What's the News: The world's population is projected to reach 7 billion this October and continue climbing, reaching 10.1 billion by the end of the 21st century, says an official United Nations report (PDF) released earlier this week. This is a significant departure from earlier projections that said the population would peak at just over 9 billion, then level off and even slightly decline. How the Heck:
Projecting the world population is based on looking at fertility and mortality rates, and how they may be affected by government policies, available services, and behavior. Starting with a few possible fertility and mortality trajectories, researchers in the Population Division of the UN Department of Economic and Social Affairs work out what those would mean for overall population.
These projections differ from earlier ones because fertility rates in many developing countries---particularly in Africa---aren't declining as quickly as demographers had thought they would. Nigeria, for instance, is currently the most populous country in Africa, with a population of about 160 million; that number is projected to rise 150%, to 390 million, by 2050, and to 730 million by the end of the century. Africa's total population is projected to increased from 1 billion today to 3.6 billion by 2100.
What's the Context:
Projections aren't the same as predictions. They show us what would happen, if demographic trends follow certain paths, but they don't claim that's what will happen.
A primary reason for the decline, John Bongaarts, a demographer at the Population Council research group, told ScienceNOW, is decreased funding for family planning programs. Such programs were a focus of development efforts in the 1970s and 1980s, but lost funding because African governments didn't make them a priority; economists discouraged investing in them, saying they didn't work; and conservative governments (such as the Bush administration) and the Vatican have been strongly against such programs.
These projections don't necessarily spell disaster, demographers say, but they're bad news. “Every billion more people makes life more difficult for everybody — it’s as simple as that,” Bongaarts told the New York Times. “Is it the end of the world? No. Can we feed 10 billion people? Probably. But we obviously would be better off with a smaller population.”
Not So Fast:
Projecting population nearly a century from now comes with a lot of caveats. Food and water shortages, wars, and other catastrophes, in addition to social, political, and economic changes, could all slow or stop population growth.
The Future Holds:
That's the big question. Changes in policy may well change population trajectory; e.g., improved education and access to family planning services could bring the numbers down.