The statistic modeling was performed by the United Nations and the University of Washington (UW) and is calling for four billion people in Africa by the end of the century by using modern statistical calculations that include estimated future birth rates.

World's Population Not Leveling Off Any Time Soon

“The U.N. in the past has been criticized for not doing complete statistics on their data and now they’ve done it exactly right,” says demography researcher John Bongaarts, vice president of the Population Council in New York City, and was not involved in the work nor risking biased statements.

In the first decade of this century, the majority of world population researchers believed that the population would reach about 9 billion and finally level off around then. However, they were working off the belief that birth rates in Africa would drop as women’s education and access to birth control became more widespread. That has just not happened much to the chagrin of researchers.

Population growth: U.N. changing its methods

The United Nations takes a look at birth and death rates every few years by speaking with statistical experts.

“Experts are pretty good at knowing where things generally stand with these rates,” says statistician Adrian Raftery of UW, a senior author on the new paper. “But what they don’t seem to be good at is integrating the newest data into future estimates in the right way.”

But the UN has shied away from this approach and dealing with experts with differing opinions and joined up with Raftery and his colleagues who used statistical equations based on real-time data and historical data to look at changing fertility rates over time and in specific regions of the world.

“The combination of a new method that’s not based on assumption but is based directly on data, and also the new data on Africa, have combined to make quite a big change to the overall population projections,” Raftery says.

Africa is key

Today in Science (online), the group published its findings calling for a 95% that the world’s population between 9 and 13.2 billion with Africa’s population growing from today’s roughly 1 billion to around 4 billion with these numbers continuing to rise after 2100.

“There’s a need to put population back on the world agenda as a major issue,” Raftery says. And figuring out what is going on in Africa is key according to the researcher.

“We’re still talking about much slower population growth than we just came through,” he says. “The world population doubled between 1960 and 1999 and we’re never going to do that again. The population is leveling off and it’s going to eventually level off under any of these scenarios, whether that’s before 2100 or after.”

While wars and epidemics can cause massive mortality, in the grand scheme of things they don’t cause that many deaths. And despite ISIS calling for the deaths of all non-believers they’re not going to be around for another 85 years.