By Deep Climate
There’s been quite a stir about NCAR Senior Scientist Kevin Trenberth and his upcoming presentation at the American Meteorological Society Annual Meeting. Some of that spilled over here in a spirited discussion of Trenberth’s failure to blockquote a cited paper by Hasselmann (there has since been a new version which appears to be a sincere if hasty fix). The original controversy, though, largely centered on Trenberth’s withering attack on the climate science contrarians and his characterization of them as “deniers” and “charlatans”, which, needless to say, has caused howls of outrage throughout the contrarian blogosphere.
No one has been more outraged by Trenberth’s broadside than Steve McIntyre, who decided to bring what Judith Curry called a “historical perspective” and revisited a “climategate” controversy about “keeping papers out” of IPCC AR4. McIntyre dismissed Trenberth’s defence of Phil Jones as a “first time IPCC writing team member” as “readily demonstrated to be untrue”. McIntyre’s ironclad proof? Despite Trenberth’s claim of being an IPCC “veteran”, both Trenberth and Jones had exactly the same IPCC resume as Chapter 2 contributing authors for the Second and the Third Assessment Reports, before becoming lead authors together in AR4.
I’m sure regular Deep Climate readers will be shocked – just shocked – to find out that a closer look behind McIntyre’s selective facts tells a completely different story. Trenberth was clearly referring to experience as a lead author (contributing authors are not on the “writing team”). And both Jones and Trenberth may have been Chapter 2 contributing authors on previous IPCC reports, but Trenberth was also both a Chapter and Technical Summary Lead Author in both 1995 and 2001. So, once again, the latest “climategate” scandal proves to be yet another outright falsehood from McIntyre.
By Deep Climate
Today I continue my examination of the key analysis section of the Wegman report on the Mann et al “hockey stick” temperature reconstruction, which uncritically rehashed Steve McIntyre and Ross McKitrick’s purported demonstration of the extreme biasing effect of Mann et al’s “short-centered” principal component analysis.
First, I’ll fill in some much needed context as an antidote to McIntyre and McKitrick’s misleading focus on Mann et al’s use of principal components analysis (PCA) in data preprocessing of tree-ring proxy networks. Their problematic analysis was compounded by Wegman et al’s refusal to even consider all subsequent peer reviewed commentary – commentary that clearly demonstrated that correction of Mann et al’s “short-centered” PCA had minimal impact on the overall reconstruction.
Next, I’ll look at Wegman et al’s “reproduction” of McIntyre and McKitrick’s simulation of Mann et al’s PCA methodology, published in the pair’s 2005 Geophysical Research Letters article, Hockey sticks, principal components, and spurious significance). It turns out that the sample leading principal components (PC1s) shown in two key Wegman et al figures were in fact rendered directly from McIntyre and McKitrick’s original archive of simulated “hockey stick” PC1s. Even worse, though, is the astonishing fact that this special collection of “hockey sticks” is not even a random sample of the 10,000 pseudo-proxy PC1s originally produced in the GRL study. Rather it expressly contains the very top 100 – one percent – having the most pronounced upward blade. Thus, McIntyre and McKitrick’s original Fig 1-1, mechanically reproduced by Wegman et al, shows a carefully selected “sample” from the top 1% of simulated “hockey sticks”. And Wegman’s Fig 4-4, which falsely claimed to show “hockey sticks” mined from low-order, low-autocorrelation “red noise”, contains another 12 from that same 1%!
Finally, I’ll return to the central claim of Wegman et al – that McIntyre and McKitrick had shown that Michael Mann’s “short-centred” principal component analysis would mine “hockey sticks”, even from low-order, low-correlation “red noise” proxies . But both the source code and the hard-wired “hockey stick” figures clearly confirm what physicist David Ritson pointed out more than four years ago, namely that McIntyre and McKitrick’s “compelling” result was in fact based on a highly questionable procedure that generated null proxies with very high auto-correlation and persistence. All these facts are clear from even a cursory examination of McIntyre’s source code, demonstrating once and for all the incompetence and lack of due diligence exhibited by the Wegman report authors.
In the “climategate” din, one accusation is shouted perhaps louder and more often than any other: the so-called “trick” supposedly played by IPCC lead author Michael Mann to “hide the decline” in Keith Briffa’s Northern Hemipshere extra tree-ring proxy-based reconstruction, featured along with three others in a key chart in the 2001 WG1 Third Assessment Report (TAR).
According to self-appointed climate science auditor Steve McIntyre, Mann took it on himself to truncate Briffa’s data set and replaced the deleted data with instrumental temperature data, thus creating less of a drop at the end of the resulting smoothed chart. But a closer examination shows the evidence for instrumental “padding” is far from certain. And the difference engendered between different possible “padding” values is minimal in any case.
Even worse, the key element of McIntyre’s narrative, namely the claim that Mann himself truncated Briffa’s data set, is false. In fact, it turns out that the actual data set used by Mann (as sent by Tim Osborn on Keith Briffa’s behalf) contains values only up to 1960 – exactly as in the figure produced in TAR. So once again, we have another egregiously false accusation from Steve McIntyre, one that has been echoed by McIntyre acolytes and CruTape Letters authors Steven Mosher and Thomas Fuller.
