The Yamal ring-width chronology of Briffa (Briffa responds to McIntyre Alert)

Briffa news release ^ | 09-30-2009 | Keith Briffa

[Thickman]

My attention has been drawn to a comment by Steve McIntyre on the Climate Audit website relating to the pattern of radial tree growth displayed in the ring-width chronology "Yamal" that I first published in Briffa (2000). The substantive implication of McIntyre's comment (made explicitly in subsequent postings by others) is that the recent data that make up this chronology (i.e. the ring-width measurements from living trees) were purposely selected by me from among a larger available data set, specifically because they exhibited recent growth increases.

This is not the case. The Yamal tree-ring chronology (see also Briffa and Osborn 2002, Briffa et al. 2008) was based on the application of a tree-ring processing method applied to the same set of composite sub-fossil and living-tree ring-width measurements provided to me by Rashit Hantemirov and Stepan Shiyatov which forms the basis of a chronology they published (Hantemirov and Shiyatov 2002). In their work they traditionally applied a data processing method (corridor standardisation) that does not preserve evidence of long timescale growth changes. My application of the Regional Curve Standardisation method to these same data was intended to better represent the multi-decadal to centennial growth variations necessary to infer the longer-term variability in average summer temperatures in the Yamal region: to provide a direct comparison with the chronology produced by Hantemirov and Shiyatov.

These authors state that their data (derived mainly from measurements of relic wood dating back over more than 2,000 years) included 17 ring-width series derived from living trees that were between 200-400 years old. These recent data included measurements from at least 3 different locations in the Yamal region. In his piece, McIntyre replaces a number (12) of these original measurement series with more data (34 series) from a single location (not one of the above) within the Yamal region, at which the trees apparently do not show the same overall growth increase registered in our data.

The basis for McIntyre's selection of which of our (i.e. Hantemirov and Shiyatov's) data to exclude and which to use in replacement is not clear but his version of the chronology shows lower relative growth in recent decades than is displayed in my original chronology. He offers no justification for excluding the original data; and in one version of the chronology where he retains them, he appears to give them inappropriate low weights. I note that McIntyre qualifies the presentation of his version(s) of the chronology by reference to a number of valid points that require further investigation. Subsequent postings appear to pay no heed to these caveats. Whether the McIntyre version is any more robust a representation of regional tree growth in Yamal than my original, remains to be established.

My colleagues and I are working to develop methods that are capable of expressing robust evidence of climate changes using tree-ring data. We do not select tree-core samples based on comparison with climate data. Chronologies are constructed independently and are subsequently compared with climate data to measure the association and quantify the reliability of using the tree-ring data as a proxy for temperature variations.

We have not yet had a chance to explore the details of McIntyre's analysis or its implication for temperature reconstruction at Yamal but we have done considerably more analyses exploring chronology production and temperature calibration that have relevance to this issue but they are not yet published. I do not believe that McIntyre's preliminary post provides sufficient evidence to doubt the reality of unusually high summer temperatures in the last decades of the 20th century.

We will expand on this initial comment on the McIntyre posting when we have had a chance to review the details of his work.

K.R. Briffa 30 Sept 2009

Briffa, K. R. 2000. Annual climate variability in the Holocene: interpreting the message of ancient trees. Quaternary Science Reviews 19:87-105. Briffa, K. R., and T. J. Osborn. 2002. Paleoclimate - Blowing hot and cold. Science 295:2227-2228. Briffa, K. R., V. V. Shishov, T. M. Melvin, E. A. Vaganov, H. Grudd, R. M. Hantemirov, M. Eronen, and M. M. Naurzbaev. 2008. Trends in recent temperature and radial tree growth spanning 2000 years across northwest Eurasia. Philosophical Transactions of the Royal Society B-Biological Sciences 363:2271-2284. Hantemirov, R. M., and S. G. Shiyatov. 2002. A continuous multimillennial ring-width chronology in Yamal, northwestern Siberia. Holocene 12:717-726.

[Thickman]

Very weak response by Briffa. He does not address the questions surrounding his aggressive efforts over the years to deny access to his data.

This is a seminal event in the battle against the CO2 propaganda machine. I believe that folks on FreeRepublic can do a great service to this nation by helping spread the word and interest in this FRAUD perpetrated on the scientific world and us!

[Paladin2]

"I do not believe that McIntyre's preliminary post provides sufficient evidence to doubt the reality of unusually high summer temperatures in the last decades of the 20th century. "

There's a strong mathematical/scientific refutation. Note there is no proposed release of his selection method(s) either. Weak indeed.

[Paladin2]

"Weak indeed. "

Oh, yeah, not peer reviewed either.

[agere_contra]

In his piece, McIntyre replaces a number (12) of these original measurement series with more data (34 series) from a single location (not one of the above) within the Yamal region, at which the trees apparently do not show the same overall growth increase registered in our data.

Yes, that would be the point. If I have understood this correctly McIntyre demonstrated that Briffa's data-analysis technique would show no hockey stick at all if Briffa hadn't carefully cherry-picked 12 trees with high growth for the most modern dataset.

Briffa apparently got a hockey stick by choosing to use only a small subset of the available data and excluding all others. Which would be farcical science.

[aruanan]

The basis for McIntyre's selection of which of our (i.e. Hantemirov and Shiyatov's) data to exclude and which to use in replacement is not clear but his version of the chronology shows lower relative growth in recent decades than is displayed in my original chronology. He offers no justification for excluding the original data; and in one version of the chronology where he retains them, he appears to give them inappropriate low weights. I note that McIntyre qualifies the presentation of his version(s) of the chronology by reference to a number of valid points that require further investigation. Subsequent postings appear to pay no heed to these caveats. Whether the McIntyre version is any more robust a representation of regional tree growth in Yamal than my original, remains to be established.

