In Spring, 1997 a group called Ozone Action issued a statement signed by six prominent scientists calling for action on climate change. The letter prompted an interesting public exchange among leading scientists about who has the authority and credentials to call for political action on issues involving science, and whether or not the IPCC is the sole legitimate voice. The exchange is worth reviewing and considering, and I’ve reproduced parts of it below..


The Six Scientists letter was criticized by a leading climate scientist, Tom Wigley, who wrote:

I thought I should tell you that, for a number of reasons, I am not willing to sign the “6 scientists” statement you distributed. To the contrary, I strongly oppose it.

While I hold the individuals in high regard, I do not consider them authorities on the climate change issue. From memory, none were lead authors of the recent IPCC reports. While this may be an advantage from some points of view, it is not sufficient to overcome the criticism implied by my first sentence. Their endorsement of IPCC is useful, but their statement goes beyond what IPCC says. This can only be damaging to the IPCC process.

Phrases like (my emphasis) “climate DISRUPTION is under way” have no scientific basis, and the claimed need for “greenhouse gas emissions (reductions) beginning immediately” is contrary to the careful assessment of this issue that is given in the IPCC reports.

No matter how well meaning they may be, inexpert views and opinions will not help. In this issue, given that a comprehensive EXPERT document exists, it is exceedingly unwise for highly regarded scientists to step outside their areas of expertise. This is not good scientific practice.

I urge the authors of the statement to endorse IPCC, but go no further. I further recommend that any other scientist considering endorsement of the present statement think very carefully before so doing. In my view, endorsing any statement that goes beyond IPCC, or which is in any way inconsistent with IPCC publications, will potentially label the individual as an advocate and reduce their credibility as an informed and dispassionate scientist.

John Holdren, an energy policy expert now at Harvard, responded strongly to these comments:

Dr. Wigley’s critique of the “6 scientists’ statement” on global climatic disruption is surprising and, in all of its principal contentions, completely unconvincing.

Consider first his apparent contention that, the IPCC having rendered its authoritative judgment on the causes, consequences, and implications of climate change, no other scientist or group of scientists now has any business offering a supplemental opinion on any part of the matter. Or perhaps he is saying that no scientists other than _climatologists_ should be offering such opinions. (More about that below.) Either way, it is a disturbing proposition, not least for being so contrary to soundly based and solidly established traditions of both scientific and policy discourse.

Assessments of complex science-and-society problems by interdisciplinary panels can make valuable contributions to consensus-building in the scientific community, to shaping research agendas, and to illuminating policy options (among other benefits), as the IPCC admirably has done. I myself have put a good deal of my professional life, over the last quarter of a century, into participating in and leading such assessments on a wide range of topics in the energy, environment, and international-security fields. But I would never have asserted that the product of any of them was sacrosanct — not to be commented or expanded upon, never mind criticized, by any group other than the original authors — as Dr. Wigley appears to be asserting for the product of the IPCC. Does he really think that truth, wisdom, and insight are now to be regarded as the exclusive franchise of giant international panels, and anybody not so empaneled (or even those who are but might wish to speak through another channel) must be quiet?

Dr. Wigley has written that he does not consider the signers of the “6 scientists’ statement” to be “authorities on the climate change issue” and that “Inexpert opinions do not help”. Since he is a climatologist, one supposes that he would have been at least somewhat less distressed if a statement of this sort had been issued by members of that profession. Do they hold the only relevant “expertise”? What part of “the climate change issue” is he talking about here?

The IPCC process engaged not only climatologists but also atmospheric chemists, soil scientists, foresters, ecologists, energy technologists, economists, statisticians, and a good many other kinds of specialists as well — and for good reason. Even the relatively narrow question of how much climate change has taken place so far is not the province of climatologists alone (since, for example, the insights of atmospheric chemists, geochemists, glaciologists, geographers, and more are needed to help understand what the climate was like before humans started messing with it).

Understanding how the climate may change in the future, of course, depends on insights not only from climatologists but also from soil scientists, oceanographers, and biologists who study the carbon cycle; from energy analysts who study how much fossil fuel is likely to be burned in the future and with what technologies; from foresters and geographers who study the race between deforestation and reforestation; and so on. Understanding the likely and possible responses of terrestrial and marine ecosystems to climate change — and the consequences for agriculture, forestry, fisheries, biodiversity, and the distribution and abundance of human-disease vectors and pathogens — is the province of another whole panoply of types of biologists, as well as agronomists, foresters, epidemiologists, and more.

Understanding what technical and policy options are available for reducing greenhouse-gas emissions, and how fast and with what costs these options might be implemented, is the province of energy technologists, economists, and policy analysts, among others. And the decision about what measures governments should take to prepare for and/or implement some suitable subset of these options is necessarily a political choice, inasmuch as it entails a value-laden set of trade-offs among costs, risks, and benefits of incommensurable types. Of course people’s thinking about these trade-offs ought to be informed by as complete a portrayal as possible of what is known and not known about the climatological, geochemical, biological, techno- logical, economic, and other characteristics of the problem. But to believe that this portrayal will be understood in exactly the same way by any two individuals — or that, if it were, its ingredients would be weighed by those individuals in exactly the same way, so as to lead them to identical policy preferences — would be naive in the extreme.

Luckily, society has worked out a way to reach conclusions about what to do in the face of multifaceted, uncertainty-laden choices about problems affecting the common good, and it involves not only science and policy analysis but also, ultimately and appropriately, politics. Neither the science part of this mix nor the policy-analysis part — not to speak of the political part — works by designating a single individual or group (no matter how distinguished) as the single arbiter of what is right, what is reasonable, or what is helpful in public discourse. . .

Thanks to folks at Carnegie Mellon University the full exchange is preserved here.