Population growth

Absolute increase in global human population per year

Population growth is the increase in the number of people in a population or dispersed group. Actual global human population growth amounts to around 83 million annually, or 1.1% per year. The global population has grown from 1 billion in 1800 to 7.9 billion in 2020. The UN projected population to keep growing, and estimates have put the total population at 8.6 billion by mid-2030, 9.8 billion by mid-2050 and 11.2 billion by 2100. However, some academics outside the UN have increasingly developed human population models that account for additional downward pressures on population growth; in such a scenario population would peak before 2100. Others have challenged many recent population projections as having underestimated population growth.

The world human population has been growing since the end of the Black Death, around the year 1350. A mix of technological advancement that improved agricultural productivity and sanitation and medical advancement that reduced mortality increased population growth. In some geographies, this has slowed through the process called the demographic transition, where many nations with high standards of living have seen a significant slowing of population growth. This is in direct contrast with less developed contexts, where population growth is still happening. Globally, the rate of population growth has declined from a peak of 2.2% per year in 1963. The global human population is projected to peak during the mid-21st century and decline by 2100.

Population growth alongside increased consumption is a driver of environmental concerns, such as biodiversity loss and climate change, due to overexploitation of natural resources for human development. International policy focused on mitigating the impact of human population growth is concentrated in the Sustainable Development Goals which seeks to improve the standard of living globally while reducing the impact of society on the environment while advancing human well-being.[citation needed]

Population
Years
passed
Year Pop.
(billions)
1800 1
127 1927 2
33 1960 3
14 1974 4
13 1987 5
12 1999 6
12 2011 7
11 2022 8
14 2037* 9
18 2055* 10
33 2088* 11
*World Population Prospects 2017
(United Nations Population Division)

History

World human population estimates from 1800 to 2100, with estimated range of future population after 2020 based on "high" and "low" scenarios. Data from the United Nations projections in 2019.

World population has been rising continuously since the end of the Black Death, around the year 1350. Population began growing rapidly in the Western world during the industrial revolution. The most significant increase in the world's population has been since the 1950s, mainly due to medical advancements and increases in agricultural productivity.

Haber process

Due to its dramatic impact on the human ability to grow food, the Haber process, named after one of its inventors, the German chemist Fritz Haber, served as the "detonator of the population explosion", enabling the global population to increase from 1.6 billion in 1900 to 7.7 billion by November 2019.

Thomas McKeown hypotheses

Some of the reasons for the "Modern Rise of Population" were particularly investigated by the British health scientist Thomas McKeown (1912–1988). In his publications, McKeown challenged four theories about the population growth:

  1. McKeown stated that the growth in Western population, particularly surging in the 19th century, was not so much caused by an increase in fertility, but largely by a decline of mortality particularly of childhood mortality followed by infant mortality,
  2. The decline of mortality could largely be attributed to rising standards of living, whereby McKeown put most emphasis on improved nutritional status,
  3. McKeown questioned the effectiveness of public health measures, including sanitary reforms, vaccination and quarantine,
  4. The “McKeown thesis" states that curative medicine measures played little role in mortality decline, not only prior to the mid-20th century but also until well into the 20th century.

Although the McKeown thesis has been heavily disputed, recent studies have confirmed the value of his ideas. His work is pivotal for present day thinking about population growth, birth control, public health and medical care. McKeown had a major influence on many population researchers, such as health economists and Nobel prize winners Robert W. Fogel (1993) and Angus Deaton (2015). The latter considered McKeown as "the founder of social medicine".

Growth rate models

The "population growth rate" is the rate at which the number of individuals in a population increases in a given time period, expressed as a fraction of the initial population. Specifically, population growth rate refers to the change in population over a unit time period, often expressed as a percentage of the number of individuals in the population at the beginning of that period. This can be written as the formula, valid for a sufficiently small time interval:

A positive growth rate indicates that the population is increasing, while a negative growth rate indicates that the population is decreasing. A growth ratio of zero indicates that there were the same number of individuals at the beginning and end of the period—a growth rate may be zero even when there are significant changes in the birth rates, death rates, immigration rates, and age distribution between the two times.

A related measure is the net reproduction rate. In the absence of migration, a net reproduction rate of more than 1 indicates that the population of females is increasing, while a net reproduction rate less than one (sub-replacement fertility) indicates that the population of females is decreasing.

Most populations do not grow exponentially, rather they follow a logistic model. Once the population has reached its carrying capacity, it will stabilize and the exponential curve will level off towards the carrying capacity, which is usually when a population has depleted most its natural resources. In the world human population, growth may be said to have been following a linear trend throughout the last few decades.