What I read HERE is that Briffa had a data set of 46 samples. He chose 12 and excluded 34. His result was the hockey stick used by Mann and everyone after him to show unprecedented warming in the last 100 or so years. When McIntyre finally got hold of the data set and used those 34 samples, he found a sharp decline in temperature over the last 100 years. 12 samples show a dramatic increase, fitting it with the global warming theology, 34 excluded samples show a large decrease, contradicting global warming theology. The 46 samples all together show a very moderate warming, consistent with a warm up from the little ice age.

From the link above:

Science is broken
So much for the repeat claims that peer review is a “rigorous process”. Those who keep telling us we have to “listen to the experts” and who put so much stock in a peer reviewed paper have been left hanging out to dry. Even if Briffa has a reason to exclude 2/3rds of the samples and somehow it’s just a coincidence that the ignored data were from slower growing trees, nothing changes the fact that he didn’t mention that in the paper, and nor, damningly, did he provide the data. It only takes a sentence to say (for example) “ABC tree chronologies excluded due to artificial herbicide damage” and it only takes a few minutes to email a data file.

[centurion316]

Very weak and very convenient. Let’s suppose that Briffa’s methodology had produced the data set used by McIntyre. Does anyone think that Mann would have used Briffa’s data? Unlikely. So, who benefited by Mann’s use of Briffa’s data? Well, in addition to the usual political suspects, my guess is that Briffa and Mann have enjoyed increased attention, praise, and funding. Just a guess.

[kidd]

It IS a weak response. And McIntyre DID analyze the situation with a bigger data set that DID include the Yamal data... and found NO AGW.

[Thickman]

There are other good reports on the chronology of McIntyre's efforts to obtain the data over several years. Check out this web site: http://bishophill.squarespace.com/blog/2009/9/29/the-yamal-implosion.html

It is amazing to what length's Briffa went in order to conceal his data. Even when he was backed into a corner it still took over a year and extraordinary efforts by McIntyre to pull the data because Briffa had not meta tagged it (similar to a document dump in response to a subpoena).

This could be a major development if it can just get some MSM legs. Fox News, where are you!

[Dr. Bogus Pachysandra]

This would seem to apply to Briffa.
From the Dinosaur DNA thread;
“Whenever any kind of evidence is concealed, one immediately questions the spoliators’ motives for doing so. The intuitive answer is that they dislike what the information would reveal. Therefore, to spoliate evidence suggests that the spoliators’ argument or theory would be weakened, or embarrassed, by that evidence. This suggestion is so strong, forensically speaking, that it is treated as a rule of presumptive inference in law courts. In other words, if someone hides evidence in this way, the law presumes that the hidden evidence was damaging to the argument of the spoliator. The spoliator then bears the burden of proof to show otherwise.”

[agere_contra]

IIRC the only reason Briffa had to disclose the data was that he had submitted to the Royal Society, who I understand strictly require submitters to enter their data to an archive that RS control.

Now the Royal Society have been hopelessly pro-AGW to date, but in this case their rules have allowed the truth to come out.

[Thickman]

The Royal Society requirement is accurate. However, McIntyre had to prod them to get Briffa to supply the data. Then McIntyre had to prod them again. To the credit of the society, they seriously followed-up and forced Briffa’s hand who responded in sophomoric fashion (difficult to extract data).

[agere_contra]

Thanks Thickman.

[Buchal]

Does anyone on this thread know whether the ring thickness methods control for the fact that tree growth rates are not just a function of temperature, but also of the amount of CO2 in the air? (I.e., higher CO2 levels may produce thicker rings quite apart from any temperature change.)

[CanaGuy]

Never-the-less, the IPCC has based its apocalyptic "hockey stick" chart of rising global temperatures that, it now turns out, is based on the historic concentric rings on exactly 12 trees. Count 'em, twelve sets of rings.

Billions of dollars ripped from the coffers of the rich countries and showered on the developing nations, industries crippled, carbon sacrificing, electricity plants shut down, etc., etc., etc. .....based on 12 trees somewhere in Russia?

It's almost laughable, if it weren't so sickening. Is it just me....or have we been had?

[kidd]

Briffa's license plate number

[Fractal Trader]

ping

[xcamel]

FReepmail me to get on or off

Ping me if you find one I've missed.

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[Old Professer]

Especially when it comes hot on the heels of this admission:

“I note that McIntyre qualifies the presentation of his version(s) of the chronology by reference to a number of valid points that require further investigation. Subsequent postings appear to pay no heed to these caveats. Whether the McIntyre version is any more robust a representation of regional tree growth in Yamal than my original, remains to be established.”

Had he the true faith in his convictions he would have simply pointed out where McIntyre’s analysis were wrong.

It’s not like the fate of the world’s economy depends on this minor detail, is it?

[Thickman]

It is my understanding that it is commonly known that trees consume less and less CO2 as they grow older. That is why it is proposed that trees be cut and replaced with faster growing young trees in order to sequester more CO2 from the atmosphere.

For this reason I am certain that algorithms are used when analyzing tree rings for the purpose of reconstructing temperature records.

Of course none of this adds validity to the use of tree rings for generating historical data, let alone just 12 of them from someplace in Russia.

[Old Professer]

Artifical, still implicating man?