With longevity trending towards uniform and stable values worldwide, the main driver of future population growth will be the evolution of the fertility rate. Map of countries by fertility rate (2020), according to the Population Reference Bureauįertility is expressed as the total fertility rate (TFR), a measure of the number of children on average that a woman will bear in her lifetime. The population of a country or area grows or declines through the interaction of three demographic drivers: fertility, mortality, and migration. Randers' "most likely scenario" predicts a peak in the world population in the early 2040s at about 8.1 billion people, followed by decline. Jørgen Randers, one of the authors of the seminal 1972 long-term simulations in The Limits to Growth, offered an alternative scenario in a 2012 book, arguing that traditional projections insufficiently take into account the downward impact of global urbanization on fertility. In 2017 the UN predicted a decline of global population growth rate from +1.0% in 2020 to +0.5% in 2050 and to +0.1% in 2100. A 2014 paper by demographers from several universities and the United Nations Population Division forecast that the world's population would reach about 10.9 billion in 2100 and continue growing thereafter. The main reason for the revision was that the ongoing rapid population growth in Africa had been underestimated. This prediction was revised in the 2010s, to the effect that no maximum will likely be reached in the 21st century. After reaching this maximum, it would decline slightly and then resume a slow increase, reaching a level of 5.11 billion by 2300, about the same as the projected 2050 figure.
In a 2004 long-term prospective report, the United Nations Population Division projected the world population would peak at 7.85 billion in 2075. Įstimates published in the 2000s tended to predict that the population of Earth would stop increasing around 2070. Walter Greiling projected in the 1950s that world population would reach a peak of about nine billion, in the 21st century, and then stop growing after a readjustment of the Third World and a sanitation of the tropics. UN World Population Projections (Average Estimates, 2019 revision) The United Nation's Population Division publishes high & low estimates (by gender) & density. 7 Population projections of the largest metropolitan areas.In contrast to the UN projections, the models of fertility developed by IHME and IIASA incorporate women's educational attainment, and in the case of IHME, also assume successful implementation of family planning.
īy 2100, the UN projects the population in Sub-Saharan Africa will reach 3.8 billion, IHME projects 3.1 billion, and IIASA is the lowest at 2.6 billion.
Other organizations project lower levels of population growth in Africa based particularly on improvement in women's education and successfully implementing family planning. It is projected that 50% of births in the 5-year period 2095-2100 will be in Africa. Īccording to the UN, about two-thirds of the predicted growth in population between 20 will take place in Africa. However, estimates outside of the United Nations have put forward alternative models based on additional downward pressure on fertility (such as successful implementation of education and family planning goals in the Sustainable Development Goals) which could result in peak population during the 2060-2070 period rather than later. A 2014 projection has the population continuing to grow into the next century. Based on this, the UN Population Division projects the world population, which is 7.8 billion as of 2020, to level out around 2100 at 10.9 billion (the median line), assuming a continuing decrease in the global average fertility rate from 2.5 births per woman during the 2015–2020 period to 1.9 in 2095–2100, according to the medium-variant projection. The 2019 projections from the United Nations Population Division show that annual world population growth peaked at 2.1% in 1968, has since dropped to 1.1%, and could drop even further to 0.1% by 2100, which would be a growth rate not seen since pre-industrial revolution days. These models use trend-based-assumptions about how populations will respond to economic, social and technological forces to understand how they will affect fertility and mortality, and thus population growth. Models of population growth take trends in human development, and apply projections into the future. These projections are an important input to forecasts of the population's impact on this planet and humanity's future well-being. Population projections are attempts to show how the human population statistics might change in the future.
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