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Human population projections

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1. World population growth 1700–2100, 2024 projection

Human population projections are attempts to show how human populations might change in the future.[1] These projections are an important input to forecasts of the population's impact on the planet and humanity's future well-being.[2] Models of population growth take trends in human development and apply projections into the future.[3] 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.[3]

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.[4] Based on this, the UN projected that the world population, 8 billion as of 2023, would peak around the year 2084 at about 10.3 billion,[5] 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).[6][7]

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.[3][8]

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.[9] Half of the growth will come from just eight countries, five of which are in Africa.[6][7] The UN predicts that the population of sub-Saharan Africa will double by 2050.[9] The Pew Research Center observes that 50% of births in the year 2100 will be in Africa.[10] Other organizations project lower levels of population growth in Africa, based particularly on improvement in women's education and successful implementation of family planning.[11]

2. World Population Prospects, 2022 projection[12]

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.[6][7]

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.[3]

History of population projections

[edit]

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

[edit]

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.[13]

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.[14]

21st century

[edit]
Projected world population by 2100 based on the 2019 UN medium population scenario.

Estimates published in the early 2000s tended to predict that the population of Earth would stop increasing around 2070.[15] 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.[16]

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.[17]

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.[18] 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.[19]

World population since 1800 in billions. Data from the 2019 United Nations projections.

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.[20]

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.[21] 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[22] 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.[23] 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.[18][7][23] 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."[23] The 2024 edition brought the peak forward to 2084, with the population topping at 10.3 billion.[24]

A table based on UN World Population Prospects reports, using the medium fertility scenario:

Revision year Peak population year Peak population, billion Population in 2100, billion
2004[25] 2075 9.2 9.1
2012[26] 2100s 10.9
2015[27] 2100s 11.2
2017[28] 2100s 11.2
2019[29] 2100s 10.9
2022[30] 2086 10.4 10.4
2024[31] 2084 10.3 10.2

Drivers of population change

[edit]

The population of a country or area grows or declines through the interaction of three demographic drivers: fertility, mortality, and migration.[2]

Fertility

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Map of countries by total fertility rate (2022–2023), referring to the average number of children that are born to a woman over her lifetime, according to the Population Reference Bureau.[32]

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.[33] In regions where fertility is relatively high, demographers generally assume that fertility will decline and eventually stabilize at about two children per woman.[2]

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.[33][34]

Mortality

[edit]

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.[35] 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.[2]

Because child mortality has declined substantially over the last several decades,[2] 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.[36][37]

Migration

[edit]

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%.[38] 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).[39]

World population projections

[edit]
Estimates of population levels in different continents between 1950 and 2050, according to the United Nations (2011 edition). The vertical axis is logarithmic and is in millions of people.

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

[edit]

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.[40]

Projected regional population (billions)
20002050Growth
Asia3.725.28+42%
Africa0.822.47+201%
Europe0.730.70-4%
Latin America & the Caribbean0.520.73+40%
Northern America[a]0.310.43+39%
Oceania0.030.06+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):[40]
     Asia      Africa      Europe      Latin America      Northern America      Oceania

After 2050

[edit]

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

[edit]

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%.[7]

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.[34][33]

Total Fertility Rate for Six Regions and the World, 1950-2100

Other projections

[edit]

Other organizations have published different forecasts.

  • A 2020 study published by The Lancet from researchers funded by the Global Burden of Disease Study promotes a lower growth scenario, projecting that world population will peak in 2064 at 9.73 billion and then decline to 8.8 billion in 2100. This projection assumes further advancement of women's rights globally. In this case, the TFR is assumed to decline more rapidly than the UN's projection, to reach 1.7 in 2100.[41]
  • An analysis from the Wittgenstein Center predicts global population to peak in 2070 at 9.4 billion and then decline to 9.0 billion in 2100.[42]
  • The Institute for Health Metrics and Evaluation (IHME) and the International Institute for Applied Systems Analysis (IIASA) project lower fertility in Sub-Saharan Africa (SSA) in 2100 than the UN. By 2100, the UN projects the population in SSA will reach 3.8 billion, IHME projects 3.1 billion, and IIASA projects 2.6 billion. IHME and IIASA incorporate women's educational attainment in their models of fertility, and in the case of IHME, also consider met need for family planning.[11]

Other assumptions can produce other results. Some of the authors of the 2004 UN report assumed that life expectancy would rise slowly and continuously. The projections in the report assume this with no upper limit, though at a slowing pace depending on circumstances in individual countries. By 2100, the report assumed life expectancy to be from 66 to 97 years, and by 2300 from 87 to 106 years, depending on the country. Based on that assumption, they expect that rising life expectancy will produce small but continuing population growth by the end of the projections, ranging from 0.03 to 0.07 percent annually. The hypothetical feasibility (and wide availability) of life extension by technological means would further contribute to long term (beyond 2100) population growth.[43][44][45]

