United Nations: India, China and Brazil countries with young populations but lower fertility face the prospect of substantial population ageing before the end of the century, according to UN projections.

The world’s population will increase from today’s 7.3 billion people to 9.7 billion in 2050 and 11.2 billion at century’s end, UN Population Division director John Wilmoth told a session focused on demographic forecasting at the 2015 Joint Statistical Meetings (JSM 2015) in Seattle on Tuesday.

The UN projection suggests there will not be an end to world population growth this century unless there are unprecedented fertility declines in those parts of sub-Saharan Africa that are still experiencing rapid population growth. The UN estimated the probability that world population growth will end within this century to be 23%.

Wilmoth’s presentation said developing countries with young populations but lower fertility—such as China, Brazil and India—face the prospect of substantial population ageing before the end of the century. “The new projection suggests these countries 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," it said.

Looking more closely at the global projections, Wilmoth said 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.

Wilmoth’s presentation ‘Populations Projections by the United Nations’ was made as part of an invited session titled ‘Better Demographic Forecasts, Better Policy Decisions’ held in Seattle. Wilmoth told the audience that 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.

In the US, the population is projected to add 1.5 million people per year on average until the end of the century, pushing the current count of 322 million people to 450 million, he said. 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. Africa’s population growth is due to persistent high levels of fertility and the recent slowdown in the rate of fertility decline.

He added that rapid population growth in high-fertility countries can exacerbate a range of existing problems— environmental (resource scarcity and pollution), health (maternal and child mortality), economic (unemployment, low wages and poverty), governmental (lagging investments in health, education and infrastructure), and social (political unrest and crime), Wilmoth said.