ABSTRACT
An understanding of the carrying capacity of the earth's basic biological systems is a prerequisite of meaningful population projections. A biological concept, carrying capacity is a management tool widely employed by ranchers, wildlife managers, and others concerned with the sustainable yield of local biological systems. The scarcity of commodities of biological origin and of cropland has been partially offset by the extensive substitution of petroleum and petroleum products. Kerosene has been substituted for firewood and charcoal. Gasoline and diesel fuels used to power tractors and irrigation pumps have been substituted extensively for draft animals and for human muscle power. Between 1950 and 1973 the world economy expanded at some 4 percent per year. This unprecedented increase in the output of goods and services was closely tied to the 7 percent annual growth in world oil output during the period. As world population approached four billion, the global economy was staggering under the first double-digit inflation during peacetime.
