BBC on "Hockey Stick Row"

Thanks to a couple of readers, who’ve pointed out both a discussion of the "Hockey Stick Row" and its inclusion as a question fo the week.

The question of the week was here

A row erupted this week over the so-called "hockey stick graph". What does this graph purport to show?

A: The bending of an "ideal" hockey stick under varying degrees of pressure
B: Temperature variation in the northern hemisphere over the last 1,000 years
C: Damage to the human ear drum caused by noises of varying volume


Interestingly, the question preceding this one was the following:

What is the name coined for the defence strategy unsuccessfully employed by former WorldCom chief executive Bernie Ebbers in his fraud trial, which ended this week?

A: The Gee Whizz defence
B: The Aw Shucks defence
C: The Blow Me Down With A Feather defence

The article is here.

Ross McKitrick was interviewed for the article. Gavin Schmidt weighed in with the usual realclimate line:

"This is a tiny step in the hockey stick analysis. If you do it in different ways, you still get the answer you got before, providing you don’t throw away any significant data."

Dr Schmidt points out that McIntyre and McKitrick use a different convention but do not alter subsequent steps in their analysis to account for this. As a result, he says, McIntyre and McKitrick’s analysis removes crucial data included in the original hockey stick work.

For recent readers, what realclimate author Schmidt means by a "different convention" is a principal components calculation carried out according to the description in the original article using "conventional" methods. MBH98 actually de-centered the data and used an uncentered method, which had the effect of mining for hockey stick shaped series. realclimate seems to be adopting the position that MBH98 contained a misrepresentation on a vital methodology, rather than an accidental error. A method which has an undisclosed data mining property is not just an alternative "convention".

The "crucial data" is of course the compromised bristlecone pine data. In a conventional PC analysis, this goes to the PC4. One of the big selling points of MBH98 was its "robustness" – they claimed that their calculations were robust even to the exclusion of dendroclimatic records altogether. Now they imply that the bristlecones are "crucial". Of course, they’ve known all along that the compromised bristlecone proxies were "crucial" – see the calculations in the BACKTO_1400-CENSORED folder. They just didn’t tell anyone: that would have spoiled the party.

The statistical question is whether the bristlecone pine data is "significant". See our E&E article for a detailed discussion of bristlecones. Passing a Preisendorfer Rule N test does not show that bristlecone pine data is a temperature proxy. For example, if you combined the 50 non-bristlecone tree ring series with 20 stock price series for dot.com’s from 1996-1998 into a principal components calculation, the dot.com prices would undoubtedly generate a PC series that would pass a Preisendorfer Rule N test: all that means is that they are a distinct pattern in the network. It doesn’t prove that they are a temperature proxy. Preisendorfer’s Rule N is at most a necessary condition for significance, not a sufficient condition: a distinction often lost on realclimate authors and a distinction obviously lost in this case. If world climate history is held to stand or fall on the bristlecones, there should be a comprehensive discussion of their properties (as we advocate in our E&E article); it should not be hidden from sight as done in MBH98.

Additionally, one of the selling points of MBH98 was its supposedly careful proxy selection. But its results come from the flawed method mining for the most flawed proxies, creating a "perfect storm" .

Phil Jones also weighs in:

"They keep going on about one data set, but there are loads of others that show the same thing."

Phil Jones is the same guy who responded to Warwick Hughes’ request for the underlying station data used to support the CRU gridded temperature calculation as follows:

Even if WMO agrees, I will still not pass on the data. We have 25 or so years invested in the work. Why should I make the data available to you, when your aim is to try and find something wrong with it.

I’ve sought information on the identity of the 387 sites used in Briffa, Jones et al. [2001] from both Briffa and Jones for nearly a year now. Here is my most recent (Nov. 2004) attempt:

Dear Phil,
I have not had any luck with Keith Briffa on this and perhaps you can help.

