Other Environmental Themes

Biodiversity Under Fire

Biodiversity—the vast profusion of plant, animal, and microbial species—constitutes nature's ultimate gift. Each organism on Earth is part of an interwoven network of communities that form the working units of nature called ecosystems. There is tremendous diversity in ecosystems themselves—from wetland to desert, Arctic tundra to tropical rainforest and alpine meadow to coral reef. Humans, of course, benefit immensely from the myriad goods and services these systems dispense.

Sixty-five million years ago, according to a widely accepted theory, a large asteroid slammed into our planet, setting off a global catastrophe that led to the disappearance of the dinosaurs and half the other species on Earth.

Another mass extinction is now in its early stages, triggered by bulldozers and chainsaws rather than by a giant rock from outer space. Human activities—habitat destruction, overconsumption of natural resources and the disposal of toxic residues from these practices—are wiping out species at the unprecedented rate of several per hour. By some accounts, we are losing species 10,000 times faster than new ones are being generated through evolution.

The World Conservation Union recently placed one out of eight known plant species, roughly a quarter of all mammals and about 10 percent of the world's birds on its list of imperiled organisms. At stake, however, is more than the survival of such celebrated endangered species as the Northern right whale, California condor or spotted owl. The health of ecosystems is at risk, as research in the past decade has shown that biologically diverse systems are more productive, more stable, and more resilient in the face of natural or human-induced change.

The Earth and its creatures could not avert a collision with an asteroid 65 million years ago. With the backing of NASA, space scientists are now exploring ways to protect our planet from an impact with a errant comet or asteroid-an effort that may or may not pay off. Meanwhile, a more pressing challenge confronts us on the ground: humans need to control a mass extinction of their own making. Progress can be made by a variety of means—curbing population growth, using resources more efficiently, reducing pollution and judicious land-use planning-to keep us from going the way of the dinosaurs.