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Observations of anthropogenic global warming

Comments on McIntyre’s claims on Briffa

Posted by Ari Jokimäki on October 2, 2009

Those who have followed climate science online have undoubtedly heard about recent claims made by McIntyre about Briffa et al. work on tree ring based reconstructions. Keith Briffa has already responded, and RealClimate has also responded. In addition to these, I have couple of things I would like to point out.

McIntyre started the claims in this post. I’ll quote the first sentence from there:

A few days ago, I became aware that the long-sought Yamal measurement data url had materialized at Briffa’s website – after many years of effort on my part and nearly 10 years after its original use in Briffa (2000).

Note that McIntyre doesn’t give a link to Briffa’s website where Briffa introduces the data, but McIntyre links directly (and only) to the page containing the data. It is of course easy to find it yourself, but it seems to be a common theme in McIntyre’s postings that as little outside information as possible is given. McIntyre also doesn’t give proper reference to Briffa (2000), this has also been left for the reader to find out.

Here is the link to Briffa’s website, where the link to the data page is given:
http://www.cru.uea.ac.uk/cru/people/briffa/
And the link there leads to more thorough presentation of the data:
http://www.cru.uea.ac.uk/cru/people/melvin/PhilTrans2008/
There then is the link to the data file McIntyre linked to:
http://www.cru.uea.ac.uk/cru/people/melvin/PhilTrans2008/YamalADring.raw

Here is the link and the reference to Briffa (2000):
Briffa, K. R. 2000. Annual climate variability in the Holocene: interpreting the message of ancient trees. Quaternary Science Reviews 19:87-105 (unfortunately this paper doesn’t seem to be freely available online).

Now, looking at Briffa’s website and McIntyre’s quote above, I note that there’s something strange here. McIntyre mentions Briffa (2000) and how it’s been 10 years from that, but there is entirely different paper being given in Briffa’s website:

Briffa et al., 2008 Phil. Trans. R. Soc. B, vol. 363, no. 1501, 2269-2282, “Trends in recent temperature and radial tree growth spanning 2000 years across northwest Eurasia” (click “full text” links on the right to read the whole paper).

So, already the first sentence of McIntyre’s post was false. This is not the data for Briffa (2000) (even if a version of it was used there), but it is the data for Briffa et al. (2008). Briffa et al. (2008) is not discussed by McIntyre, but is mentioned once in the caption of Figure 1:

Figure 1. Comparison of the (smoothed) Yamal reconstruction (Briffa 2000, Briffa et al 2008, Kaufman et al 2009 and many others) to the Polar Urals Update (Esper et al 2002).

It is quite ironic that McIntyre’s Figure 1 only contains two curves, “Briffa (2000)” and “Esper update”. I also wonder what exactly is this “(smoothed) Yamal reconstruction” as McIntyre seems to use only raw data (or at least doesn’t say otherwise) from Briffa et al. (2008). Also, again no proper references for any of the mentioned papers.

So, the data is from Briffa et al. (2008). That means we have to consult Briffa et al. (2008) in order to see what has been the data selection process (which McIntyre didn’t do). On Yamal data, they say:

Siberian larch (Larix sibirica) data from the area immediately east of the northern Ural Mountains, previously used by Hantemirov & Shiyatov (2002), were used as the Yamal regional chronology,…

So, it appears they use data from Hantemirov & Shiyatov (2002). Here is the link to that paper (but not freely accessible for everyone):
Hantemirov & Shiyatov, 2002, The Holocene, Vol. 12, No. 6, 717-726, “A continuous multimillennial ring-width chronology in Yamal, northwestern Siberia”

Curiously enough, McIntyre starts discussing Hantemirov & Shiyatov (2002) paper, and I think he shows that he is not aware that Briffa et al. (2008) used the data of Hantemirov & Shiyatov (2002), McIntyre says:

There is one other version of these series that readers may encounter: Hantemirov and Shiyatov archived a Yamal reconstruction at NCDC that has no hockey stick blade whatever. This version was promoted by a commenter (Lucy Skywalker) at Jeff Id’s as being a priori more valid than Briffa’s. Although the Hantemirov and Briffa chronologies have a very different visual appearance (especially the non_HSness of the Hantemirov version), there is an extremely high correlation between the very different looking Hantemirov-Shiyatov and Briffa Yamal chronologies. (If you regress the Briffa recon against the Hantemirov recon for the pre-1800 version, you get a huge r^2 of 0.81). The two series clearly have the same raw material.

That would go without saying, if McIntyre would have looked at Briffa et al. (2008), where he got the data from.

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10 Responses to “Comments on McIntyre’s claims on Briffa”

  1. Luis Dias said

    What?!?!? Get over yourself! The paper that McIntyre is after is Briffa 2000, for it is the basis of spaghetti graphs, including Briffa’s own. How can you state that McIntyre was making false claims? Because Briffa made another paper on 2008? Is this your level of reasoning? Wow, I’ll never come back! Good luck in your life.

  2. Jason said

    It is rather amusing to see you criticize McIntyre while seemingly not having read his posts.

