(Part of the How to Talk to a Global Warming Skeptic guide)

Objection: Sure, Oreskes found no one bucking the consensus, but her paper was refuted by Benny Peiser, who did the exact same survey and found very different results.

Answer: True, Benny Peiser did attempt a similar study and submitted it as a letter to Science responding to the Oreskes study. But for very good reasons, it was not published.

Peiser claimed to find 34 articles in his "reject or doubt the consensus view" category. That's 3 percent of the total, so even taken at face value it doesn't cast much doubt on the consensus. But it is greater than the 0 percent Oreskes found, and serves as ammunition for the "there is no consensus" crowd.

Tim Lambert has already done an excellent dissection of Peiser's letter here, and because Peiser was forthcoming enough to disclose the 34 abstracts in question, I encourage everyone to draw their own conclusions (they can all be seen on Tim's blog). I will quote a few and let that speak for itself.

Benny Peiser thinks the following abstracts reject or doubt the scientific consensus on anthropogenic global warming:

• (14) - The variations of global mean sea level are an important indicator of global climate change, and their measurement can provide important information for determining the socioeconomic impact of sea level change on coastal land use ... [snip] ... Future research will focus on establishing a realistic error budget for these measurements of global mean sea level, so that they can be put in the proper context with other observations of global climate change.
• (18) - The relationship of global climate change to plant growth and the role of forests as sites of carbon sequestration have encouraged the refinement of the estimates of root biomass and production. However, tremendous controversy exists in the literature as to which is the best method to determine fine root biomass and production. This lack of consensus makes it difficult for researchers to determine which methods are most appropriate for their system ... [snip] ... Until the different root methods can be compared to some independently derived root biomass value obtained from total carbon budgets for systems, one root method cannot be stated to be the best and the method of choice will be determined from researcher's personal preference, experiences, equipment, and/or finances.
• (22) - The paper discusses annual to decadal climate variability and change in the European Alps by utilizing the procedure of synoptic downscaling, i.e. it investigates the influence of global to continental scale synoptic structures and processes on the regional climate of the Alps ... [snip] ... There is a question over whether this phenomenon is a consequence of natural climate variability or the beginning of an anthropogenic climate change.
• (24) - Global climate change does not necessarily imply that temperature or precipitation is increasing at specific locations. [snip]
• (25) - This paper addresses the representation of scientific uncertainty about global warming and climate change in the U.S. popular press. An examination of popular press articles about global warming from 1986 to 1995 reveals that scientific uncertainty was a salient theme. [snip]
• (30) - Vegetation productivity and desertification in sub-Saharan Africa may be influenced by global climate variability attributable to the North Atlantic Oscillation (NAO) and El Nino Southern Oscillation (ENSO) ... [snip] ... The combined indices explained much of the interannual variability in vegetation productivity in the Sahelian zone and southern Africa, implying that both the NAO and ENSO may be useful for monitoring effects of global climate change in sub-Saharan Africa.

Those are just the ones that have no excuse whatsoever being categorized as doubting or rejecting AGW. Many others are highly questionable.

But there are a couple in his list that do indeed reject the notion of human-caused climate change. Why did Oreskes ignore those? Well, it turns out that they are editorials or letters, not peer-reviewed papers, and should not have been included except that Peiser altered the search criteria. Peiser included "all documents" in the ISI Web of Science database rather than just scientific articles, as Oreskes did, but Oreskes searched only "Sciences," while Peiser included "Social Sciences" and "Arts & Humanities."

If anything, Peiser's effort strengthens Oreskes' finding of a widespread consensus -- this questionable interpretation of an inappropriate dataset was the strongest argument he was able to make.

[Update] Since this was first written, there have been a couple of developments. First, I crossed Benny Peiser's path on the Prometheus blog. In the course of a lengthy thread under this post, I asked him directly about abstract (18) above, to which he replied, "I accept that it was a mistake to include the abstract you mentioned (and some other rather ambiguous ones) in my critique of the Oreskes essay."

Second, it appears he has since gone even further when pressed by an Australian television program, Media Watch. The transcript is here, and Tim Lambert summarizes it here. The gist is that he has backed down to the position that just one of his 34 abstracts fit his description as rejecting the consensus view on climate change -- and it was an editorial, not research of any kind.

The reason I still present this article in full, despite the backpedalling, is that as far as I can tell the retraction has been quiet and not proactive. Citations of Peiser's "work" continue to show up all over the place.

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