Roger Revelle was one of the most distinguished oceanographers of the twentieth century. During World War II, he served in the navy, eventually rising to the rank of commander and director of the Office of Naval Research–a scientific arm of the navy that Revelle helped create. He oversaw the first tests of atomic bombs following the end of World War II, at Bikini Atoll in 1946. In 1950, Revelle became director of the Scripps Institute of Oceanography.
In 1957, he and his Scripps colleague Hans Suess published what was probably the most influential article of their careers. It concerned the rate at which carbon dioxide is absorbed into the ocean.
Physicists had recognized since the mid-nineteenth century that carbon dioxide is what we now call a “greenhouse gas”: it absorbs infrared light. This means it can trap heat near the earth’s surface, which in turn raises surface temperatures. You have likely experienced precisely this effect firsthand, if you have ever compared the experience of spending an evening in a dry, desert environment with an evening in a humid environment. In dry places, the temperature drops quickly when the sun goes down, but not in areas of high humidity. Likewise, without greenhouse gases in our atmosphere, the earth would be far colder, with average surface temperatures of about 0 degrees Fahrenheit (or −18 degrees Celsius).
When Revelle and Suess were writing, there had already been half a century of work on the hypothesis–originating with the Swedish Nobel laureate Svante Arrhenius and the American geologist T. C. Chamberlin–that the amount of carbon dioxide in the atmosphere was directly correlated with global temperature and that variations in atmospheric carbon dioxide explained climactic shifts such as ice ages. A British steam engineer named Guy Callendar had even proposed that carbon dioxide produced by human activity, emitted in large and exponentially growing quantities since the mid-nineteenth century, was contributing to an increase in the earth’s surface temperature.
But in 1957 most scientists were not worried about global warming. It was widely believed that the carbon dioxide introduced by human activity would be absorbed by the ocean, minimizing the change in atmospheric carbon dioxide–and global temperature. It was this claim that Revelle and Suess refuted in their article.
Using new methods for measuring the amounts of different kinds of carbon in different materials, Revelle and Suess estimated how long it took for carbon dioxide to be absorbed by the oceans. They found that the gas would persist in the atmosphere longer than most other scientists had calculated. They also found that as the ocean absorbed more carbon dioxide, its ability to hold the carbon dioxide would degrade, causing it to evaporate out at higher rates. When they combined these results, they realized that carbon dioxide levels would steadily rise over time, even if rates of emissions stayed constant. Things would only get worse if emissions rates continued to increase–as indeed they have done over the sixty years since the Revelle and Suess article appeared.
This work gave scientists good reasons to doubt their complacency about greenhouse gases. But just as important was Revelle’s activism, beginning around the time he wrote the article. He helped create a program on Atmospheric Carbon Dioxide at Scripps and hired a chemist named Charles David Keeling to lead it. Later, Revelle helped Keeling get funding to collect systematic data concerning atmospheric carbon dioxide levels. Keeling showed that average carbon dioxide levels were steadily increasing–just as Revelle and Suess had predicted–and that the rate of increase was strongly correlated with the rate at which carbon dioxide was being released into the atmosphere by human activity.
In 1965, Revelle moved to Harvard. There he encountered a young undergraduate named Al Gore, who took a course from Revelle during his senior year and was inspired to take action on climate change. Gore went on to become a U.S. congressman and later a senator. Following an unsuccessful presidential run in 1988, he wrote a book, Earth in the Balance, in which he attributed to Revelle his conviction that the global climate was deeply sensitive to human activity. The book was published in 1992, a few weeks before Gore accepted the Democratic nomination for vice president.
Gore’s book helped make environmental issues central to the election. And he distinguished himself as an effective and outspoken advocate for better environmental policy. Those who wished to combat Gore’s message could hardly hope to change Gore’s mind, and as a vice presidential candidate, he could not be silenced. Instead, they adopted a different strategy–one that went through Revelle.
In February 1990, Revelle gave a lecture at the annual meeting of the American Association for the Advancement of Science, the world’s largest general scientific society. The session in which he spoke was specifically devoted to policy issues related to climate change, and Revelle’s talk was about how the effects of global warming might be mitigated. Afterward, it seems that Fred Singer, a physicist who had served on–and disagreed with the majority findings of–the 1982 Acid Rain Review Panel convened by the Reagan administration, approached Revelle and asked whether he would be interested in coauthoring an article based on the talk.
