Study: World Population to Stop Growing

Aug. 1 -- People may finally be nearing their limit.

Despite a growth burst that more than doubled the global human population over the past 50 years, a study released today predicts it will peak at 9 billion by the year 2070 and then begin to decline.

"People thought for many years that we would breed ourselves out of existence," says Warren Sanderson, a professor of economics and history at State University of New York at Stonybrook and co-author of the study appearing in this week's Nature. "They thought we'd produce so many children, there would be no standing room left on the planet. But now it seems our population will peak.

"And that's an optimistic message."

The study is the first to pinpoint an end to the burgeoning population. The scientists estimate there is an 85 percent chance the species will taper to about 8.4 billion by the year 2100. The current world population is counted at 6.1 billion.

Previous demographic studies by the United Nations had projected higher populations of 9.32 billion by the year 2050, with no decline in growth. Part of the reason for the different predictions is the new study anticipates the number of children born per woman will go down.

Forecasts Never Certain

Like the weather, population is tricky to predict since it is dependent on so many independent factors, including disease, wars and social trends. Demographers in the 1930s, for example, never predicted the post-World War II baby boom that caused populations to spike in the United States. Later, they also missed that U.S. birth rates would drop significantly by the 1970s.

In order to reflect the uncertainty of population prediction, the researchers, based at the International Institute for Applied Systems Analysis in Laxenburg, Austria, framed their findings in probabilities.

The team determined there is a 20 percent chance the population will peak by the year 2050, a 55 percent chance it will peak by 2075 and an 85 percent chance numbers will reach their limit in the next century. Sanderson says this method can provide policy makers with a more precise estimate of what to expect.