In the United States, the need to protect plant and animal species has become a highly controversial and sharply political issue since the passage of the Endangered Species Act in 1973. The act, designed to protect species, in effect requires the preservation of the species' habitats, and policies that preserve land and forests compete with economic interests. In the 1990's, for example, the loggers of forests in the Western United States were challenged legally in their attempt to cut trees for lumber in the Cascade Mountains. The challenge was mounted to protect the endangered spotted owl, whose remaining population occupies these forests and requires the intact, ancient forest for survival. The dilemma pitted the interests of environmentalists against those of corporations and of individuals who stood to lose jobs.
Similar tensions exist between the developed and the developing nations.
Many people in industrialized nations, for example, believe that developing nations in tropical regions should do more to protect their rain forests and other natural areas. But the developing countries may be impoverished, with populations growing so rapidly that using the land is a means to temporarily avoid worsening poverty and starvation. Many of the changes to Earth that concern scientists have the potential to rob the planet of its biological richness. The destruction of Earth's ozone layer, for example, could contribute to the general process of impoverishment by allowing ultraviolet rays to harm plants and animals. And global warming could wipe out species unable to quickly adapt to changing climates.