There has been another exchange between Keith Briffa and Matt Ridley in the pages of the Times. Briffa's new letter was as follows:

Ridley quotes me as saying my “research was validated by the inquiry chaired by Sir Muir Russell.” I said no such thing. The Independent Climate Change Email Review had no remit to “validate” any research. What I actually said was that I had not “cherry-picked” my data to produce a desired result, which was the specific accusation levelled at me in Ridley’s piece ( Opinion, Jan 6 ). Sir Muir Russell’s team examined this specific accusation and found that I had not.

What I in fact said was that I reprocessed the same data set used by different researchers in their version of this chronology. This was in order to improve the representation of long-timescale information in these data. Ridley persists in the repeated claim that a “larger tree-ring chronology from the same region did not have a hockey stick shape”, implying that a chronology based on more tree-ring data would invalidate our conclusions and insinuating that just such an “adverse” chronology had been concealed by us and would not have come to light without a Freedom of Information (FOI) request. He is wrong on both counts. An FOI request was made to the University of East Anglia for a chronology whose existence was revealed as a result of the theft of emails from the Climatic Research Unit. The Information Commissioner’s Office and the Information Tribunal rejected this request, accepting our explanation that the chronology in question was produced as part of ongoing research intended for publication. This chronology was subsequently published, but as a demonstration of how a failure to recognise and account for inhomogeneities in the underlying measurement sets can produce an unreliable indication of tree growth and inferred summer temperature changes.

He says that I said I reprocessed a tree-ring data set “rather than ignoring it because it gave less of an uptick in temperatures in later decades than the small sample of Siberian larch trees” that I published.

Matt has sent me a copy of his response which is as follows:

My original intention in mentioning this example, chosen from many in climate science of the same phenomenon, was to draw attention to the fact that non-publication of adverse data is not a problem confined to the pharmaceutical industry, but also occurs in government-funded, policy-relevant areas of academic science.

This is Stephen McIntyre’s response to me commenting on the letters from Professor Keith Briffa to the Times in response to my column on the widespread problem of withheld adverse data. It makes very clear that my account was accurate, that my account was mischaracterized by Professor Briffa in serious ways, and that nothing in his letters refutes my original claim that had a key dataset not been ignored, a very much less striking result would have been published. Professor Briffa now says he was reprocessing the data, but in 2009 he said “we simply did not consider these data at this time”. Neither explanation fits the known facts well.

Steve McIntyre's comments were as follows:

Briffa’s new letter does not rebut anything that you had written in your reply or original article. Instead, it is a pastiche of comments that are either incoherent, not responsive to points in your reply, untrue or highly contentious.

Review of Events

Let me first do a brief reprise of events.

Figure 1 shows five different Yamal/Yamal region chronologies for the period 900 on, converted to Standard Deviation units. The first three panels show versions from Briffa 2000, Briffa et al 2008 and Briffa 2009 (Climatic Research Unit (CRU) website). All have pronounced Hockey-stick (HS) shapes. Panels four and five show the 2006 and 2013 versions, both of which end at elevated but not HS values.

Figure 1. Five Yamal chronologies. Top – Briffa (2000); second – Briffa et al 2008; third – Briffa 2009 at CRU website; fourth – 2006 regional chronology mentioned in Climategate dossier and eventually shown in Briffa et al 2013 Supplementary Material 7; fifth – regional chronology (“Yamalia”) from Briffa et al 2013. The dotted horizontal line shows, for orientation, the closing value of the Briffa et al 2013 regional chronology (smoothed). The first four panels end in 1996 (denoted by a dashed vertical red line), while the 2013 chronology ends in 2006. The smooth for 2000, 2008 and 2009 is smooth as used in the original articles, while the smooth for the bottom two panels is a running 11-year mean.

The Briffa (2000) chronologies for Yamal, Tornetrask and Taimyr have been widely (almost universally) applied in subsequent multiproxy temperature estimates. Its Yamal chronology re-processed the Yamal measurement dataset subsequently published in Hantemirov and Shiyatov 2002.

In 2006, Briffa and/or Osborn calculated “regional” chronologies for the Yamal, Tornetrask and Taimyr regions. These regional chronologies supplemented the measurement data used in Briffa 2000 with other measurement data in the region e.g. measurements taken by Schweingruber and Vaganov not used in the 2000 calculation. These three regional chronologies were discussed in a Climategate email (684. 1146252894.txt) on April 28, 2006, which mentioned the Yamal/Urals regional chronology as follows:

“URALS” (which includes the Yamal and Polar Urals long chronologies, plus other shorter ones).