The logistic growth of a population

Unfortunately this statement is somewhat unhelpful since any continuous curve (including an exponential) can be approximated by a line and therefore be said to be following a linear trend.

Logistic equation

The growth of a population can often be modelled by the logistic equation

where

  • = the population after time t;
  • = time a population grows;
  • = the relative growth rate coefficient;
  • = the carrying capacity of the population; defined by ecologists as the maximum population size that a particular environment can sustain.

As it is a separable differential equation, the population may be solved explicitly, producing a logistic function:

,

where and is the initial population at time 0.

Population growth rate

A world map showing global variations in fertility rate per woman according to the CIA World Factbook's 2016 data
Estimates of population evolution in different continents between 1950 and 2050 according to the United Nations. The vertical axis is logarithmic and is in millions of people. (2011)
World population growth rates between 1950 and 2050

The world population growth rate peaked in 1963 at 2.2% per year and subsequently declined. In 2017, the estimated annual growth rate was 1.1%. The CIA World Factbook gives the world annual birthrate, mortality rate, and growth rate as 1.86%, 0.78%, and 1.08% respectively. The last 100 years have seen a massive fourfold increase in the population, due to medical advances, lower mortality rates, and an increase in agricultural productivity made possible by the Green Revolution.

The annual increase in the number of living humans peaked at 88.0 million in 1989, then slowly declined to 73.9 million in 2003, after which it rose again to 75.2 million in 2006. In 2017, the human population increased by 83 million. Generally, developed nations have seen a decline in their growth rates in recent decades, though annual growth rates remain above 2% in some countries of the Middle East and Sub-Saharan Africa, and also in South Asia, Southeast Asia, and Latin America.

In some countries the population is declining, especially in Eastern Europe, mainly due to low fertility rates, high death rates and emigration. In Southern Africa, growth is slowing due to the high number of AIDS-related deaths. Some Western Europe countries might also experience population decline. Japan's population began decreasing in 2005.

The United Nations Population Division projects world population to reach 11.2 billion by the end of the 21st century. The Institute for Health Metrics and Evaluation projects that the global population will peak in 2064 at 9.73 billion and decline to 8.89 billion in 2100. A 2014 study in Science concludes that the global population will reach 11 billion by 2100, with a 70% chance of continued growth into the 22nd century. The German Foundation for World Population reported in December 2019 that the global human population grows by 2.6 people every second, and could reach 8 billion by 2023.

Growth by country

According to United Nations population statistics, the world population grew by 30%, or 1.6 billion humans, between 1990 and 2010. In number of people the increase was highest in India (350 million) and China (196 million). Population growth rate was among highest in the United Arab Emirates (315%) and Qatar (271%).

Growth rates of the world's most populous countries
Rank Country Population Annual Growth (%)
1990 2010 2020 (est.) 1990–2010 2010–2020
World 5,306,425,000 6,895,889,000 7,503,828,180 1.3% 0.8%
1 China China 1,139,060,000 1,341,335,000 1,384,688,986 0.8% 0.3%
2 India India 873,785,000 1,224,614,000 1,333,000,000 1.7% 0.9%
3 United States United States 253,339,000 310,384,000 329,256,465 1.0% 0.6%
4 Indonesia Indonesia 184,346,000 239,871,000 262,787,403 1.3% 0.9%
5 Brazil Brazil 149,650,000 194,946,000 208,846,892 1.3% 0.7%
6 Pakistan Pakistan 111,845,000 173,593,000 207,862,518 2.2% 1.8%
7 Nigeria Nigeria 97,552,000 158,423,000 203,452,505 2.5% 2.5%
8 Bangladesh Bangladesh 105,256,000 148,692,000 159,453,001 1.7% 0.7%
9 Russia Russia 148,244,000 142,958,000 142,122,776 -0.2% −0.1%
10 Japan Japan 122,251,000 128,057,000 126,168,156 0.2% −0.1%

Many of the world's countries, including many in Sub-Saharan Africa, the Middle East, South Asia and South East Asia, have seen a sharp rise in population since the end of the Cold War. The fear is that high population numbers are putting further strain on natural resources, food supplies, fuel supplies, employment, housing, etc. in some of the less fortunate countries. For example, the population of Chad has ultimately grown from 6,279,921 in 1993 to 10,329,208 in 2009, further straining its resources. Vietnam, Mexico, Nigeria, Egypt, Ethiopia, and the DRC are witnessing a similar growth in population.

