Introduction
The advancement of technological development and scientific knowledge that began 500-600 years ago
not only laid the foundation for the great voyages of discovery and the Industrial Revolution, but also
enabled the human population to multiply at an accelerating rate and set humans on a path to becom-
ing a dominant element of nature. By the early 1800s, Thomas Malthus and others were predicting
that eventually there would be insufficient land to support this massive population growth. Such a dire
outcome was staved off in the nineteenth century by among other things, the opening of new lands,
including the American West, and in the twentieth century by the Green Revolution. Now, however, envi-
ronmentalists and scientists are warning that the accelerating pace of recent chemical, biological, and
physical transformations of the earth’s environment may be triggering uncontrollable and irreversible
alterations of our planet, and that these changes will have a profound, unpredictable impact on all forms
of life on Earth.^1
Although the population growth and technological innovations of the past few centuries created
some previously unknown environmental problems, many current problems are merely exacerbations
of the kinds that have arisen whenever significant numbers of humans have settled in a region for long
periods of time. Concern about resource depletion, See notes on page 413 pollution, environmental
degradation, and population growth has existed for centuries. Problems stemming from too little water
or land to support dense population centers may have contributed to the collapse of various ancient
civilizations, including the Anasazi and the Maya. Nearly 2300 years ago Plato wrote about the degrada-
tion of land in Greece.^2 In colonial America the damming of waterways to supply energy for mills had
to be regulated because it interfered with the spawning of fish, and the dumping of waste into Atlantic
coast harbors caused pollution that required control. By the mid-nineteenth century, air pollution, inad-
equate clean water, and urban sanitation were acknowledged problems in the United States as well as in
Europe, and American voices were being raised in opposition to the wanton destruction of wildlife and
calling for the preservation of forests and scenic land. It was not until the 1890s, though, when the U.S.
western frontier had disappeared and there was no longer open land for Americans to expand into, that