The chronology in this email is shown in the fourth panel above. It obviously lacks the pronounced HS of the 2000 version; in addition, its medieval values are somewhat greater than modern values.

In another Climategate email (780. 1172776463.txt) the following year (March 2007), Osborn discussed with Briffa the differences in versions of the Yamal/Urals regional chronology that were in a CRU presentation that Osborn had sent to Briffa.

Six months after this email (November 2007), Briffa and coauthors published an article (Briffa et al 2008) purporting to provide “regional chronologies” for the three northern Eurasian regions previously considered in Briffa 2000. In the other two regions (Tornetrask, Taymir), Briffa et al had dramatically expanded the data sets by incorporating, for example, Schweingruber datasets in the Taymir region. However, despite the implication of Briffa et al 2008 that they had used expanded datasets, the Yamal dataset of Briffa et al 2008 was the same as the dataset of Briffa 2000, even though the 2000 Yamal chronology had a much smaller number (12) of samples in the modern period relative to the other 2000 chronologies, let alone their 2008 expansions. This chronology is shown in the second panel.

In September 2009, after obtaining measurement data for the three regions as used by Briffa, I observed that Briffa et al 2008 had incorporated Schweingruber datasets into the 2008 Taimyr regional chronology, that there were seemingly equivalent Schweingruber datasets in the Yamal region (noting Khadyta River KHAD as an example) and that inclusion of such Schweingruber data would attenuate the very pronounced HS of the Briffa 2008 Yamal chronology. (BTW this observation has been supported by the 2013 regional chronology.) It seemed highly implausible that Briffa and associates wouldn’t have done a regional chronology calculation for the Yamal/Urals region. I speculated that Briffa and associates must have done a regional chronology calculation, also obtaining highly attenuated non-HS modern values and, for some reason not disclosed in the article itself, not chosen not to report it.

This surmise, which later proved to be true, was sharply rebuked at the time. In an online article at the CRU website in October 2009, Briffa conceded that the KHAD site met their criteria for inclusion in a regional chronology, but claimed that they “simply did not consider” the data at the time.

Judged according to this criterion it is entirely appropriate to include the data from the KHAD site (used in McIntyre's sensitivity test) when constructing a regional chronology for the area. However, we simply did not consider these data at the time, focussing only on the data used in the companion study by Hantemirov and Shiyatov and supplied to us by them. We would never select or manipulate data in order to arrive at some preconceived or regionally unrepresentative result.

At the time, the Climategate emails were not available and, while this assertion seemed implausible, neither could it be contradicted with then available information. However, the following month (November 2009), Climategate emails became available. Yamal appears to have been of particular interest to the hacker/leaker of the Climategate emails based both on the selection of documents and emails and the limited information on access times.

Yamal was mentioned in one of the questions in the Muir Russell Issues Paper as follows. (In passing, it’s interesting to note that, while the Muir Russell report has been derided on many counts, its neglect of issues raised in the Issues Paper was under-discussed.)

Have you been selective in utilizing tree ring evidence from Yamal in Siberia; and if so, what is the justification for selectivity and does the selection influence the deduced pattern of hemispheric climate change during the last millennium?

The reference in the March 2006 Climategate email to a regional chronology incorporating Yamal, Polar Urals and “other shorter” datasets was quickly noticed, as it obviously appeared to contradict CRU’s October 2009 response. In my submission to the Muir Russell review, I specifically drew attention to this email as an example of cherrypicking the Yamal chronology over a “still unavailable combined chronology attested in Climategate Letter 1146252894.txt.”

In their submission to the Muir Russell panel in February 2010, CRU did not address the unpublished regional chronology. They stated to Muir Russell that the purpose of both Briffa 2000 and Briffa et al 2008 was to “reprocess” the Hantemirov and Shiyatov dataset and that they “made no selection of what data to include”. They incorporated their October 2009 website article in their submission – an article, which, as noted above, said that “simply did not consider” the inclusion of Schweingruber data into a regional chronology at the time. While the purpose of Briffa 2000 included reprocessing the Hantemirov and Shiyatov dataset using RCS standardization, this was not the stated purpose of Briffa et al 2008, which, instead, purported to present regional chronologies. “Reprocessing” was nowhere mentioned in the article. Nor is it correct to say that Briffa et al 2008 “made no selection of what data to include”. They decided against using the expanded regional data used in the 2006 regional chronology. Even if that were a justifiable decision (as CRU later argued), it was still a decision about what data to include and, to that extent, their submission to Muir Russell was misleading.

