7 |
 mortality rate in many countries by improved sanitation and medical advances, and a massive increase in agricultural productivity attributed to the Green Revolution. [99][100][101]
In 2000, the United Nations estimated that the world's population was growing at an annual rate of 1.1% (equivalent to around 75 million people),[102] down from a peak of 88 million per year in 1989. By 2000, there were approximately ten times as many people on Earth as there had been in 1700. Globally, the population growth rate has been steadily declining from its peak of 2.2% in 1963, but growth remains high in Latin America, the Middle East, and Sub-Saharan Africa.[103]
During the 2010s, Japan and some countries in Europe began to encounter negative population growth (i.e. a net decrease in population over time), due to sub-replacement fertility rates.[98]
In 2006, the United Nations stated that the rate of population growth was visibly diminishing due to the ongoing global demographic transition. If this trend continues, the rate of growth may diminish to zero by 2050, concurrent with a world population plateau of 9.2 billion.[104] However, this is only one of many estimates published by the UN; in 2009, UN population projections for 2050 ranged between around 8 billion and 10.5 billion.[105] An alternative scenario is given by the statistician Jorgen Randers, who argues that traditional projections insufficiently take into account the downward impact of global urbanization on fertility. Randers' "most likely scenario" reveals a peak in the world population in the early 2040s at about 8.1 billion people, followed by decline.[106] Adrian Raftery, a University of Washington professor of statistics and of sociology, states that "there’s a 70 percent probability the world population will not stabilize this century. Population, which had sort of fallen off the world’s agenda, remains a very important issue."[107]
Estimated world population figures, 10,000 BC–AD 2000
Estimated world population figures, 10,000 BC–AD 2000 (in log y scale)
World population figures, 1950–2017
Estimated global growth rates, 1950–2050
Estimated and projected populations of the world and its continents (except Antarctica) from 1950 to 2100. The shaded regions correspond to the range of projections by the United Nations Department of Economic and Social Affairs.
Annual population growth
The table shown below shows the Annual global population growth and its percentage of growth starting from the year 2000. This table shows the accurate variation of the yearly population changes and growth.
Global Annual Population Growth[108]
Year
|
Population
|
Yearly change
|
Net change
|
Density (pop/km2)
|
Urban Population
|
Urban pop %
|
2020
|
7,795,000,000
|
1.1%
|
81,331,000
|
52
|
4,378,900,000
|
56%
|
2019
|
7,713,468,000
|
1.1%
|
82,377,000
|
52
|
4,299,439,000
|
56%
|
2018
|
7,631,091,000
|
1.1%
|
83,232,000
|
51
|
4,219,817,000
|
55%
|
2017
|
7,547,859,000
|
1.1%
|
83,837,000
|
51
|
4,140,189,000
|
55%
|
2016
|
7,464,022,000
|
1.1%
|
84,225,000
|
50
|
4,060,653,000
|
54%
|
2015
|
7,379,797,000
|
1.2%
|
84,506,000
|
50
|
3,981,498,000
|
54%
|
2014
|
7,295,291,000
|
1.2%
|
84,709,000
|
49
|
3,902,832,000
|
53%
|
2013
|
7,210,582,000
|
1.2%
|
84,754,000
|
48
|
3,824,990,000
|
53%
|
2012
|
7,125,828,000
|
1.2%
|
84,634,000
|
48
|
3,747,843,000
|
52%
|
2011
|
7,041,194,000
|
1.2%
|
84,371,000
|
47
|
3,671,424,000
|
52%
|
2010
|
6,956,824,000
|
1.2%
|
84,057,000
|
47
|
3,594,868,000
|
51%
|
2009
|
6,872,767,000
|
1.2%
|
83,678,000
|
47
|
3,516,830,000
|
51%
|
2008
|
6,789,089,000
|
1.2%
|
83,142,000
|
46
|
3,439,719,000
|
50%
|
2007
|
6,705,947,000
|
1.2%
|
82,429,000
|
45
|
3,363,610,000
|
50%
|
2006
|
6,623,518,000
|
1.3%
|
81,611,000
|
44
|
3,289,446,000
|
50%
|
2005
|
6,541,907,000
|
1.3%
|
80,748,000
|
44
|
3,215,906,000
|
49%
|
2004
|
6,461,159,000
|
1.3%
|
79,974,000
|
43
|
3,143,045,000
|
48%
|
2003
|
6,381,185,000
|
1.3%
|
79,412,000
|
43
|
3,071,744,000
|
48%
|
2002
|
6,301,773,000
|
1.3%
|
79,147,000
|
42
|
3,001,808,000
|
47%
|
2001
|
6,222,627,000
|
1.3%
|
79,133,000
|
42
|
2,933,079,000
|
47%
|
2000
|
6,143,494,000
|
1.3%
|
79,255,000
|
41
|
2,868,308,000
|
46%
|
Population growth by region
The table below shows historical and predicted regional population figures in millions.[109][110][111] The availability of historical population figures varies by region.
