World population

From Wikipedia, the free encyclopedia - View original article

World population (millions)[17]
#Top ten most populous countries199020082025*
3United States250304352
World total5,2676,6898,004
Top ten most populous (%)60.0%58.9%57.5%
+ China1,1411,3331,458
+ OECD Pacific*187202210
+ Russia149143137
+ 11 Soviet Republics*134136146
4Latin America355462550
5North America*359444514
6Middle East132199272
European Union – 27 states473499539
US + Canada278338392
Soviet Union291286289
Geographical definitions as in IEA Key Stats 2010 p. 66
  • Europe = OECD Europe + Non-OECD Europe and
    excluding Russia and including Estonia, Latvia and Lithuania
  • 11 Soviet Republics = USSR excluding Russia and Baltic states
  • North America = US, Canada, Mexico
  • OECD Pacific = Australia, Japan, Korea, New Zealand
  • 2025 = with constant annual 2007/2008 growth until 2025
Jump to: navigation, search
World population estimates from 1800 to 2100, based on "high", "medium" and "low" United Nations projections in 2010 (colored red, orange and green) and US Census Bureau historical estimates (in black). Actual recorded population figures are colored in blue. According to the highest estimate, the world population may rise to 16 billion by 2100; according to the lowest estimate, it may decline to 6 billion.

The world population is the total number of living humans on Earth. As of today, it is estimated to number 7.167 billion by the United States Census Bureau (USCB).[1] The USCB estimates that the world population exceeded 7 billion on March 12, 2012.[2] According to a separate estimate by the United Nations Population Fund, it reached this milestone on October 31, 2011.[3][4][5]

The world population has experienced continuous growth since the end of the Great Famine and the Black Death in 1350, when it was near 370 million.[6] The highest growth rates – global population increases above 1.8% per year – occurred briefly during the 1950s, and for longer during the 1960s and 1970s. The global growth rate peaked at 2.2% in 1963, and has declined to below 1.1% as of 2012.[7] Total annual births were highest in the late 1980s at about 138 million,[8] and are now expected to remain essentially constant at their 2011 level of 134 million, while deaths number 56 million per year, and are expected to increase to 80 million per year by 2040.[9]

Current UN projections show a continued increase in population in the near future with a steady decline in population growth rate; global population is expected to reach between 8.3 and 10.9 billion by 2050.[10][11] UN Population Division estimates for the year 2150 range between 3.2 and 24.8 billion;[12] one of many independent mathematical models supports the lower estimate.[13] Some analysts have questioned the sustainability of further world population growth, highlighting the growing pressures on the environment, global food supplies, and energy resources.[14][15][16]

World population (millions)[17]
#Top ten most populous countries199020082025*
3United States250304352
World total5,2676,6898,004
Top ten most populous (%)60.0%58.9%57.5%
+ China1,1411,3331,458
+ OECD Pacific*187202210
+ Russia149143137
+ 11 Soviet Republics*134136146
4Latin America355462550
5North America*359444514
6Middle East132199272
European Union – 27 states473499539
US + Canada278338392
Soviet Union291286289
Geographical definitions as in IEA Key Stats 2010 p. 66
  • Europe = OECD Europe + Non-OECD Europe and
    excluding Russia and including Estonia, Latvia and Lithuania
  • 11 Soviet Republics = USSR excluding Russia and Baltic states
  • North America = US, Canada, Mexico
  • OECD Pacific = Australia, Japan, Korea, New Zealand
  • 2025 = with constant annual 2007/2008 growth until 2025

Population by region[edit]

Six of Earth's seven continents are permanently inhabited on a large scale. Asia is the most populous continent, with its 4.3 billion inhabitants accounting for 60% of the world population. The world's two most populated countries alone, China and India, together constitute about 37% of the world's population. Africa is the second most populated continent, with around 1 billion people, or 15% of the world's population. Europe's 733 million people make up 12% of the world's population (as of 2012), while the Latin American and Caribbean regions are home to around 600 million (9%). Northern America, primarily consisting of the United States and Canada, has a population of around 352 million (5%), and Oceania, the least-populated region, has about 35 million inhabitants (0.5%).[18] Though it is not permanently inhabited by any fixed population, Antarctica has a small, fluctuating international population, based mainly in polar science stations. This population tends to rise in the summer months and decrease significantly in winter, as visiting researchers return to their home countries.[19]

Population by continent[edit]

(billions, 2013 estimates)
Most populous countryMost populous city
Asia96.44.298 China (1,361,000,000)[20]Japan Greater Tokyo Area (35,676,000)
Africa36.71.111 Nigeria (173,120,000)Egypt Cairo (19,439,541)
Europe72.90.742 Russia (143,700,000;
approx. 110 million in Europe)
Russia Moscow (14,837,510)
North America[21]22.90.565 United States (317,996,000)Mexico Mexico City/Metro Area (8,851,080 / 21,163,226)
South America22.80.407 Brazil (201,032,714)Brazil São Paulo City/Metro Area (11,316,149 / 27,640,577)
Oceania4.50.038 Australia (23,475,992)Australia Sydney (4,575,532)
0.000 004
(non-permanent, varies)[22]
N/A[note 1]McMurdo Station (1,200) (non-permanent, varies)


Antiquity and Middle Ages[edit]

Until the development of agriculture around the 11th millennium BC, it is estimated that the world population stabilized at about three million people,[23] who subsisted through hunting and foraging – a lifestyle that by its nature ensured a low population density. The total world population probably never exceeded 15 million inhabitants before the invention of agriculture.[24] By contrast, it is estimated that around 50–60 million people lived in the combined eastern and western Roman Empire in the 4th century AD.[25]

The plague which first emerged during the reign of Emperor Justinian caused Europe's population to drop by around 50% between the 6th and 8th centuries AD.[26] The population of Europe was more than 70 million in 1340.[27] The Black Death pandemic of the 14th century may have reduced the world's population from an estimated 450 million in 1340 to between 350 and 375 million in 1400;[28] it took roughly 200 years for Europe's population to regain its 1340 level.[29] China experienced a population decline from an estimated 123 million around 1200 to an estimated 65 million in 1393,[30] which was presumably due to a combination of Mongol invasions, famine and plague.[31]

