In the poorest countries of the world, population is soaring. With more mouths to feed, other national resources will be squeezed further, leading to food shortages, ill health, and environmental decline.
Population is expected to reach 9.3 billion by 2050, according to a United Nations medium projection from 2001, with 97% of the increase occurring in developing countries.
Yet the industrialised world has seen falling birthrates. The global fertility rate has halved in the last 40 years, and demographers now predict that the world population will eventually settle at about 8.4 billion.
But this still represents a population growth of more than two billion people – in countries least able to cope. The rich world is faced with some tough choices. Will it close its doors and let its populations shrink, or will it welcome economic migrants?