World historical and predicted populations (in millions)[112][113][114]
Region |
1500 |
1600 |
1700 |
1750 |
1800 |
1850 |
1900 |
1950 |
1999 |
2008 |
2010 |
2012 |
2050 |
2150
|
World
|
585 |
660 |
710 |
791 |
978 |
1,262 |
1,650 |
2,521 |
6,008 |
6,707 |
6,896 |
7,052 |
9,725 |
9,746
|
Africa
|
86 |
114 |
106 |
106 |
107 |
111 |
133 |
221 |
783 |
973 |
1,022 |
1,052 |
2,478 |
2,308
|
Asia
|
282 |
350 |
411 |
502 |
635 |
809 |
947 |
1,402 |
3,700 |
4,054 |
4,164 |
4,250 |
5,267 |
5,561
|
Europe
|
168 |
170 |
178 |
190 |
203 |
276 |
408 |
547 |
675 |
732 |
738 |
740 |
734 |
517
|
Latin America[Note 1]
|
40 |
20 |
10 |
16 |
24 |
38 |
74 |
167 |
508 |
577 |
590 |
603 |
784 |
912
|
North America[Note 1]
|
6 |
3 |
2 |
2 |
7 |
26 |
82 |
172 |
312 |
337 |
345 |
351 |
433 |
398
|
Oceania
|
3 |
3 |
3 |
2 |
2 |
2 |
6 |
13 |
30 |
34 |
37 |
38 |
57 |
51
|
World historical and predicted populations by percentage distribution[112][113]
Region |
1500 |
1600 In 2000, the United Nations estimated that the world's population was growing at an annual rate of 1.1% (equivalent to around 75 million people),[102] down from a peak of 88 million per year in 1989. By 2000, there were approximately ten times as many people on Earth as there had been in 1700. Globally, the population growth rate has been steadily declining from its peak of 2.2% in 1963, but growth remains high in Latin America, the Middle East, and Sub-Saharan Africa.[103]
During the 2010s, Japan and some countries in Europe began to encounter negative population growth (i.e. a net decrease in population over time), due to sub-replacement fertility rates.[98]
In 2006, the United Nations stated that the rate of population growth was visibly diminishing due to the ongoing global demographic transition. If this trend continues, the rate of growth may diminish to zero by 2050, concurrent with a world population plateau of 9.2 billion.[104] However, this is only one of many estimates published by the UN; in 2009, UN population projections for 2050 ranged between around 8 billion and 10.5 billion.[105] An alternative scenario is given by the statistician Jorgen Randers, who argues that traditional projections insufficiently take into account the downward impact of global urbanization on fertility. Randers' "most likely scenario" reveals a peak in the world population in the early 2040s at about 8.1 billion people, followed by decline.demographic transition. If this trend continues, the rate of growth may diminish to zero by 2050, concurrent with a world population plateau of 9.2 billion.[104] However, this is only one of many estimates published by the UN; in 2009, UN population projections for 2050 ranged between around 8 billion and 10.5 billion.[105] An alternative scenario is given by the statistician Jorgen Randers, who argues that traditional projections insufficiently take into account the downward impact of global urbanization on fertility. Randers' "most likely scenario" reveals a peak in the world population in the early 2040s at about 8.1 billion people, followed by decline.[106] Adrian Raftery, a University of Washington professor of statistics and of sociology, states that "there’s a 70 percent probability the world population will not stabilize this century. Population, which had sort of fallen off the world’s agenda, remains a very important issue."[107]
Estimated world population figures, 10,000 BC–AD 2000
World population figures, 1950–2017
World population figures, 1950–2017

Estimated and projected population Estimated and projected populations of the world and its continents (except Antarctica) from 1950 to 2100. The shaded regions correspond to the range of projections by the United Nations Department of Economic and Social Affairs.
