Mobilizing to Combat Global Warming.

• Author: Hayes, Denis (American environmental scholar)

Homo sapiens has always altered its immediate environment. For example, ancient farmers converted the Fertile Crescent--the fabled Babylon--into the desert wastes of Iraq. But only in the last few decades have we had the capacity to literally change the entire planet. Only recently have we become a geophysical force.

Jane Lubchenco, the former president of the prestigious American Association for the Advancement of Science, spoke forcefully about this new phenomenon in her farewell address to the AAAS. Looking out over a sea of the nation's top scientists, Lubchenco warned:

During the last few decades, humans have emerged as a new force of nature. We are modifying physical, chemical, and biological systems in new ways, at faster rates, and over larger spatial scales than ever recorded on Earth. Humans have unwittingly embarked upon a grand experiment with our planet.

In 1992, 3,500 scientists from around the world signed a World Scientists' Warning to Humanity that stated:

Our massive tampering with the world's interdependent web of life--coupled with the environmental damage inflicted by deforestation, species loss, and climate change--could trigger widespread adverse effects, including unpredictable collapses of critical biological systems whose interactions and dynamics we only imperfectly understand.

These are not exhortations from overwrought extremists, but carefully phased warnings from some of the world's finest scientists. While the "news" is dominated by sex scandals, celebrity athletes, and car wrecks, these scholars are trying to call public attention to the fact that the world has entered a dangerous new era. A few stark examples:

* Most of the world's great biological systems are in a state of collapse because we have logged, trawled, or cultivated them to maximize short-term production. Plant and animal species are going extinct at the fastest rate in 65 million years.

* The world's existing human population is already three times as great as the planet's long-term carrying capacity if all people seek a level of affluence comparable to that currently enjoyed in, say, Sweden.[*]

* Although the Cold War is over, little if any progress has been made in removing the single most imminent threat to the global environment--nuclear holocaust. A respectable body of opinion holds that a nuclear war is more likely today than it was under Brezhnev.

* We have carved two giant holes in the ozone layer, increasing the exposure of people...