    McIntyre is plainly aware that Briffa used data from the Russians. That is the point he is trying to make.

    By way of procedures that we do not yet understand, hundreds of cores were taken (which do not show a hockey stick), and out of those cores 10 made their way in to Briffa’s 2000 paper, showing a massive hockey stick.

    McIntyre uses data that was collected by Briffa collaborators from the same location specifically _because_ Briffa has also use this data. This means that he was aware of this data, and that he had no reservation using it in peer reviewed research.

    I hope this website is an experiment in trolling and not a serious effort.

  3. Turboblocke said

    I find the deniers preoccupation with the “hockey stick” so amusing. First of all there are two seperate bits to look at: the handle and the blade. The handle goes back a few centuries and is relatively flat. The blade is quite recent and rises steeply. The blade is not dependant on tree core reconstructions and it is ridiculous for the deniers to claim that. Why use a proxy for temperature when we have the instrument record? So claiming that the blade is broken by Yamal is just daft.

    As for the handle, some deniers like to claim that the Medieval Warm Period was a time of higher global temperature for a couple of centuries. They are difficult to pin down accurately, but seem to claim that it was from 2-4°C warmer between roughly 1000 AD to 1400 AD. Firstly, this claim is based on a relatively few proxy measurements which are difficult to date precisely to an exact year, so a global temperature is difficult to establish. However, the big problem for the deniers with the MWP (if it did exist), is what caused it? Because what they’re claiming is an average temperature rise and fall of about 0.1-2°C per decade with no obvious mechanism. So if there was a mechanism it must have been some thing that doesn’t show up in any of the usual proxies that measure solar variation or anything mentioned in writings of the time. The implication therefore is that climate sensitivity must be extremely high, which means that the climates’s response to CO2 forcing is going to be high.

  4. MikeN said

    You really should try to understand things before you criticize McIntyre. The posts are generally read by people who have read his previous posts on the subject. In fact the data released is from Briffa 2000. He previously had not released the data despite repeated requests. He reused the data in 2006 in a paper in Science, and Science did not make him release that data, because it was from an older paper. He then used it again in Phil Trans B, and that journal made him release the data for his older paper as well, so people could evaluate his findings.
    The Russian paper H&S 2002 is a different paper that used the same underlying data that they collected, and Briffa did a different analysis of this data and managed to get published 2 years earlier than the Russians with their own data!

  5. Ari Jokimäki said

    Jason:

    “McIntyre is plainly aware that Briffa used data from the Russians. That is the point he is trying to make.”

    I perhaps should have used past tense, but I really meant that McIntyre didn’t seem to know that at the time of the writing. You don’t need to do statistical tests to prove that they are from the same source if you already know it. Simple peek to the Briffa et al. (2008) would have shown that without a doubt, as it is explicitly mentioned there that the data is from Hantemirov & Shiyatov (2002).

    “By way of procedures that we do not yet understand, hundreds of cores were taken (which do not show a hockey stick), and out of those cores 10 made their way in to Briffa’s 2000 paper, showing a massive hockey stick.”

    The data is from Briffa et al. (2008). Their table 1 says that they used 611 samples from Yamal. McIntyre talks about how Hantemirov & Shiyatov (2002) used 17 cores in the 19th and 20th century. In a later post he went on and removed selected 12 out of them. That is, he removed about 70 % of the sample. I have no idea where you get the 10 number.

    MikeN:

    “In fact the data released is from Briffa 2000.”

    The facts that we have are:

    – Link given by McIntyre is to Briffa et al. (2008), as is shown here:

    http://www.cru.uea.ac.uk/cru/people/melvin/PhilTrans2008/

    – Briffa et al. (2008) say that the data is from Hantemirov & Shiyatov (2002).

    However, I haven’t claimed that the data used in Briffa (2000) is different data set. I said: “This is not the data for Briffa (2000) (even if a version of it was used there),…” The RealClimate article says that Briffa (2000) used a “preliminary set of this data”. My point is that McIntyre didn’t seem to be consulting proper references for the data he used.

  6. mike said

    douche.

  7. Ari Jokimäki said

    There are couple of interesting posts about this issue here:
    http://delayedoscillator.wordpress.com/2009/10/05/yamal-emulation-ii-divergence/
    http://delayedoscillator.wordpress.com/2009/10/05/yamal-emulation-i/

  8. TCO said

    McI is MISERABLE about not including proper footnoted references. Don’t feel bad if you could not follow his tortured snail shell. And the whole, you have to have followed other posts of McI (as if we should have to read his entire site, comments included) just furthers the idiocy.

    And this is coming from someone WELL MORE RIGHT WING than McI. But someone who hates crappy science writing. And McI is a 5 year tease.

  9. Ari Jokimäki said

    Another interesting post aboout this:

    http://deepclimate.org/2009/10/07/let-the-backpedalling-begin/

    Check out also the Craig Allen’s comment there. :)

  10. [...] http://agwobserver.wordpress.com/2009/10/02/comments-on-mcintyres-claims-on-briffa/ http://delayedoscillator.wordpress.com/2009/10/05/yamal-emulation-i/ [...]

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