Briffa et al (JGR 2001), of which you were a co-author, refers to 387 sites, but does not provide a listing of the sites or an FTP location for the underlying data, although AGU data policies theoretically require such information. I presume that there is a convenient listing of the sites, and I would appreciate a copy. Additionally, I would appreciate information on an FTP location for the data used in the study (or a password to the SOAP location if it is located there.)

Thank you for your consideration, Steve McIntyre

Jones brings up Moberg as the new study in town. The ink is barely dry on Moberg. It looks to me like there are many issues with it as well. It will take a little while to deconstruct their methods. I suspect that many climate scientists, who are quick to praise the results as a bail-out from MBH98-99, don’t know much about wavelet methods. In the simulations for our GRL article, I used a method from Brandon Whitcher’s wavelet package and have a bit of a leg up on this. I plan to try to replicate Moberg results. Moberg does a much better job than most studies in data citation, but, like previous multiproxy studies, throws in a couple of unarchived series, making exact replication frustrating. Moberg continues to use proxies ending by 1980 with the usual splice of instrumental records. I would very much like to see some evidence that the Moberg proxies would pick up the warm 1990s. – it doesn’t seem like that much to ask. If they don’t pick up the warm 1990s, then the error bars may be about the size of total climate variability.


12 Comments

  1. Peter Hearnden
    Posted Mar 18, 2005 at 9:57 AM | Permalink

    So negative and picky I hardly had the will to read it all. Does anyone else feel as uncomfortable as I do at the public dispaly of other peoples correspondence? Pro

    First hint of a swipe at Moberg05 too? I thought you welcomed it?
    Btw, I’d have replied to Warwick Hughes in the same way.

  2. Peter Hearnden
    Posted Mar 18, 2005 at 9:58 AM | Permalink

    woops did I hit send :(

  3. David H
    Posted Mar 18, 2005 at 12:42 PM | Permalink

    Peter This is supposed to be a discussion about the most serious problem facing the planet. Why would anyone not publish correspondence that supports their point of view? If you had an email from an expert in PCA that said he had looked at what Mann et al. did and understood it and that he endorsed the method, would you post it here?

  4. Dave Dardinger
    Posted Mar 18, 2005 at 9:13 PM | Permalink

    re comment 1:

    I don’t doubt you’d have replied to Warwick Hughes the same way, but that’s because you appear not to understand how science works. People do research, derive results and/or theories from it and publish the same. In some cases all the data is included with the publication, but in most cases it’s not. Other scientists then try to replicate the resuts and if successful the initial results are considered confirmed. If not, then the results are not confirmed and the data is given more careful scrutiny or the results withdrawn. In most cases, the authors of a result are only too happy to help someone who is having trouble verifying their results, as failure to do so will place their results in doubt.

    Here we have a case of authors who not only didn’t try either before or after contrary results were obtained by others, but who claim that they have a right to hold their data secret even though it looks bad to any objective observer. Obviously M&M can’t say it, but it looks to me like Mann et. al. are trying to hide something, or many things. They may have a right to declare the scientific equilivant of the 5th Amendment, but for me that says they’re guilty of shoddy work bordering on fraud.

    I’ve kept a low profile up to now on this subject (not that anyone would notice me no matter what sort of profile I kept), but I think a tipping point has come. Either Mann comes clean or his work is hereafter in the junk-science category.

    In summary, if you’re not willing to let others ‘find something wrong’ with your data, you’re not a scientist.

  5. Louis Hissink
    Posted Mar 19, 2005 at 1:34 AM | Permalink

    Peter,

    Jones is paid by the taxpayers, so his data is public property. That he refuses to give it to Warwick Hughes is that there probably is something to be found in that data which might cause an alternative result. As it is, simply averaging temperature means in arbitrary lat/long grid cells is nothing but he arbitrary addition of intensive variables. But this is another technical matter which is off topic.