The details of what happened next are controversial and have been the subject of numerous contradictory op-eds and articles, and at least one libel suit. But this much is clear. In 1991, an article appeared in the inaugural issue of a journal called Cosmos, listing Singer as first author and Revelle as a coauthor. The article asserted (with original emphasis), “We can sum up our conclusions in a simple message: The scientific base for a greenhouse warming is too uncertain to justify drastic action at this time.” (If this sounds identical to Singer’s message on acid rain, that is because it was.)
What was much less clear was whether Revelle truly endorsed this claim, which in many ways contradicted his life’s work. (Revelle never had a chance to set the record straight: he died on July 15, 1991, shortly after the article appeared in print.)
It is certainly true that Revelle did not write the quoted sentence. What Cosmos published was an expanded version of a paper Singer had previously published, as sole author, in the journal Environmental Science and Technology; whole sentences and paragraphs of the Cosmos article were reproduced nearly word for word from the earlier piece. Among the passages that were lifted verbatim was the one quoted above.
Singer claimed that Revelle had been a full coauthor, contributing ideas to the final manuscript and endorsing the message. But others disagreed. Both Revelle’s personal secretary and his long-term research assistant claimed that Revelle had been reluctant to be involved and that he contributed almost nothing to the text. And they argued that when the article was finalized, Revelle was weak following a recent heart surgery–implying that Singer had taken advantage of him. (Singer sued Revelle’s research assistant, Justin Lancaster, for libel over these statements. The suit was settled in 1994, with Lancaster forced to retract his claim that Revelle was not a coauthor. In 2006, after a ten-year period during which he was not permitted to comment under the settlement, Lancaster retracted his retraction and issued a statement on his personal website in which he “fully rescind[ed] and repudiate[d] [his] 1994 retraction.” Singer told his own version of the story, which disagreed with Lancaster’s in crucial respects, in a 2003 essay titled “The Revelle-Gore Story.”)
Ultimately, though, what Revelle believed did not matter. The fact that his name appeared on the article was enough to undermine Gore’s environmental agenda. In July 1992, New Republic journalist Gregg Easterbrook cited the Cosmos article, writing, “Earth in the Balance does not mention that before his death last year, Revelle published a paper that concludes: ‘The scientific base for a greenhouse warming is too uncertain to justify drastic action at this time.’” A few months later, the conservative commentator George Will wrote essentially the same thing in the Washington Post.
It was a devastating objection: it seemed that Revelle, Gore’s own expert of choice, explicitly disavowed Gore’s position.
Admiral James Stockdale–running mate of Reform Party candidate Ross Perot–later took up the issue during the vice presidential debate. “I read where Senator Gore’s mentor had disagreed with some of the scientific data that is in his book. How do you respond to those criticisms of that sort?” he asked Gore. Gore tried to respond–first over laughter from the audience, but then, when he claimed Revelle had “had his remarks taken completely out of context just before he died,” to boos and jeers. He was made to look foolish, and his environmental activism naive.
What happened to Gore was a weaponization of reputation. The real reason to be concerned about greenhouse gases has nothing to do with Roger Revelle or his opinion. One should be concerned because there is strong evidence that carbon dioxide levels are rapidly rising in the atmosphere, because increased carbon dioxide leads to dramatic changes in global climate, and because there will be (indeed there already are) enormous human costs if greenhouse gas emissions continue. There is still uncertainty about the details of what will happen or when–but that uncertainty goes in both directions. The chance is just as good that we have grossly underestimated the costs of global warming as that we have overestimated them. (Recall how scientists underestimated the dangers of CFCs.)
More, although the conclusion of the Cosmos article was regularly quoted, no evidence to support that conclusion was discussed by Easterbrook or Will in their articles. Indeed, the article offered no novel arguments at all. If Revelle had devastating new evidence that led him to change his mind about global warming, surely that should have been presented. But it was not.
But Gore himself had elevated Revelle’s status by basing his environmentalism on Revelle’s authority. This gave Singer–along with Will, Stockdale, and the many others who subsequently quoted the Cosmos article–new grounds for attacking Gore. Indeed, anyone who tended to agree with Gore was particularly vulnerable to this sort of argument, since it is precisely they who would have given special credibility to Revelle’s opinion.