The following table gives some example countries or territories:

Country/territory Population in Life expectancy
in years (2008)
Total population
growth from 1960s
to 2007–2011
1967 1990 1994 2002 2008
Eritrea Eritrea* N/A* N/A* 3,437,000 4,298,269 5,673,520 61 2,236,520
Ethiopia Ethiopia* 23,457,000* 50,974,000* 54,939,000 67,673,031(2003) 79,221,000 55 55,764,000
Sudan Sudan 14,355,000† 25,204,000† 27,361,000† 38,114,160 (2003)† 42,272,000† 50† 27,917,000
Chad Chad 3,410,000 5,679,000 6,183,000 9,253,493(2003) 10,329,208 (2009) 47 6,919,205
Niger Niger 3,546,000 7,732,000 8,846,000 10,790,352 (2001) 15,306,252 (2009) 44 11,760,252
Nigeria Nigeria 61,450,000 88,500,000 108,467,000 129,934,911 158,259,000 47 96,809,000
Mali Mali 4,745,000 8,156,000 10,462,000 11,340,480 14,517,176(2010) 50 9,772,176
Mauritania Mauritania 1,050,000 2,025,000 2,211,000 2,667,859 (2003) 3,291,000 (2009) 54 2,241,000
Senegal Senegal 3,607,000 7,327,000 8,102,000 9,967,215 13,711,597 (2009) 57 10,104,597
The Gambia Gambia 343,000 861,000 1,081,000 1,367,124 (2000) 1,705,000 55 1,362,000
Algeria Algeria 11,833,126 25,012,000 27,325,000 32,818,500 (2003) 34,895,000 74 23,061,874
Democratic Republic of the Congo The DRC/Zaire 16,353,000 35,562,000 42,552,000 55,225,478 (2003) 70,916,439 54 54,563,439
Egypt Egypt 30,083,419 53,153,000 58,326,000 70,712,345 (2003) 79,089,650 72 49,006,231
Réunion Réunion
(overseas region of France)
418,000 N/A N/A 720,934 (2003) 827,000 (2009) N/A 409,000
Falkland Islands Falkland Islands
(British Overseas Territory)
2,500 N/A N/A 2,967 (2003) 3,140(2010) N/A 640
Chile Chile 8,935,500 13,173,000 13,994,000 15,116,435 17,224,200 (2011) 77 8,288,700
Colombia Colombia 19,191,000 32,987,000 34,520,000 41,088,227 45,925,397 (2010) 73 26,734,397
Brazil Brazil 85,655,000 150,368,000 153,725,000 174,468,575 (2000) 190,732,694 (2010) 72 105,077,694
Mexico Mexico 45,671,000 86,154,000 93,008,000 103,400,165 (2000) 112,322,757 (2010) 76 66,651,757
Fiji Fiji 476,727 (1966) 765,000 771,000 844,330 (2001) 849,000 (2010) 70 372,273
Nauru Nauru 6,050 10,000 N/A 12,329 9,322 (2011) N/A 3,272
Jamaica Jamaica 1,876,000 2,420,000 2,429,000 2,695,867 (2003) 2,847,232(2010) 74 971,232
Australia Australia 11,540,764 17,086,000 17,843,000 19,546,792 (2003) 26,786,538 (2010) 82 10,066,508
Albania Albania 1,965,500 (1964) 3,250,000 3,414,000 3,510,484 2,986,952 (July 2010 est.) 78 1,021,452
Poland Poland 31,944,000 38,180,000 38,554,000 38,626,349 (2001) 38,192,000 (2010) 75 6,248,000
Hungary Hungary 10,212,000 10,553,000 10,261,000 10,106,017 9,979,000 (2010) 73 -142,000
Bulgaria Bulgaria 8,226,564 (1965) 8,980,000 8,443,000 7,707,495(2000) 7,351,234 (2011) 73 -875,330
United Kingdom United Kingdom 55,068,000 (1966) 57,411,000 58,091,000 58,789,194 62,008,048 (2010) 79 7,020,048
Republic of Ireland Ireland 2,884,002 (1966) 3,503,000 3,571,000 3,840,838 (2000) 4,470,700 (2010) 78 1,586,698
China People's Republic of China 720,000,000 1,139,060,000 1,208,841,000 1,286,975,468 (2004) 1,339,724,852 (2010) 73 619,724,852
Japan Japan 98,274,961 (1965) 123,537,000 124,961,000 127,333,002 127,420,000 (2010) 82 28,123,865
India India# 511,115,000 843,931,000 918,570,000 1,028,610,328 (2001) 1,210,193,422 (2011) 69 699,078,422
Singapore Singapore 1,956,000 (1967) 3,003,000 (1990) 2,930,000 (1994) 4,452,732 (2002) 5,076,700 (2010) 82 (2008) 3,120,700
Monaco Monaco 24,000 (1967) 29,000 (1990) N/A (1994) 31,842 (2000) 35,586 (2010) (2008) 11,586