At the founding of the Ming Dynasty in 1368, China's population was reported to be close to 60 million; toward the end of the dynasty in 1644, it may have approached 150 million.[32] England's population reached an estimated 5.6 million in 1650, up from an estimated 2.6 million in 1500.[33] New crops that were brought to Asia and Europe from the Americas by Spanish colonists in the 16th century are believed to have contributed to population growth.[34][35] Since their introduction by Portuguese traders in the 16th century,[36] maize and cassava have replaced traditional African crops as that continent’s most important staple food crops.[37]

Around 300 BC, the population of India was between 100 million and 140 million.[38] The population of India in 1600 was around 100 million. Hence, from 300 BC to 1600, India's population was more or less stable.[39]

The total population of the Americas in 1500 may have been between 50 and 100 million.[40] The pre-Columbian North American population probably numbered somewhere between 2 million and 18 million.[41] Encounters between European explorers and populations in the rest of the world often introduced local epidemics of extraordinary virulence.[42] The most extreme claims are that 90% of the Native American population of the New World died due to Old World diseases such as smallpox, measles and influenza.[43] Over the centuries, the Europeans had developed high degrees of immunity to these diseases, while the indigenous peoples had no such immunity.[44]

Modern era[edit]

Map showing urban areas with at least one million inhabitants in 2006. Only 3% of the world's population lived in cities in 1800; this proportion had risen to 47% by 2000, and reached 50.5% by 2010.[45] By 2050, the proportion may reach 70%.[46]

During the European Agricultural and Industrial Revolutions, the life expectancy of children increased dramatically.[47] The percentage of the children born in London who died before the age of five decreased from 74.5% in 1730–1749 to 31.8% in 1810–1829.[48][49] Between 1700 and 1900, Europe’s population increased from about 100 million to over 400 million.[50] Altogether, the areas of European settlement comprised 36% of the world's population in 1900.[51]

Population growth in the West became more rapid after the introduction of compulsory vaccination and improvements in medicine and sanitation.[52] As living conditions and health care improved during the 19th century, the United Kingdom's population doubled every fifty years.[53] By 1801, the population of England had grown to 8.3 million, and by 1901 it had reached 30.5 million; the population of the United Kingdom reached 60 million in 2006.[54] The United States saw its population grow from around 5.3 million in 1800 to 106 million in 1920, exceeding 307 million in 2010.[55]

The first half of the 20th century in Russia and the Soviet Union was marked by a succession of wars, famines and other disasters, each accompanied by large-scale population losses.[56] In recent decades, Russia's population has declined significantly – from 150 million in 1991 to 143 million in 2012[57] – but as of 2013 this decline appears to have halted.[58]

Many countries in the developing world have experienced rapid population growth over the past century. China's population rose from approximately 430 million in 1850 to 580 million in 1953,[59] and now stands at over 1.3 billion. The population of the Indian subcontinent, which stood at about 125 million in 1750, reached 389 million in 1941;[60] today, India, Pakistan and Bangladesh are collectively home to about 1.5 billion people.[61] The population of Java increased from about five million in 1815 to more than 130 million in the early 21st century.[62] Mexico's population grew from 13.6 million in 1900 to about 112 million in 2010.[63][64] Between the 1920s and 2000s, Kenya's population grew from 2.9 million to 37 million.[65]

Milestones by the billions[edit]

World population milestones (USCB estimates)[1]
(in billions)
Years elapsed between milestones12333141312131519

It is estimated that the world population reached one billion for the first time in 1804. It was another 123 years before it reached two billion in 1927, but it took only 33 years to reach three billion in 1960.[66] Thereafter, the global population reached four billion in 1974, five billion in 1987, six billion in 1999 and, according to the United States Census Bureau, seven billion in March 2012.[1] The United Nations, however, estimated that the world population reached seven billion in October 2011.[3][4][5]

According to current projections, the global population will reach eight billion by 2030, and will likely reach around nine billion by 2050. Alternative scenarios for 2050 range from a low of 7.4 billion to a high of more than 10.6 billion.[67] Projected figures vary depending on underlying statistical assumptions and the variables used in projection calculations, especially the fertility variable. Long-range predictions to 2150 range from a population decline to 3.2 billion in the "low scenario", to "high scenarios" of 24.8 billion.[67] One extreme scenario predicted a massive increase to 256 billion by 2150, assuming the global fertility rate remained at its 1995 level of 3.04 children per woman; however, by 2010 the global fertility rate had declined to 2.52.[12][68]

There is no estimation for the exact day or month the world's population surpassed one or two billion. The days of three and four billion were not officially noted, but the International Database of the United States Census Bureau places them in July 1959 and April 1974 respectively. The United Nations did determine, and celebrate, the "Day of 5 Billion" on July 11, 1987, and the "Day of 6 Billion" on October 12, 1999. The "Day of 7 Billion" was declared by the Population Division of the United Nations to be October 31, 2011.[69]

Global demographics[edit]

Chart showing geographic distribution of the world population in 2005.

As of 2012, the global sex ratio is approximately 1.01 males to 1 female. The greater number of men is possibly due to the significant gender imbalances evident in the Indian and Chinese populations.[70][71] Approximately 26.3% of the global population is aged under 15, while 65.9% is aged 15–64 and 7.9% is aged 65 or over.[70] The global median age was 30.4 years in 2012, and is expected to rise to 37.9 years by 2050.[72]

The global average life expectancy is 67.07 years,[70] with women living an average of 69 years and men approximately 65 years.[70] In 2010, the global fertility rate was estimated at 2.52 children per woman.[68] In June 2012, British researchers calculated the total weight of Earth's human population as 287 million tonnes, with the average person weighing 62 kilograms (137 lb).[73]

The nominal 2012 gross world product was estimated at US$71.83 trillion by the CIA, giving an annual global per capita figure of around US$10,000.[74] Around 1.29 billion people (18.4% of the world population) live in extreme poverty, subsisting on less than US$1.25 per day;[75] approximately 870 million people (12.25%) are undernourished.[76] 83% of the world's over-15s are considered literate.[70] In June 2012, there were around 2.4 billion global Internet users, constituting 34.2% of the world population.[77]

