The relationships of population size and growth to resources have been subject to intense debate and substantial confusion. Much of the debate centres on the scarcity of resources and whether they are running out, or being used up too fast, as a result of rapid population growth. Several insights are germane to analysing this issue.
First, for resources that are traded in well-functioning markets, the price of the resource is the best single assessment of its scarcity. Scarcity should not be measured simply by the amount of resources remaining or yet to be discovered, but rather by reference to demand or value to end-users. A resource with tiny supply and no demand is not scarce; a resource with substantial supply and huge demand may well be scarce.
Second, by the price measure, and based on historical evidence of relatively constant or declining real prices over time, most non-renewable resources are not particularly scarce, nor are they becoming increasingly scarce. Expansion of supply and/or curtailments of demand have been more than sufficient to maintain a long-run balance of resources vis-à-vis their use. Changes in demand and supply for resources have been heavily influenced by new discoveries, changes in technology resulting in reduced use of relatively scarce resources, and the capacity of consumers and producers to make appropriate substitutions of relatively abundant for relatively scarce resources.
Third, historically the major cause of an expanded demand for resources has not been rapid population growth, but rather rises in income. Prosperous countries, where population growth is slow, consume an inordinate amount of resources. In the future, as Third-World countries become more prosperous and given their predictably large populations resulting from rapid population growth in recent and future decades, upward pressures on resource prices will become considerably stronger. This resource scarcity will be increasingly costly to circumvent.
Fourth, over-use of resources due to population or income pressures is most likely to occur where market prices do not adequately reflect true present and future scarcity, and where governments are unable or unwilling to provide appropriate and offsetting regulations. Forests, fisheries, clean air, clean water, and even common land represent areas where markets and prices can fail to allocate resources well. This is because property rights are in some settings difficult to establish, monitor and enforce. After all, one cannot sell something that one does not own for a price; thus prices are not available to signal scarcity in such cases. Moreover, the true demand or value of some resources is quite uncertain. An important example is the value that individuals and/or societies place on the existence of plant and animal species, and on biological diversity. While population pressures are not the primary cause of over-use of resources where markets and government policies are deficient, population pressures are indeed an exacerbating cause, and sometimes an important one.
Very little is known operationally about the optimal size of population vis-à-vis resources, although there is much discussion about sustainable population levels. Estimates of the earth’s carrying capacity for various important resources (mainly land and water for food production) vary from 5 billion to 30 billion people. Estimates of the capacity of biological and ecological systems to regenerate, or be sustainable on a long-term basis, are equally vague. Current predictions are for a world population of 9 billion to 12 billion by the end of the twenty-first century. Whether this population size will be sustainable—whether it will preserve over time a reasonable stock of resources for future generations—is not known with any degree of certainty.
Allen C.Kelley
Duke University
Further reading
Marquette, C.M. and Bilsborrow, R. (1994) ‘Population and the environment in developing countries: literature survey and research bibliography’, UN Document ESA/P/WP. 123, 16 February, New York.
Panayotou, T. (1993) Green Markets: The Economics of Sustainable Development, San Francisco, CA.
Simon, J. (1981) The Ultimate Resource, Princeton, NJ.
United Nations (1994) World Resources 1994–95: People and the Environment, New York.