Annual population growth
The table shown below shows the Annual global population growth and its percentage of growth starting from the year 2000. This table shows the accurate variation of the yearly population changes and growth.
Global Annual Population Growth[108]
Year
|
Population
|
Yearly change
|
Net change
|
Density (pop/km2)
|
Urban Population
|
Urban pop %
|
2020
|
7,795,000,000
|
1.1%
|
81,331,000
|
52
|
4,378,900,000
< The table shown below shows the Annual global population growth and its percentage of growth starting from the year 2000. This table shows the accurate variation of the yearly population changes and growth.
Global Annual Population Growth[109][110][111] The availability of historical population figures varies by region.
World historical and predicted populations (in millions)[112][113][114]
Region |
1500 |
1600 |
1700 |
1750 |
1800 |
1850 |
1900 |
1950 |
1999 |
2008 |
2010 |
2012 |
2050 |
2150
|
World
|
585 |
660 |
710 |
791 |
978 |
1,262 |
1,650 |
2,521 |
6,008 |
6,707 |
6,896 |
7,052 |
9,725 |
9,746
|
Africa
|
86 |
114 |
106 |
106 |
107 |
111 |
133 |
221 |
783 |
973 |
1,022 |
1,052 |
2,478 |
2,308
|
Asia
|
282 |
350 |
411 |
502 |
635 |
809 |
947 |
1,402 |
3,700 |
4,054 |
4,164 |
4,250 |
5,267 |
5,561
|
Europe
|
168 |
170 |
178 |
190 |
203 |
276 |
408 |
547 |
675 |
732 |
738 |
740 |
734 |
517
|
Latin America[Note 1]
|
40 |
20 |
10 |
16 |
24 |
38 |
74 |
167 |
508 |
577 |
590 |
603 |
784 |
912
|
North America[Note 1]
|
6 |
3 |
2 |
2 |
7 |
26 |
82 |
172 |
312 |
337 |
345 |
351 |
433 |
398
|
Oceania
|
3 |
3 |
3 |
2 |
2 |
2 |
6 |
13 |
30 |
34 |
37 |
38 |
57 |
51
|
World historical and predicted populations by percentage distribution[112][113]
Region |
1500 |
1600 |
1700 |
1750 |
1800 |
1850 |
1900 |
1950 |
1999 |
2008 |
2010 |
2012 |
2050 |
2150
|
Africa
|
14.7 |
17.3 |
14.9 |
13.4 |
10.9 |
8.8 |
8.1 |
8.8 |
13.0 |
14.5 |
14.8 |
15.2 |
25.5 |
23.7
|
Asia
|
48.2 |
53.0 |
57.9 |
63.5 |
64.9 |
64.1 |
57.4 |
55.6 |
61.6 |
60.4 |
60.4 |
60.3 |
54.2 |
57.1
|
Europe
|
28.7 |
25.8 |
25.1 |
20.6 |
20.8 |
21.9 |
24.7 |
21.7 |
11.2 |
10.9 |
10.7 |
10.5 |
7.6 |
5.3
|
Latin America[Note 1]
|
6.8 |
3.0 |
1.4 |
2.0 |
2.5 |
3.0 |
4.5 |
6.6 |
8.5 |
8.6 |
8.6 |
8.6 |
8.1 |
9.4
|
North America[Note 1]
|
1.0 |
0.5 |
0.3 |
0.3 |
0.7 |
2.1 |
5.0 |
6.8 |
5.2 |
5.0 |
5.0 |
5.0 |
4.5 |
4.1
|
Oceania
|
0.5 |
0.5 |