The Han Chinese are the world's largest single ethnic group, constituting over 19% of the global population in 2011.[78] The world's most-spoken first languages are Mandarin Chinese (spoken by 12.44% of the world's population), Spanish (4.85%), English (4.83%), Arabic (3.25%) and Hindustani (2.68%).[70] The world's largest religion is Christianity, whose adherents account for 33.35% of the global population; Islam is the second-largest religion, accounting for 22.43%, and Hinduism the third, accounting for 13.78%.[70] In 2005, around 16% of the global population were reported to be non-religious.[79]

Largest populations by country[edit]

Further information: List of countries by population
A map of the world's countries by total population, with darker shading indicating larger populations.
10 most populous countries
RankCountry / TerritoryPopulationDateApprox. % of world
1 China[note 2]1,364,820,000June 4, 201419%[80]
2 India1,244,940,000June 4, 201417.4%[81]
3 United States318,155,000June 4, 20144.44%[82]
4 Indonesia247,008,052November 22, 20133.45%[83]
5 Brazil201,032,714July 1, 20132.8%[84]
6 Pakistan186,636,000June 4, 20142.6%[85]
7 Nigeria173,615,000July 1, 20132.42%[86]
8 Bangladesh152,518,015July 16, 20122.13%[87]
9 Russia143,657,134January 1, 20142%[88]
10 Japan127,180,000February 1, 20141.77%[89]

Approximately 4.154 billion people live in these ten countries, representing around 58% of the world's population as of October 2013.

Most densely populated countries[edit]

The tables below list the world's most densely populated countries, both in absolute terms and in comparison to their total populations.

Population density (people per km2) map of the world in 1994. Red and pink areas denote regions of highest population density.
10 most densely populated countries (with population above 1 million)
RankCountry/RegionPopulationArea (km2)Density
(Pop. per km2)
1 Singapore5,399,2007107605
2 Bahrain1,234,5717501646
3 Bangladesh149,772,364147,5701101
4 Taiwan23,361,14736,190645
5 Mauritius1,257,9002,040617
6 South Korea50,219,66999,538505
7 Lebanon4,822,00010,452461
8 Netherlands16,848,208[90]41,526406
9 Rwanda10,537,22226,338400
10 Haiti10,413,21127,065385
Countries ranking highly in terms of both total population (more than 15 million people) and population density (more than 250 people per square kilometer):
CountryPopulationArea (km2)Density
(Pop. per km2)
 India1,244,940,0003,287,240379Growing country
 Bangladesh149,772,364147,5701101Growing country
 Japan127,180,000377,873337Declining in population[91]
 Philippines98,698,000300,076329Growing country
 Vietnam90,388,000331,689268Growing country
 United Kingdom63,705,000243,610262Growing country
 South Korea50,219,66999,538505Slowly growing country[92]
 Taiwan23,361,14736,190645Declining in population[93][94]
 Sri Lanka20,328,59765,610309Slowly growing country
 Netherlands16,848,20841,526406Steady in population[95]


Main article: Population growth
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.

Population size fluctuates at differing rates in differing regions. Nonetheless, population growth is the long-standing trend on all inhabited continents, as well as in most individual states. According to the United Nations, population growth on Earth's inhabited continents between 2000 to 2005 totalled:

During the 20th century, the global population saw its greatest increase in known history, rising from about 1.6 billion in 1900 to over 6 billion in 2000. This increase was due to a number of factors, including the lessening of the mortality rate in many countries by improved sanitation and medical advances, and a massive increase in agricultural productivity attributed to the Green Revolution.[96][97][98]

In 2000, the United Nations estimated that the world's population was growing at an annual rate of 1.14% (equivalent to around 75 million people),[99] 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. According to data from the CIA's 2005–2006 World Factbooks, the world population increased by an average of 203,800 people every day in the mid-2000s.[citation needed] The World Factbook increased this estimate to 211,090 people every day in 2007, and again to 220,980 people every day in 2009.

A world map showing global variations in fertility rate per woman, according to the CIA World Factbook's 2013 data.

Globally, the population growth rate has been steadily declining from its peak of 2.19% in 1963, but growth remains high in Latin America, the Middle East and Sub-Saharan Africa.[100]

In some countries, there is negative population growth (i.e. a net decrease in population over time), especially in Europe – this is mainly due to low fertility rates. During the 2010s, Japan and some countries in Europe began to encounter negative population growth, due to sub-replacement fertility rates.[91]

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.[101] 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.[102] An alternative scenario is given by 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.[103]


Long-term global population growth is difficult to predict. The United Nations and the US Census Bureau both give different estimates – according to the latter, the world population reached seven billion in March 2012,[104] while the UN asserted that this occurred in late 2011.[105] 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 March 14, 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.

