The Last Harvest: The Genetic Gamble That Threatens to Destroy American Agriculture
Our Children’s Toxic Legacy: How Science and Law Fail to Protect Us from Pesticides
Noah’s Choice: The Future of Endangered Species
Losing Ground: American Environmentalism at the Close of the Twentieth Century
In 1864, in his remarkable book Man and Nature, George Perkins Marsh contended that man’s small disturbances of the equilibrium of the natural world could transform and harm the land and its creatures, leading to disaster. Marsh was not a scientist but, by turns, a congressman, businessman, diplomat, and polymathic scholar. His idea ran contrary to the scientific thinking of the day, which held that man was puny and nature formidable; but in both his native Vermont and regions abroad, he had seen with his own eyes evidence of the human impact on nature, including the alterations of landscape, the flooding, and the disruption of natural cycles that came with the destruction of forests and damming of streams. He noted that once-fertile lands in the Middle East had been turned into deserts. He warned that man in the era of rapid urbanization and industrialization was fast making the earth “an unfit home for its noblest inhabitant.”
Now, a century later, Marsh’s eastern forests have largely restored themselves, not mainly by human design but because coal, oil, and gas have been substituted for wood fuel and there has been low demand in this century for arable northeastern farmland. But it requires no special insight to recognize the continuing impact of human beings on nature. Satellite photos reveal the huge parts of the Amazon rain forest that have been slashed and burned to make way for agriculture; and we know the logging practices that continue in the old-growth forests of the Pacific Northwest are causing the irreversible destruction of ancient trees. Most of us intuitively deplore such assaults on nature, valuing it as we do for the aesthetic and spiritual pleasure it provides. But scientists inform us that we have a great deal more to regret about its disappearance.
For one thing, trees suck carbon dioxide out of the air and give back oxygen in return. With fewer trees, the level of carbon dioxide in the atmosphere rises, contributing to global warming. For another, forest cover retains ground water. Once it is gone, the earth hardens and rainwater runs off, carrying away soil and raising the levels of streams and rivers. Farming compounds the loss. Each year in the continental United States, some 3 billion tons of topsoil are washed into lakes, oceans, and rivers. Throughout the world, since 1972, some 500 million acres have been turned into deserts; and farmers have lost 480 million tons of topsoil, more than all of the topsoil on all US farmland. In recent years, growth in grain yields has not been making up for losses in grain-growing land.
The more forests we destroy to make way for farms or shopping centers, the more we reduce the chances of numerous species of plants and animals to survive. Not that the destruction of species is unique to modern man. The migration of people from Asia to the North American continent some ten thousand years ago gradually led to the extinction of numerous …