In this installment, I’ll look at another technique in the climate auditor’s toolbox, namely selective quotation. Once again, our example case study will involve accusations by Steve McIntyre concerning the use of paleoclimatologist Keith Briffa’s tree-ring based reconstruction in a key figure from the IPCC Third Assessment Report.
Arguing from a cherrypicked selection of quotes from the “Climategate” emails, McIntyre has claimed that IPCC authors Chris Folland and Michael Mann pressured Briffa to submit a reconstruction that would not “dilute the message” by showing “inconsistency” with multi-proxy reconstructions from Mann and Briffa’s CRU colleague Phil Jones. Briffa “hastily re-calculated his reconstruction”, sending one with a supposedly larger post-1960 decline before. According to McIntyre, Mann resolved this new “conundrum” and simply “chopped off the inconvenient portion of the Briffa tree-ring data”.
But a review of the emails – including some that have never been quoted before – clearly contradicts McIntyre’s version of events:
- Jones and Briffa were concerned that Mann had an outdated version of the Briffa reconstruction, and both urged the adoption of the newer “low frequency” one, more appropriate for comparison with other multi-century reconstructions.
- Far from pressuring Briffa to change his reconstruction right away, Mann questioned whether an immediate change was required, or even possible, and counselled waiting for the next revision.
- CRU colleague Tim Osborn advised Mann that he and Briffa “usually stopped” the “low frequency” reconstruction in 1960, and went one better in his later “resend” to Mann, by explicitly removing the post-1960 data.
I’ll also show how McIntyre has changed his narrative along the way , in an effort to prove that the true “context” of the famous “trick” to “hide the decline” is somehow an indictment of the IPCC. (Speaking of which, be sure to take the poll at the end about McIntyre’s next move). But first, once again, here is the cause of all the fuss, namely Figure 2-21 from Chapter 2 of the IPCC Third Assessment Report – Working Group I: The Scientific Basis (2001).
Do you have what it takes to be a climate auditor? Try the following fun test and find out. And at the same time, you can’t help but learn something about the fine art of argumentation from charts as practiced by the master himself, Steve McIntyre, and refined in his most devoted media outlet, the U.K. based Mail on Sunday.
Here is the chart that is held to epitomize the “trick” to “hide the decline”: figure 2-21 from the IPCC ‘s Third Assessment Report, showing key temperature reconstructions.
How do they get away with it? That’s the inevitable question as I examine one of the most specious – and despicable – “climategate” allegations from contrarians, namely the oft-repeated claim that climate scientists at East Anglia University’s Climate Research Unit inappropriately adjusted certain tree-ring temperature proxy data to provide a better match with instrumental temperature record.
In an extraordinary interview with FoxNews in December of last year, economist Ross McKitrick alleged that scientists were “faking the match” between proxy and temperature data. McKitrick averred this was “not being honest with the reader” and even invoked a comparison to falsified experimental medical research. Stephen McIntyre of ClimateAudit recently claimed that the “artificial correction” seemed “to have entered the CRU toolkit” (in his submission to the U.K. parliamentary committee examining allegations arising from stolen CRU emails, no less).
Yet a close examination of the computer code and ensuing research bears out the key contention of the firm rebuttals from East Anglia University, as well as CRU scientist Tim Osborn, namely that the specific adjustments in question were for private exploration only and never incorporated into CRU scientists’ subsequent published research temperature reconstructions. So, once again, McIntyre and McKitrick have made odious and unfounded accusations, based on non-existent evidence. They should withdraw these specious allegations immediately.
[Updated Feb. 8: (editing and extension of summary and document list update)]
Perhaps the most disturbing episode in the “hockey stick” controversy was the investigation of climate scientists by the U.S. House Energy and Commerce Committee under Republican representatives Joe Barton and Ed Whitfield, and a subsequent report for that same committee by an “independent” panel led by George Mason University statistics professor Edward Wegman. In light of various renewed “skeptic” allegations of scientific misconduct against Michael Mann and Phil Jones, and my recent revelation of possible plagiarism and other questionable scholarship in the Wegman report, a complete review of the events of 2005-2006 would seem to be in order.
In short, the Energy and Commerce Committee refused the offer of a proper scientific review from the National Academy of Sciences in favour of an investigative process that was ad hoc, biased and unscientific. And the report resulting from that process is tainted with highly questionable scholarship.
I can now fill in important gaps in the timelines of the initial investigation and the Wegman panel. But more importantly my review has led to some startling conclusions:
- Not only was the original Barton-Whitfield investigation (in the form of intimidating letters) inspired by the allegations of “climate science auditor” Steve McIntyre, but the defining impetus seems to have been a little known Cooler Heads Coalition-Marshall Institute sponsored presentation by McIntyre and sidekick economist Ross McKitrick in Washington barely a month beforehand.
- Energy and Commerce Committee Republican staffer Peter Spencer played a key but hitherto undisclosed role in the investigation and the subsequent Wegman panel report, and apparently acted as the main source and gatekeeper of climate science information for the panel.
- Steve McIntyre was in communication with the Wegman panel, at least concerning technical questions around replication of his work. The full extent of McIntyre’s communications or meetings with Spencer or other staffers, as well as Wegman panelists, is still unknown. However, the record shows there were at least two intriguing opportunities for face-to-face meetings in Washington during the Wegman panel’s mandate.
All this, along with new information about the circumstances of the Wegman panel’s formation and mandate, raises serious doubts about the supposed independence of the Wegman panel.