The rate of growth of population has declined significantly in recent years, thanks to falling fertility in most regions, and recent population forecasts from the United Nations indicate that, under a medium-fertility scenario, the global population is likely to peak at about 8 900 million in 2050 (United Nations Population Division 1998a). This projection assumes that all developing countries will achieve replacement fertility levels (2.1 children per woman) over the next half century. If fertility rates were to exceed the medium scenario by just half a child per couple, the world population would rise to some 27 000 million people (United Nations Population Division 1998b).
Given that many natural resources (such as water, soil, forests and fish stocks) are already being exploited to or beyond their limits, in at least some regions, the efforts required to meet the needs of an additional 3 000 million people in the next 50 years will be immense, even at present consumption levels. If poverty is to be reduced and economic benefits distributed more equitably, then a further major increase in production will be required, not to mention significant modifications to economic, social and political systems. Whether the planetary environment can meet these demands, and under what conditions, is an open question.