One generation passeth away, and another generation cometh: but the earth abideth forever.
No, not forever. At the outside limit, the earth will probably last another 4 billion to 5 billion years. By that time, scientists predict, the sun will have burned up so much of its own hydrogen fuel that it will expand and incinerate the surrounding planets, including the earth. A nuclear cataclysm, on the other hand, could destroy the earth tomorrow. Somewhere within those extremes lies the life expectancy of this wondrous, swirling globe. How long it endures and the quality of life it can support do not depend alone on the immutable laws of physics. For man has reached a point in his evolution where he has the power to affect, for better or worse, the present and future state of the planet.
Through most of his 2 million years or so of existence, man has thrived in earth's environment -- perhaps too well. By 1800 there were 1 billion human beings bestriding the planet. That number had doubled by 1930 and doubled again by 1975. If current birthrates hold, the world's present population of 5.1 billion will double again in 40 more years. The frightening irony is that this exponential growth in the human population -- the very sign of homo sapiens' success as an organism -- could doom the earth as a human habitat.
The reason is not so much the sheer numbers, though 40,000 babies die of starvation each day in Third World countries, but the reckless way in which humanity has treated its planetary host. Like the evil genies that flew from Pandora's box, technological advances have provided the means of upsetting nature's equilibrium, that intricate set of biological, physical and chemical interactions that make up the web of life. Starting at the dawn of the Industrial Revolution, smokestacks have disgorged noxious gases into the atmosphere, factories have dumped toxic wastes into rivers and streams, automobiles have guzzled irreplaceable fossil fuels and fouled the air with their detritus. In the name of progress, forests have been denuded, lakes poisoned with pesticides, underground aquifers pumped dry. For decades, scientists have warned of the possible consequences of all this profligacy. No one paid much attention.
^ This year the earth spoke, like God warning Noah of the deluge. Its message was loud and clear, and suddenly people began to listen, to ponder what portents the message held. In the U.S., a three-month drought baked the soil from California to Georgia, reducing the country's grain harvest by 31% and killing thousands of head of livestock. A stubborn seven-week heat wave drove temperatures above 100 degrees F across much of the country, raising fears that the dreaded "greenhouse effect" -- global warming as a result of the buildup of carbon dioxide and other gases in the atmosphere -- might already be under way. Parched by the lack of rain, the Western forests of the U.S., including Yellowstone National Park, went up in flames, also igniting a bitter conservationist controversy. And on many of the country's beaches, garbage, raw sewage and medical wastes washed up to spoil the fun of bathers and confront them personally with the growing despoliation of the oceans.