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« Ross McKitrick on Yamal | Main | Briffa responds »

Yamal - the debate continues

So, Briffa has responded to McIntyre and there's another riposte up at Real Climate. I'll try to explain what is going on.

Let's first remind ourselves of the guts of McIntyre's argument. This is that Briffa had an very small set of tree ring cores in the latter years of his Yamal series and that when you removed this and replaced it with a somewhat larger set of data from the same region, the uptick in the hockey stick shape disappeared. Therefore Briffa's results weren't robust.

Now we'll look at Briffa's response.


Firstly he says McIntyre is implying that he, Briffa, cherrypicked uptrending series so as to get a hockey stick. In reply, McIntyre quotes what he said in his early post:

It is highly possible and even probable that [Briffa's] selection is derived from a prior selection of old trees described in Hantemirov and Shiyatov 2002...

and also a comment he made on another of the Yamal posts

It is not my belief that Briffa crudely cherry picked.

This seems to refute Briffa's accusation that McIntyre was implying malfeasance.


From a scientific perspective, this part of the debate has moved us forward slightly, in that Briffa has now confirmed that the selection of the 12 cores from the much larger population available was due to the Russians. What the reason was for their only using 12 cores remains a mystery. Briffa's response has, however, opened up a new part of the debate that I've not touched on before - this concerns standardisation of the raw tree ring data.

During its lifetime, a tree does not grow at a uniform pace. Tree rings are generally wider when a tree is young than when it is older. If you are using a set of tree rings in climatology, therefore, unless you do something about it, your "treemometer" would always show declining temperatures, regardless of what is going on in the outside world. Standardisation is the process by which this fix is applied, and it involves removing a kind of "average growth curve" from the record to adjust for these changes in growth rate. There are various ways of doing this, the details of which are beyond my ken, but as I understand it, the Russians used the "corridor" method. This works well when you have small numbers of tree cores so it was presumably a suitable choice.

The problem with the corridor method is that it tends to obscure long-term trends in the data, which is precisely what you're interested in when you are doing paleoclimate work. Because of this, when Briffa picked up the seventeen cores for use in his version of Yamal, he applied a different standardisation procedure called RCS, which is better suited to the retention of long-term information.

My application of [RCS] to these same data was intended to better represent the [long-term] growth variations ... to provide a direct comparison with the chronology produced by Hantemirov and Shiyatov.

This is problematic. RCS is not suited to dealing with small numbers of cores (I recall reading somewhere that it is not considered suitable with less than 50, but I'm not swearing to that). I also wonder about the nature of Briffa's paper. It strikes me that if the purpose was to "provide a direct comparison with the chronology produced by Hantemirov and Shiyatov",  then there can be no arguing with the use of the same data. However, review of Briffa's original paper from 2000 suggests that intercomparison of standardisation methods was not part of his purpose at the time. The paper is a review of developments in paleoclimate and the calculation of a new temperature reconstruction using some of the new data. This being the case, the logical thing to do would surely to have used as much data as possible.


Briffa's other concerns are with McIntyre's sensitivity test - replacing the 12 Briffa cores with the Schweingruber 34 - different cores taken from the same area. This is how he puts it:

The basis for McIntyre's selection of which of our ... data to exclude and which to use in replacement is not clear... He offers no justification for excluding the original data.

 McIntyre's comeback on this is that he was very clear about the reasons for excluding the Briffa 12, namely that the number of cores was small. He wanted to test the robustness of the answer by swapping in a larger dataset that had not been used by Briffa.

As well as seeing what happened when the Briffa 12 were swapped for the Schweingruber 34, McIntyre also did a slightly different calculation to see what would happen when both were put in the mix. Briffa says that when McIntyre did this, he underweighted the 12 (i.e. making the loss of hockey stick shape more marked than it should have been). McIntyre has pointed out that Briffa has equally underweighted the Schweingruber 34 by not using them at all, and that debate about the weights doesn't affect the main point, which is that using the Schweingruber 34 makes the hockey stick shape disappear.

Briffa continues

Whether the McIntyre version is any more robust a representation of regional tree growth in Yamal than my original, remains to be established.

 This one has been doing the rounds for years. McIntyre has been clear from the start that he is not creating an alternative reconstruction. He is testing "official" studies for robustness.


