The biosphere is the region of the earth that supports life; it includes all land, water, and the thin layer of air above the earth. A sustainable biosphere is one with the continuing ability to support life.

Some scientists have suggested that the oceans and atmosphere in the biosphere adjust to ensure the continuation of life—a theory known as the Gaia hypothesis. British scientist James Lovelock first proposed it in the late 1970s. He argued that in the last 4,500 years of the earth's approximately five billion years of existence, humans have been placing increasingly greater stress on the biosphere. He called for a new awareness of the situation and insisted that changes in human behavior were necessary to maintain a biosphere capable of supporting life. Maintaining a sustainable biosphere involves the integrated management of land, water, and air.

The land management practices that many believe...