World's Population to Explode to 11 Billion by 2100 Instead of 9 Billion

The world's population is exploding and as it's only growing faster as time goes on. Now, scientists have used modern statistical tools to find out what the world's population will be in 2100. It turns out that the number of people on Earth may reach a staggering 11 billion by then, which is about 2 billion higher than previous estimates.

"The consensus over the past 20 years or so was that world population, which is currently around 7 billion, would go up to 9 billion and level off or probably decline," said Adrian Raftery, corresponding author of the new study, in a news release. "We found there's a 70 percent probability the world population will not stabilize this century. Populations, which has sort of fallen off the world's agenda, remains a very important issue."

Most of the anticipated population growth is calculated to occur in Africa. There, the model estimated that the population will quadruple from about 1 billion today to 4 billion by the end of the century. This is mainly due to the fact that birth rates in sub-Saharan Africa have not been going down as fast as expected. In fact, there's an 80 percent chance that the population in Africa will be between 3.5billion and 5.1 billion by the end of the century.

That's a start contrast to other regions. In North America, Europe, Latin America and the Caribbean, populations are expected to stay below 1 billion each. In Asia, the population should turn from 4.4 billion to about 5 billion.

The findings are in stark contrast to early projections, which estimated far lower population numbers. That said, earlier techniques relied largely on expert opinion for how trends were expected to change. This newest forecast instead uses statistical models to combine government data and expert forecasts.

"This paper brings together the research from the past seven years, and also brings in recent data," said Raftery. "We can answer questions about future population growth using standard principles of statistical interference, which has never really been done before."

The findings are published in the journal Science.