The authors point out that never before in history have human numbers so dominated the Earth and its resources. The current population of 5 billion is exerting major pressures on energy and environmental resources. Resource constraints have limited global economic growth several times during this century; however, by employing new technologies and cheap energy, the constraints were pushed back.
Brown and colleagues raise the interesting question: what is the carrying capacity of the Earth's resources, especially the biological resources? Biologists and agriculturalists have long been able to estimate the carrying capacities of various ecosystems. A natural grassland, for example, can be calculated to support a certain number of cattle or sheep. In a similar manner, a fishery can supply the protein needs for a certain number of people, and the forest close to a rural village can supply firewood to a certain number of families. If the number of people ...