0.4 The following table gives estimates, in millions, of population in the past. The data for 1750 to 1900 are from the UN report "The World at Six Billion"[115] whereas the data from 1950 to 2015 are from a UN data sheet.[14]
Year
|
World
|
Africa
|
Asia
|
Europe
|
Latin America & Carib.[Note 1]
|
North America [Note 1]
|
Oceania
|
Notes
|
70,000 BC
|
< 0.015
|
|
|
|
0
|
0
|
|
[116]
|
10,000 BC
|
4
|
|
|
|
|
|
|
[117]
|
8000 BC
|
5
|
|
|
|
|
|
|
|
6500 BC
|
5
|
|
|
|
|
|
|
|
5000 BC
|
5
|
|
|
|
|
|
|
|
4000 BC
|
7
|
|
|
|
|
|
|
|
3000 BC
|
14
|
|
|
|
|
|
|
|
2000 BC
|
27
|
|
|
|
|
|
|
|
1000 BC
|
50
|
7
|
33
|
9
|
|
|
|
[citation needed]
|
500 BC
|
100
|
14
|
66
|
16
|
|
|
|
|
AD 1
|
200
|
23
|
141
|
28
|
|
|
|
|
1000
|
400
|
70
|
269
|
50
|
8
|
1
|
2
|
|
1500
|
458
|
86
|
243
|
84
|
39
|
3
|
3
|
|
1600
|
580
|
114
|
339
|
111
|
10
|
3
|
3
|
|
1700
|
682
|
106
|
436
|
125
|
10
|
2
|
3
|
|
1750
|
791
|
106
|
502
|
163
|
16
|
2
|
2
|
|
1800
|
1,000
|
107
|
656
|
203
|
24
|
7
|
3
|
|
1850
|
1,262
|
111
|
809
|
276
|
38
|
26
|
2
|
|
1900
|
1,650
|
133
|
947
|
408
|
74
|
82
|
6
|
|
1950
|
2,525
|
229
|
1,394
|
549
|
169
|
172
|
12.7
|
[118]
|
1955
|
2,758
|
254
|
1,534
|
577
|
193
|
187
|
14.2
|
|
1960
|
3,018
|
285
|
1,687
|
606
|
221
|
204
|
15.8
|
|
1965
|
3,322
|
322
|
1,875
|
635
|
254
|
219
|
17.5
|
|
- ^ a b c d e f North America comprises the northernmost countries and territories of North America: Canada, the United States, Greenland, Bermuda, and St. Pierre and Miquelon. Latin America & Carib. comprises Mexico, Central America, the Caribbean, and South America.
Projections
Long-term global population growth is difficult to predict. The United Nations and the US Census Bureau both give different estimates – according to the UN, the world population reached seven billion in late 2011,[109] while the USCB asserted that this occurred in March 2012.[119] The UN has issued multiple projections of future world population, based on different assumptions. From 2000 to 2005, the UN consistently revised these projections downward, until the 2006 revision, issued on 14 March 2007, revised the 2050 mid-range estimate upwards by 273 million.
Average global birth rates are declining fast, but vary greatly between developed countries (where birth rates are often at or below replacement levels) and developing countries (where birth rates typically remain high). Different ethnicities also display varying birth rates. Death rates can change rapidly due to disease epidemics, wars and other mass catastrophes, or advances in medicine.