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Reader Comments (21)

This has got to be a joke - it wasn't me it was the Russians! This farce is now verging on the pathetic. There can be no excuse for purporting to establish a robust temperature record based on a few trees. There is also no excuse for accepting such an extreme conclusion from such a lack of data for publication. Did none of the "experts" think to ask how much data there was? Did it really take the efforts of a lone blogger to shed light on this scam? It beggars belief.

However, there is a back story episode that might be a fascinating read. I cannot believe that the journals that published Briffa's chronology over the last 10 years, failed to enforce their data archival policy without coercion. Whoever made the final decision at Phil. Trans. Roy. Soc. to force Briffa to archive his data, was probably put under extreme pressure from several quarters not to do so. That person deserves a round of applause!

Oct 1, 2009 at 11:17 PM | Unregistered CommenterRecyclist

Well what did everyone expect? That these so called scientists would just roll over and accept their lifes work being destroyed in front of them?

The fight back was to be expected, however what wasnt to be expected is just how crude and uninformed that fight back has been so far.

So, if Biffa believes he is right...then release ALL the data he used, including his meta data in a common format (not in punch card form!).

Biffa, let your data prove McIntyre is wrong!



Oct 1, 2009 at 11:21 PM | Unregistered CommenterMailman

Here is the response I have to RealClimate's post. Of course they delete everything.

The RealClimate response is very odd. First they name McIntyre by name, which they generally avoid, so they did take it seriously, but not seriously enough to cover the facts.

Normally they love shooting at low hanging fruit, but her they don't even do that. They link to Delingpole's "A Massive Lie," and don't even bother to point out that Mann's hockey stick was in 1998 and this study was in 2000. They also don't go with 'McIntyre is trying to add in some other data that is irrelevant. What an idiot.'

Instead they do some horrendous things like saying McIntyre based his critiques on data he found on the internet.
Well, they based their critique on data they found on the internet, and anyone who uses RealClimate to critique McIntyre or anyone else is basing their critique on data found on the internet. Really, is that their opinion of Schweingruber's work.
They just are not willing to give McIntyre any credibility at all.

> ‘telegraphed’ across the denial-o-sphere while being embellished along the way to apply to anything ‘hockey-stick’ shaped and any and all scientists, even those not even tangentially related. The usual suspects become hysterical with glee that finally the ‘hoax’ has been revealed and congratulations are handed out all round. After a while it is clear that no scientific edifice has collapsed and the search goes on for the ‘real’ problem which is no doubt just waiting to be found. Every so often the story pops up again because some columnist or blogger doesn’t want to, or care to, do their homework. Net effect on lay people? Confusion. Net effect on science? Zip.

The same could be said of their work every time they issue a new hockey stick paper or model result.

>Having said that, it does appear that McIntyre did not directly instigate any of the ludicrous extrapolations of his supposed findings highlighted above, though he clearly set the ball rolling. No doubt he has written to the National Review and the Telegraph and Anthony Watts to clarify their mistakes and we’re confident that the corrections will appear any day now…. Oh yes.

This is absurd. He corrected Watts with regards to using the Hantemirov paper. Watts doesn't understand the difference and is still using the chart. I don't think RealClimate will be crediting him for that. And how often does RealClimate correct activists or other reporters who get facts wrong, if they report things in an alarmist fashion?
No, they add to it with statements like
Some aspects of climate change are progressing faster than was expected a few years ago – such as rising sea levels, the increase of heat stored in the ocean and the shrinking Arctic sea ice.
All of those stats were down at the time, as shown by Roger Pielke.

October 1, 2:13 PM
MikeN says:
As for the hockey stick charts they followup with, showing a chart from 1400 doesn't prove anything. Everyone knows it has warmed since then. The whole point of the hockey sticks is to claim that the warming is unprecedented. Warmer than medieval times of 800-1400. Mann's hockey stick flattened out that period and the Little Ice Age due to bad math.

The first chart is Wahl and Ammann, and Bishop Hill covered that in "Caspar Ammann and the Jesus Paper." There the scientists again refused to provide all the data needed to evaluate, and when they finally revealed key data, it tore the conclusions apart. Even with the graph RealClimate shows, if you look closely, you can see that McIntyre's criticisms show a warmer period at the beginning, right after the part they cutoff.