The details of how Singer and others used Revelle’s reputation to amplify their message may seem like a special case. But this extreme case shows most clearly a pattern that has played a persistent role in the history of industrial propaganda in science. It shows that how we change our beliefs in light of evidence depends on the reputation of the evidence’s source. The propagandist’s message is most effective when it comes from voices we think we can trust.
Using the reputations of scientists was an essential part of the Tobacco Strategy. Industry executives sought to staff the Tobacco Industry Research Committee (TIRC) with eminent scientists. They hired a distinguished geneticist named C. C. Little to run it precisely because his scientific credentials gave their activities stature and credibility. Likewise, they established an “independent” board of scientific advisors that included respected experts. These efforts were intended to make the TIRC look respectable and to make its proindustry message more palatable. This is yet another reason why selective sharing can be more effective than biased production–or even industrial selection. The more independence a researcher has from industry, the more authority he or she seems to have.
Even when would-be propagandists are not independent, there are advantages in presenting themselves as if they were. For instance, in 2009 Fred Singer, in collaboration with the Heartland Institute, a conservative think tank, established a group called the Nongovernmental International Panel on Climate Change (NIPCC). The NIPCC is Singer’s answer to the U.N.’s Intergovernmental Panel on Climate Change (IPCC). In 2007 the IPCC (with Gore) won the Nobel Peace Prize for its work in systematically reviewing the enormous literature on climate change and establishing a concrete consensus assessment of the science.
The NIPCC produces reports modeled exactly on the IPCC’s reports: the same size and length, the same formatting–and, of course, reaching precisely the opposite conclusions. The IPCC is a distinguished international collaboration that includes the world’s most renowned climate scientists. The NIPCC looks superficially the same, but of course has nothing like the IPCC’s stature. Such efforts surely mislead some people–including journalists who are looking for the “other side” of a story about a politically sensitive topic.
It is not hard to see through something as blatant as the NIPCC. On the other hand, when truly distinguished scientists turn to political advocacy, their reputations give them great power. The founders of the George C. Marshall Institute, for instance, a conservative think tank, included William A. Nierenberg, who had taken over as director of the Scripps Institute after Revelle moved to Harvard; Robert Jastrow, the founding director of NASA’s Goddard Institute for Space Studies; and Frederick Seitz, the former president of both the National Academy of Sciences and Rockefeller University, the premier biomedical research institution in the United States.
These scientists truly had made major contributions to their respective fields, and their reputations rightly put them in positions to exert influence even in areas where they had far less expertise. It was Nierenberg’s status as former director of Scripps and a member of the National Academy of Sciences that qualified him to serve as chair of the Acid Rain Peer Review Panel–and then gave him the opportunity to modify its executive statement.
These men’s reputations also put them in a special position to criticize other scientists. Perhaps the most striking example came in the aftermath of the second Assessment Report of the IPCC (not the NIPCC!), published in 1995. This report included, for the first time, a chapter devoted to what is known as “fingerprinting,” a set of methods for distinguishing climate change caused by human activity from that produced by sources such as sun cycles or volcanic activity. The chapter on this topic was written by a collaboration of distinguished scientists, but the “convening lead author,” responsible for collecting the material together and orchestrating the whole chapter, was an American climate scientist named Ben Santer.
Santer was relatively junior when he took on this position–though he had already made major contributions to fingerprinting methods and in many ways was ideally situated to convene that chapter. After the report was published, however, Seitz and others went on the attack. In an editorial published in the Wall Street Journal, Seitz accused Santer of violating scientific protocol by changing the final report to “deceive policy makers.” But while it is true that Santer orchestrated late revisions to the chapter, they were made at the direction of IPCC chairman Bert Bolin, in response to comments from peer reviewers. Rather than a violation, they were in fact mandated by scientific protocol.
The Seitz letter reads as what it was: one of the most distinguished physicists in the United States publicly taking a much more junior scholar to task for impropriety: “The report’s lead author, Benjamin D. Santer,” Seitz writes, “must presumably take the major responsibility.” Bolin and forty other scientists signed a letter refuting Seitz’s claims and asserting that Santer’s work had been appropriate, to which Seitz and Singer both replied by more or less repeating the original accusations, but now with the implication that the whole IPCC was in on it.
