9 Billion and Counting

This week, the United Nations Population Division made a radical shift in its population projections. Previously, the organization had estimated that the number of people living on the planet would reach around 9 billion by 2050 -- and then level off. Now everything has changed: Rather than leveling off, the population size will continue to grow, reaching 10 billion or more at century's end.

Why is this happening? Put simply, fertility rates. Across much of the world, women are having fewer children, but in African countries, the decline is far slower than expected. Part of this shift was supposed to come from preferences about family size and better access to family planning to make that possible. Sadly, however, that access hasn't come. Another factor, many expected, would come from the deleterious impact of high HIV/AIDS rates. But even Uganda -- with one of the highest numbers of AIDS cases in sub-Saharan Africa -- is projected to almost triple its population by 2050. In fact, outside a handful of countries, HIV/AIDS has only a tiny impact on overall population. Consider this: In the first five months of this year, the world population grew by enough to equal all the AIDS deaths since the epidemic began 30 years ago.