Geotimes Logo POLITICAL SCENE February 1998

Scientific Consensus and Political Controversy

As scientists, we want policymakers to base their decisions on the best available scientific information, and we complain that too often science is ignored or paid lip service. But what happens when science becomes the focus of debate in the political arena? Scientists who are accustomed to arguing the fine points of an issue long after the major points are settled suddenly find both their agreements and disagreements used as debating points for policymakers and interest groups alike. Presenting the current debate over long-term global climate change as an example, this month's column focuses on the problems that arise when scientific consensus -- or lack thereof -- becomes a political commodity.

The climate change debate

In The Amicus Journal, Natural Resources Defense Council Executive Director John Adams writes that as a result of an industry-led public relations campaign, "some people in this country have the vague idea that 'scientists don't agree' on global warming. The reality is that a handful of scientists think global warming will probably never happen, while 2,500 [other scientists] around the world have joined a consensus statement that global warming has probably already begun." What is the scientific consensus and what does it signify?

Those who advocate taking action on climate change repeatedly point to the 1996 scientific assessment by the United Nations Intergovernmental Panel on Climate Change (IPCC), in which more than 2,000 international scientists took part. The statement most frequently cited is from that report's executive summary for policymakers: "The balance of evidence suggests that there is a discernible human influence on global climate." This statement is so often quoted that there appears to be an unwritten rule (clearly adhered to in this column) that no article on climate change can appear without quoting it. Why so? The statement's popularity may stem from its ambivalence. Champions point to the awesome implication that we humans can affect something as immense as the global climate, whereas critics are quick to note what the statement does not say -- particularly the lack of a magic bullet directly linking global warming to human activity. The IPCC statement raises two questions: Does it represent scientific consensus and, if so, does popularity confer truth?

With respect to the first question, global warming skeptics argue that this statement and other policy recommendations in the IPCC report were drafted by a small fraction of the total number of scientists associated with the assessment, and that the policy recommendations were never passed back to the larger group for comment or approval. To counter this criticism, global warming proponents point to an even stronger statement signed by more than 2,600 scientists that calls on President Clinton to enter into binding agreements at the Kyoto conference. But critics have noted that the signatories (primarily solicited through mailings) were, for the most part, not atmospheric scientists but individuals from a wide range of unrelated disciplines, including veterinarians and sociologists.

Even assuming that scientific agreement on this issue does exist, the second question targets the fallibility of scientific consensus. Scientists themselves tend to view strength- in-numbers arguments with skepticism, and scientific progress has never been a popularity contest. If it were, plate tectonics would have lost in a landslide during its formative years. The shifting consensus on climate change has been a major talking point for global warming skeptics. A recent editorial in The Economist delighted in reprinting two quotes, one from Newsweek in 1975 and the other from Vice-President Al Gore in 1992. Both state the almost unanimous consensus of scientists that global change was taking place, but the first consensus was on global cooling and the second on global warming. Although such a turnabout makes for good copy, in fairness it should be noted that changes in consensus generally represent progress. Today, plate tectonics would win in an even larger landslide.

The IPCC assessment may very well prove to be correct, but its vulnerability to criticism illustrates the difficulties that policy-makers face in using scientific consensus to help forge political consensus. Even minor scientific disagreements can be exploited in the policy arena into a simplified case of two opposing viewpoints, equally weighted. When an issue is portrayed in an adversarial setting, it is often difficult to determine whether 99 percent are on one side and 1 percent on the other, or whether the scientific community is evenly divided. Perhaps as a result of this policy wrangling, scientists are starting to frame their own debates in legal terms. When asked by the Washington Post about the likelihood that increased solar intensity was causing global warming, Jerry Mahlman, a scientist with the National Oceanic and Atmospheric Administration, replied that "a grand jury would throw it out in 20 minutes."

Who develops scientific consensus?

In the case of climate change, consensus comes through an intergovernmental process, but for many policy issues, Congress and federal agencies look to the National Research Council and its reports by committees of experts. Even their consensus is often hard won on contentious issues such as nuclear waste disposal, and increased pressure to produce more timely reports has led to the increased inclusion of minority views.

Is there a role for scientific societies? As organizations of scientists, these groups are uniquely positioned to provide a unified voice for their memberships, but how are their memberships best served? Should scientific societies adopt a role akin to the League of Women Voters, dedicated to informing and increasing their members' participation in the policy process, or should they advocate specific positions? The former approach seeks to lower the threshold for action by individual scientists, regardless of what action that may be. The latter sets the stage for action on behalf of a large group. Individual action requires no more than consultation with one's conscience, whereas group action requires extensive consultation to achieve consensus.

How extensive? If societies step forward with a position, should it reflect the consensus of the experts on a given subject within that society or should the combined views of the broader community be represented? Should such positions be limited to scientific findings or extend to the scientists' collective opinion on the broader policy at issue? Do societies gain credibility for being societally aware and making their work relevant to the policy process, or do they lose credibility by speaking out on topics outside their scientific ken?

I present many more questions than answers, but these are the questions that must be addressed as the geoscience community seeks to become more effective in policy matters. The problems associated with the use of scientific consensus in making policy will continue as long as politicians require consensus to make progress, but scientists do not.

David Applegate

AGI Director of Government Affairs

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