    Let’s remember the Hadley Centre was initially formed to supply scientific evidence to counter the UK Miners Union during the Thatcher period of government. From this overt politicisation of science global warming and Kyoto developed.

  6. Ed Snack
    Posted Mar 19, 2005 at 2:03 AM | Permalink

    Peter, all you seem to be saying is that you don’t care if the data is entirely made up and inaccurate, you want to believe it. If your data is valid and stands scrutiny, why shouldn’t you allow it to be examined. I have read Warwick’s site, although a definite climate skeptic, his analysis of the surface temperature records is worth reading. He makes cogent points that I am sure that Jones and others would rather were not widely known, the inclusion of sites for example with significant, demonstrable, and apparently uncorrected UHI effects. I’m sure you would say the same to Warwick, but then you show absolutely no interest in whether the evidence offered for AGW is true or not, but seem only interested in making sure that any genuine evidence against the dominant interpretation is suppressed.

    Stevs’s reply above is far from picky. Any article where one protagonoist apparently allowed to make unsubstantiated and apparently untrue allegations without challenge is hardly a reasoned debate. So, I challenged you before, lets try once again, do you think that the Bristlecone Pine series used in Mann et al 1998&99 are a reasonable temperature proxy or not. If you want to claim, as you have before, that this is a subject beyond you, then find out. Look at the data, it is available on this site as well as others, and form an opinion. In particular, look at the original data in the Idso paper where they state directly that the BCP’s are NOT apparently responding to temperature in the 20th century. Don’t hide behind faux ignorance, study the data. That is the difference to you and almost every other poster on this site, they have looked at the source data, and they, and I, see something that does not seem to add up. Most of us could be persuaded, the cheques from Big Oil aren’t all that big after all, but the standard response is the Jones to Hughes type, you know, push off and don’t rock the gravy train. If the evidence in favour of MBH is so good, demonstrate that to us, don’t keep using the old bulldust baffles brains approach.

  7. Peter Hearnden
    Posted Mar 19, 2005 at 5:10 AM | Permalink

    David H, so you *do* think AGW a serious problem then :). I don’t think I’ve ever published others correspondence without prior permission (and maybe Steve had that permission?).

    Others. Of course I agreee with you about what good science is: testable, repeatable, open that kind of thing – and of course MBH99 has been published and poured over for yonks, and nit picked here to an extraordinary degree. My dispute is that I think the aim here is not to test MBH99 but to rubbish it. That’s absolutely clear from peoples other comments. How many people here think AGW a serious future problem, or are even open to it being so? Just me (and John Hunter I think). So, *all of you* come at this not from a viewpoint of simply testing MBH99 but from a point of *wanting it demolished*. Why? I think it’s because you believe, or perhaps want o believe, there isn’t a problem so MBH99 *must* therefore be wrong. That’s my view and in my view that’s not good science! And me, well, yes, maybe my pov is the opposite ;). However, in my defence, I noticed the data showing warming first (mid 80’s, and my own weather watching experiences) and then looked for the explaination second – but, of course, you’ve only my word for that.

    But, to anyone here, show me your climatological reconstructions. Tell me what you think the climate of the past 2000 years, north and south hemisphere, really was – not whats wrong with other ones. Show me your correct reconstructions. Then we can get away from criticism of others and onto what you lot think :). I bet NO ONE takes up my challenge.

  8. Peter Hearnden
    Posted Mar 19, 2005 at 5:15 AM | Permalink

    Ed

    I do hope I’m more open to other explaination than you imply.

    I’m certainly not saying what SM has done is ‘entirely made up and inaccurate’. Are you suggesting MBH99 is that? I don’t rest my case for AGW on MBH99. But the case against AGW (atm at least) does seem to rest on MBH99 being wrong….

  9. John A
    Posted Mar 19, 2005 at 7:08 AM | Permalink

    Re: #7

    …of course MBH99 has been published and poured over for yonks, and nit picked here to an extraordinary degree. My dispute is that I think the aim here is not to test MBH99 but to rubbish it.

