Human population projections are attempts to show how human populations might change in the future. These projections are an important input to forecasts of the population's impact on the planet and humanity's future well-being. Models of population growth take trends in human development and apply projections into the future. 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.
The 2022 projections from the United Nations Population Division (UN) (chart #1) show that annual world population growth peaked at 2.2% per year in 1964, has since dropped to 0.9% in 2023, equivalent to about 74 million people each year, and could drop even further to minus 0.1% by 2100. Based on this, the UN projected that the world population, 8 billion , would peak around the year 2084 at about 10.3 billion, and then start a slow decline, assuming a continuing decrease in the global average fertility rate from 2.5 births per woman during the 2015–2020 period to 1.8 by the year 2100 (the medium-variant projection).
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 United Nations' Sustainable Development Goals) which could result in peak population during the 2060–2070 period rather than later.
According to the UN, all of the predicted growth in world population between 2020 and 2050 will come from less developed countries and more than half will come from sub-Saharan Africa. Half of the growth will come from just eight countries, five of which are in Africa. The UN predicts that the population of sub-Saharan Africa will double by 2050. The Pew Research Center observes that 50% of births in the year 2100 will be in Africa. Other organizations project lower levels of population growth in Africa, based particularly on improvement in women's education and successful implementation of family planning.
During the remainder of this century, some countries will see population growth and some will see population decline. For example, the UN projects that Nigeria will gain about 340 million people, about the present population of the US, to become the third most populous country, and China will lose about half of its population.
Even though the global fertility rate continues to fall, chart #2 shows that because of population momentum the global population will continue to grow, although at a steadily slower rate, until the mid-2080s (the median line).
The main driver of long-term future population growth is projected to be the continuing evolution of fertility and mortality.
History of population projections Projections of global human population are generally based on birth rates and death rates, and since these are difficult to predict very far into the future, forecasts of global population numbers and growth rates have changed over time.
20th century 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 an improvement in public health in less developed countries.Walter Grieling: Wie werden wir leben? ("How are we going to live?") Econ publishers, Munich 1954
In 1983, astrophysicist Brandon Carter developed the Doomsday Argument, a probabilistic argument that postulates it is unlikely for humans born today to be randomly selected at an early position in the ordering of all humans who will ever live. In the original formulation, there is a 95% chance that the total number of humans will be less than 1.2 trillion and that extinction will occur before the year 9120.
In 1992, the United Nations published five projections of long-term world population growth. According to their medium projection, the world population would grow to 10.0 billion by 2050, 11.2 billion by 2100, and 10.8 billion by 2150.
21st century
Estimates published in the early 2000s tended to predict that the population of Earth would stop increasing around 2070.Ciro Pabón y Ciro Pabón, Manual de Urbanismo, Editorial Leyer, Bogotá, 2007, For example, in a 2004 long-term prospective report, the United Nations Population Division projected that world population would peak at 9.2 billion in 2075 and then stabilize at a value close to 9 billion out to as far as the year 2300.United Nations Department of Economic and Social Affairs. World Population to 2300. 2004. Executive Summary, p. 1.
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. Randers' "most likely scenario" predicted a peak in world population in the early 2040s at about 8.1 billion people, followed by decline.
In 2012, the UN changed its prediction to the effect that no maximum would likely be reached in the 21st century, and that by the year 2100 world population would increase to somewhere in the range 9.6 to 12.3 billion with 10.9 billion being the midpoint of that range. The main reason for the revision was a recognition that the high fertility rate in Africa was not declining as fast as had been previously assumed.
Another 2014 paper by demographers from several universities, using data from the UN's 2014 report and their own statistical methods, forecast that the world's population would reach about 10.9 billion in 2100 and continue growing thereafter.
In 2017 the UN predicted that global population would reach 11.2 billion by 2100 and still be growing then at the rate of 0.1% per year. In 2019 it was updated to 10.9 billion by 2100 and still growing.
The 2022 revision of the UN's World Population Prospects report represents a departure from the pattern of the previous ten years, it was the first to project a peak in the 21st century. It expected that a slowing of the population growth rate will lead to a population peak of 10.4 billion in 2086 in the medium scenario, after which it would then begin to slowly fall. This shift from earlier projections of peak population and predicted date of zero population growth comes from a more rapid drop in Africa's birth rate than previous projections had expected. For example, the 2012 report predicted that the population of Nigeria, Africa's most populous country, would rise to 914 million by 2100; the 2022 report lowers that to 546 million, a reduction of 368 million; the 2024 report lowered that further to 477 million, a reduction of 69 million. Jose Rimon of Johns Hopkins University suggested, "We have been underestimating what is happening in terms of fertility change in Africa. Africa will probably undergo the same kind of rapid changes as east Asia did." The 2024 edition brought the peak forward to 2084, with the population topping at 10.3 billion.
