WASHINGTON — WASHINGTON -- The nuclear arms race is history. The world's industrial nations are at peace. But the Union of Concerned Scientists is still, well, concerned.
The 23-year-old anti-nuclear group yesterday issued a "World Scientists Warning to Humanity," signed by about 1,580 top scientists from 69 countries, declaring that governments everywhere must act quickly to save the planet from doom.
"Human beings and the natural world are on a collision course," the "Warning" admonishes. "Human activities inflict harsh and often irreversible damage on the environment and on critical resources."
For the past two decades, the Cambridge-based group, which has 100,000 contributors, has warned that nuclear weapons and unsafe nuclear power plants threatened the globe. But in the late 1980s, as the arms race slowed and the atomic power industry stagnated, the group began shifting focus.
Yesterday, at a news conference presided over by five scientists, the Union sounded the alarm about a Molotov cocktail of maladies -- everything from ozone destruction to soil erosion to the loss of plant and animal species to human overpopulation.
The 3 1/2 -page "Warning" does not prescribe specific remedies. Instead, it generally counsels moving away from fossil fuels to more benign energy sources; halting the loss of species through habitat destruction; making more efficient use of water, energy and other resources; stabilizing the world's population; "eventually" eliminating poverty; ensuring sexual equality and giving "women control over their own reproductive decisions."
There have been similar jeremiads in the past from other environmental groups, conceded Henry Kendall, a Massachusetts Institute of Technology physicist who is chairman of the union. "But these warnings have generally been disregarded by world leaders and people as not being valid or being exaggerated."
The "Warning," he said, was endorsed by an "astonishing number" of prominent scientists, including 99 of the 196 living scientists who have won the prestigious Nobel Prize. (Dr. Kendall himself won a Nobel in 1990).
Scientists are sharply divided over some environmental issues. The "Warning" itself says global warming "may" be triggered by rising levels of carbon dioxide and other greenhouse gases, created by industry and agriculture, in the atmosphere. A number of scientists think there is still no credible evidence the globe is heating up.
But Sir Martin John Rees, an astrophysicist at Cambridge University, told reporters that political leaders shouldn't use uncertainty as an excuse for inaction. "If you were diagnosed as having a potentially lethal disease, you'd be foolhardy to delay treatment by even one day," he said.
The "Warning" is dead certain about the danger posed by a shopping list of threats -- including acid rain, water pollution, overfishing, soil erosion, deforestation and overpopulation.
"Something has to be done to keep the population within reasonable limits," Johanna Dobereiner, a soil biologist from Brazil, told reporters. "Not by some extreme [laws], but by education."
Edward O. Wilson, a Harvard biologist, said that in the next 30 years, 30 percent of the estimated 10 million to 100 million plant and animal species on Earth could be wiped out -- and that, with new environmental controls, that loss might be cut to 10 percent.
"This loss is unique in the realm of environmental trends," Dr. Wilson said.
Critics of the environmental movement don't buy it.
"It's clear these guys are just recycling the same old environmental trash," said David Rothbard, president of the Committee for a Constructive Tomorrow, a Washington-based group supported by mining, manufacturing and land development interests.
He called global warming, acid rain, ozone depletion and other environmental ills "bogus," and criticized the union. "Once that cash cow of nuclear weapons was gone, they had to find some new way to keep their organization going, and they simply moved into the environmental area," Mr. Rothbard said.
He said many environmentalists use the threat of pollution to justify the extension of state power and new limits on individual liberties. "They have a very radical goal and political agenda," he said.