Those opposed to action on climate change are compelled to attack the Intergovernmental Panel on Climate Change (IPCC) and its reports. Not doing so would cede the scientific high-ground of the argument and essentially doom their preferred do-nothing policy approach.

One way to attack the IPCC is to describe it as a nameless bureaucracy pursuing its own political agenda, and entirely disconnected from the scientific community. For example, a report from the Fraser Institute makes this argument explicitly:

[A] compelling problem is that the Summary for Policymakers, attached to the IPCC Report, is produced, not by the scientific writers and reviewers, but by a process of negotiation among unnamed bureaucratic delegates from sponsoring governments. Their selection of material need not and may not reflect the priorities and intentions of the scientific community itself.

This argument is transparently false on several counts. First, the authors are not nameless, but are listed prominently on the first page of the Summary. In addition, they are not bureaucrats, but all have scientific credentials in the arena of climate change.

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Second, the conclusions of the IPCC’s Summary for Policymakers (SPM) do in fact reflect the scientific consensus. The negotiations over the SPM for the IPCC’s working group II provides a unique insight into the interplay between science and politics in the production of the SPM.

The Associated Press reported that:

Two distinctly different groups, data-driven scientists and nuanced offend-no-one diplomats, collided and then converged this past week. At stake: a report on the future of the planet and the changes it faces with global warming.

An inside look at the last few hours of tense negotiations at the Intergovernmental Panel on Climate Change reveals how the diplomats won at the end thanks to persistence and deadlines. But scientists quietly note that they have the last say.

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Here’s how negotiations went, based on interviews and an unusual opportunity for The Associated Press to observe the last 3 1/2 hours of debate.

The four-day meeting was supposed to end Thursday afternoon but was extended to Friday morning. A news conference was scheduled for 10 a.m. Friday to release the report, but the document wasn’t finished until after that time.

Interpreters had been sent home at 2 a.m. Friday due to financial issues. Some pages had not been discussed and some of the most critical issues were still not solved as small group negotiations stalled.

Panel co-chairman Martin Parry of the United Kingdom acknowledged that some parts of the document were eliminated “because there was not enough time to work it through as well.”

With such deadline problems, some countries — especially China, Saudi Arabia and at times Russia and the United States — were able to play hard ball.

China and Saudi Arabia wanted to lower the level of scientific confidence (from more than 90 percent to 80 percent) that the report had in a statement about current global warming effects and it looked like they would win because they wouldn’t accept the original wording. That’s when Rosenzweig protested and walked.

A U.S.-based compromise saved the day, avoiding any mention of scientific confidence.

A comparison of the original document, written by scientists, and the finished paper showed major reductions in forecasts for hunger and flooding victims. Instead of “hundreds of millions” of potential flood victims, the report said “many millions.” A key mention of up to 120 million people at risk of hunger because of global warming was eliminated.

The bottom line is that the IPCC’s SPMs are “consensus documents,” meaning that all member governments need to agree to the science described in them. Countries that want to do nothing about climate change have incentives to water down the SPMs, while countries that want strong responses have incentives to highlight potential disasters.

And the scientists have an important veto: they can walk out and declare that one side or another is trying to subvert the science. All countries have incentives to be seen as credible on this issue, and so cannot afford to be designated as anti-science.

In the end, it looks like the Working Group II SPM was slightly watered down by those opposed to action. But competing pressures from other groups kept out major changes. In the end, most climate scientists would agree that the SPM fairly reflects the science of climate change.