Perhaps the group of forty internationally recognized climate scientists who signed the Bolin response defending Santer were enough to bolster Santer’s reputation. But even if that is right, the end result is a display of authority on both sides, suggesting that there was a real controversy–not only on the facts, but on the scientific method itself–when in fact there was none. As the tobacco industry has shown, merely creating the appearance of controversy is often all the propagandist needs to do.
The weaponization of reputation is deeply connected to polarization models in which the key factor is trust. It is the people whose opinions we trust who can exert the most influence over us; and as we come to trust some people more and others less, groups begin to diverge, leading to polarized outcomes.
The proxy we use for trust in these models is difference in belief on the matter at hand. This captures an important part of how polarization comes about–and it also explains some aspects of how reputation can be useful to the propagandist. After all, Revelle was admired by many people precisely because of his influential work on climate change. And it was at least in part because those people tended to agree with him on that topic that they were prepared to take any evidence he offered very seriously. (At least, the fact that Gore agreed with him suggests that Gore himself should take Revelle’s opinion seriously.) When Easterbrook and Will implied that new evidence had influenced Revelle, that suggested it should also influence those who agreed with him.
But trust based on agreement about the topic at hand does not capture some of the other ways reputation can be weaponized. Trust often depends on other qualities–such as past behavior, personal connections, or professional training. Surely a lot of individual psychology is involved, too, in whom we trust and why. Even so, we can use our models to capture some interesting and important aspects of the weaponization of reputation by looking at the relationship between trust, belief, and scientific success.
In some models of polarization, everyone is trying to solve one problem and using credences about that problem to decide whom to trust. But in most real-world cases, we have more to go on than just the problem at hand. Suppose we have a network of scientists who are trying to solve two problems, instead of just one. For one of these problems, they are trying to choose between actions A and B; for the other, unrelated problem, they need to choose between actions Y and Z. Now suppose that for each problem, when deciding whom to trust, they consider their beliefs about both problems. The basic dynamics of the model are the same as before: each scientist uses “Jeffrey’s rule,” after the Princeton philosopher Dick Jeffrey, which specifies how to update beliefs when you are not certain about evidence, but now the uncertainty they assign to a person’s evidence depends on the distance between their beliefs on both topics.
In this model, we find that groups polarize, just as they do when only one problem is at stake. But now, perhaps surprisingly, when they polarize, they tend to form subcommunities whose beliefs on both problems are highly correlated. One finds, say, a subcommunity whose members all hold A and Z and another whose members all hold B and Y. Note that the true beliefs do not necessarily correlate with one another: the model often yields cases in which the two communities each hold one true and one false belief.
These models suggest that one way to influence the opinions of members of a group is to find someone who already agrees with them on other topics and have that person share evidence that supports your preferred position. The idea is that people are relying on scientists’ success on other problems to judge their general reliability. In other words, a scientist might think: “I am not so sure about actions A and B, but I am certain that action Z is better than Y. If another scientist shares my opinion on action Z, I will also trust that person’s evidence on actions A and B.”
These sorts of effects can help to explain how weaponized reputation sometimes works. We look to people who have been successful in solving other problems and trust them more when evaluating their evidence. Established scientists with distinguished careers can presumably point to many past successes in correctly evaluating evidence. More, their peers–other scientists–have evaluated their past work and deemed it strong and reliable. When the established scientists present new evidence and arguments–even on topics that are completely unrelated to the field in which they established their reputations–you have good reason to trust them. In fact, philosophers of science Jeffrey Barrett, Brian Skyrms, and Aydin Mohseni have used network epistemology models to show that paying attention to this sort of past reliability can drastically improve the accuracy of a community’s beliefs, on the assumption, of course, that no one is using reputation as a weapon. These sorts of results can also help explain why someone like Seitz can be influential on a range of issues, including climate change, that are quite far from that person’s previous research.
These issues of trust, on the problem at hand and more generally, surely play an important role in explaining how reputation gives some people outsized influence–at least within parts of a community. But it is not the whole story. Conformity and network structure are also critical to understanding the social role of reputation in propaganda.
