclimatic indicators.

    On the third point, despite an extensive discussion in MM05b of bristlecones (and cedars), including the potential of the proxy being contaminated by CO2 fertilization, WA fail to discuss or rebut these criticisms. Their only argument on this point is that the bristlecones increase the statistic. However, this can also be done by any series with a nonclimatic trend.

    It is very obvious that WA realize that MBH98 are not “robust” to presence/absence of dendroclimatic indicators, since they realize that MBH98 results are not robust to presence/absence of bristlecones. WA argue that bristlecones should be included because they improve the RE statistics. They are entitled to argue this point (although I believe that their arguments are very weak). However, prior to doing so, they need to plainly acknowledge the base point that MBH98 results are not robust to presence/absence of bristlecones and discuss prior misrepresentations by MBH98 in a straightforward way. Instead, they omit a discussion of these points and engage in an elaborate subterfuge of using code words like “full information” rather than a clear discussion of the validity of bristlecones as a proxy and their impact on MBH98 results.”

  7. Deano said,

    March 23, 2007 at 7:28 pm

    you got anything re # 176?

    like a reason why all of the world’s major science acadamies are wrong?

  8. mikep said,

    March 23, 2007 at 8:47 pm

    Stick to the point Deano. I have taken no position on the causes of global warming, only on what we know about the temperature for the last millennium, namely not a lot with any confidence.

  9. mikep said,

    March 23, 2007 at 8:59 pm

    It’s people like you who will not engage on issues but keep changing the subject and introducing irrelevancies who are in danger of making me become a “climate change denier”.

  10. liverpoolmiss said,

    March 23, 2007 at 11:25 pm

    This is a good illustration of how sceptics try to invent controversies when none actually exist (and hence create doubt and policy delay).

    Wegman recommended:

    – that Mann et al should use a slightly different statistical methodology. Mann et al agreed with Wegman’s point and the superior Wegman techniques have been used on all subsequent hockey stick analyses

    – that climatologists should use the world’s best statisticans in future. Mann et al agreed and in the past decade there has been an explosion in the climate-statistics specialty. These experts have been closely involved in all subsequent hockey stick analyses.

    – that data and codes should be freely accessible to other researchers. Mann et al released all their data and codes, though pointed out that other researchers such as Ammann and Wahl didn’t in fact need the codes to be able to replicate the process.

    – that scientists shouldn’t have links with other scientists via co-authorship etc, because it damages independence. Mann et al disagreed, on the grounds that this is silly in the real world.

    – that no scientific paper should be published until it has been replicated by independent researchers. Mann et al disagreed, on the grounds that this is completely bonkers.

    So what has happened in the decade since the first hockey stick graph, now that world class statisticans using the best possible statistical techniques are repeating the hockey stick process time after time?

    – all independent hockey stick analyses in the past decade (nearly a dozen) have given the same basic shape as the original

    – the discredited McIntyre and McKitrick graph remains the most outlying, with a stronger apparent Medieval Warm Period, yet M&M still indicated temperatures at the end of the 20th Century were higher than during the Medieval Warm Period.

    – none of the dozen analyses in the past decade have given any support to sceptics (hence the need to resort to faking graphs).

  11. mikep said,

    March 24, 2007 at 9:49 am

    Liverpool Miss persists in outright misrepresentation. Her version of history is demonstrably wrong. Repetition of an error does not make it the truth. Read the Wegman report. Or even read the quotes I posted. They contradict what she says. There is no McKitrick Macintyre graph to be discredited because, as Wegman says and I quoted above, all M&M were doing were trying to see how Mann et al got their results (and ss Wegman points out, even the code that was finally revealed in 2006, eight years after the original publication did not allow replication). M&M found that the Mann results were very sensitive to the inclusion/exclusion of bristlecone pines and their relations. Therefore the results were not robust.

  12. EssTee said,

    March 24, 2007 at 1:09 pm

    “I see you are studiously avoiding the forum.”

    Only if posting to the forum is “studiously avoiding it”. Once again, an entirely baseless statement from Dean.

    “You’ve attacked me on the basis of ‘religious convictions’ – which as an Atheist I find a bit strange – but is then your explanation for why:”

    Your religion is environmentalism, Dean. You’re just in denial about it. That’s why you religiusly defend any bad science if criticism of it undermines any single anthropogenic global warming hypothesis.

    “he clearly doesn’t want the facts to interfere with his cherished beliefs.”

    Oh, sweet irony.

  13. Tim Wogan said,

    March 24, 2007 at 2:00 pm

    I’m interested in the following comment from EssTee:

    “By the time we’ve established what scientists agree on, it has lost its scientific meaning.”

