Washington: There will be no end to world population growth in this century, says the UN, adding that the world's population will increase from 7.3 billion people to 9.7 billion in 2050 and 11.2 billion at the century's end.
Asia, with a current population of 4.4 billion, is likely to remain the most populous continent, with its population expected to peak around the middle of the century at 5.3 billion and then to decline to around 4.9 billion people by the end of the century.
Developing countries with young populations but lower fertility like India face the prospect of substantial population ageing before the end of the century.
"India, along with China and Brazil, need to invest some of the benefits of their demographic dividend in the coming decades toward provisions for the older population of the future such as social security, pensions and health care," said John R Wilmoth, director of the United Nations' (UN) Population Division.
"The probability that world population growth will end within this century to be 23 percent," he added while addressing a session focused on demographic forecasting at the "2015 Joint Statistical Meetings" (JSM 2015) in Seattle on August 10.
The world population growth will not stop in this century unless there are unprecedented fertility declines in those parts of sub-Saharan Africa that are still experiencing rapid population growth.
According to models of demographic change derived from historical experience, it is estimated the global population will be between 9.5 and 13.3 billion people in 2100.
The primary driver of global population growth is a projected increase in the population of Africa.
The continent's current population of 1.2 billion people is expected to rise to between 3.4 billion and 5.6 billion people by the end of this century.
"The continent's population growth is due to persistent high levels of fertility and the recent slowdown in the rate of fertility decline," Mr Wilmoth noted.
The total fertility rate (TFR) has been declining in Africa over the past decade, but has been doing so at roughly one-quarter of the rate at which it declined in Asia, Latin America and the Caribbean in the 1970s.
The results have important policy implications for governments across the globe.
"Rapid population growth in high-fertility countries can exacerbate a range of existing problems - environmental, health, economic, governmental and social," said Mr Wilmoth.