The Carrying Capacity Of Earth's Resources

State of the World 1987: A Woridwatch Institute Report on Progress Toward a Sustainable Society. Lester R. Brown et al. W.W. Norton & Co., New York, 1987. 268 pp. $18.95 HB, $9.95 PB. The Worldwatch Institute has performed a valuable service for the public and governments with the publication of this detailed report, State of the World 1987, which examines the interdependencies of human population growth, resources, the environment and the world economy. Lester Brown, president of the institute, and his colleagues assess the influence of rapid population growth on soil erosion, overgrazing, deforestation, air pollution, and water and energy shortages. With this as a basis, the influence of natural resource degradation and resource shortages on food supplies, the economy, and the standard of living of people is analyzed. 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 depending on these resources becomes excessive, then the biological resources will decline and eventually be destroyed. Humans have already exceeded the sustainable carrying capacities of certain environments in the world. The authors justifiably devote a great deal of attention to the sustainability of world agriculture. They point out the serious soil erosion problem in the world and discuss how this is undermining agricultural productivity. Up to the present, soil degradation has been offset by irrigation, fertilizers and pesticides. This is why food production has increased even while agricultural practices have been degrading the resource base. The combination of the growing number of people on Earth and increased affluence for some is increasing the amounts of chemicals and garbage being produced daily in the world. Brown and colleagues spend about 40 pages describing the seriousness of the pollution problem and the need for stabilizing chemical cycles, and recycling garbage and other wastes. The environmental and energy benefits of recycling are enormous, and as we exhaust current landfills, recycling will be forced on many communities. In a chapter entitled "Designing Sustainable Economies," the authors point out that sustained development will be unlikely without improved energy efficiency as fossil fuel supplies decline and environmental problems grow. An essential part of sustained development for many nations will be limiting human numbers. Without population control, development will be impossible. State of the World 1987 is a thorough examination of the influence of human populations on soil, water, air, energy and biological resources. Particularly helpful and timely are the proposed solutions to various complex problems. I strongly recommend this exceptionally well-written report to scientists and others who desire to prevent further environmental deterioration and improve the quality of life for all people. Pimentel is a professor of entomology at Cornell University, Ithaca, NY 14853.

The Carrying Capacity Of Earth's Resources

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