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Climatologist Dr. Judith Curry: ‘Re-evaluating the manufacture of the climate consensus’

Re-evaluating the manufacture of the climate consensus

by Judith Curry

A new book by Oppenheimer, Oreskes et al. entitled ‘Discerning Experts: The Practices of Scientific Assessment for Environmental Policy‘ makes a case against consensus seeking in climate science assessments.

I have long railed against the consensus-seeking process used by the IPCC (see my previous blog posts on this topic). And particularly, my paper:

Oppenheimer has long voiced concerns about consensus (e.g. his 2007 paper). However, Oreskes has been consensus enforcer in chief, originating the 97% thingy.

I haven’t read their new book, but authors Oreskes, Oppenheimer and Jamison have written an essay on their book in Scientific American, entitled Scientists have been underestimating the rate of climate change.

You can see where this is going from the title of this article; most of this is an attempt to justify alarmism. But they make some interesting points. Excerpts:

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“In our new book, Discerning Experts, we explored the workings of scientific assessments for policy, with particular attention to their internal dynamics, as we attempted to illuminate how the scientists working in assessments make the judgments they do. Among other things, we wanted to know how scientists respond to the pressures—sometimes subtle, sometimes overt—that arise when they know that their conclusions will be disseminated beyond the research community—in short, when they know that the world is watching. The view that scientific evidence should guide public policy presumes that the evidence is of high quality, and that scientists’ interpretations of it are broadly correct. But, until now, those assumptions have rarely been closely examined.”

“Among the factors that appear to contribute to underestimation is the perceived need for consensus, or what we label univocality: the felt need to speak in a single voice. Many scientists worry that if disagreement is publicly aired, government officials will conflate differences of opinion with ignorance and use this as justification for inaction. Others worry that even if policy makers want to act, they will find it difficult to do so if scientists fail to send an unambiguous message. Therefore, they will actively seek to find their common ground and focus on areas of agreement; in some cases, they will only put forward conclusions on which they can all agree.”

“The push toward agreement may also be driven by a mental model that sees facts as matters about which all reasonable people should be able to agree versus differences of opinion or judgment that are potentially irresolvable. If the conclusions of an assessment report are not univocal, then (it may be thought that) they will be viewed as opinions rather than facts and dismissed not only by hostile critics but even by friendly forces. The drive toward consensus may therefore be an attempt to present the findings of the assessment as matters of fact rather than judgment.

“The combination of these three factors—the push for univocality, the belief that conservatism is socially and politically protective, and the reluctance to make estimates at all when the available data are contradictory—can lead to “least common denominator” results—minimalist conclusions that are weak or incomplete.”

Moreover, if consensus is viewed as a requirement, scientists may avoid discussing tricky issues that engender controversy (but might still be important), or exclude certain experts whose opinions are known to be “controversial” (but may nevertheless have pertinent expertise). They may also consciously or unconsciously pull back from reporting on extreme outcomes. (Elsewhere we have labeled this tendency “erring on the side of least drama.”) In short, the push for agreement and caution may undermine other important goals, including inclusivity, accuracy and comprehension.”

“In our book, we make some concrete recommendations. While scientists in assessments generally aim for consensus, we suggest that they should not view consensus as a goal of the assessment. Depending on the state of scientific knowledge, consensus may or may not emerge from an assessment, but it should not be viewed as something that needs to be achieved and certainly not as something to be enforced. Where there are substantive differences of opinion, they should be acknowledged and the reasons for them explained (to the extent that they can be explained).Scientific communities should also be open to experimenting with alternative models for making and expressing group judgments, and to learning more about how policy makers actually interpret the findings that result.”

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JC reflections

In seeking to defend “it’s worse than we thought” about climate change, Oppenheimer, Oreskes et al. have opened up a welcome can of worms. Consensus seeking and consensus enforcement have trivialized and politicized climate science for decades.

It has been clear for some time that the conclusions of the IPCC Assessment Reports are too tame for the activist/alarmists. In fact, quoting the IPCC is a favored strategy of the so-called ‘contrarians’ (including myself). It remains to be seen if Oreskes can drop the 97% consensus rhetoric (I doubt it).

In twitter discussion on this article, Gavin hits the nail on the head:

Whenever Michael Mann interacts with me, he comes loaded with this statement “uncertainty is not your friend,” “uncertainty is a two-edged sword.” In the same vein, there are two tails to these distributions. The problem is not only extreme events on the high end, but all the neglected natural processes that have been marginalized (e.g. in attribution analyses) or neglected (e.g. in future projections); these natural processes can contribute to tails on both ends of the distribution.

My solution to the problem identified by Gavin is addressed in my new paper, which will be posted tomorrow. Stay tuned.

Lets stop manufacturing consensus about climate change. Lets open up the scientific debate on climate change and celebrate disagreement and use it to push the knowledge frontier of climate science. The whole consensus thing has done little to reduce global CO2 emissions, which was the point of the whole exercise. It’s time for new approaches to both science and policy.