The Global Challenge

Population Reports, Fall, 2000

Pollution. Air pollution, already a serious problem in many cities, is becoming worse as urban populations grow and the number of motor vehicles rises. Water pollution is a serious problem almost everywhere (220). Biologist Peter Vitousek and colleagues have warned that human numbers and actions risk fundamentally disrupting nature's basic cycling of water, nitrogen, phosphorus, and carbon among the ecosystems. Largely by releasing carbon dioxide into the atmosphere and by destroying or altering biological resources, humanity is causing "rapid, novel, and substantial" changes to the environment (247).

Climate change. At the Rio Earth Summit in 1992, whether the global climate was changing was still a matter of debate. Since then, the evidence has mounted (see box, p. 16). In 1990 atmospheric concentrations of carbon dioxide--the main climate-changing gas--were measured at about 355 parts per million (135). In 1997 concentrations were measured at about 364 parts per million (233). Since 1950 carbon dioxide emissions have increased fourfold (21).

Poverty. During the 1990s the number of people in poverty increased by about 1 billion. In 1990 about 2 billion people were subsisting on the equivalent of US$2 a day or less (222). By 2000 that number had risen to about 3 billion--half of the world's population (236).

Population and Sustainable Development

Environmentalists and economists increasingly agree that efforts to protect the environment and to achieve better living standards can be closely linked and are mutually reinforcing. Slowing the increase in population, especially in the face of rising per capita demand for natural resources, can take pressure off the environment and buy time to improve living standards on a sustainable basis (92, 196, 245,254).

Although it is not clear whether in the long run rapid population growth causes poverty, "it is clear that high fertility leading to rapidly growing population will increase the number of people in poverty in the short run and, in some cases, make escape from poverty more difficult," observes researcher Dennis A. Ahlburg (7). It is difficult to make investments for the future when resources are already fully used trying to keep up with the current needs of rapidly growing populations.

As population growth slows, countries can invest more in education, health care, job creation, and other improvements that help boost living standards (245). In turn, as individual income, savings, and investment rise, more resources become available that can boost productivity. This dynamic process has been identified as one of the key reasons that the economies of many Asian countries grew rapidly between 1960 and 1990 (144).

In recent years fertility has been falling in many developing countries and, as a result, annual world population growth has fallen to about 1.4% in 2000 compared with about 2% in 1960. The UN estimated recently that population is growing by about 78 million per year, down from about 90 million estimated early in the 1990s (243). Still, at the current pace world population increases by about 1 billion every 13 years. World population surpassed 6 billion in 1999 and is projected to rise to over 8 billion by 2025.