    Thanks for a neater summation of my point that I could provide: if we want scientific analysis to guide political decision making, then a majority verdict must be acceptable. If we insist on universal consensus then science will never give any meaningful advice about anything.

  14. Deano said,

    March 24, 2007 at 4:17 pm

    If you were about to board a plane that you were told had a a 95 percent chance of crashing would you board anyway because there wasn’t 100 percent certainty of the fact??

  15. GMcP said,

    March 24, 2007 at 5:10 pm

    mikep #177,178: Thanks for the links – I’ll have a look at those.

    In the meantime I’d be interested to know which temperature reconstructions you would trust – for the last 100, 500 and 1000 years, say.

  16. mikep said,

    March 24, 2007 at 6:10 pm

    100 we have actual temperatures. Not sure really about any of the multi-proxy studies, but I think it’s virtually certain that it is now warmer than it has been for 400 years, because there are quite a lot of proxies and the message is fairly consistent. Beyond that the proxies are few and their interpretation difficult. 500 is too far for me.

  17. mikep said,

    March 24, 2007 at 9:51 pm

    I promised a discussion of the other multi-proxy reconstructions. Obviously it is impossible to be exhaustive but people can get the flavour here

    Note in particular how these three studies all use the bristlecone pine series which are the subject of controversy.

    “Here’s a quick summary of the overlap of proxies in three widely publicized “independent” 2006 studies. The number of proxies are all small (Juckes -18; Osborn – 14; Hegerl – 12). All three use multiple bristlecone/foxtail chronologies: Juckes 4; OSborn 2; Hegerl 2.”

    Follow the links on the left to see plenty of discussion of the other reconstructions which are claimed to be independent.

    I am not going to waste any more of my time trying to talk to Deano and Liverpool Miss, but I may respond if someone puts forward a favoured reconstruction for discussion as the definitive re-construction, or even one which avoids most of the pitfalls we know about already.

  18. GMcP said,

    March 25, 2007 at 1:23 am

    mikep: You’ve obviously done a fair bit of research into this. Can you give an example of a global temperature reconstruction for the last few hundred years which you think gets pretty close to the mark?

    You don’t have to give it unconditional support; I’m just looking for an example where you think the researchers have taken broadly the right approach, and where you have some confidence in their results.

  19. Deano said,

    March 25, 2007 at 11:08 pm

    Oh yes – Climate audit by Steve McIntyre

    “Stephen McIntyre is, according to the Wall Street Journal, a “semiretired Toronto minerals consultant” who has spent “two years and about $5,000 of his own money trying to double-check the influential graphic” known as the “hockey stick” that illustrates a reconstruction of average surface temperatures in the Northern hemisphere, created by University of Virginia climatologist Michael Mann.”

  20. Deano said,

    March 26, 2007 at 12:03 am

    I think you meant ‘bin man’ ST.

    I just didn’t want mikep to labour under the misapprehension that McIntyre was a ‘scientist’ ST – you’re usually get hot under the collar about that sort of thing – I’m surprised I don’t have your support in this?

  21. mikep said,

    March 29, 2007 at 10:32 pm

    Deano you are the one who argues like a astrologer. Put some content in your posts and we might have a discussion. Perhaps we might start with your discussion of the 1974 paper by Granger and Newbold on spurious regression. Given your apparent omniscience and the paper’s age I am sure you have read it and can explain why Macintyre has got it wrong. For the record I think astrology, homoeopathy, intelligent design and crop circles are nonsense and I have never voted conservative and I think George Bush’s foreign policy is disastrous. I’m a not quite classic Guardian reader. And what category does Edward Wegman, who said that all of Macintyre and Mckitrick criticisms were valid, fit into?

  22. mikep said,

    March 30, 2007 at 9:09 am

    Another fine example of Deano jumping to unjustifiable conclusions. I voted Lib Dem last time round and I am not (and never have been) a Marxist or a Trotskyite. You can never resist the chance of a cheap sneer can you Deano. Stick to issues and people might take you seriously.

  23. Deano said,

    March 30, 2007 at 4:06 pm

    “Another fine example of Deano jumping to unjustifiable conclusions. I voted Lib Dem last time round and I am not (and never have been) a Marxist or a Trotskyite.”

    I’m happy to take your word for it mikep – although you are a bit of an oddball – most people that push the denialist viewpoint are from the extreme left or right. Durkin is a fine example as a member of the ‘Living Marxism’ who pushes an extreme right ‘Libertarian’ agenda on the potty theory that this will hasten the demise of capitalism. You may wish to ignore this on the basis that you want to be fair to the chap – but he demonstrably distorts scientific data, and the words of scientists to make his point, think you’re being more than a little naive – I don’t believe that Durkin deserves the ‘benefit of the doubt’ ( but then you Lib Dems have alway been a bit soft on serial offenders).