UN (medium variant – 2012 revision) and US Census Bureau (June 2012) estimates[106][107]
YearUN est.
DifferenceUSCB est.
UN 2012 estimates and medium variant projections (in millions)[106]
YearWorldAsiaAfricaEuropeLatin America/CaribbeanNorthern AmericaOceania
20106,9164,165 (60.2%)1,031 (14.9%)740 (10.7%)596 (8.6%)347 (5.0%)37 (0.5%)
20157,3244,385 (59.9%)1,166 (15.9%)743 (10.1%)630 (8.6%)361 (4.9%)39 (0.5%)
20207,7174,582 (59.4%)1,312 (17.0%)744 (9.6%)662 (8.6%)376 (4.9%)42 (0.5%)
20258,0834,749 (58.8%)1,468 (18.2%)741 (10.1%)691 (9.2%)390 (4.8%)45 (0.6%)
20308,4254,887 (58.0%)1,634 (19.4%)736 (8.7%)717 (8.5%)403 (4.8%)47 (0.6%)
20358,7434,997 (57.2%)1,812 (20.7%)730 (8.3%)739 (8.5%)415 (4.8%)50 (0.6%)
20409,0395,080 (56.2%)1,999 (22.1%)724 (8.0%)757 (8.4%)426 (4.8%)52 (0.6%)
20459,3085,136 (55.2%)2,194 (23.6%)717 (7.7%)771 (8.3%)436 (4.7%)55 (0.6%)
20509,5515,164 (54.1%)2,393 (25.1%)709 (7.4%)782 (8.2%)446 (4.7%)57 (0.6%)
20559,7665,168 (52.9%)2,595 (26.6%)700 (7.2%)788 (8.1%)456 (4.7%)59 (0.6%)
20609,9575,152 (51.7%)2,797 (28.1%)691 (6.9%)791 (7.9%)465 (4.7%)61 (0.6%)
206510,1275,120 (50.6%)2,998 (29.6%)681 (6.7%)791 (7.8%)474 (4.7%)63 (0.6%)
207010,2775,075 (49.4%)3,195 (31.1%)673 (6.5%)788 (7.6%)482 (4.7%)64 (0.6%)
207510,4095,019 (48.2%)3,387 (32.5%)665 (6.4%)783 (7.5%)490 (4.7%)66 (0.6%)
208010,5244,957 (47.1%)3,570 (33.9%)659 (6.3%)776 (7.4%)496 (4.7%)67 (0.6%)
208510,6264,894 (46.1%)3,742 (35.2%)653 (6.1%)767 (7.2%)502 (4.7%)68 (0.6%)
209010,7174,833 (45.1%)3,903 (36.4%)649 (6.1%)757 (7.1%)506 (4.7%)69 (0.6%)
209510,7944,773 (44.2%)4,051 (37.6%)644 (6.0%)747 (6.9%)510 (4.7%)69 (0.6%)
210010,8544,712 (43.4%)4,185 (38.6%)639 (5.9%)736 (6.8%)513 (4.7%)70 (0.6%)

Population growth by region[edit]

The table below shows historical and predicted regional population figures in millions.[105][108][109] The availability of historical population figures varies by region.

World historical and predicted populations (in millions)[110][111]
Latin America and the Caribbean[Note 1]39101016243874167511577590603809912
Northern America[Note 1]332272682172307337345351392398
World historical and predicted populations by percentage distribution[110][111]
Latin America and the Caribbean[Note 1]
Northern America[Note 1]

Note: in the table below, the figures for North America only refer to post-European contact settlers, and not native populations from before European settlement.

Estimated world and regional populations at various dates (in millions)
YearWorldAfricaAsiaEuropeLatin America[Note 1]Northern AmericaOceaniaNotes
70,000 BC< 0.015[112]
10,000 BC1
9000 BC3
8000 BC5[113]
7000 BC7
6000 BC10
5000 BC15
4000 BC20
3000 BC25
2000 BC35
1000 BC50[113]
500 BC100[113]
AD 1200[114]
20106,9721,0224,25273258035135.6[citation needed]
  1. ^ a b c d e Northern America comprises the northern-most countries and territories of North America: Canada, the United States, Greenland, Bermuda, and St. Pierre and Miquelon. Latin America comprises Mexico, Central America, the Caribbean and South America.

Mathematical approximations[edit]

In 1975, Sebastian von Hoerner proposed a formula for population growth which represented hyperbolic growth with an infinite population in 2025.[116] 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.[117] The transition from hyperbolic growth to slower rates of growth is related to the demographic transition.

According to Sergei Kapitsa,[118] the world population grew between 67,000 BC and 1965 according to the following formula:

 N = \frac{C}{\tau} \arccot \frac{T_0-T}{\tau}


Years for world population to double[edit]

Using linear interpolation and extrapolation of UNDESA population estimates, the world population has doubled, or will double, in the following years (with two different starting points). Note how, during the 2nd millennium, each doubling took roughly half as long as the previous doubling, fitting the hyperbolic growth model mentioned above. However, after 2025 it is unlikely that there will be another doubling of the global population in the 21st century.[119]

Historic chart showing the periods of time the world population has taken to double, from 1700 to 2000.
Starting at 500 million
(in billions)
Years elapsed3041234751
Starting at 375 million
(in billions)
Years elapsed5441667939


Main article: Human overpopulation

Predictions of scarcity[edit]

Greater Los Angeles lies on a coastal desert that is able to support at most 1 million people on its own water; as of 2014, it has a population of over 18 million.

In his 1798 work An Essay on the Principle of Population, as it affects the future improvement of society with remarks on the speculations of Mr. Godwin, M. Condorcet, and other writers; the British scholar Thomas Malthus incorrectly predicted that continued population growth would exhaust the global food supply by the mid-19th century. The essay was written to refute what Malthus called, the unattainable Utopian ideas of William Godwin and Marquis de Condorcet; presented in Political Justice and The Future Progress of the Human Mind. In 1968, Paul R. Ehrlich reprised this argument in The Population Bomb, predicting that mass global famine would occur in the 1970s and 1980s.[120] 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%.[121] 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.[122] However, neo-Malthusians point out that the energy for the Green Revolution was provided by fossil fuels, 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 could potentially have global repercussions.[123]

Graph of the global human population from 10,000 BC to 2000 AD, from the US Census Bureau. The graph shows the extremely rapid growth in the world population that has taken place since the 18th century.

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),[124] global population growth,[125] the effects of climate change,[126] the loss of agricultural land to residential and industrial development,[127][128] and growing consumer demand in the population centres of China and India.[129][130] Food riots subsequently occurred in some countries.[131][132] However, oil prices then fell sharply, and remained below $100/barrel until around 2010. 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.[133][134]

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 2013 is over 310 million.[135] 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" by 2030. Beddington claimed that food reserves were at a fifty-year low, and that the world would require 50% more energy, food and water by 2030.[136][137] According to a 2009 report by the United Nations Food and Agriculture Organisation (FAO), the world will have to produce 70% more food by 2050 to feed a projected extra 2.3 billion people.[138]

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.[139] The 2009 FAO estimates showed an even more dramatic increase, to 1.02 billion.[140]

Environmental impacts[edit]

Illegal slash-and-burn agriculture in Madagascar, 2010.