As is well known, Muir Russell himself did not even bother attending the one interview of CRU personnel on Hockey Stick matters (which was conducted by Geoffrey Boulton.) Following this interview, Boulton asked CRU to comment on McKitrick’s October 2009 op ed about Yamal – an article published prior to Climategate and which therefore did not refer to or discuss the 2006 regional chronology. The panel did not ask CRU to comment on the regional chronology. In their response to Muir Russell, CRU re-iterated their implausible claim that the “purpose” of Briffa et al 2008 was merely to “reprocess” the original Hantemirov dataset. They also inconsistently said that they had considered the incorporation of more data (presumably including Khadyta River) and indeed even “intended to explore an integrated Polar Urals/Yamal larch series”, but had “felt that this work could not be completed in time”. Needless to say, this incompleteness had not been disclosed to editors or readers of Briffa et al 2008. CRU conspicuously did not disclose to the Muir Russell panel that they had previously calculated a Yamal/Urals regional chronology or discuss its supposed defects.

It’s too bad that Muir Russell neglected this and other issues in their report. A more competent panel would have settled some of these issues.

Since the regional chronology was not addressed by Muir Russell, I submitted an FOI request both for the chronology and for a list of the sites. In their response, University of East Anglia (UEA) confirmed the existence of the chronology, but refused to release it or the list of sites.

I appealed to the Information Commissioner. The Information Commissioner required UEA to disclose the list of sites immediately. In negotiations between the Information Commissioner and UEA, UEA undertook to publish the requested regional chronology within six months, an undertaking which was a major improvement, but which was still (in my opinion) a delaying tactic. The Information Commissioner accepted UEA’s undertaking but noted my concern, stating that failure on the part of the University to live up to its undertaking would open up the possibility of a different position for a fresh FOI request:

The complainant has expressed doubts as to whether the University really intends to publish the information by the date specified and believes this to be a delaying tactic on the University's part. The Commissioner is not aware of any evidence to support such a contention, but given the written assurances which have been received from the University as to the publication date, he considers that any delay beyond October 2012 will need to be reasonably explained by the University if the withheld information is to remain exempt from disclosure by virtue of regulation 12(4)(d), if a further request was made.

Having no confidence in UEA’s undertaking, I appealed the Information Commissioner’s decision. As matters turned out, UEA did not make the slightest attempt to live up to their undertaking. They submitted an article to Nature without the requested regional chronology. This submission was rejected. So six months later, they had not even begun to comply with their undertaking to the Information Commissioner. The appeal at the Information Tribunal proceeded, with exchanges and submissions to the Information Tribunal becoming increasingly acrimonious.

Tim Osborn stated that to the Information Tribunal that release of the regional chronology (shown in the fourth panel above) would have “adverse reputational consequences” to Briffa and CRU and lead to criticism that would “damage the reputation of individual CRU scientists as well as CRU's reputation as a leading centre of excellence in the field of climate change research”:

49. Looking at the situation more narrowly, there would also inevitably be adverse reputational consequences for the individual scientists involved in this work and the University itself if disclosure had been effected. This is because biases in the 2006 chronology, which in CRU's view limit its value as evidence of past temperature changes, would doubtless be seized upon by climate change sceptics as demonstrating that there were fundamental failings in CRU's approach to the science of climate change. Whilst such charges would be entirely unfair in all the circumstances, they would serve to damage the reputation of individual CRU scientists as well as CRU's reputation as a leading centre of excellence in the field of climate change research.

Meanwhile, CRU had finally commenced preparation of the article previously promised to the Information Commissioner. The new article (Briffa et al 2013) presented a new regional chronology incorporating Yamal and Polar Urals, but not Khadyta River. This is shown in the bottom panel. In its Supplementary Material 7, they presented the 2006 regional chronology (fourth panel) together with a litany of supposed defects. In April 2013, the Information Tribunal rejected my appeal. While it seemed to me that they erred in their decision, the issue became moot with the publication of Briffa et al 2013 and I did not pursue it further.

Returning to Figure 1, it is obvious that the modern portion of the 2013 regional chronology is dramatically attenuated relative to the pronounced HS of the 2000, 2008 and 2009 chronologies and is much more comparable to the despised and unreported 2006 regional chronology. The main difference between the 2006 and 2013 regional chronologies is the shaving of medieval values through a new policy requiring the exclusion of radially asymmetric root collar samples from Polar Urals. As I observed at Climate Audit at the time, strip bark bristlecones have far more dramatic radial asymmetry and it is this radial asymmetry that causes the extreme Hockey Stick shape of the Graybill bristlecone chronologies.