Evolutionary biology also suggests that the demographic transition may reverse itself and global population may continue to grow in the long term.[46] Some researchers, such as Jane N. O'Sullivan, contend that many recent population projections have underestimated population growth. She notes that in the last decades, "support for family planning has waned, and global fertility decline has decelerated as a result".[47]

Growth regions

[edit]

The table below shows that from 2020 to 2050 and beyond to 2100, the bulk of the world's population growth is projected to take place in Africa. Of the additional 1.9 billion people projected between 2020 and 2050, 1.2 billion will be added in Africa, 0.7 billion in Asia and zero in the rest of the world. Africa's share of global population is projected to grow from 17% in 2020 to 25% in 2050 and 38% by 2100, while the share of Asia will fall from 60% in 2020 to 55% in 2050 and 45% in 2100.[6][7] The strong growth of the African population will happen regardless of the rate of decrease of fertility, because of the high proportion of young people already living today, who are in, or approaching, their fertile years. For example, the UN projects that the population of Nigeria will surpass that of the United States by about 2050.[7]

Projected regional populations
Region 2020 2050 Change
2020–50

(bn)

2100 Change

2020–2100

(bn)

bn % of
Total
bn % of
Total
bn % of
Total
Africa 1.3 17 2.5 25 +1.2 3.9 38 +2.6
Asia 4.6 60 5.3 55 +0.7 4.7 45 +0.1
Other 1.9 23 1.9 20 0.0 1.8 17 -0.1
More Developed 1.3 17 1.3 13 0.0 1.2 12 -0.1
Less Developed 6.5 83 8.4 87 +1.9 9.2 88 +2.7
World 7.8 100 9.7 100 +1.9 11.2 100 +2.6

The population of the More Developed regions is slated to remain mostly unchanged, at 1.2-1.3 billion for the remainder of the 21st century. All population growth comes from the Less Developed regions.[6][7]

The table below breaks out the UN's future population growth predictions by region[6][7]

Projected annual % changes in population for three periods in the future
Region 2020–25

(%/yr)

2045–50

(%/yr)

2095–2100

(%/yr)

Africa 2.5 1.7 0.4
Asia 0.7 0.2 -0.2
Europe -0.1 −0.3 −0.3
Latin America & the Caribbean 0.7 0.2 −0.5
Northern America 0.5 0.2 0.1
Oceania 1.2 0.7 0.2
World 0.9 0.5 -0.1

The UN projects that between 2020 and 2100 there will be declines in population growth in all six regions, that by 2100 three of them will be undergoing population decline, and the world will have entered a period of global population decline.

Most populous nations by 2050 and 2100

[edit]
Population of the present-day top seven most-populous countries, 1800 to 2100. Future projections are based on the 2024 UN's medium-fertility scenario. Chart created by Our World In Data in 2024.

The UN Population Division has calculated the future population of the world's countries, based on current demographic trends. The UN's 2024 report projects world population to be 8.1 billion in 2024, about 9.6 billion in 2050, and about 10.2 billion in 2100. The following table shows the largest 15 countries by population as of 2024, 2050 and 2100 to show how the rankings will change between now and the end of this century.[48]

World Population Share Projections (2024)
  1. India (17.8%)
  2. China (17.4%)
  3. United States (4.23%)
  4. Indonesia (3.47%)
  5. Pakistan (3.08%)
  6. Nigeria (2.85%)
  7. Brazil (2.60%)
  8. Bangladesh (2.13%)
  9. Russia (1.78%)
  10. Ethiopia (1.62%)
World Population Share Projections (2050)
  1. India (17.4%)
  2. China (14.1%)
  3. United States (3.94%)
  4. Indonesia (3.31%)
  5. Pakistan (3.85%)
  6. Nigeria (3.71%)
  7. Brazil (2.25%)
  8. Bangladesh (2.22%)
  9. Russia (1.41%)
  10. Ethiopia (2.33%)
World Population Share Projections (2100)
  1. India (14.8%)
  2. China (6.22%)
  3. United States (4.14%)
  4. Indonesia (2.91%)
  5. Pakistan (5.02%)
  6. Nigeria (4.69%)
  7. Brazil (1.60%)
  8. Bangladesh (2.05%)
  9. Russia (1.24%)
  10. Ethiopia (3.61%)
Projected population growth of the top 15 countries in 2024, 2050, and 2100
Country Population (millions) Rank
2024 2050 2100 2024 2050 2100
India 1,451 1,680 1,505 1 1 1
China 1,419 1,360 633 2 2 2
Pakistan 251 372 511 5 4 3
Nigeria 233 359 477 6 5 4
Democratic Republic of the Congo 109 218 431 15 8 5
United States 345 381 421 3 3 6
Ethiopia 132 225 367 10 7 7
Indonesia 283 320 296 4 6 8
Tanzania 69 130 263 22 15 9
Bangladesh 174 215 209 8 10 10
Egypt 117 162 202 13 11 11
Brazil 212 217 163 7 9 12
Angola 38 74 150 42 27 13
Sudan 50 85 137 30 21 14
Mexico 131 149 130 11 12 15
Russian Federation 145 136 126 9 13 17
Philippines 115 134 114 14 14 19
Japan 124 105 77 12 17 32
World 8,162 9,664 10,180