A number of scientists have argued that the current global population expansion and accompanying increase in resource consumption threatens the world's ecosystem, as well as straining humanity's ability to feed itself.[141][142] The InterAcademy Panel Statement on Population Growth, which was ratified by 58 member national academies in 1994, called the growth in human numbers "unprecedented", and stated that many environmental problems, such as rising levels of atmospheric carbon dioxide, global warming, and pollution, were aggravated by the population expansion.[143] Indeed, some analysts claim that overpopulation's most serious impact is its effect on the environment.[15] 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.

Population control[edit]

India is anticipated to overtake China as the world's most populous country by the mid-21st century.

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,[144] with religious organizations such as the Roman Catholic Church explicitly opposing any intervention in the human reproductive process.[145]

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."[146] 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.[147]

Overpopulation as a myth[edit]

Some scientists, religious commentators and public policy analysts have criticised predictions of overpopulation and attendant resource scarcity, with some describing overpopulation as a "myth".[148] They argue that advances in agricultural, medical and industrial technology have allowed global economic productivity to keep pace with rising populations despite Malthusian predictions to the contrary, and point out that family sizes are naturally declining worldwide due to higher living standards and better economic opportunities for women.[149][150] Some identify individual overconsumption as a greater threat to world resources than population growth.[150]

Number of humans who have ever lived[edit]

Further information: Paleodemography

An estimate of the total number of humans who have ever lived was prepared by Carl Haub of the nonprofit Population Reference Bureau in 1995, and was subsequently updated in 2002 and 2011; the 2011 figure was approximately 107 billion.[151][152][153] 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".[152] Various estimates published in the first decade of the 21st century give figures ranging from approximately 100 billion to 115 billion.

Estimation methodologies[edit]

An accurate estimate of the number of humans who have ever lived is difficult to produce for numerous reasons. Firstly, the set of specific characteristics that define a "human" is a matter of definition, and it is open to debate which members of early Homo sapiens and earlier or related species of Homo to include in the estimate (see also Sorites paradox). Even if the scientific community reached a broad consensus regarding which characteristics distinguished human beings, it would be nearly impossible to pinpoint the time of their first appearance to even the nearest millennium, due to the scarcity of fossil evidence. However, the very small size of the world population in prehistoric times (as compared to its current size) makes this uncertainty of limited importance.

More importantly, robust population data only exist 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 Persian Empire, the focus was on counting merely a subset of the population for purposes of taxation or military service.[154] Thus, there is a significant margin of error when estimating ancient global populations.

Another critical factor for such an estimate is life expectancy, which depends significantly on infant mortality rates; these figures are very difficult to estimate for ancient times. Haub's numbers suggest that around 40% of those who have ever lived did not survive beyond their first birthday.[152] Haub also stated that "life expectancy at birth probably averaged only about ten years for most of human history".[152]

See also[edit]


  1. ^ The Antarctic Treaty System limits the nature of national claims in Antarctica. Of the territorial claims in Antarctica, the Ross Dependency has the largest population.
  2. ^ Figure refers to Mainland China only. It excludes Taiwan and the special administrative regions of Hong Kong and Macau.


