The Built and Natural Environments

Although the effects of lower fertility on health may be visible fairly quickly, the effects on public investments may take longer to work themselves out. Pressures from high fertility can last for an extended period, as the housing situation in Thailand illustrates. In the early 1960s expenditures on housing were 90 percent of what was required to keep up with the growth in number of households (which grow proportionally more rapidly than the population). By around 1980, even though fertility had declined substantially, households were still increasing rapidly, and expenditures had fallen to 50-60 percent of what was needed to prevent a decline in previous standards. Merely to maintain housing growth comparable to the growth of households, Thailand would have had to put 40 percent of all investment into housing in the 1990-1995 period. With substantially lower fertility, this proportion will fall, by 2005-2010, to 31 percent of all investment, and by 2010-2015 to 25 percent. In 15 years the number of housing starts will have to be 18 percent more numerous to maintain housing quality. But if fertility had not fallen as much, the number of housing starts would have to be even greater. In 15 years in the Philippines (where fertility is now roughly twice as high as in Thailand), annual housing starts will have to be 53 percent more numerous (Mason, 1996).

Besides raising the need for housing, high fertility produces more mouths to be fed. The link from this to increased food production to the clearance of forests is probably the most carefully studied of the environmental threats from rapid population growth. Studies of Thailand's poorest and most populous region, the northeast, illustrate the problem. Given few job opportunities in the 1970s and 1980s and a population with little cash and no special skills, farming absorbed most of the labor. But with soil fertility low, forests had to be cleared to provide more land, and the fallow cycle became shorter and shorter. Econometric studies show that a 10-percent increase in population growth contributed to a 3.3-percent increase in deforestation (Panayotou, 1994, pp. 172-173). A broader metanalysis of quantitative studies by Palloni (1994) indicates that population growth, in association with other factors, does make a modest contribution to deforestation cross nationally.

Other aspects of the environment, from fish stocks to water supplies, may feel a similar pressure from rapid population growth. In each case, appropriate technology and institutions to control access to and use of common resources could limit environmental damage and preserve resources for the future. But lower fertility and slower population growth, it is argued, would also relieve some of the pressure on resources and allow time to develop and institute the necessary policies. Even where the contribution of population growth to an environmental problem is small - as it is, for instance, for air pollution from carbon dioxide emissions - reducing population growth may still be cost-effective, requiring proportionally less investment than various technological or other policy measures (Birdsall, 1994).¹⁴

¹⁴For broad overviews of environmental and political effects, see Population Action International (1996) and Mazur (1997).

Lower fertility therefore provides societies with opportunities, especially in the form of increased savings that could spur investment and economic growth, a "demographic bonus" that could be spent to improve education, and fewer high-risk births that could lead to healthier childhoods, if other health risks can be contained. Additional opportunities include reduced pressure on public expenditures and the grace period that lower fertility and slower population growth provide for dealing with pressures on the environment and for managing such typically limited resources as a society's water supplies. Seizing such opportunities could provide a political bonus to regimes that need to be increasingly concerned with the welfare of their populations and could eventually be part of the process that transforms a society into a stable and prosperous contributor to the international order. But none of this is automatic, even with substantial fertility decline. Each of the potential benefits of such a decline will only be realized with appropriate governmental policies - on investment, on education, on health, on environmental protection, and so on.