October 1, 2:34 PM
MikeN says:
The second graph is of glaciers back to 1600. Says nothing about medieval periods, or even before the little ice age.

The 3rd graph is Osborn and Briffa, where again they didn't reveal data. This was published in Science. They concluded that several proxies were correlated to temperature even though another paper Darrigo et al reached the opposite conclusion.
Science actually published a comment critical of the method used.
method of selecting proxies by screening a potentially large number of candidates for positive correlations runs the danger of choosing a proxy by chance. This is aggravated if the time series show persistence, which reduces the degrees of freedom for calculating correlations (6) and, accordingly, enhances random fluctuations of the estimates. Persistence, in the form of strong trends, is seen in almost all temperature and many proxy time series of the instrumental period. Therefore, there is a considerable likelihood of a Type I error.

Briffa and Osborn also made use of two bristlecone series, that the NAS Panel said should not be used. There are many other problems talked about at ClimateAudit, including a novel calculation of variance.

The fourth graph only goes back to 1500.
The fifth graph is not a temperature hockey stick, but of CO2, which is at its highest in thousands of years. CO2 was actually much higher if you go even further back in time, and you'll notice this is one chart they don't give a link for.

The sixth graph is Kaufmann 09 which shows a higher medieval warm period if you orient the Tiljander proxy properly. ClimateAudit also disputes 4 other proxies in that study.

The seventh graph has the temperature record added on to the end, so it's not even clear what they are comparing.

Oct 2, 2009 at 12:52 AM | Unregistered CommenterMikeN

Its worth reading Mcintyres lates:
Briffa's comment leads off with the accusation that I had implied that the recent data had in this chronology had been "purposely selected" by Briffa "specifically because they exhibited recent growth increases". I want to dispense with this up front. While I expressed surprise that there were so few cores, not only did I not imply that Briffa did any sub-selecting, but I specifically said the opposite.
bender, I agree with your point. I've tried to steer a careful line here. If you think otherwise, can you give me particulars as I don't wish to unintentionally feed views that I don't hold. It is not my belief that Briffa crudely cherry picked. My guess is that the Russians selected a limited number of 200-400 year trees - that's what they say - a number that might well have been appropriate for their purpose and that Briffa inherited their selection

Nor do I follow the Daily Telegraph blog. Now that its' been brought to my attention, I sent the email to James Delingpole at (as I have not yet received a password for the Daily Telegraph blog):
A couple of points on your blog article.

You've conflated two different studies. There are many issues pertaining to the Mann hockey stick, but the Yamal controversy is not one of them. Other than in the sense that "independent" reconstructions using the Yamal series in disputes are said to support the Mann hockey stick.
That is not what I"discovered". In fact, my opinion was the exact opposite as I stated at Climate Audit. It was my opinion ... that he had inherited a subset that had already been selected by the Russians, ....
There are real issues with the Briffa study, but it is unreasonable and unfair to go beyond the facts in evidence.

Oct 2, 2009 at 6:09 AM | Unregistered Commenterthefordprefect

Two comments:

MikeN: I've given up trying to post at RealClimate. They don't like to be contradicted, corrected or even slightly disagreed with, as thousands of blggers can confirm. The censorship they employ speaks volumes to me. I try not to look at RealClimate too often as I usually come away with a feeling of nausea.

The second and equally telling point is that Briffa has not stated why he refused to publish the data until compelled to. Again, the refusal to publish the data and the refusal to state why he refused to publish the data, speak volumes. Anything else he says is just flannel until he answers that question.

Oct 2, 2009 at 6:57 AM | Unregistered CommenterPhillip Bratby

I hope you have re-read your entry above and in doing so see how rediculous it sounds:

McIntyre's ... was very clear about the reasons for excluding the Briffa 12, namely that the number of cores was small. He wanted to test the robustness of the answer by swapping in a larger dataset that had not been used by Briffa.