  1. ^ a b c "U.S. Census Bureau – World POPClock Projection". July 2012–July 2013 data.  The number on this page is automatically updated daily.
  2. ^ "World Population Clock – Worldometers". Retrieved April 12, 2012. 
  3. ^ a b "Population seven billion: UN sets out challenges". BBC. October 26, 2011. Retrieved October 27, 2011. 
  4. ^ a b Coleman, Jasmine (October 31, 2011). "World's 'seven billionth baby' is born". The Guardian (London). Retrieved October 31, 2011. 
  5. ^ a b "7 billion people is a 'serious challenge'". UPI. October 31, 2011. Retrieved November 9, 2011.
  6. ^ Jean-Noël Biraben (1980), "An Essay Concerning Mankind's Evolution". Population, Selected Papers. Vol. 4. pp. 1–13. Original paper in French: (b) Jean-Noël Biraben (1979)."Essai sur l'évolution du nombre des hommes". Population. Vol. 34 (no. 1). pp. 13–25.
  7. ^ "Exponential Population Growth". Kivu. May 10, 2012. Retrieved July 22, 2013. 
  8. ^ World Population Prospects, 2010 revision (686 million births from 1985–1990). United Nations. Retrieved February 14, 2013.[dead link]
  9. ^ "World Population estimates by the US Census Bureau". USCB. Retrieved May 22, 2012. [dead link]
  10. ^ "World Population Prospects, the 2012 Revision – "Low variant" and "High variant" values". UN. 2012. Retrieved June 15, 2013. 
  11. ^ "World population projected to reach 9.6 billion by 2050 – UN report". UN News Centre. June 14, 2013. Retrieved June 16, 2013. 
  12. ^ a b Key Findings (PDF). "Long-Range Population Projections". Proceedings of the United Nations Technical Working Group on Long-Range Population Projections (New York: United Nations: Department of Economic and Social Affairs). 2003. Retrieved July 3, 2010. 
  13. ^ "A model predicts that the world's populations will stop growing in 2050". April 4, 2013. Retrieved June 3, 2013. 
  14. ^ Peter P. Rogers, Kazi F. Jalal and John A. Boyd (2008). An Introduction To Sustainable Development. Earthscan. p.53.
  15. ^ a b "Overpopulation's Real Victim Will Be the Environment". TIME. October 26, 2011. Retrieved February 18, 2013.
  16. ^ Zehner, Ozzie (2012). Green Illusions. Lincoln and London: University of Nebraska Press. pp. 187–331. 
  17. ^ CO2 Emissions from Fuel Combustion. Population 1971–2008 (PDF, pp. 83–85). IEA (OECD/World Bank). Retrieved July 9, 2013.
  18. ^ "World Population Prospects: The 2010 Revision Population Database". United Nations. April 15, 2011. Retrieved April 21, 2012. 
  19. ^ "Life on an Antarctic Station". Antarctic Connection. Retrieved October 28, 2011.
  20. ^ Excluding its Special Administrative Regions (SARs) of Hong Kong and Macau.
  21. ^ Including Central America and Caribbean
  22. ^ Antarctica. CIA World Factbook. March 2011 data. Retrieved December 24, 2011.
  23. ^ "Life Expectancy in the Paleolithic". 2010. Retrieved July 10, 2013. 
  24. ^ Luc-Normand Tellier (2009). "Urban world history: an economic and geographical perspective". PUQ. p.26. ISBN 2-7605-1588-5
  25. ^ "Population estimates of the Roman Empire". Dr. Kenneth W. Harl. 1998. Retrieved December 8, 2012.
  26. ^ "Plague, Plague Information, Black Death Facts, News, Photos". National Geographic. Retrieved November 3, 2008. 
  27. ^ "History of Europe – Demographic and agricultural growth". Encyclopædia Britannica. 2012. Retrieved December 17, 2012.
  28. ^ "Historical Estimates of World Population". Retrieved November 3, 2008. 
  29. ^ "A Distant Mirror". TIME Europe. July 17, 2000. Vol. 156 No. 3. Retrieved July 9, 2013.
  30. ^ Horst R. Thieme (2003). "Mathematics in population biology". Princeton University Press. p.285. ISBN 0-691-09291-5.
  31. ^ Graziella Caselli, Gillaume Wunsch, Jacques Vallin (2005). "Demography: Analysis and Synthesis, Four Volume Set: A Treatise in Population". Academic Press. p.34. ISBN 0-12-765660-X.
  32. ^ "Qing China's Internal Crisis: Land Shortage, Famine, Rural Poverty". 2009. Columbia University: Asia for Educators. Retrieved July 9, 2013.
  33. ^ "History of Europe – Demographics". Encyclopædia Britannica. Retrieved July 9, 2013.
  34. ^ "China's Population: Readings and Maps". Columbia University: East Asian Curriculum Project. Retrieved December 18, 2012.
  35. ^ "The Columbian Exchange". University of North Carolina. Retrieved December 18, 2012.
  36. ^ "Super-Sized Cassava Plants May Help Fight Hunger In Africa". Ohio State University. May 24, 2006. Retrieved July 9, 2013.
  37. ^ Albert Schweitzer: a biography. James Brabazon (2000). Syracuse University Press. p.242. ISBN 0-8156-0675-3.
  38. ^ S. Chandrasekhar (2013). Infant Mortality, Population Growth and Family Planning in India: An Essay on Population Problems and International Tensions. Routledge. ISBN 1136883061. pp. 24.7
  39. ^ Maheshwari, Shriram (1996), The Census Administration Under the Raj and After, Concept Publishing Company ISBN 817022585X pp. 14
  40. ^ J. N. Hays (1998). The burdens of disease: epidemics and human response in western history. p 72. ISBN 0-8135-2528-4.
  41. ^ "Microchronology and Demographic Evidence Relating to the Size of Pre-Columbian North American Indian Populations". Science. June 16, 1995. Retrieved July 9, 2013.
  42. ^ Arthur C. Aufderheide, Conrado Rodríguez-Martín, Odin Langsjoen (1998). The Cambridge encyclopedia of human paleopathology. Cambridge University Press. p.205. ISBN 0-521-55203-6.
  43. ^ "The Story Of... Smallpox – and other Deadly Eurasian Germs". Public Broadcasting Service (PBS). 2005. Retrieved April 24, 2013.
  44. ^ Austin Alchon, Suzanne (2003). A pest in the land: new world epidemics in a global perspective. University of New Mexico Press. p. 31. ISBN 0-8263-2871-7. 
  45. ^ World Demographics Profile 2012. Index Mundi. Retrieved May 22, 2012.
  46. ^ "By 2050, 70% of the world's population will be urban. Is that a good thing?" Fast Co. Design. 2012. Retrieved May 1, 2012.
  47. ^ "Population crises and cycles in history". A review of Population Crises and Population Cycles by Claire Russell and W.M.S. Russell.
  48. ^ Buer, Mabel C. (1926). Health, Wealth and Population in the Early Days of the Industrial Revolution. London: George Routledge & Sons. p. 30. ISBN 0-415-38218-1. 
  49. ^ "The Foundling Hospital". BBC History. Updated October 5, 2012. Retrieved April 22, 2013.
  50. ^ "Modernization – Population Change". Encyclopædia Britannica. Retrieved February 6, 2013.
