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, John R. Wilmoth, the director of the United Nations (UN) Population Division, told a session focused on demographic forecasting at the 2015 Joint¹ Statistical² Meetings (JSM 2015) today in Seattle. The UN projection³ suggests there will not be an end to world population growth this century unless there are unprecedented⁴ 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--"Populations Projections⁵ by the United Nations"--was made as part of an invited session titled "Better Demographic Forecasts, Better Policy Decisions" held here today.

 

Wilmoth told the audience that according to models of demographic change derived⁶ from historical experience, it is estimated the global population will be between 9.5 and 13.3 billion people in 2100. In the United States, 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. The continent's population growth is due to persistent⁷ high levels of fertility and the recent slowdown in the rate of fertility decline. 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.

 

In some African countries, the TFR decline appears to have stalled. For instance, in Nigeria--the continent's most-populous country--the high fertility rate would result in a more than fourfold projected increase in total population by 2100--from 182 million to 752 million people. Wilmoth said although there is considerable uncertainty⁸ about these future trends, there is a 90% chance Nigeria's population will exceed 439 million people in 2100, which is nearly 2.5 times its current size.

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