The population delusion

THINK of the biggest crowd you've ever been in - perhaps 50,000 in a sports stadium. Just 6 hours from now there will be that many more people in the world, and another 50,000 in the following 6 hours, and on and on... No wonder that the burgeoning human population is often seen as is the single biggest problem facing our world.

There are nearly 7 billion humans alive today, twice as many as there were in 1965, with 75 million more being added each year. UN predictions say there could be an extra 2 to 4 billion of us by 2050. The planet has never experienced anything like it.

Can the world sustain this growing horde? It's a contentious question. While it is clear that the population cannot go on increasing forever, history is littered with dire but failed predictions of famine and death resulting from over-population. Most famously, Thomas Malthus warned more than two centuries ago that population would be held in check by rising mortality. What he failed to anticipate was the ability of newly industrialised societies to support large numbers of people.

Today, the "population problem" is firmly back on the agenda. Earlier this year the UK government's chief scientific adviser John Beddington predicted a population-led global crisis by 2030, and a group of influential billionaires including Bill Gates and George Soros identified overpopulation as the greatest threat facing humanity. Every time we publish an article in New Scientist detailing yet another of the planet's environmental woes, readers respond by arguing that the real problem is overpopulation.

The population statistics are indeed staggering. Yet the raw numbers hide a multitude of complexities. Look closely, and it becomes clear that the common-sense assumption that population is the root of all evil is simplistic.

For example, while the human population is growing in absolute terms, the rate of growth is slowing - from a peak of 2 per cent in the early 1960s to around 1 per cent today. In Japan, Russia and many European countries, women are having so few children that populations are shrinking or will do so soon - an unprecedented state of affairs other than in times of war or plague (see "Days when the world has shrunk"). At the same time, the populations of many of the least developed nations are exploding, with women in some countries giving birth to more than five children on average.

In the articles that follow, we unpick some of these complexities. Paul Ehrlich, who reignited debate a generation ago with his best-seller The Population Bomb, is sticking to his assertion that we need to act to rein in fertility ("Paul Ehrlich: Population, development and the poor"). Conversely, Fred Pearce insists on page 40 that focusing on population is a dangerous distraction from the real issue: consumption. Then there's the brave new world of population shrinkage that Europe is entering, as demographer Reiner Klingholz explains on page 41. Lastly, perhaps human ingenuity will solve the problem. Techno-optimist Jesse Ausubel certainly thinks so, and in our interview on page 38 he explains why.

"We are burdensome to the world, the resources are scarcely adequate for us... already nature does not sustain us." So wrote Tertullian, an early Christian, back in the 3rd century. At that time, the world population stood at some 200 million. Eighteen centuries on and with 34 times as many people on the planet, the debate continues.