    MBH99 may have been published, but nobody “poured over it” or attempted replication until Steve McIntyre. It should be “nitpicked” since it forms a key piece of evidence for AGW and the justification for the Kyoto Protocol, something which you and I are paying for as British taxpayers. That you think that “the intention is not to test MBH99 but to rubbish it” is simply untrue. The point is that MBH99 is deeply flawed and its conclusions unreliable. The point of testing something is to find out whether it is true or not. Testing important things for quality is a vital part of our lives, why is MBH (which has become part of our lives) exempt?

    You are also in no doubt that the case for AGW and the Hockey Stick are inextricably linked – and I agree.

    How many people here think AGW a serious future problem, or are even open to it being so? Just me (and John Hunter I think). So, *all of you* come at this not from a viewpoint of simply testing MBH99 but from a point of *wanting it demolished*. Why? I think it’s because you believe, or perhaps want o believe, there isn’t a problem so MBH99 *must* therefore be wrong. That’s my view and in my view that’s not good science!

    The question is “why do you think that AGW is a serious future problem?” Is it simply your beliefs? You accuse some of us of an a priori assumption that MBH99 “must be demolished”, but if MBH99 does not bear the conclusion placed on it, why must we believe in those conclusions? Because you believe them? Because Michael Mann believes them? Or John Houghton? Or Tony Blair? Because “50 million Frenchmen cannot be wrong”?

    But, to anyone here, show me your climatological reconstructions. Tell me what you think the climate of the past 2000 years, north and south hemisphere, really was – not whats wrong with other ones. Show me your correct reconstructions. Then we can get away from criticism of others and onto what you lot think :). I bet NO ONE takes up my challenge.

    I don’t have any reconstructions, but I can point to other reconstructions of the past 2000 years, which I think are more likely to be correct. Whether any construction is “correct” is difficult since we don’t have the global coverage of climatological data for the first 1975 years that we do for the last 26. I’ll post one such reconstruction tomorrow.

  10. David H
    Posted Mar 19, 2005 at 8:45 AM | Permalink

    Peter I said “supposed”. Tony and Sir David keep telling us so. I have said before that I think poverty and AIDs rank well above it even if all the AGW theory is proved right. MBH98/99 has not been fully replicated and can not be until Mann releases all the programme code and data. If he did we could all move on.

  11. Dave Dardinger
    Posted Mar 19, 2005 at 7:53 PM | Permalink

    Concerning #7
    It doesn’t matter the motives of someone examaining existing research. The question is what, objectively, the results of the examination are. It’s usually helpful if someone has a strong motive to doubt an existing result.

    Your call for skeptics to produce their own data is oddly familiar, though misguided. You wouldn’t perhaps be one of my usual debaters writing under another name, would you? The problem is that such a challenge misses the whole point of scientific debate. A scientific theory must be falisifiable. The trust which people place in it depends on it being able to withstand the most careful and the most ruthless examinations. If a theory can’t withstand such testing it must be modified or rejected.

    In the present case at least a couple of counter-theories can be presented without any need for special research. One is that just as weather has a large component of chaos in it, so does climate. Yes, there are things like volcanic eruptions and continental movements which have long and short-term effects, but part of the ebb and flow of climate in a given region may be intrinsically unknowable.

    A second theory is simply to revert to the Status Quo Ante. This would reduce the importance of any actual warming via human release of CO2, but wouldn’t deny that some exists and more might follow.

  12. Ed Snack
    Posted Mar 20, 2005 at 3:10 PM | Permalink

    Like I thought Peter, reiteration of your convictions, and an apparent deliberate desire to avoid looking at data. There are significant issues with all climate reconstructions, and yet you want to uncritically accept all reconstructions that reinforce your prejudices. Until you are willing to engage with at least some of the data, can I suggest that you stop trolling.

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