Consistent adoption of Briffa’s new policy would require the rejection of the many reconstructions using strip bark bristlecones. Otherwise, one simply moves to a new form of cherrypicking by IPCC paleoclimatologists: accepting radial asymmetry when it contributes to a HS and rejecting it when it doesn’t.

Briffa’s New Letter

As noted above, Briffa’s second letter is a pastiche of incoherency, irrelevancy and disinformation.

First Paragraph Is Incoherent

In his first paragraph, Briffa challenged the following sentence in Ridley’s reply letter:

Professor Keith Briffa says that he was "reprocessing" a data set rather than ignoring it because it gave less of an uptick in temperatures in later decades than the embarrassingly small sample of Siberian larch trees he published.

As noted above, Briffa had stated (for example to Muir Russell) that the “purpose” of Briffa et al 2008 was to “reprocess” the small Hantemirov and Shiyatov 2002 Yamal dataset and denied that this decision had anything to do with the adverse (non-HS) results from their 2006 regional chronology calculations. Although Briffa objected strongly to the above sentence, I, for one, do not see any relevant difference between Ridley’s characterization and Briffa’s new declaration:

This reprocessing was not motivated by consideration of any “uptick in temperatures”.

Here Briffa’s animosity has descended to incoherence.

Second Paragraph is Irrelevant

Briffa’s next two sentences are irrelevant to any issue raised in either Ridley’s original opinion or reply.

Ridley had not suggested that the Yamal chronology was “dependent” on the Mann bristlecones (or vice versa). Thus Briffa’s following strident declaration that the two series are “independent” is simply irrelevant to any actual issue:

in his Opinion Piece he describes my publication of this version of the Yamal chronology as a “relaunch” of the hockey-stick graph of Northern Hemisphere average temperatures. My work was independent of the so-called “hockey-stick” graph and I and my colleagues have long ago demonstrated that the conclusions drawn in that work are not dependant on the inclusion of my Yamal chronology.

As a nit, the original Yamal chronology was published (2000) some years prior to my entry into the field (2003-2005) and was therefore not a “relaunch” of the Hockey Stick in response to our criticisms. More accurately, it was Briffa’s entry into the Hockey Stick market, as, up to this point, his primary published reconstructions (Briffa et al 1998; Briffa et al 2001) had marked post-1960 declines, well known through “hide the decline”.

The Withheld Regional Chronology

Briffa then made a series of highly inaccurate and/or misleading statements about the unpublished and adverse 2006 regional chronology as follows:

Ridley then persists in the repeated claim that a “larger tree-ring chronology from the same region did not have a hockey stick shape”. Leaving to one side the questions of what constitutes a “larger chronology” and what does or does not represent a “hockey-stick shape”, this statement implies that a chronology based on more tree-ring data from this region would invalidate the conclusions from our published temperature reconstructions. He also insinuates that just such an “adverse” chronology had been concealed by us and would not have come to light without a Freedom of Information (FOI) request. He is wrong again on both counts. This presumably refers to an FOI request made to the University of East Anglia for a chronology whose existence was revealed as a result of the theft of emails from the Climatic Research Unit. Both the Information Commissioners Office and the Information Tribunal (appeal number EA/2012/0156) rejected this request, accepting our explanation that this chronology was produced as part of ongoing research intended for publication.

This chronology was indeed subsequently published, but as a demonstration of how inappropriate statistical processing, allied with a failure to recognise and account for inhomogeneities in the underlying measurement sets, can produce what is an unreliable indication of regional tree growth and inferred summer temperature changes in this area. Ridley’s description of this chronology as a withheld “adverse” result is, therefore, unjustified.

First, CRU did not disclose the existence of the 2006 regional chronology or efforts to develop a Yamal/Urals regional chronology in Briffa et al 2008, their October 2009 website article or in their submissions to Muir Russell. Does this imply that CRU “concealed” the existence of the chronology? In this case, “conceal” is Briffa’s word, not Ridley’s. Ridley’s letter as submitted used the perhaps more neutral phrase “failed to report” – a claim that is true.

