IF President Clinton signs the Rio accord to protect rare and endangered species, he will place scientific truth in greater danger than endangered species.
A fair reading of the available data suggests a rate of extinction not even one-thousandth as great as doomsayers claim. If the rate were any lower, evolution itself would need to be questioned.
The World Wildlife Fund, the main promulgator of alarm about biodiversity and the extinction of species, frames the issue in the starkest terms: "Without firing a shot, we may kill one-fifth of all species of life on this planet in the next 10 years."
This assertion is utterly without scientific underpinning and runs counter to all the existing evidence. Such apocalyptic claims are used to bludgeon the federal government for money and action.
A long-running fund-raising pitch from World Wildlife Fund's president, Russell E. Train, describes how the organization rallied support for reauthorization of the Endangered Species Act by telling Congress that "some scientists believe that up to one million species of life will become extinct by the end of this century" unless governments "do something."
Mr. Train added: "When we talk about the loss of one million species, we are talking about a global loss with consequences that science can scarcely begin to predict. The future of the world could be altered drastically if we allow a million species to disappear by the year 2000."
The warning is amplified by the media. The Washington Post quoted the claim of a top Smithsonian conservation biologist, Thomas Lovejoy, that "a potential biological transformation of the planet unequaled perhaps since the disappearance of the dinosaur" is about to occur.
The Post also cited Harvard University's Edward O. Wilson, a biologist, on "the folly our descendants are least likely to forgive us."
The emotions behind such sweeping statements cause partisans to believe that the matter is too important to be subjected to the standards of normal science.
Recommendations that leading biologists and ecologists base on nonfacts are staggering. Professor Wilson and Stanford University's Paul Ehrlich, a biologist, actually ask that governments "reduce the scale of human activities."
They want us "to cease 'developing' any more relatively undisturbed land" because "every new shopping center built in the California chaparral . . . every swamp converted into a rice paddy or shrimp farm means less biodiversity."
The standard source of all the apocalyptic forecasts is a 1979 book, "The Sinking Ark," by a conservation biologist, Norman Myers. Mr. Myers' work rests on two statistics: the estimated extinction rate of known species of animals between the years 1600 and 1900 (about one every four years) and the estimated rate from 1900 to the present (about one a year).
Mr. Myers abruptly departs from those modest estimates and goes on to say that some scientists have "hazarded a guess" that the extinction rate "could now have reached" 100 species a year.
This pure conjecture about an upper limit of present extinction of species is then increased and used by Mr. Myers and Mr. Lovejoy as the basis for the projections quoted everywhere.
In fact, Mr. Lovejoy -- after converting an estimated upper limit into a simple estimate -- says that government inaction is "likely to lead" to the extinction of 14 to 20 percent of all species before the year 2000. Mr. Lovejoy's extinction rate, which is a thousand times greater than the observed rate, is pure guesswork. Yet it is widely published and erroneously viewed as scientific fact.
In articles in the mid-1990s in New Scientist magazine, in newspapers, in books and at conferences, both of us have documented the complete absence of evidence for the claim that the extinction of species is going up rapidly -- or even going up at all.
No one has disputed our documentation. Nor has anyone cited new evidence that would demonstrate rapid extinction. Instead, until recently, the biologists sounding the alarm simply ignored the data that challenged their claims.
But recently the World Conservation Union published an inquiry into the extent of extinctions, "Tropical Deforestation and Species Extinction."
Every author included agreed that the rate of known extinctions has been and continues to be very low. One wrote, "Forests of the Eastern United States were reduced over two centuries to fragments totaling 1-2 percent of their original extent. . . . During this destruction, only three forest birds went extinct."
We are delighted that this species of truth, which we thought was dead, is stirring into life.
President Clinton should heed this astonishing scientific assessment. We are not suggesting that he ignore the possible dangers to species. But everyone should start from an unbiased view of the gains and losses in order to help judge how much time and money to spend guarding our biological assets.
Julian L. Simon is professor of business at the University of Maryland College Park. Aaron Wildavsky is professor of political science at the University of California.