  51. ^ Graziella Caselli, Gillaume Wunsch, Jacques Vallin (2005). "Demography: Analysis and Synthesis, Four Volume Set: A Treatise in Population". Academic Press. p.42. ISBN 0-12-765660-X.
  52. ^ History – Victorian Medicine – From Fluke to Theory. BBC. February 1, 2002. Retrieved February 17, 2013.
  53. ^ "A portrait of Britain in 2031". The Independent. October 24, 2007. Retrieved February 17, 2013.
  54. ^ "UK population breaks through 60m". BBC. August 24, 2006. Retrieved April 14, 2012.
  55. ^ "US population through history". Retrieved April 14, 2012.
  56. ^ Mark Harrison (2002). "Accounting for War: Soviet Production, Employment, and the Defence Burden, 1940–1945". Cambridge University Press. p.167. ISBN 0-521-89424-7
  57. ^ "Vladimir Putin vows to reverse Russian population decline". The Daily Telegraph. February 13, 2012. Retrieved April 13, 2012.
  58. ^ "Russia’s Population Decline Said To Have 'Stopped'". Radio Free Europe. May 27, 2013. Retrieved June 15, 2013. 
  59. ^ "China's demographic evolution 1850–1953 reconsidered". The China Quarterly via JSTOR. 1978. Retrieved April 13, 2012.
  60. ^ "Reintegrating India with the World Economy" (PDF). Peterson Institute for International Economics. 2003. Retrieved November 8, 2012.
  61. ^ India. CIA World Factbook. July 2012 estimate. Retrieved October 21, 2012.
  62. ^ Java (island, Indonesia). Encyclopædia Britannica. Retrieved July 7, 2013.
  63. ^ Jorge Durand. "From Traitors to Heroes: 100 Years of Mexican Migration Policies". University of Guadalajara. March 2004. Retrieved July 16, 2013.
  64. ^ "Population and Housing Census: Mexico 2010" (PDF). University of Minnesota. March 3, 2011. Retrieved July 16, 2013. 
  65. ^ Gunnar Heinsohn. "Kenya's Violence: Exploding population". The New York Times. January 7, 2008. Retrieved July 7, 2013.
  66. ^ "The World at Six Billion: Introduction" (PDF). United Nations. 1999. Retrieved July 14, 2013. 
  67. ^ a b
  68. ^ a b "Total fertility estimates, 1950–2010". UN Population Division. April 2011. Retrieved June 14, 2012. 
  69. ^ "World Population Prospects, the 2008 Revision – Frequently Asked Questions". Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat. Updated November 10, 2010. Retrieved January 26, 2010.
  70. ^ a b c d e f g "World Demographics Profile 2011". Index Mundi. Retrieved November 18, 2011. 
  71. ^ "Sex-ratio imbalance in Asia: Trends, consequences and policy responses" (PDF). UNFPA. 2007. Retrieved May 20, 2012. 
  72. ^ Janneh, Abdoulie (April 2012). "General debate on national experience in population matters: adolescents and youth" (PDF). United Nations Economic Commission for Africa. Retrieved February 19, 2014. 
  73. ^ "Global weight gain more damaging than rising numbers". BBC. June 18, 2012. Retrieved February 12, 2013. 
  74. ^ "World". CIA World Factbook. 2013. Retrieved July 6, 2013. 
  75. ^ "What It Will Take to 'Graduate' 1.2 Billion People Out of Extreme Poverty". Huffington Post. April 4, 2012. Retrieved April 26, 2012.
  76. ^ Food and Agriculture Organization of the United Nations, The State of Food Insecurity in the World. 2012. Retrieved April 26, 2012.
  77. ^ Internet World Stats. June 2012 data. Retrieved July 6, 2013.
  78. ^ "World’s Most Typical Person: Han Chinese Man". Wall Street Journal. March 4, 2011. Retrieved November 18, 2011.
  79. ^ Religions by adherents. 2005 data. Retrieved December 19, 2011.
  80. ^ Chinese Official Population Clock (in Chinese). Updated daily. Retrieved May 22, 2012.
  81. ^ Indian population clock
  82. ^ United States Official Population Clock. USCB. Updated daily. Retrieved May 22, 2012.
  83. ^ "2010 Population Census (PowerPoint)". February 28, 2012. Retrieved November 13, 2012. 
  84. ^ Official estimate
  85. ^ Official Pakistani Population Clock. Population Census Organization of Pakistan. Retrieved November 15, 2012.
  86. ^ UN estimate based on 2012 publication
  87. ^ Official estimate
  88. ^ Official estimate
  89. ^ Official Japan Statistics Bureau
  90. ^ Official population clock Retrieved Nov 15, 2013 12:00
  91. ^ a b Demetriou, Danielle (April 17, 2013). "Japan's population suffers biggest fall in history". Daily Telegraph (London). Retrieved July 22, 2013. 
  92. ^ Official Estimates
  93. ^ "Why Has Taiwan's Birthrate Dropped So Low?" TIME. December 7, 2009. Retrieved December 17, 2011.
  94. ^ "Taiwan Birth Rate Falls to World’s Lowest". Voice of America. August 17, 2011. Retrieved December 17, 2011.
  95. ^ "Fewer people move to Holland as the population growth slows". February 7, 2013. Retrieved July 23, 2013. 
  96. ^ "The limits of a Green Revolution?". BBC. March 29, 2007. Retrieved August 1, 2010. 
  97. ^ "The Real Green Revolution". Archived from the original on June 23, 2008. Retrieved August 1, 2010. 
  98. ^ World Population to 2300 (PDF). Economic and Social Affairs (United Nations). 2004. Retrieved June 16, 2013.
  99. ^ "International Programs". USCB. January 7, 2009. Retrieved December 16, 2012. 
  100. ^ Ron Nielsen (2006). The little green handbook. Picador (New York). ISBN 0-312-42581-3.
  101. ^ "2006 report highlights" (PDF). United Nations. Retrieved August 1, 2010. 
  102. ^ "UN population estimates and projections, database query, August 2009". United Nations. March 11, 2009. Retrieved August 1, 2010. 
  103. ^ Randers, Jorgen (2012). 2052: A Global Forecast for the Next Forty Years. Vermont: Chelsea Green Publishing. p. 62.
  104. ^ "Notes on the World POPClock and World Vital Events". US Census Bureau. Retrieved February 12, 2013. 
  105. ^ a b "World Population Prospects: The 2008 Revision" (PDF). Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat. June 2009. Retrieved June 20, 2013. 
  106. ^ a b "World Population Prospects: The 2012 Revision" (XLS). Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat. June 2013. Retrieved August 7, 2013. 
  107. ^ "World Population – Total Midyear Population for the World: 1950–2050". June 2012. Retrieved August 12, 2013. 
  108. ^ "The World at Six Billion". United Nations. October 12, 1999. Retrieved August 1, 2010. 
  109. ^ "Population Growth over Human History". University of Michigan. January 4, 2006. Retrieved March 9, 2013. 
  110. ^ a b Figures include the former Soviet countries in Europe. Caselli, Graziella; Gillaume Wunsch, Jacques Vallin (December 20, 2005). Demography: Analysis and Synthesis, Four Volume Set: A Treatise in Population. Academic Press. p. 42. ISBN 978-0-12-765660-1. 
  111. ^ a b "UN report – 2004 data" (PDF). Retrieved August 1, 2010. 