A table based on UN World Population Prospects reports, using the medium fertility scenario: +Revision yearPeak population yearPeak population, billionPopulation in 2100, billion 200420759.29.120122100s10.920152100s11.220172100s11.220192100s10.92022208610.410.42024208410.310.2
Drivers of population change The population of a country or area grows or declines through the interaction of three demographic drivers: fertility, mortality, and migration.
Fertility
Fertility 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. With longevity trending towards uniform and stable values worldwide, the main driver of future population growth will be the evolution of the fertility rate. In regions where fertility is relatively high, demographers generally assume that fertility will decline and eventually stabilize at about two children per woman.
During the period 2015–2020, the average world fertility rate was 2.1 children per woman, about half the level in 1950–1955 (5 children per woman). In the medium variant, global fertility is projected to decline further to 2.0 in 2045–2050 and to 1.8 in 2095–2100.
Mortality Mortality rate, or death rate, is a measure of the number of deaths in a particular population, scaled to the size of that population, per unit of time. If the mortality rate is relatively high and the resulting life expectancy is therefore relatively low, changes in mortality can have a material impact on population growth. When the mortality rate is low and life expectancy is relatively high, a change in mortality has much less of an effect.
Because child mortality has declined substantially over the last several decades, global life expectancy at birth, has risen from 47 years in 1950 to 71 years in 2021 and is expected to keep rising to reach 82 years in 2100. In the more developed regions, life expectancy has risen from 64 years in 1950 to 78 years in 2021 and is projected to reach 90 in 2100. Among the less developed countries, life expectancy has risen from 41 years in 1950 to 70 years in 2021 and is expected to rise to 81 years by 2100.
Migration
Migration can have a significant effect on population change. Global south–south migration accounts for 38% of total migration, and global south–north for 34%. For example, the United Nations reports that during the period 2010–2020, fourteen countries will have seen a net inflow of more than one million migrants, while ten countries will have seen a net outflow of similar proportions. The largest migratory outflows have been in response to demand for workers in other countries (Bangladesh, Nepal, and the Philippines) or to insecurity in the home country (Myanmar, Syria, and Venezuela). Belarus, Estonia, Germany, Hungary, Italy, Japan, Russia, Serbia, and Ukraine have experienced a net inflow of migrants over the decade, helping to offset population losses caused by a negative natural increase (births minus deaths).
World population projections
This section describes near-term population changes, up to the year 2050, and long-term population changes, out to the year 2100.
Up to 2050 The median scenario of the UN's 2022 World Population Prospects predicts the following populations by region in 2050 compared to population in 2000 and shows the differing growth rates for each over the first half of this century. +Projected regional population (billions) 2000 2050 GrowthAsia 3.72 5.28 +42%Africa 0.82 2.47 +201%Europe 0.73 0.70 -4%Latin America & the Caribbean 0.52 0.73 +40%Northern America 0.31 0.43 +39%Oceania 0.03 0.06 +100%World6.139.66 +58%
UN estimates (as of 2024) for world population by continent in 2000 and in 2050 (pie chart area to scale):
After 2050 Projections of population beyond the year 2050 tend to vary depending on the organization making them because each make their own assumptions of the drivers of population change: fertility, mortality and migration.
United Nations projections The UN Population Division report of 2022 projects world population to continue growing after 2050, although at a steadily decreasing rate, to peak at 10.4 billion in 2086, and then to start a slow decline to about 10.3 billion in 2100 with a growth rate at that time of -0.1%.
This projected growth of population, like all others, depends on assumptions about vital rates. For example, the chart below shows that the UN Population Division assumes that the total fertility rate (TFR), which has been steadily declining since 1963, will continue to decline, at varying paces depending on circumstances in individual regions, to a below-replacement level of 1.8 by 2100. Between now (2020) and 2100, regions with a TFR currently below this rate, for example Europe, will see their TFR rise. Regions with a TFR above this rate will see their TFR continue to decline.
Other projections