As well as seeing what happened when the Briffa 12 were swapped for the Schweingruber 34, McIntyre also did a slightly different calculation to see what would happen when both were put in the mix. Briffa says that when McIntyre did this, he underweighted the 12 (i.e. making the loss of hockey stick shape more marked than it should have been). McIntyre has pointed out that Briffa has equally underweighted the Schweingruber 34 by not using them at all, and that debate about the weights doesn't affect the main point, which is that using the Schweingruber 34 makes the hockey stick shape disappear.

I. McIntyre has stated that all data is valid in tree ring analysis otherwise cherry picking results.
2. Why are 34 trees from a slightly different area more valid than 12 from the area in question?
3. The magic tree no mentioned above. It is valid data in mus be included. Its effect must no be weighted. Why does McIntyre only want it included if its hockeystick shape is lowered.

There is only McIntyre valid data. All else is mere noise.

McIntyre has written to the Telegraph, but there are so many blogs and papers caught up in the Mcintyre/Watts misinformation/misdirection campaign that they should write a public apology.
Just look at Watts blog and the Morohasy entry
Broken Hockey Stick Fallout: Leading UK Climate Scientists Must Explain or Resign
Mcintyre now says that Briffa did NOT fudge the data.
How many entries use the word FRAUD where none occurred.???

Oct 2, 2009 at 10:29 AM | Unregistered Commenterthefordprefect


Swapping the 12 for the 34 and getting a different result shows that the result with the 12 was not robust. This is not to say that the result with the 34 is robust, just that Briffa's findings aren't. McIntyre is clear that he is not creating a better reconstruction, he is showing that Briffa's can't be relied upon.

Oct 2, 2009 at 11:03 AM | Unregistered CommenterBishop Hill

I put this comment up at Climate Audit, but it's the sort of thing that Steve might "snip" - so I hope you don't mind if I post it here too.

If I were a policeman I would be used to distinguishing between Theft and Receiving stolen goods. I would doubtless get used to the Receiver crying "It wasn't me, guv, it was the bad boys - I just bought them, I didn't know. It's not my fault." I might even have met before the claim that the bad boys were Russians - there are a lot of them about in London nowadays. I dare say I would be used to replying "You can't be too careful, Sir. Anyway, you're nicked."

Oct 2, 2009 at 11:37 AM | Unregistered Commenterdearieme

October 2, 2009 | Bishop Hill
In my view tree rings are a poor thermometer!. I do not care whose sub-samples are correct.
My objection is the mud slinging initiated by McIntyres headlines and continued by his followers.
McIntyre has now stated that there is nothing fraudulent with Briffa. But the damage has been done and hundreds of bloggers/paper/tv will/have latched on to the fraud aspect. A very sad result in my opinion.

Bishop you may wish to trim this bit out.
Beware of allowing posters to defame (for that is what it is unless you have absolute proof!) any person on either side of this debate. As the owner of the blog you may be hauled up before the high court to firstly provide posters detail, and secondly to pay damages. I have been embroiled, for 2 years, in something (go here and type advfn in the search) which has cost me dearly in money and especially time. It costs a claimant nothing to force you to provide posters detais and It only costs them £1700 to start a defamation case. You have to prove your innocence (not the usual claimant proving your guilt).
My email is valid if you want to contact me!

Oct 2, 2009 at 12:03 PM | Unregistered Commenterthefordprefect

Missed the link off!

Oct 2, 2009 at 12:04 PM | Unregistered Commenterthefordprefect

The point is a good one. If you could point anything out that you think crosses the line then let me know. I'm struggling to keep up with the comments.

Oct 2, 2009 at 1:52 PM | Registered CommenterBishop Hill

A quick glance shows it better than I thought when I 1st read it!
Possibles are:
Media reaction - entry repeating others statements is also defamation
the yamal implosion
Richard sept 30
Tenuc 30th
treeman 30th
Appologies to these authors!

Oct 2, 2009 at 2:38 PM | Unregistered Commenterthefordprefect

These two studies (this plus Mann) are highly politically sensitive so extra paranosa is probably justified. It makes the historical record of European medieval warming look more reliable than current science and weakens the proposition that human beings are endangering their own futures with Co2.

Oct 2, 2009 at 3:44 PM | Unregistered CommenterEric Smith

Sorry paranoia, not paranosa (or Pondarosa).

