It's not a small world after all: world population will soar

Contrary to some earlier projections, the world's population will soar through the end of the 21st century thanks largely to sub-Saharan Africa's higher-than-expected birth rates, United Nations and other population experts said on Thursday.

There is an 80 percent likelihood that the number of people on the planet, currently 7.2 billion, will increase to between 9.6 billion and 12.3 billion by 2100, the researchers said. They also saw an 80 percent probability that Africa's population will rise to between 3.5 billion and 5.1 billion by 2100 from about 1 billion today.