Greece Greece 8,716,000 (1967) 10,123,000 (1990) 10,426,000 (1994) 10,964,020 (2001) 11,305,118 (2011) N/A (2008) 2,589,118
Faroe Islands Faroe Islands
(Danish dependency)
38,000 (1967) N/A (1990) N/A (1994) 46,345 (2000) 48,917 (2010) N/A (2008) 18,917
Liechtenstein Liechtenstein 20,000 (1967) 29,000 (1990) N/A (1994) 33,307 (2000) 35,789 (2009) (2008) 15,789
South Korea South Korea 29,207,856 (1966) 42,793,000 (1990) 44,453,000 (1994) 48,324,000 (2003) 48,875,000 (2010) (2008) 19,667,144
North Korea North Korea 12,700,000 (1967) 21,773,000 (1990) 23,483,000 (1994) 22,224,195 (2002) 24,051,218 (2010) (2008) 11,351,218
Brunei Brunei 107,200 (1967) 266,000 (1990) 280,000 (1994) 332,844 (2001) 401,890 (2011) 76 (2008) 306,609
Malaysia Malaysia 10,671,000 (1967) 17,861,000 (1990) 19,489,000 (1994) 21,793,293 (2002) 27,565,821 (2010) (2008) 16,894,821
Thailand Thailand 32,680,000 (1967) 57,196,000 (1990) 59,396,000 (1994) 60,606,947 (2000) 63,878,267 (2011) (2008) 31,198,267
Lebanon Lebanon 2,520,000 (1967) 2,701,000 (1990) 2,915,000 (1994) 3,727,703 (2003) 4,224,000 (2009) - (2008)
Syria Syria 5,600,000 (1967) 12,116,000 (1990) 13,844,000 (1994) 17,585,540 (2003) 22,457,763 (2011) -(2008)
Bahrain Bahrain 182,00 (1967) 503,000 (1990) 549,000 (1994) 667,238 (2003) 1,234,596 (2010) 75 (2008)
Sri Lanka Sri Lanka 11,741,000 (1967) 16,993,000 (1990) 17,685,000 (1994) 19,607,519 (2002) 20,238,000 (2009) - (2008)
Switzerland Switzerland 6,050,000 (1967) 6.712,000 (1990) 6,994,000 (1994) 7,261,200 (2002) 7,866,500 (2010) - (2008)
Luxembourg Luxembourg 335,000 (1967) 381,000 (1990) 401,000 (1994) 439,539 (2001) 511,840 (2011) - (2008)
Romania Romania 19,105,056 (1966) 23,200,000 (1990) 22,736,000 (1994) 21,680,974 (2002) 21,466,174 (2011) - (2008)
Niue Niue
(associated state of New Zealand)
1,900 (1966) N/A (1990) N/A (1994) 2,134 (2002) 1,398 (2009) N/A (2008) -502
Tokelau Tokelau
(New Zealand territory)
5,194 (1966) N/A (1990) N/A (1994) 1,445 (2001) 1,416 (2009) N/A (2008) -3,778
Jamaica Jamaica 1,876,000 (1967) 2,420,000 (1990) 2,429,000 (1994) 2,695,867 (2003) 2,847,232 (2010) 74 (2008) 971,232
Argentina Argentina 32,031,000 (1967) 32,322,000 (1990) 34,180,000 (1994) 37,812,817 (2002) 40,091,359 (2010) 74 (2008) 8,060,359
France France 49,890,660 (1967) 56,440,000 (1990) 57,747,000 (1994) 59,551,000 (2001) 63,136,180 (2011) 81 (2008)
Italy Italy 52,334,000 (1967) 57,662,000 (1990) 57,193,000 (1994) 56,995,744 (2002) 60,605,053 (2011) 80 (2008)
Mauritius Mauritius 774,000 (1967) 1,075,000 (1990) 1,104,000 (1994) 1,179,137 (2000) 1,288,000 (2009) 75 (2008) 514,000
Guatemala Guatemala 4,717,000 (1967) 9,197,000 (1990) 10,322,000 (1994) 12,974,361 (2000) 13,276,517 (2009) 70 (2008) 8,559,517
Cuba Cuba 8,033,000 (1967) 10,609,000 (1990) 10,960,000 (1994) 11,177,743 (2002) 11,239,363 (2009) 77 (2008)
Barbados Barbados 246,000 (1967) 255,000 (1990) 261,000 (1994) 250,012 (2001) 284,589 (2010) 73 (2008) 18,589
Samoa Samoa 131,377 (1967) 164,000 (1990) 164,000 (1994) 178,173 (2003) 179,000 (2009) N/A (2008)
Sweden Sweden 7,765,981 (1967) 8,559,000 (1990) 8,794,000 (1994) 8,920,705 (2002) 9,354,462 (2009) 81 (2008)
Finland Finland 4,664,000 (1967) 4,986,000 (1990) 5,095,000 (1994) 5,175,783 (2002) 5,374,781 (2010) N/A (2008)
Portugal Portugal 9,440,000 (1967) 10,525,000 (1990) 9,830,000 (1994) 10,355,824 (2001) 10,647,763 (2011) N/A (2008)
Austria Austria 7,323,981 (1967) 7,712,000 (1990) 8,031,000 (1994) 8,032,926 (2001) 8,404,252 (2011) N/A (2008)
