The Cairo plan.

• Author: Brown, Lester R.
• Position: Cairo Conference on Population and Development; World Population Plan of Action - Editorial

In September, the 180 nations represented at the Cairo Conference on Population and Development reached agreement on a plan to stabilize world population at 7.8 billion by no later than 2050. The delegates rejected the idea that human numbers could be allowed to continue growing until they reached 10 to 14 billion as projected, and opted instead for an ambitious Plan of Action to stabilize population at a much lower level.

Perhaps the boldest initiative ever undertaken by the United Nations, the Plan reflects a justifiable sense of urgency, and an awareness that growing human demands are already exceeding some of the earth's natural limits.

The world is already bumping up against three natural limits that affect the food supply. One is the sustainable yield of oceanic fisheries. Marine biologists have long doubted that oceanic fisheries could sustain a catch of more than 100 million tons per year, the level reached in 1989. If this is the sustainable limit, then the seafood catch per person will continue to decline until population stabilizes. Meanwhile, seafood prices will continue to rise.

Water, too, is becoming a constraint. In many countries, pumping of underground water, mostly to irrigate crops, is exceeding aquifer recharge rates, leading to a fall in water tables. As a result, the growth in world irrigation, once greatly exceeding the growth in population, has now slowed to a snail's pace.

Perhaps even more surprisingly, farmers in some countries have fully exploited the capacity of existing crop varieties to use much additional fertilizer. In major food-producing regions such as North America...