"Urban transport systems based on a combination of rail lines, bus lines, bicycle pathways, and pedestrian walkways offer the best of all possible worlds in providing mobility, low-cost transportation, and a healthy urban environment." –Lester R. Brown, Plan B 4.0: Mobilizing to Save Civilization.
Chapter 2. Stopping at Seven Billion: Introduction
In early 2003, U.N. demographers announced that the HIV/AIDS epidemic has reduced life expectancy for the 700 million people of sub-Saharan Africa from 62 to 46 years. For the first time in the modern era, the rise in life expectancy has been reversed for a large segment of humanity, marking a major setback in the march of progress. Is this an isolated development? Or does this reversal mark the beginning of a new era where the failure of societies to manage other life-threatening trends, such as falling water tables and rising temperatures, will also disrupt progress and reduce life expectancy? 1
Over the last three decades, some 35 European countries and Japan have reduced fertility and achieved population stability. Indeed, in many of these countries population is projected to decline somewhat over the next half-century. In all these cases population growth ceased because rising living standards and expanding opportunities for women were reducing births. But now populations are projected to decline in some countries for the wrong reason. In countries with the highest HIV infection rates—Botswana, South Africa, and Swaziland—rising death rates are projected to shrink populations in the decades ahead. 2
After peaking at an all-time high of 2 percent in 1970, world population growth slowed to 1.2 percent in 2004. This is the good news. The bad news is that part of the slowdown has come from more deaths, mostly from AIDS. Perhaps more important, even slower-growing populations are still outstripping the carrying capacity of the earth’s natural systems—its fisheries, forests, rangelands, aquifers, and croplands. Once the demands of a growing population surpass the sustainable yield threshold of an ecosystem, any growth in human numbers is a matter of concern. For example, whether the population-driven demand on a fishery exceeds the sustainable yield by 1 percent or 10 percent a year makes little difference over the long term. The end result is the same: depletion of stocks and collapse of the fishery. 3
For some areas, population growth now threatens food security. In developing countries, land holdings are parceled out among heirs with each successive generation until they are so small that they can no longer feed a family. The pressure of a larger population can mean a shrinking water supply, leading to hydrological poverty—a situation where there is no longer enough water to drink, to produce food, and for bathing. The continuing growth of population in resource-scarce, low-income countries is undermining future food security in many of them. 4
1. United Nations, World Population Prospects: The 2002 Revision (New York: 2003).
2. Population Reference Bureau (PRB), 2004 World Population Data Sheet, wall chart (Washington, DC: 2004).
3. United Nations, op. cit. note 1.
4. R. K. Pachauri and P. V. Sridharan, eds., Looking Back to Think Ahead (abridged version), GREEN India 2047 Project (New Delhi: Tata Energy Research Institute, 1998), p. 7.
Copyright © 2004 Earth Policy Institute