A new statistical analysis shows the world population could reach nearly 11 billion people by the end of the century, according to a U.N. report issued June 13. That's about 800 million, or 8%, more than the previous projection of 10.1 billion, issued in 2011.
The projected rise is mostly due to fertility in Africa, where the U.N. had expected birth rates to decline more quickly than they have.
"The fertility decline in Africa has slowed down or stalled to a larger extent than we previously predicted, and as a result the African population will go up," said Adrian Raftery, a University of Washington professor of statistics and of sociology.
The current African population is about 1.1 billion and it is now expected to reach 4.2 billion, nearly a fourfold increase, by 2100.
The new U.N. estimates use statistical methods developed by Raftery and his colleagues at the University of Washington Center for Statistics & the Social Sciences. The group's improved fertility forecasting methods, combined with updated data collected by the U.N., were used to project the long-term consequences of the fertility change in Africa since the last population estimate two years ago.
New to this year's projection are finer-tuned statistics that anticipate the life expectancies of women and men across this century.
In other areas of the world, fewer major population changes are expected. Europe may see a small decline because of fertility continuing below replacement level, and other nations around the globe may see modest increases due to longer life expectancies, Raftery said.
There's no end in sight for the increase of world population, he added, yet the topic has gone off the world's agenda in favor of other pressing global issues, including poverty and climate — both of which have ties to world population.
Global population reached 7 billion in 2011. It passed 6 billion in 1999.