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When I tell friends I am skeptical that global warming threatens the survival of mankind, I am greeted with shocked disbelief. I remind them it was once nearly unanimously believed that the sun rotated around the earth until Copernicus demonstrated just the opposite was true. Copernicus, my friends reply, lived in a prescientific age. Surely today when there is a scientific consensus you can rely on its accuracy. As a matter of fact, in the last three decades there have been many cases of mistaken scientific consensus.
Embarrassingly for global warming alarmists, in the 1970s there was a prior scientific consensus about climate trends, only then it was that the earth was rapidly cooling. Many scientists began predicting the coming of a new mini ice age accompanied by a catastrophic decline in food production. In a 1975 story, "The Cooling World," Newsweek reported that "the evidence in support of these predictions has now begun to accumulate so massively that meteorologists are hard-pressed to keep up with it." Since nothing was done to address the "problem" of global cooling (some climatologists thought it might be necessary to melt the Arctic cap by covering it with black soot), no harm resulted from this scare. Unfortunately, the same cannot be said about other severe cases of mistaken scientific consensus.
In the 1980s, several observational studies indicated that hormone (estrogen) replacement therapy, which had long been used to alleviate the discomforts many menopausal women experienced, provided protection against cardiovascular disease and osteoporosis as well. Pharmaceutical manufacturers, physicians and the popular media now began to beat the drums for HRT, and soon it became standard medical practice to prescribe a combined regimen of estrogen and progestin on a long-term basis for nearly all menopausal and postmenopausal women.
The practice did not stop until 2002, when the Women's Health Initiative, a massive (161,809 postmenopausal women), randomized, double-blind, placebo-controlled clinical trial (often referred to as the "gold standard" in medical research), revealed that, contrary to the prevailing scientific consensus, long-term HRT increased the risk of heart attacks, blood clots, stroke and breast cancer.
In 1992, the Food and Drug Administration banned the use of silicone implants, which were widely used for breast augmentation and reconstruction after mastectomies. The FDA acted after allegations that silicone implants were causing autoimmune diseases were seized upon by the media and feminists, who claimed that, at bottom, it was a story of corporate malfeasance and male exploitation of women. A tidal wave of lawsuits engulfed Dow Corning, the principal manufacturer of silicone implants, forcing it into bankruptcy, with devastating consequences for its employees and the residents of Corning, N.Y. Further scientific investigation revealed that silicone implants did not cause lupus and cancer, and in 2006 the FDA reversed its ban "now that the products have been determined to be safe and effective."
In 1988, Surgeon General C. Everett Koop proclaimed that high-fat foods, such as ice cream and red meat, posed as great a danger to public health as cigarettes. The depth of the science basis underlying this finding, Koop mistakenly declared, "is even more impressive than that for tobacco and health in 1964."
Dr. Koop should not be judged too harshly for his error, for he was expressing what he believed to be the scientific consensus. By the time Koop issued his warning, the belief that a low-fat diet was the best way to protect against heart disease had been endorsed by the American Heart Association, a U.S. Senate committee headed by George McGovern and the U.S. Department of Agriculture.
When the National Academy of Sciences reported that there was little scientific evidence to warrant recommending a low-fat diet for all Americans, "the report's authors," writes John Tierney of the New York Times, "were promptly excoriated on Capitol Hill and in the news media" for denying a widely accepted danger and "the scientists, despite their impressive credentials, were accused of bias because some of them had done research financed by the food industry."
Some medical and nutritional authorities believe that by inducing excessive consumption of carbohydrates, low-fat diets have contributed to the epidemic of obesity in America.
The moral of these stories is that the public, government agencies and even scientists can be stampeded into deciding important issues without sufficient evidence. Contrary to what Al Gore has famously said, the jury is still out on man's responsibility for global warming, about which we know almost nothing, and the danger it poses.
By STUART GALISHOFF
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