    But I wouldn’t want to discourage you from voting Lib-Dem – they were the first mainstream party to accept the reality of climate change – and constantly press for the most radical measures to tackle it…

  24. Deano said,

    March 30, 2007 at 5:36 pm

    Hey ST – where have you been hiding?

    or are the questions about your politics too embarrassing for you?

    Incidentally there are a number of very reasonable questions others have for you on Ben’s forum.

    I’m assuming your tactic is to:

    1. hide…

    See you at:

    if you have a better explanation…

  25. EssTee said,

    March 30, 2007 at 5:43 pm

    Just as Dean thinks that deferring the scientific argument by hiding behind the “consensus” counts as making a scientific argument, he thinks copying and pasting from Monbiot articles, and sourcewatch and greenpeace webpages counts as “politics”.

    Dean constantly defers the argument.

  26. Deano said,

    March 30, 2007 at 5:46 pm

    Still hiding then ST??

  27. Deano said,

    March 30, 2007 at 5:56 pm

    ST you do realise you give the game away when you use big words like


    especially as it’s one your hero Comrade Furedi likes to use when he’s attacking Environmentalists as ‘religiously motivated’.

  28. Deano said,

    March 30, 2007 at 6:05 pm

    Come over to Ben’s forum to discus it then ST – what are you afraid of?

  29. pv said,

    March 31, 2007 at 9:19 pm

    As the great Lord Russell once wrote, “lack of facts promote an argument”.
    Carry on chaps!

  30. GMcP said,

    April 2, 2007 at 8:45 am

    Hamish Mykura, Head of History, Science and Religion on Channel 4, appeared on the Today programme a couple of weeks ago. He claimed that TGGWS was commissioned as part of “a season of opinionated polemical films about global warming”, including George Monbiot’s film Greenwash.

    George Monbiot takes exception to this.

  31. Deano said,

    April 3, 2007 at 11:17 pm

    Thanks for that GMcP – funny to see Hamish ducking and diving…

  32. JohnA said,

    April 7, 2007 at 7:24 pm

    Unfortunately the duped appear to be the commentors and the author of this blog. The global temperature scale is produced in secret by just three people and conflicts with the satellite record, which shows a very mild warming since 1979 and none at all since 1998.

    The bottom two records are the climate change records produced in the IPCC Second AR and the “Hockey Stick” produced in the TAR. The Hockey Stick has been thoroughly debunked as “bad science” and bad statistics by multiple independent investigators. There are not a few scientists who claim that the “Hockey Stick” may well be a scientific fraud. It certainly has no legitimacy as a reconstruction of past climate when key statistical metrics show that it has no statistical significance.

    Personally I regard the “Hockey Stick” as a key indicator of “Real Climate Change Denial” since its purpose appears to be to reduce natural climate change to a minimum while purporting to show a climate recketing out of control since the end of the 19th Century – it is a false picture of past climate but a totem for environmentalists.

    So I have no idea what Durkin is meant to be accused of

  33. Deano said,

    April 7, 2007 at 11:55 pm

    Well done JohnA – you are by far the most bonkers climate denialist here yet.

    If you after reading these two hundred entries you have still have no idea of what Durkin is accused of you are rather spectacularly clueless I’m afraid.

    If anyone is at all interested why your comments are completely, absolutely, demonstrably wrong they could consider what some actual climate scientists have to say about the stock myths peddled by denialists like yourself:

    If you want to dispute this JohnA – perhaps you’d like to come over to the forum – the link is above…

  34. Munin said,

    May 8, 2007 at 10:58 am

    Steve Connor at the Independent has picked up the Friis-Christensen story.

    “After 1985 we don’t see any rise or shortening of the solar cycles compared to what we saw in the temperature [record],” Dr Friiss-Christensen said.

    The article doesn’t record Durkin’s response to this point, but he does admit to an error in the temperature graph.

    “Thank you for highlighting the error on the 400-year graph. It is an annoying mistake which all of us missed and is being fixed for all future transmissions of the film. It doesn’t alter our argument,” Mr Durkin said.

    The correction doesn’t make it onto the first cut of the DVD.

    Elsewhere, Durkin has admitted that the claim made in the documentary that volcanoes emit more CO2 than humans is also false (corrected on the DVD).

    The admission appears in a subscription-only article in the Scotsman, conveniently available for free over here (though possibly not for long).

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