From 2024 to 2050, the eight highlighted countries are expected to account for about half of the world's projected population increase: India, Nigeria, the Democratic Republic of the Congo, Pakistan, Ethiopia, Tanzania, Egypt, and Indonesia.[48]

Population projections of the largest metropolitan areas

[edit]

Large urban areas are hubs of economic development and innovation, with larger cities underpinning regional economies and local and global sustainability initiatives. As of 2016, 757 million people live in the 101 largest cities;[49] these cities are home to 11% of the world's population.[49] By the end of the century, the world population is projected to grow, with estimates ranging from 6.9 billion to 13.1 billion;[49] the percentage of people living in the 101 largest cities is estimated to be 15% to 23%.[49]

The following are the 30 metropolitan areas with the largest population in 2025, and the projections for the years 2050, 2075, and 2100, according to the European Commission's Global Human Settlement Layer.[50]

Projected populations in millions
RankCityPop. 2025CityPop. 2050CityPop. 2075CityPop. 2100
1Indonesia Jakarta41.91Bangladesh Dhaka52.12Bangladesh Dhaka57.87Bangladesh Dhaka55.01
2Bangladesh Dhaka36.59Indonesia Jakarta51.78Indonesia Jakarta52.94Indonesia Jakarta49.70
3Japan Tokyo33.41China Shanghai34.91Pakistan Karachi40.75Pakistan Karachi43.69
4India Delhi30.22India Delhi33.89Egypt Cairo35.73Egypt Cairo36.75
5China Shanghai29.56Pakistan Karachi32.59India Delhi34.16India Delhi31.97
6China Guangzhou27.56Egypt Cairo32.37China Shanghai31.77Angola Luanda30.65
7Egypt Cairo25.57Japan Tokyo30.66Angola Luanda27.32Pakistan Lahore24.76
8Philippines Manila24.74China Guangzhou29.24Japan Tokyo26.64China Shanghai24.67
9India Kolkata22.55Philippines Manila27.12Philippines Manila25.83Japan Tokyo24.07
10South Korea Seoul22.49India Kolkata23.77China Guangzhou24.78Philippines Manila22.41
11Pakistan Karachi21.42India Mumbai23.06Pakistan Lahore23.70India Mumbai21.51
12India Mumbai20.20South Korea Seoul21.22India Mumbai23.09India Kolkata20.46
13Brazil São Paulo18.95Thailand Bangkok20.46India Kolkata22.79Tanzania Dar es Salaam20.05
14Thailand Bangkok18.18Pakistan Lahore20.39Thailand Bangkok19.36China Guangzhou18.09
15Mexico Mexico City17.73Angola Luanda20.29Vietnam Ho Chi Minh City17.89Nigeria Lagos17.92
16China Beijing17.01Brazil São Paulo18.22Nigeria Lagos17.84Thailand Bangkok17.56
17Pakistan Lahore15.16China Beijing18.00Tanzania Dar es Salaam17.48Vietnam Ho Chi Minh City17.08
18Turkey Istanbul15.01Mexico Mexico City17.68Mexico Mexico City16.25Russia Moscow16.3
19Russia Moscow14.52Vietnam Ho Chi Minh City17.20South Korea Seoul16.12Democratic Republic of the Congo Kinshasa14.86
20Vietnam Ho Chi Minh City14.05Turkey Istanbul16.30Russia Moscow15.89United States Los Angeles14.69
21Argentina Buenos Aires14.02Nigeria Lagos16.18Brazil São Paulo15.65Ivory Coast Abidjan14.61
22United States New York City13.92Russia Moscow15.52China Beijing15.37Ethiopia Addis Ababa14.42
23China Shenzhen13.19China Shenzhen14.66Turkey Istanbul15.12Mexico Mexico City14.16
24India Bengaluru13.19India Bengaluru14.26India Hajipur14.88India Hajipur13.94
25Japan Osaka12.96Argentina Buenos Aires14.24United States Los Angeles14.38Cameroon Yaoundé13.23
26Nigeria Lagos12.79United States Los Angeles13.86Democratic Republic of the Congo Kinshasa14.36India Bengaluru13.08
27United States Los Angeles12.74India Hajipur13.22India Bengaluru14.07Brazil São Paulo12.74
28Angola Luanda11.37United States New York City13.22Ethiopia Addis Ababa13.26Turkey Istanbul12.48
29India Chennai11.15Democratic Republic of the Congo Kinshasa13.21Argentina Buenos Aires13.02United Kingdom London12.37
30Democratic Republic of the Congo Kinshasa10.94Tanzania Dar es Salaam13.16Peru Lima12.68Egypt Luxor12.30

See also

[edit]

Notes

[edit]
  1. Northern America consists of Bermuda, Canada, Greenland, Saint Pierre and Miquelon, and the United States.

References

[edit]
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