2012 United Nations projections show a continued increase in population in the near future with a steady decline in population growth rate; the global population is expected to reach between 8.3 and 10.9 billion by 2050.[120][121] 2003 UN Population Division population projections for the year 2150 range between 3.2 and 24.8 billion.[73] One of many independent mathematical models supports the lower estimate,[122] while a 2014 estimate forecasts between 9.3 and 12.6 billion in 2100, and continued growth thereafter.[123][124] The 2019 Revision of the UN estimates gives the "medium variant" population as; nearly 8.6 billion in 2030, about 9.7 billion in 2050 and about 10.9 billion in 2100.[125] In December 2019, the German Foundation for World Population projected that the global population will reach 8 billion by 2023 as it increases by 156 every minute.[109] while the USCB asserted that this occurred in March 2012.[119] The UN has issued multiple projections of future world population, based on different assumptions. From 2000 to 2005, the UN consistently revised these projections downward, until the 2006 revision, issued on 14 March 2007, revised the 2050 mid-range estimate upwards by 273 million.
Average global birth rates are declining fast, but vary greatly between developed countries (where birth rates are often at or below replacement levels) and developing countries (where birth rates typically remain high). Different ethnicities also display varying birth rates. Death rates can change rapidly due to disease epidemics, wars and other mass catastrophes, or advances in medicine.
2012 United Nations projections show a continued increase in population in the near future with a steady decline in population growth rate; the global population is expected to reach between 8.3 and 10.9 billion by 2050.[120][121] 2003 UN Population Division population projections for the year 2150 range between 3.2 and 24.8 billion.[73] One of many independent mathematical models supports the lower estimate,[122] while a 2014 estimate forecasts between 9.3 and 12.6 billion in 2100, and continued growth thereafter.[123][124] The 2019 Revision of the UN estimates gives the "medium variant" population as; nearly 8.6 billion in 2030, about 9.7 billion in 2050 and about 10.9 billion in 2100.[125] In December 2019, the German Foundation for World Population projected that the global population will reach 8 billion by 2023 as it increases by 156 every minute.[126] In a modelled future projection by the Institute for Health Metrics and Evaluation the global population was projected to peak in 2064 at 9.73 billion people and decline to 8.79 billion in 2100.[127] Some analysts have questioned the sustainability of further world population growth, highlighting the birth rates are declining fast, but vary greatly between developed countries (where birth rates are often at or below replacement levels) and developing countries (where birth rates typically remain high). Different ethnicities also display varying birth rates. Death rates can change rapidly due to disease epidemics, wars and other mass catastrophes, or advances in medicine.
2012 United Nations projections show a continued increase in population in the near future with a steady decline in population growth rate; the global population is expected to reach between 8.3 and 10.9 billion by 2050.[120][121] 2003 UN Population Division population projections for the year 2150 range between 3.2 and 24.8 billion.[73] One of many independent mathematical models supports the lower estimate,[122] while a 2014 estimate forecasts between 9.3 and 12.6 billion in 2100, and continued growth thereafter.[123][124] The 2019 Revision of the UN estimates gives the "medium variant" population as; nearly 8.6 billion in 2030, about 9.7 billion in 2050 and about 10.9 billion in 2100.[125] In December 2019, the German Foundation for World Population projected that the global population will reach 8 billion by 2023 as it increases by 156 every minute.[126] In a modelled future projection by the Institute for Health Metrics and Evaluation the global population was projected to peak in 2064 at 9.73 billion people and decline to 8.79 billion in 2100.[127] Some analysts have questioned the sustainability of further world population growth, highlighting the growing pressures on the environment,[128] global food supplies, and energy resources.[129][130][131]
In 1975, Sebastian von Hoerner proposed a formula for population growth which represented hyperbolic growth with an infinite population in 2025.[134] The hyperbolic growth of the world population observed until the 1970s was later correlated to a non-linear second order positive feedback between demographic growth and technological development. This feedback can be described as follows: technological advance → increase in the carrying capacity of land for people → demographic growth → more people → more potential inventors → acceleration of technological advance → accelerating growth of the carrying capacity → faster population growth → accelerating growth of the number of potential inventors → faster technological advance → hence, the faster growth of the Earth's carrying capacity for people, and so on.[135] The transition from hyperbolic growth to slower rates of growth is related to the demographic transition.
