The Earth will have 11 billion people by 2100, a new estimation shows.
This new calculation, carried out by researchers from the University of Washington and UN demographer Patrick Gerland, found that the population of the world will continue growing throughout the century and the number of people on Earth will be about two billion higher than earlier estimated.
"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," corresponding author Adrian Raftery, a UW professor of statistics and of sociology, said in a news release.
"We found there's a 70 percent probability the world population will not stabilize this century. Population, which had sort of fallen off the world's agenda, remains a very important issue."
Africa is expected to have the highest population explosion- from the current one billion to 4 billion – by 2100. Inability to control birth rates in sub-Saharan Africa, mainly contributed to this. Also the decline in fertility rates first noticed in nations like Nigeria in the 1980s did not last long, the authors, while explaining the reasons, said.
Population in Nigeria, where almost all women bear at least six children, will shoot from the present 200 m to 900 m by the end of the 21st century, The Guardian reported.
Asia with a 4.4 billion population will hit five million by 2050, before starting to decline. North America, Europe, Latin America and Caribbean will have a population below 1 billion by 2100.
The new figures, that used modern statistical tool called Bayesian statistics to combine government data with expert forecasts, are expected to be more accurate and useful than previous estimations.
"Earlier projections were strictly based on scenarios, so there was no uncertainty," Gerland said. "This work provides a more statistically driven assessment that allows us to quantify the predictions, and offer a confidence interval that could be useful in planning."
Population growth can worsen the existing world problems like climate change and can bring in more problems like poverty and infectious diseases, the authors said. They expected that contraceptives and creating more awareness among women can help control population.
The study has been reported in Science.