With the population still growing by about 80 million each year, it’s hard not to be alarmed. Right now on Earth, water tables are falling, soil is eroding, glaciers are melting, and fish stocks are vanishing. Close to a billion people go hungry each day. Decades from now, there will likely be two billion more mouths to feed, mostly in poor countries. There will be billions more people wanting and deserving to boost themselves out of poverty. If they follow the path blazed by wealthy countries—clearing forests, burning coal and oil, freely scattering fertilizers and pesticides—they too will be stepping hard on the planet’s natural resources. How exactly is this going to work?

Robert Kunzig goes on to outline just how the global population grew so quickly, explaining that as in Europe the average woman had six children in the 18th-century, making up for high child mortality rates, and as medical science and social conditions advance it takes time for the population to adjust. In the interim there is a population boom as couples still aim for six births. It’s a pattern which is repeated around the world in different times and places.

Demographers call this evolution the demographic transition. All countries go through it in their own time. It’s a hallmark of human progress: In a country that has completed the transition, people have wrested from nature at least some control over death and birth. The global population explosion is an inevitable side effect, a huge one that some people are not sure our civilization can survive.

It’s a mixed message. The population is still growing, but around the world the rate of growth has decreased since the early 1970s by around 40 percent. That still means the numbers are going up, though.

Many people are justifiably worried that Malthus will finally be proved right on a global scale—that the planet won’t be able to feed nine billion people. Lester Brown, founder of Worldwatch Institute and now head of the Earth Policy Institute in Washington, believes food shortages could cause a collapse of global civilization.

… For centuries population pessimists have hurled apocalyptic warnings at the congenital optimists, who believe in their bones that humanity will find ways to cope and even improve its lot. History, on the whole, has so far favored the optimists, but history is no certain guide to the future. Neither is science. It cannot predict the outcome of People v. Planet, because all the facts of the case—how many of us there will be and how we will live—depend on choices we have yet to make and ideas we have yet to have.

Full article: http://ngm.nationalgeographic.com/2011/01/seven-billion/kunzig-text/1