According to the Russian demographer Sergey Kapitsa,[136] the world population grew between 67,000 BC and 1965 according to the following formula:

where
- N is current population
- T is the current year
- C = (1.86±0.01)·1011
- T0 = 2007±1
= 42±1
Years for world population to double
According to linear interpolation and extrapolation of UNDESA population estimates, the world population has doubled, or will double, in the years listed in the tables below (with two different starting points). During the 2nd millennium, each doubling took roughly half as long as the previous doubling, fitting the hyperbolic growth model mentioned above. However, after 2024, it is unlikely that there will be another doubling of the global population in the 21st century.[137]
Historic chart showing the periods of time the world population has taken to double, from 1700 to 2000
Starting at 500 million
Population (in billions)
|
0.5 |
1 |
2 |
4 |
8
|
Year
|
1500 |
1804 |
1927 |
1974 |
2024
|
Years elapsed
|
304 |
123 |
47 |
50
|
Starting at 375 million
Population (in billions)
|
0.375 |
0.75 |
1.5 |
3 |
6
|
Year
|
1171 |
1715 |
1881 |
1960 |
1999
|
Years elapsed
|
544 |
166 |
79 |
39
|
Overpopulation
Predictions of scarcity
Sergey Kapitsa, [136] the world population grew between 67,000 BC and 1965 according to the following formula:
where
- N is current population
- T is the current year
- C = (1.86±0.01)·1011
- T0 = 2007±1
= 42±1
Years for world population to double
According to linear interpolation and extrapolation of UNDESA population estimates, the world population has doubled, or will double, in the years listed in the tables below (with two different starting points). During the 2nd millennium, each doubling took roughly half as long as the previous doubling, fitting the hyperbolic growth model mentioned above. According to linear interpolation and extrapolation of UNDESA population estimates, the world population has doubled, or will double, in the years listed in the tables below (with two different starting points). During the 2nd millennium, each doubling took roughly half as long as the previous doubling, fitting the hyperbolic growth model mentioned above. However, after 2024, it is unlikely that there will be another doubling of the global population in the 21st century.[137]
Historic chart showing the periods of time the world population has taken to double, from 1700 to 2000
Starting at 500 million
Populatio In his 1798 work An Essay on the Principle of Population, the British scholar Thomas Malthus incorrectly predicted that continued population growth would exhaust the global food supply by the mid-19th century. Malthus wrote the essay to refute what he considered the unattainable utopian ideas of William Godwin and Marquis de Condorcet, as presented in Political Justice and The Future Progress of the Human Mind. In 1968, Paul R. Ehrlich reprised Malthus' argument in The Population Bomb, predicting that mass global famine would occur in the 1970s and 1980s.[139]
The predictions of Ehrlich and other neo-Malthusians were vigorously challenged by a number of economists, notably Julian Lincoln Simon, and advances in agriculture, collectively known as the Green Revolution, forestalled any potential global famine in the late 20th century. Between 1950 and 1984, as the Green Revolution transformed agriculture around the world, grain production increased by over 250%.[140] The world population has grown by over four billion since the beginning of the Green Revolution, but food production has so far kept pace with population growth. Most scholars believe that, without the Revolution, there would be greater levels of famine and malnutrition than the UN presently documents.[141] However, neo-Malthusians point out that fossil fuels provided the energy for the Green Revolution, in the form of natural gas-derived fertilizers, oil-derived pesticides, and hydrocarbon-fueled irrigation, and that many crops have become so genetically uniform that a crop failure in any one country could potentially have global repercussions.[142]
In 2004, a meta-analysis of 70 quantitative studies estimating a sustainable limit to the world population generated a meta-estimate of 7.7 billion people.[143]