  112. ^ Fewer than 15,000 individuals, according to the Toba catastrophe theory. See: "Humans lived in tiny, separate bands for 100,000 years". Retrieved February 12, 2013.
  113. ^ a b c an average of figures from different sources as listed at the US Census Bureau's Historical Estimates of World Population; see also *Kremer, Michael (1993). "Population Growth and Technological Change: One Million B.C. to 1990" in The Quarterly Journal of Economics 108(3): 681–716.
  114. ^ The range of figures from different sources as listed at the US Census Bureau's Historical Estimates of World Population put the world population in AD 1 between 170 million and 400 million.
  115. ^ Sebastien von Hoerner (1975). "Population Explosion and Interstellar Expansion". Journal of the British Interplanetary Society (28): 691–712. 
  116. ^ Introduction to Social Macrodynamics. Andrey Korotayev et al.. For a rigorous mathematical analysis of this issue, see "A Compact Mathematical Model of the World System Economic and Demographic Growth, 1 CE – 1973 CE".
  117. ^ Sergei P. Kapitsa. "The phenomenological theory of world population growth." Physics-Uspekhi 39(1) 57–71 (1996). Retrieved July 26, 2013.
  118. ^ "Letters to Nature: Doubling of world population unlikely". Nature. June 19, 1997. Retrieved October 23, 2012.
  119. ^ Jowit, Juliette (October 23, 2011). "Paul Ehrlich, a prophet of global population doom who is gloomier than ever". The Guardian (London). Retrieved July 22, 2013. 
  120. ^ Kindall, Henery W & Pimentel, David (May 1994). "Constraints on the Expansion of the Global Food Supply". Ambio. 23 (3). 
  121. ^ "The limits of a Green Revolution?". BBC News. March 29, 2007. Retrieved February 18, 2013.
  122. ^ "Host Plant Resistance and Conservation of Genetic Diversity". Radcliffe's IPM World Textbook. University of Minnesota. Updated March 2013. Retrieved July 20, 2013. 
  123. ^ "The global grain bubble". Christian Science Monitor. January 18, 2008. Retrieved February 18, 2013. 
  124. ^ James Randerson, science correspondent (March 7, 2008). "Food crisis will take hold before climate change, warns chief scientist". The Guardian (London). Retrieved February 18, 2013. 
  125. ^ John Vidal, environment editor (November 3, 2007). "Global food crisis looms as climate change and fuel shortages bite". The Guardian (London). Retrieved February 18, 2013. 
  126. ^ Walsoft (February 22, 2008). "Experts: Global Food Shortages Could ‘Continue for Decades'". Retrieved February 18, 2013. 
  127. ^ Moya K. Mason. "Has Urbanization Caused a Loss to Agricultural Land?". Retrieved July 9, 2013. 
  128. ^ Walt, Vivienne (February 27, 2008). "The World's Growing Food-Price Crisis". Time. Retrieved February 18, 2013. 
  129. ^ "The cost of food: Facts and figures". BBC. October 16, 2008. Retrieved February 18, 2013.
  130. ^ Julian Borger (February 26, 2008). "Feed the world? We are fighting a losing battle, UN admits". The Guardian (London). Retrieved February 18, 2013. 
  131. ^ Buchanan, Emily (April 22, 2008). "Assessing the global food crisis". BBC. Retrieved April 6, 2010. 
  132. ^ "Half of all food 'wasted' report claims". BBC. January 10, 2013. Retrieved January 10, 2013. 
  133. ^ "Oil shock could push world food prices higher". CNN Money. March 3, 2011. Retrieved February 18, 2013.
  134. ^ P. Crabbè (2000). North Atlantic Treaty Organization. Scientific Affairs Division (2000). Implementing ecological integrity: restoring regional and global environmental and human health. Springer. p.411. ISBN 0-7923-6351-5.
  135. ^ "World faces 'perfect storm' of problems by 2030, chief scientist to warn". The Guardian. March 18, 2009. Retrieved February 18, 2013.
  136. ^ "Global crisis 'to strike by 2030'". BBC. March 19, 2009. Retrieved February 18, 2013.
  137. ^ "Global food production will have to increase 70% for additional 2.3 billion people by 2050". September 24, 2009. Retrieved February 18, 2013.
  138. ^ Food and Agriculture Organization Economic and Social Development Department. “The State of Food Insecurity in the World, 2008: High food prices and food security – threats and opportunities”. Food and Agriculture Organization of the United Nations. 2008. p. 2. Retrieved December 8, 2012.
  139. ^ “One sixth of humanity undernourished – more than ever before”. Food and Agriculture Organization of the United Nations. 2009. Retrieved December 8, 2012.
  140. ^ "Ecological Debt Day". Retrieved February 18, 2013. 
  141. ^ "Planetary Boundaries: Specials". Nature. September 23, 2009. Retrieved February 18, 2013. 
  142. ^ IAP (login required). Retrieved February 18, 2013.
  143. ^ Some population control programs, such as China's one-child policy, entail the use of forced late-term abortions, sparking domestic anger and international condemnation: "China one-child policy leads to forced abortions, mothers' deaths". Los Angeles Times. June 15, 2012. Retrieved August 29, 2012.
  144. ^ "Fighting poverty to build peace". Vatican. January 1, 2009. Retrieved October 24, 2011.
  145. ^ Zehmer, Ozzie (2012). Green lllusions. Lincoln and London: University of Nebraska. p. 188. 
  146. ^ Connelly, Matthew (2008). Fatal Misconception: The Struggle to Control World Population. Harvard University Press via Google Books. 
  147. ^ "Debunking the Myth of Overpopulation". Population Research Institute. 2013. Retrieved 19 February 2014. 
  148. ^ Ellis, Erle C. (13 September 2013). "Overpopulation Is Not the Problem". New York Times. Retrieved 19 February 2014. 
  149. ^ a b "The overpopulation myth". Prospect. 8 March 2010. Retrieved 19 February 2014. 
  150. ^ Curtin, Ciara (March 1, 2007). "Fact or Fiction?: Living People Outnumber the Dead". Scientific American (Scientific American, Inc., published September 2007) 297 (3): 126. doi:10.1038/scientificamerican0907-126. Retrieved August 4, 2008.  Note: text of paper publication slightly different from text of on-line publication
  151. ^ a b c d Haub, Carl (November–December 2002). "How Many People Have Ever Lived on Earth?" (PDF). Population Today (Population Reference Bureau) 30 (8): 3–4. Retrieved August 4, 2008. 
  152. ^ Haub, Carl (October 2011). "How Many People Have Ever Lived on Earth?". Population Reference Bureau. Retrieved April 29, 2013. 
  153. ^ Kuhrt, A. (1995). The Ancient Near East, c. 3000–330 BC. Vol. 2. London: Routledge. p. 695.

External links[edit]

Further reading
Statistics and maps
Population clocks