Libya Libya 1,738,000 (1967) 4,545,000 (1990) 5,225,000(1994) 5,499,074 (2002) 6,420,000 (2009) 77 (2008)
Peru Peru 12,385,000 (1967) 21,550,000 (1990) 23,080,000(1994) 27,949,639 (2002) 29,496,000 (2010) 70 (2008)
Guinea-Bissau Guinea Bissau 528,000 (1967) 965,000 (1990) 1,050,000 (1994) 1,345,479 (2002) 1,647,000 (2009) 48 (2008)
Angola Angola 5,203,066 (1967) 10,020,000 (1990) 10,674,000 (1994) 10,766,500 (2003) 18,498,000 (2009) 38 (2008)
Equatorial Guinea Equatorial Guinea 277,000 (1967) 348,000 (1990) 389,000 (1994) 474,214 (2000) 676,000 (2009) 61 (2008)
Benin Benin 2,505,000 (1967) 4,736,000 (1990) 5,246,000 (1994) 8,500,500 (2002) 8,791,832 (2009) 59 (2008)
Laos Laos 2,770,000 (1967) 4,139,000 (1990) 4,742,000 (1994) 5,635,967 (2002) 6,800,000 (2011) 56 (2008)
Nepal Nepal 10,500,000 (1967) 18,961,000 (1990) 21,360,000 (1994) 25,284,463 (2002) 29,331,000 (2009) - (2008)
Iran Iran 25,781,090 (1966) 54,608,000 (1990) 59,778,000 (1994) 66,622,704 (2002) 75,330,000 (2010) 71 (2008) 49,548,910
Canada Canada 20,014,880 (1966) 26,603,000 (1990) 29,248,000(1994) 31,081,900 (2001) 32,623,490 (2011) 81 (2008)
United States United States 199,118,000 (1967) 249,995,000 (1990) 260,650,00(1994) 281,421,906 (2000) 308,745,538 (2010) 78 (2008)
Uganda Uganda 7,931,000 (1967) 18,795,000 (1990) 20,621,000 (1994) 24,227,297 (2002) 32,369,558 (2009) 52 (2008)
Notes
* Eritrea left Ethiopia in 1991.
† Split into the nations of Sudan and South Sudan during 2011.
‡ Japan and the Ryukyu Islands merged in 1972.
# India and Sikkim merged in 1975.
Population growth 1990–2012 (%)
Africa 73.3%
Middle East 68.2%
Asia (excl. China) 42.8%
China 19.0%
OECD Americas 27.9%
Non-OECD Americas 36.6%
OECD Europe 11.5%
OECD Asia Oceania 11.1%
Non-OECD Europe and Eurasia -0.8%
Bangladesh is one of the most densely populated countries in the world. The capital, Dhaka, bustles around Nilkhet Mor.

Future population

1. World population growth 1700–2100, 2022 projection

Population projections are attempts to show how the human population statistics might change in the future. These projections are an important input to forecasts of the population's impact on this 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 (chart #1) show that annual world population growth peaked at 2.3% per year in 1963, has since dropped to 0.9% in 2023, equivalent to about 74 million people each year, and projected that it could drop even further to minus 0.1% by 2100. Based on this, the UN projected that the world population, 8 billion as of 2023, would peak around the year 2086 at about 10.4 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 UN's Sustainable Development Goals) which could result in peak population during the 2060–2070 period rather than later.

According to the UN, of the predicted growth in world population between 2020 and 2050, all of that change 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.
2. World population prospects, 2022 projection
During the remainder of this century some countries will see population growth, 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 3rd most populous country, and China will lose almost 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 on this planet is projected to be the continuing evolution of fertility and mortality.
Estimated size of human population from 10,000 BCE to 2000 CE
The majority of world population growth today is occurring in less developed countries.

See also


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