If any doubts lingered that the environment was going to be the cause celebre of the 1990s, the ongoing Earth Day celebrations should have put them to rest by now.

Worldwide demonstrations, blanket media coverage and a variety of corporate sponsors all marked the 20th anniversary of the first Earth Day.

But all the glitz symbolized what has become a quiet revolution in Americans' consciousness. The environment has risen to the top of many peoples' political agendas--and its influence is increasing.

"Public interest has skyrocketed in recent years," says Robert A. Stavins, an environmental expert at the Kennedy School of Government. "A substantial number of Americans now list the environment as their number-one concern, whereas before it would be second or third or even further down the list."

But problems of ozone depletion, toxic pollution, climatic warming and mass extinction of species--the areas Harvard biologist Edward O. Wilson has identified as the "four horsemen of the environmental apocalypse" --have existed for many years. It is only recently that they have come to play such a major part in American political and social landscapes.

The sweeping phenomenon can be attributed to a combination of factors, experts say, including a string of highly publicized environmental disasters, an expansion in the amount and quality of hard evidence on environmental problems and a transformation of the international political climate.

"We are entering a new phase of environmental studies and activism," Wilson says. "Conservation is more linked to economic development than opposed to it, focused on biological diversity rather than just individual star species such as the panda and the bald eagle and tilted southward to put increasing emphasis on tropical countries, where by far the most severe environmental problems exist."

According to Wilson, the growth of scientific knowledge has been the major catalyst of the recent explosion in the environmental movement.

"We know the rate at which carbon dioxide is accumulating in the atmosphere; we know there is a hole in the ozone layer; we know the rainforests are disappearing; and we know what the consequences are," says Wilson, adding that the days when the environmental movement was fueled by a spiritual devotion to "wholism" are over.

"Its thrust," Wilson says, "has become less ideological and more pragmatic, more scientific and less New Age."

The increasingly rigorous scientific grounding has in turn altered the political context of the debate, blurring the battle lines between liberals and conservatives over environmental policy, Wilson says.

"Two years ago,...environmental issues were regarded as threats of ideological conflict, where champions of Nature battled champions of Progress," says Wilson. "Liberals... blocked dams to save oddly named small fish, while conservatives destroyed the environment for short-term profits."

Today he notes, these stereotypes are disappearing.

"You cannot have real economic progress without careful environmental planning, nor can you have an effective environmental movement without economic stability," Wilson says.

Ecological Disasters