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A few weeks ago, I provided some data which demonstrated the extent to which “the practice of scientists responsible for writing IPCC assessments reviewing their own work” was prevalent in the Intergovernmental Panel on Climate Change (IPPC)’s Fourth Assessment Report (AR4).

I had observed that:

[…] 884 were the authors (or co-authors) of material that was cited in a chapter they were writing. Or, in the case of Review Editors, charged with ensuring that the material written in a chapter in which their own work was cited, represented “a comprehensive, objective, and balanced view of the areas they cover”.

In a guest posting, today (July 5), at Judith Curry’s, Nic Lewis had written:

The IPCC’s alteration of Forster & Gregory’s model-independent climate sensitivity results

The IPCC Fourth Assessment Report of 2007 (AR4) contained various errors, including the well publicised overestimate of the speed at which Himalayan glaciers would melt. However, the IPCC’s defenders point out that such errors were inadvertent and inconsequential: they did not undermine the scientific basis of AR4. Here I demonstrate an error in the core scientific report (WGI) that came about through the IPCC’s alteration of a peer-reviewed result. This error is highly consequential, since it involves the only instrumental evidence that is climate-model independent cited by the IPCC as to the probability distribution of climate sensitivity, and it substantially increases the apparent risk of high warming from increases in CO2 concentration.


Of the eight studies for which [probability density functions] PDFs are shown, only one – Forster/Gregory 06 [Forster and Gregory, 2006] – is based purely on observational evidence, with no dependence on any climate model simulations. [emphasis added -hro]

The issue of “climate sensitivity” is, I gather, quite controversial – and crucial to the case the IPCC presents. For those who are technically inclined – and far less statistically-challenged than I – please do read Lewis’s post. Mytakeaway from his work is that, in effect, the IPCC have played some highly questionable statistical games with Forster and Gregory’s work, so that the results that the IPCC attributed to Forster and Gregory are a distortion of the actual results of their peer-reviewed research.

Needless to say, this has generated considerable discussion in the blogosphere. Andrew Montford (aka Bishop Hill) has highlighted this, as has Steve McIntyre and Anthony Watts.

When I was working on Donna Laframboise’s “climate bible” report card last year, I did my own compilation of all the references cited in the 41 Chapters of AR4.

In reviewing these references, I found that:

1. Assuming that “Forster, P.M.F.”, “Forster, P.M.D.”, “Forster, P.M. de F.” and “Forster, P.M.D.F” are all one and the same author (consistency in citing references is far from being an IPCC strong point!), Forster had ten papers to which there were 17 references in WG I.

2. J.M. Gregory was somewhat more prolific (or at least considerably more present) with 33 papers to which there were 43 references in WG I and 14 in WG II. One thing that struck me as I skimmed the titles of his papers was the predominance of “model(s)” and “simulation(s)”.

As a public service, I have extracted the Forster & Gregory references into a Googledocs spreadsheet which can be found here.

In his polite response to an impudent troll at Judith Curry’s, Lewis wrote:

I didn’t ask Forster and Gregory to comment on my analysis in advance. I thought that would put them in a difficult position, as they were Contributing authors for chapter 9 of AR4:WG1 and, presumably, accepted (at least tacitly) the IPCC’s treatment of their results. The thrust of my post is very much consistent with what they wrote in their 2006 paper.

I have drawn the post to their attention.

Meanwhile, over at Bishop Hill … another member of the “model” IPCC in-crowd, Richard Betts dropped by to note:

Just a small point. Both Forster and Gregory (my friends Piers and Jonathan) were contributing authors on chapter 9 of IPCC AR4 WG1 which is being said to have misrepresented their results, and they were also involved in a major way elsewhere in the report (Piers was [Coordinating Lead Author] CLA of chapter 2 and Jonathan was an [Lead Author] LA in another chapter, can’t remember which) so one would assume that they were happy with what the chapter 9 lead authors did.

I decided to help Betts out; so I took a wild guess as to the Chapter of which his friend, Jonathan, was a Lead Author. Truth be told, it wasn’t so wild, actually. 18 of Gregory’s 33 papers were referenced in WG I, Chapter 10. Thanks to AccessIPCC, I was able to quickly confirm that my guess was correct: Gregory was a Lead Author of WG I, Chapter 10.

Whether or not Betts’ assumption is correct, from where I’m sitting, it would appear that Gregory had at least 33 32 good reasons to throw the conclusions of Forster and Gregory (2006) silently under the bus. And, if there is any truth to the aphorism that ‘silence is acquiescence’, my hunch is that – notwithstanding the fact that Lewis has drawn his post to their attention – we can expect to hear sounds of deafening silence from both Forster and Gregory.

It would seem that politics, once again, may well have taken precedence over scientific integrity.

The View from Here, 6 July 2011