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, experts in demographic forecasting have predicted

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%. 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. 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. Although there is considerable uncertainty about these future trends, there is a 90% chance that Nigeria's population will exceed 439 million people in 2100, which is nearly 2.5 times its current size.