Oct 2, 2009 at 3:49 PM | Unregistered CommenterEric Smith

Adding data is fine, but why is McIntyre throwing out data??

Is it because it disagrees with his political agenda?

Oct 2, 2009 at 4:35 PM | Unregistered CommenterAndrew

TFP, I don't think you understand what is happening with McIntyre's tests of Briffa's data.
These trees in Briffa's study did not come from one place, but from a large area covering the range
67 to 67.50' N and 68.30'E to 71E, according to the Russian authors.
Schweingruber additional 34 trees were inside that area.

Previously Briffa supplemented Taimyr with trees from Avam that were 400 km away from the Taimyr area to build the Taimyr-Avam chronology.
It is good that you are questioning, but you might consider questioning both sides.

Oct 2, 2009 at 5:16 PM | Unregistered CommenterMikeN

Philip, post any rejected comments at

Oct 2, 2009 at 5:17 PM | Unregistered CommenterMikeN

I take the thefordprefect comments seriously and try to avoid direct accusations. What this thread deals with though is also extremely serious. We have a respected scientist who apparently produces a scientific work which supports the hockey stick thesis. He does this with an extremely small sample and on this builds or allows to be built an argument that the world population must change their collective behaviour or face devastating consequences. This research is not made public, despite the extreme life style changes that are inevitable from following it. Immediately it is made public after many years it is shown to be flawed! My expectation is that due diligence must have been shown and this case it just does not appear so. You must ask
1. What is the worth of any tree ring research in respect of AGW?
2. Why scientific journals act like secret societies?
3. Why are politicians willing to change economies on the opinions of a few?

Oct 5, 2009 at 2:41 AM | Unregistered Commenterdhmo

dhmo, I agree with your points entirely. Although McIntrye's results are restricted to his blog and are reported/commented on in other blogs does not mean that they should not be taken seriously, bearing in mind the weight placed on all 'hockey stick' type curves by international policy makers. In my view our government should institute an independent review of Briffa's work and McIntyre's critique, remembering that Briffa is funded by the UK taxpayer. Especially after McIntyre's and McKitricks success in falsifying Mann et al (1998), after such an independent review in the USA..

Oct 5, 2009 at 12:07 PM | Unregistered CommenterPeter Stroud

Mr. Prefect, I assume you are British by your words and username. However, Michael Mann is American, and so American defamation law would apply. I am not certain about how the British version works, but in America, you have to prove that the words are:
False (and known to be false by the speaker. This completely excludes opinions),
Malicious (done with the intent to harm), and
Have caused measurable harm

This is nearly impossible to do when the words are directed against a public figure, and any form of political speech (and this is political) is granted the overwhelming protected by our First Amendment. I appreciate your concern for your fellow commenters, but defamation isn't going to be a problem here.

Oct 5, 2009 at 1:51 PM | Unregistered CommenterBen

I think the fact that, despite any commentary or concessions now, Briffa KNEW he was only using data from 12 trees, and NEVER AMIDST ALL THE QUESTIONING AND DEBUNKING acknowledged what he is now begrudgingly... BLAMING ON THE RUSSIANS. Amazing!

This is me CLEARLY AND FOR ALL TO HEAR accusing Briffa of cherry picking data, or at least knowingly using very questionable tactics in treating his data then purposely never answering direct questions about these methods. That case is made clearly and obviously by Briffa's own actions and lack of action concurrently.

Furthermore, regardless of what was intentional and what was not, the amount of discussion of how you're "supposed" to make corrections, compensate for this or that, or whatever is in no way shape or form SCIENCE. Manipulating a dataset one unique way, one unique time, to "make it right" is the exact and polar opposite of the repeatibility and reproducibility that science requires. So to assert some scientific certainty to what are basically a set of assumptions that a million doubts have been, and continue to be cast upon, is a big freaking joke.

I'm more pissed than anything simply about the fact that these clowns call themselves scientists, or call this mathematical manipulation science. This is nothing more than a con left for someone else to figure out how to profit off of. Exactly what has happened. And this makes Briffa a crappy scientist and a crappy con man. But he deserves all the anger, furor, accusations and reprimand his failed attempts at both have warranted...

Oct 5, 2009 at 9:00 PM | Unregistered CommenterDerek D

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