In May 2008, the price of grain was pushed up severely by the increased cultivation of biofuels, the increase of world oil prices to over $140 per barrel ($880/m3),[144] global population growth,[145] the effects of climate change,[146] the loss of agricultural land to residential and industrial development,[147][148] and growing consumer demand in the population centres of China and India.[149][150] Food riots subsequently occurred in some countries.[151][152] However, oil prices then fell sharply. Resource demands are expected to ease as population growth declines, but it is unclear whether mass food wastage and rising living standards in developing countries will once again create resource shortages.[153][154]
David Pimentel, p The predictions of Ehrlich and other neo-Malthusians were vigorously challenged by a number of economists, notably Julian Lincoln Simon, and advances in agriculture, collectively known as the Green Revolution, forestalled any potential global famine in the late 20th century. Between 1950 and 1984, as the Green Revolution transformed agriculture around the world, grain production increased by over 250%.[140] The world population has grown by over four billion since the beginning of the Green Revolution, but food production has so far kept pace with population growth. Most scholars believe that, without the Revolution, there would be greater levels of famine and malnutrition than the UN presently documents.[141] However, neo-Malthusians point out that fossil fuels provided the energy for the Green Revolution, in the form of natural gas-derived fertilizers, oil-derived pesticides, and hydrocarbon-fueled irrigation, and that many crops have become so genetically uniform that a crop failure in any one country could potentially have global repercussions.[142]
In 2004, a meta-analysis of 70 quantitative studies estimating a sustainable limit to the world population generated a meta-estimate of 7.7 billion people.[143]
In May 2008, the price of grain was pushed up severely by the increased cultivation of biofuels, the increase of world oil prices to over $140 per barrel ($880/m3),[144] global population growth,[145] the effects of climate change,[146] the loss of agricultural land to residential and industrial development,[147][148] and growing consumer demand in the population centres of China and India.[149][150] Food riots subsequently occurred in some countries.[151][152] However, oil prices then fell sharply. Resource demands are expected to ease as population growth declines, but it is unclear whether mass food wastage and rising living standards in developing countries will once again create resource shortages.[153][154]
David Pimentel, professor of ecology and agriculture at Cornell University, estimates that the sustainable agricultural carrying capacity for the United States is about 200 million people; its population as of 2015 is over 300 million.[155] In 2009, the UK government's chief scientific advisor, Professor John Beddington, warned that growing populations, falling energy reserves and food shortages would create a "perfect storm" of shortages of food, water, and energy by 2030.[138][156] According to a 2009 report by the United Nations Food and Agriculture Organization (FAO), the world will have to produce 70% more food by 2050 to feed a projected extra 2.3 billion people.[157]
The observed figures for 2007 showed an actual increase in absolute numbers of undernourished people in the world, with 923 million undernourished in 2007, versus 832 million in 1995.[158] The 2009 FAO estimates showed an even more dramatic increase, to 1.02 billion.[159]
A number of scientists have argued that the current global population expansion and accompanying increase in resource consumption threatens the world's ecosystem.[160][161]
The InterAcademy Panel Statement on Population Growth, which was ratified by 58 member national academies in 1994, states that "unprecedented" population growth aggravates many environmental problems, including rising levels of atmospheric carbon dioxide, global warming, and pollution.[162] Indeed, some analysts claim that overpopulation's most serious impact is its effect on the environment.[130]
The situation has continued to worsen, as at the time of the 1994 IAP statement, the world population stood at 5.5 billion and lower-bound scenarios predicted a peak of 7.8 billion by 2050, a number that current estimates state will be reached in the late 2020s.
