Yesterday afternoon, Judy and I finally saw An Inconvenient Truth (a.k.a. "The Al Gore movie"), belatedly fulfilling the pledge we had made to see it "on opening weekend." (No harm done, I trust: Raleigh-Durham is far enough "out in the provinces" that the film didn't open here until its fourth week of release, by which time we weren't going to affect any subsequent distribution decisions by Paramount Classics anyway.)
The film lived up to its billing. Its compelling message was presented as vividly, coherently, and accurately as a collection of mathematical forecasting models could possibly be communicated to a lay audience. Having had some experience with such models myself, I did feel deprived of a glimpse "under the hood" of Gore's graphs and charts: observational constraints, control variables, assumed feedback mechanisms, confidence intervals, and the like. But my experience in presenting such models to non-technical audiences also left me with an especially profound appreciation of Gore's achievement.
Perhaps the most important talking point that comes out of the film is the fact that any remaining controversy over the causal relationship between human activities and observed, unprecedented, global warming has been manufactured by a well-funded disinformation campaign in the mass media. Gore cited two studies, one of which found no such controversy among a large sample of peer-reviewed scientific articles on climate change, and another which found most mass media reports on climate change to describe the issue as a live controversy. The two studies in question appear to be, respectively, Naomi Oreskes, Beyond the Ivory Tower: The Scientific Consensus on Climate Change, 306 Science 1686 (2004) and Jules Boycoff & Maxwell Boycoff, Journalistic Balance as Global Warming Bias, Fairness and Accuracy in Reporting Extra!, November/December 2004. For those of you interested in looking "under the hood" of this talking point, here are the details.
Oreskes cites several scientific organizations' statements on the existing consensus on the causes of climate change, quoting two of them explicitly:
World Meteorological Organization/UN Environmental Programme Intergovernmental Panel on Climate Change (IPCC):
"Human activities ... are modifying the concentration of atmospheric constituents ... that absorb or scatter radiant energy. ... [M]ost of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations."
National Academy of Sciences:
"Greenhouse gases are accumulating in Earth's atmosphere as a result of human activities, causing surface air temperatures and subsurface ocean temperatures to rise.... The IPCC's conclusion that most of the observed warming of the last 50 years is likely to have been due to the increase in greenhouse gas concentrations accurately reflects the current thinking of the scientific community on this issue."
Oreskes then reports on her content analysis of 928 abstracts published in scientific journals between 1993 and 2003, representing a random 10 percent sample of the articles listed in Thomson Scientific's ISI database under the keywords "climate change":
The 928 papers were divided into six categories: explicit endorsement of the consensus position, evaluation of impacts, mitigation proposals, methods, paleoclimate analysis, and rejection of the consensus position. Of all the papers, 75% fell into the first three categories, either explicitly or implicitly accepting the consensus view; 25% dealt with methods or paleoclimate, taking no position on current anthropogenic climate change. Remarkably, none of the papers disagreed with the consensus position.
Admittedly, authors evaluating impacts, developing methods, or studying paleoclimatic change might believe that current climate change is natural. However, none of these papers argued that point.
The Boycoffs analyzed a random sample of 636 articles taken from the 3,543 articles published in the New York Times, Washington Post, Los Angeles Times and Wall Street Journal between 1988 and 2002 containing the search term "global warming":
Our results showed that the majority of these stories were, in fact, structured on the journalistic norm of balanced reporting, giving the impression that the scientific community was embroiled in a rip-roaring debate on whether or not humans were contributing to global warming.
More specifically, we discovered that:
- 53 percent of the articles gave roughly equal attention to the views that humans contribute to global warming and that climate change is exclusively the result of natural fluctuations.
- 35 percent emphasized the role of humans while presenting both sides of the debate, which more accurately reflects scientific thinking about global warming.
- 6 percent emphasized doubts about the claim that human-caused global warming exists, while another 6 percent only included the predominant scientific view that humans are contributing to Earth's temperature increases.
Through statistical analyses, we found that coverage significantly diverged from the IPCC consensus on human contributions to global warming from 1990 through 2002. In other words, through adherence to the norm of balance, the U.S. press systematically proliferated an informational bias.
Taken together, the two studies illustrate the fundamental incompatibility between journalistic balance and peer review as organizing principles for the pursuit of truth, particularly in a field susceptible to domination by wealthy, self-interested speakers. In designing legal and technological structures to accommodate rather than silence scientists, we should therefore take care that such structures do not privilege journalistic balance and the norms of rhetoric over peer review and the norms of science.
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