Cynthia Rosenzweig is a research scientist who works at James Hansen’s Goddard Institute of Space Studies. Once I might have described her as a senior Intergovernmental Panel on Climate Change (IPCC) author. But she’s actually more than that.

It turns out Rosenzweig is a member of a small clique of people who wore multiple hats during the writing of the 2007 climate bible. When I hear that thousands of the world’s best scientists participate in the IPCC I envision each of them making a focused contribution in the narrow field in which they possess exceptional research expertise. But that’s not how it works.

Rosenzweig, for example, served in six distinct capacities. She was:

• one of the two most senior authors for a chapter titled Assessment of Observed Changes and Responses in Natural and Managed Systems
• a contributing author for a chapter titled Assessment of Adaptation Practices, Options, Constraints and Capacity
• a lead author of the Working Group 2 Technical Summary document
• a drafting author of the Working Group 2 Summary for Policymakers document
• a member of the core writing team for the Synthesis report
• and an expert reviewer for Working Group 2

In other words, certain names pop up again and again in IPCC reports. If shadowy interests were trying to “control the message” in these documents, entrusting key tasks to a small group of people might be an effective strategy.

Like Rosenzweig, Australian meteorologist David Karoly filled six separate IPCC roles. He served as a lead author and as a review editor. Along with Rosenzweig he was a lead author of a Technical Summary, a drafting author of a Summary for Policymakers, a member of the core writing team for the Synthesis Report, and was also an expert reviewer.

Similarly, David Vaughan, a scientist employed by the Antarctic Survey, wore six hats. He served as a coordinating lead author for one chapter, a contributing author for two more (see the second one here), and an expert reviewer. Additionally, he joined both Rosenzweig and Karoly in serving as a lead author of the Working Group 2 Technical Summary and as a drafting author of the Working Group 2 Summary for Policymakers.

Gabriele Hegerl, a climate modeler, has all of the above beat. Her name turns up in seven distinct roles. She was:

• one of the two most senior authors for a chapter devoted to Understanding and Attributing Climate Change
• a contributing author of a chapter titled Historical Overview of Climate Change Science
• a contributing author (along with Vaughan) of the chapter about Global Climate Projections
• an expert reviewer for Working Group 1
• an expert reviewer for Working Group 2
• a lead author of the Working Group 1 Technical Summary document
• a drafting author of the Working Group 1 Summary for Policymakers

Last week I mentioned that Sari Kovats was a lead author in one chapter and a contributing author in three more (a search of this 9-page PDF reveals all four), in addition to serving as an expert reviewer. That’s five hats.

Then there’s Bettina Menne, a medical doctor employed by the World Health Organization. She appears to have only 14 published papers to her name – the earliest of which extends back a mere 12 years. It’s odd that the IPCC considers her a top expert on issues such as climate change and malaria when people with 30+ years research experience aren’t difficult to find. (That five of Menne’s papers were co-authored with Kovats provides an indication of just how small the IPCC world of experts actually is.)

How many hats did Menne wear? There’s that lucky number five again. She was one of two most senior authors for the latest health chapter. She was a contributing author to a chapter titled Perspectives on Climate Change and Sustainability. She helped draft a Summary for Policymakers document, was a lead author for a Technical Summary, and was a core writing team member for the Synthesis Report.

I’ve also recently blogged about Bill Hare, the Greenpeace “legend” and IPCC insider. I pointed out that he was a lead author, a core writing team member for the Synthesis Report, and an expert reviewer for both Working Group 1 and Working Group 2 – which adds up to four hats.

In that same blog post I further observed that Malte Meinshausen, another individual associated with Greenpeace, served as a contributing author to three different chapters. What I neglected to mention is that he, too, was an expert reviewer for Working Group 1 as well as Working Group 2. Which makes five hats.

What are the consequences of these sorts of dynamics? Why should we care?

A few weeks ago Roger Pielke Sr. testified before a committee of the US House of Representatives. One needs to appreciate that this meteorologist is not a climate skeptic. He believes human activities do have an effect on climate. In his view, though, the IPCC is fixated on carbon dioxide and plays down other important factors (such as land use).

It received no media attention, of course, but the written version of Pielke’s testimony contains a searing accusation that the public surely has the right to hear about. In his view:

The climate science assessments of the IPCC…are completed by a small subset of climate scientists… [bold added, p. 2]

At that same hearing John Christy, a professor of atmospheric science – who is a climate skeptic – voiced the identical concern. In his words:

The content of [IPCC] reports is actually under the control of a relatively small number of individuals – I often refer to them as the “climate establishment” – who through the years, in my opinion, came to act as gatekeepers of scientific opinion and information… [bold added, p. 17]

Looking at the multiple roles played by Rosenzweig, Karoly, Vaughan, Hegerl, Kovats, Menne, Hare, and Meinshausen it’s clear that Pielke and Christy are not imagining things.

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