Second, contrary to Briffa’s assertion, nothing in the Information Commissioner’s decisions contradicts a view that the 2006 regional chronology would not have come to light without the FOI requests. In my opinion, while CRU may well have re-opened the file on Yamal as at the time of my FOI request, I do not believe that they then had the faintest intention of including the 2006 regional chronology in any putative publication. I can’t prove this, but it’s what I think. The Information Commissioner appears to me to have taken a fairly firm position with UEA during negotiations. He required UEA to release the list of sites used in the regional chronology, though this was done during negotiations rather than in a decision. This was an important victory for me, as it enabled me to do my own estimate of the regional chronology – an estimate that was virtually identical to the then withheld chronology. It also seems to me that the Information Commissioner took a relatively practical position on the chronology itself. UEA said that they were working on the data and undertook to release the data as part of a publication within six months. The Commissioner accepted this undertaking, but warned UEA that he would take a different position on a fresh request if UEA failed to live up to their undertaking. At no point did the Commissioner opine on whether the regional chronology would have been disclosed without the FOI request.

Third, Briffa took issue with the characterization of the unpublished 2006 regional chronology as an “adverse” result. But Osborn himself stated that release of this chronology would have “adverse” reputational consequences for Briffa and other CRU scientists and would “damage” the reputation of CRU. So, by their own admission, CRU believed these results to be “adverse”.

Finally, Briffa et al 2013 (Supplementary Material 7) did indeed contain a tirade against the 2006 chronology. I entirely agree that “failure to recognise and account for inhomogeneities in the underlying measurement sets” is a pernicious problem in the regional chronology methodology proposed in Briffa et al 2008. All the more reason why the supposed failure of this methodology on the Yamal/Urals dataset should have been reported in the earlier article.

Ridley’s description of the regional chronology as both “withheld” and “adverse” is completely justified.

“Validated” by Muir Russell

Briffa’s final issue is little more than a cavil. Briffa’s first letter had stated:

The accusation of “cherry-picked publication” was investigated by the Independent Climate Change Email Review, which concluded in 2010 that our “rigour and honesty as scientists are not in doubt”.

Ridley’s reply, as submitted, stated:

Briffa further claims that his research was validated by the inquiry chaired by Sir Muir Russell. Yet Sir Muir did not even attend the only interview with academics at the University of East Anglia on the Hockey stick. Nor did the panel interview critics of the UEA group. Nor did the Muir Russell panel even ask Briffa and Jones about their destruction of documents to evade FOI requests. The inquiry did not explore, let alone endorse, the specific data sets in question.

This was shortened by the editors to:

Briffa claims that his research was validated by the inquiry chaired by Sir Muir Russell, but that inquiry did not explore, let alone endorse, the specific data sets in question.

Briffa now complains that there is a relevant distinction between saying that the accusation of cherry-picked publication being investigated by Muir Russell and saying that their research was “validated” by Muir Russell:

Ridley again misquotes me as saying “my research was validated by the inquiry chaired by Sir Muir Russell.” I clearly said no such thing. The Independent Climate Change Email Review had no remit to “validate” any research. In my opinion this can be done only through reinforcement by consistent results produced in repeated, continuing research and published in the peer-review literature. What I actually said was that I had not “cherry picked” my data to produce a desired result, which was the specific accusation levelled at me in his Opinion Piece. Sir Muir Russell’s team examined this specific accusation and found that I had not.

The distinction is really immaterial. Ridley’s letter could have been rephrased as follows without changing the point.

Briffa further claims that allegations of cherry-picking had been settled by the investigations of the Muir Russell panel. This is not the case. Sir Muir did not even attend the only interview with academics at the University of East Anglia on the Hockey stick. Nor did the panel interview critics of the UEA group. Nor did the Muir Russell panel obtain the contested regional chronology from Briffa and/or associates or carry out any investigation of the circumstances of the contested chronology. Nor did the Muir Russell panel even ask Briffa and Jones about their destruction of documents to evade FOI requests. The inquiry did not explore, let alone endorse, the specific data sets in question.

Conclusion

The issue in the original Opinion Piece was the failure to report adverse results, with the lugubrious story of Briffa’s unpublished and unreported 2006 regional Yamal/Urals chronology being an example. Nothing in Briffa’s letter refutes Ridley’s original claim.

In retrospect, when one compares the very attenuated blade of the 2013 regional chronology with the similarly attenuated blade of the despised 2006 regional chronology, all the past excuses for withholding the 2006 chronology and all the past attempts to sustain the superblade of the 2000, 2008 and 2009 chronologies ring increasingly hollow.