Scientists contend that human overpopulation, continued human population growth and overconsumption, particularly by the wealthy, are the primary drivers of mass species extinction.[163][164][165][166] By 2050 population growth, along with profligate consumption, could result in oceans containing more plastic than fish by weight.[165] In November 2017, a statement by 15,364 scientists from 184 countries asserted th Scientists contend that human overpopulation, continued human population growth and overconsumption, particularly by the wealthy, are the primary drivers of mass species extinction.[163][164][165][166] By 2050 population growth, along with profligate consumption, could result in oceans containing more plastic than fish by weight.[165] In November 2017, a statement by 15,364 scientists from 184 countries asserted that rapid human population growth is the "primary driver behind many ecological and even societal threats."[167] African wildlife populations are declining significantly as growing human populations encroach on protected ecosystems, such as the Serengeti.[168] The Global Assessment Report on Biodiversity and Ecosystem Services, released by IPBES in 2019, states that human population growth is a factor in biodiversity loss.[169][128] According to a 2020 World Wildlife Fund Living Planet Report and its Living Planet Index, global wildlife populations have plummeted by 68% since 1970 as a result of overconsumption, population growth and intensive farming, which experts assert is further evidence that humans have unleashed a sixth mass extinction event on earth.[170][171]
A July 2017 study published in Environmental Research Letters argued that the most significant way individuals could mitigate their own carbon footprint is to have fewer children, followed by living without a vehicle, foregoing air travel, and adopting a plant-based diet.[172]
Human population control is the practice of intervening to alter the rate of population growth. Historically, human population control has been implemented by limiting a region's birth rate, by voluntary contraception or by government mandate. It has been undertaken as a response to factors including high or increasing levels of poverty, environmental concerns, and religious reasons. The use of abortion in some population control strategies has caused controversy,[173] with religious organizations such as the Roman Catholic Church explicitly opposing any intervention in the human reproductive process.[174]
The University of Nebraska publication Green Illusions argues that population control to alleviate environmental pressures need not be coercive. It states that "Women who are educated, economically engaged, and in control of their own bodies can enjoy the freedom of bearing children at their own pace, which happens to be a rate that is appropriate for the aggregate ecological endowment of our planet."[175] The book Fatal Misconception by Matthew Connelly similarly points to the importance of supporting the rights of women in bringing population levels down over time.[176] Paul Ehrlich also advocates making "modern contraception and back-up abortion available to all and give women full equal rights, pay and opportunities with men," noting that it could possibly "lead to a low enough total fertility rate that the needed shrinkage of population would follow. [But] it will take a very long time to humanely reduce total population to a size that is sustainable." Ehrlich places the optimum globa The University of Nebraska publication Green Illusions argues that population control to alleviate environmental pressures need not be coercive. It states that "Women who are educated, economically engaged, and in control of their own bodies can enjoy the freedom of bearing children at their own pace, which happens to be a rate that is appropriate for the aggregate ecological endowment of our planet."[175] The book Fatal Misconception by Matthew Connelly similarly points to the importance of supporting the rights of women in bringing population levels down over time.[176] Paul Ehrlich also advocates making "modern contraception and back-up abortion available to all and give women full equal rights, pay and opportunities with men," noting that it could possibly "lead to a low enough total fertility rate that the needed shrinkage of population would follow. [But] it will take a very long time to humanely reduce total population to a size that is sustainable." Ehrlich places the optimum global population size at 1.5 to 2 billion people.[177]
Other academicians and public figures have pointed to the role of agriculture and agricultural productivity of increasing human carrying capacity, which results in population overshoot, as with any other species when their food supply experiences an increase, which in turn results in resource depletion and mass poverty and starvation in the case of humans.[178][179][180][181]
Estimates of the total number of humans who have ever lived range in the order of 100 billion. It is difficult for estimates to be better than rough approximations, as even modern population estimates are fraught with uncertainties on the order of 3% to 5%.[22] Kapitza (1996) cites estimates ranging between 80 and 150 billion.[182] Haub (1995) prepared another figure, updated in 2002 and 2011; the 2011 figure was approximately 107 billion.[183][184][185] Haub characterized this figure as an estimate that required "selecting population sizes for different points from antiquity to the present and applying assumed birth rates to each period".[184]
Robust population data only exists for the last two or three centuries. Until the late 18th century, few governments had ever performed an accurate census. In many early attempts, such as in Ancient Egypt and the Ancient Egypt and the Persian Empire, the focus was on counting merely a subset of the population for purposes of taxation or military service.[186] Thus, there is a significant margin of error when estimating ancient global populations.
Another critical factor for such an estimate is the question of pre-modern infant mortality rates; these figures are very difficult to estimate for ancient times due to a lack of accurate records. Haub (1995) estimates that around 40% of those who have ever lived did not survive beyond their first birthday. Haub also stated that "life expectancy at birth probably averaged only about ten years for most of human history",[184] which is not to be mistaken for the life expectancy after reaching adulthood. The latter equally depended on period, location and social standing, but calculations identify averages from roughly 30 years upward.
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