Leading Article: Prosperity is the best means of birth control

TAKEN AT face value, the figures are terrifying. In a few months' time, the world's population will reach 6 billion, having doubled in less than 40 years. It took all of history until 1804 for humankind to chalk up its first billion. Adding a sixth one has taken just 12 years and, according to data presented to the current UN Population Forum in The Hague, world population will cease growing only around 2200, when it will have reached 11 billion. That is assuming that climatic catastrophe, environmental collapse or military Armageddon has not already put us out of our overcrowded misery.

But there is no reason to despair. For one thing, the population explosion reflects well, not badly, on our species. It has been caused not by some malign genetic failure, but by success - by advances in techniques of food production, sanitation and health care that have increased wealth and life expectancy beyond the dreams of even 100 years ago.

Second, history, and above all the history of this ever-faster-forward century, is littered with false predictions of apocalypse. Not long before it began, wise souls were forecasting that on then current trends in public transport, London would soon be buried under several feet of horse manure. Two decades ago, we were being warned of how only coal and nuclear energy could prevent an energy shortage that would halt economic expansion in its tracks. Today, the oil price stands at less than a third of its 1979 level, nuclear power is discredited, and boundless reserves of far cleaner natural gas have sent the coal industry the way of the horse- drawn carriage. And now the micro-processor and the microchip: a third industrial revolution still in its infancy, which will surely make it easier, in ways we can hardly imagine, for this much-abused planet to accommodate still more of us.

Even so, simple Micawberism is not enough. We cannot trust for ever that some technological deus ex machina will save us from our fecundity. Nor have we in the developed world the right to demand that the poorer two- thirds of humanity forgo the economic wealth we enjoy, in the interests of the ozone layer and of preventing global warming. Indeed, as demographers tirelessly point out, nothing is as effective in reducing the size of Third-World families as rising living standards. Growth, in short, must be encouraged. The question is, what sort of growth?

Clearly, the developing world cannot take the old smokestack road to riches. Even this long-suffering Earth could not tolerate everyone in India and China generating as much waste and pollution as the average American (or, indeed, Briton). But there is nothing intrinsically wrong with a world with 6 billion cars and 6 billion fridges. What is essential is that they do not damage the ozone layer and raise carbon monoxide levels. And the same principle applies for human beings. It matters not how many of us there are - but whether we can live in happiness and dignity.