At the time, there was a concerted desire to avoid nuclear war. If nuclear winter made nuclear war look awful, why investigate too closely? Who wanted to disagree? Only people like Edward Teller, the "father of the H bomb."
Teller said, "While it is generally recognized that details are still uncertain and deserve much more study, Dr. Sagan nevertheless has taken the position that the whole scenario is so robust that there can be little doubt about its main conclusions." Teller's view was ignored; for most people, the fact that nuclear winter was a scenario riddled with uncertainties did not seem to be relevant.
I say it is hugely relevant. Once you abandon strict adherence to what science tells us, once you start arranging the truth in a press conference, then anything is possible. In one context, perhaps you will get mobilization against nuclear war. But in another context, you get Lysenkoism. In another, you get Nazi euthanasia. The danger is always there, if you subvert science to political ends.
That is why it is so important for the future of science that the line between what science can say with certainty, and what it cannot, be drawn clearly--and defended.
What happened to nuclear winter? Even as the media glare faded, its robust scenario appeared less persuasive; John Maddox, editor ofNature , repeatedly criticized its claims; within a year, Stephen Schneider, one of the leading figures in the climate model, began to speak of "nuclear autumn." It just didn't have the same ring.
A final media embarrassment came in 1991, when Carl Sagan predicted onNightline that Kuwaiti oil fires would produce a nuclear winter effect, causing a "year without a summer," and endangering crops around the world. Sagan stressed this outcome was so likely that "it should affect the war plans." None of it happened.
What, then, can we say were the lessons of Nuclear Winter? I believe the lesson was that given a catchy name, a strong policy position, and an aggressive media campaign, nobody will dare to criticize the science, and in short order, a terminally weak thesis can be established as fact. After that, any criticism becomes beside the point. The war is already over, without a shot being fired. That was the lesson, and we had a textbook application soon afterward, with second hand smoke.
In 1993, the Environmental Protection Agency (EPA) announced that second-hand smoke was "responsible for approximately 3,000 lung cancer deaths each year in nonsmoking adults," and that it "impairs the respiratory health of hundreds of thousands of people." In a 1994 pamphlet, the EPA said that the eleven studies it based its decision on were not by themselves conclusive, and that these studies collectively assigned second-hand smoke a risk factor of 1.19. (For reference, a risk factor below 3.0 is too small for action by the EPA under its own rules. Nor is it sufficient for publication in theNew England Journal of Medicine , for example, which requires a risk factor of 3-4.) Furthermore, since there was no statistical association between second-hand smoke and health risk at the 95% confidence limits, the EPA lowered the limit to 90%. They then classified second-hand smoke as a Group A Carcinogen.
This was openly fraudulent science, but it formed the basis for bans on smoking in restaurants, offices, and airports. California banned public smoking in 1995. Soon, no claim was too extreme. By 1998, theChristian Science Monitor was saying that "Second-hand smoke is the nation's third-leading preventable cause of death." The American Cancer Society announced that 53,000 people died each year of second-hand smoke. The evidence for this claim is nonexistent.
In 1998, a Federal judge held that the EPA had acted improperly, had "committed to a conclusion before research had begun," and had "disregarded information and made findings on selective information." The reaction of Carol Browner, head of the EPA was: "We stand by our science....there's wide agreement. The American people certainly recognize that exposure to second-hand smoke brings...a whole host of health problems." Again, note how the claim of consensus trumps hard science. In this case, it isn't even a consensus of scientists that Browner evokes! It's the consensus of the American people.
Meanwhile, ever-larger studies failed to confirm any association. A large, seven-country World Health Organization (WHO) study in 1998 found no association. Nor have subsequent well-controlled studies, to my knowledge. Yet we now read that second-hand smoke is a cause of a range of ills, from breast cancer to autism. At this point you can say pretty much anything you want about second-hand smoke.