# World population

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In demographics, the world population is the total number of humans currently living, and was estimated to have reached 7,800,000,000 people as of March 2020. [2] [3] It took over 2 million years of human prehistory and history for the world's population to reach 1 billion, [4] and only 200 years more to reach 7 billion. [5]

## Contents

The world population has experienced continuous growth following the Great Famine of 1315–1317 and the end of the Black Death in 1350, when it was near 370 million. [6] The highest global population growth rates, with increases of over 1.8% per year, occurred between 1955 and 1975 peaking at 2.1% between 1965 and 1970. [7] The growth rate declined to 1.2% between 2010 and 2015 and is projected to decline further in the course of the 21st century. [7]

The global population is still increasing, but there is significant uncertainty about its long-term trajectory due to changing rates of fertility and mortality. [8] The UN Department of Economics and Social Affairs projects between 9-10 billion people by 2050, and gives an 80% confidence interval of 10-12 billion by the end of the 21st century. [9]

Total annual births were highest in the late 1980s at about 139 million, [10] and as of 2011 were expected to remain essentially constant at a level of 135 million, [11] while deaths numbered 56 million per year and were expected to increase to 80 million per year by 2040. [12] The median age of the world's population was estimated to be 30.4 years in 2018. [13]

World population (millions, UN estimates) [14]
#Top ten most populous countries200020152030 [upper-alpha 1]
1 China [upper-alpha 2] 1,2701,3761,416
2 India 1,0531,3111,528
3 United States 283322356
4 Indonesia 212258295
5 Pakistan 136208245
6 Brazil 176206228
7 Nigeria 123182263
9 Russia 146146149
10 Mexico 103127148
World total6,1277,3498,501
Notes:
1. 2030 = Medium variant.
2. China excludes Hong Kong and Macau.

## Population by region

Six of the Earth's seven continents are permanently inhabited on a large scale. Asia is the most populous continent, with its 4.64 billion inhabitants accounting for 60% of the world population. The world's two most populated countries, China and India, together constitute about 36% of the world's population. Africa is the second most populated continent, with around 1.34 billion people, or 17% of the world's population. Europe's 747 million people make up 10% of the world's population as of 2020, while the Latin American and Caribbean regions are home to around 653 million (8%). North America, primarily consisting of the United States and Canada, has a population of around 368 million (5%), and Oceania, the least populated region, has about 42 million inhabitants (0.5%). [15] Antarctica only has a very small, fluctuating population of about 1200 people based mainly in polar science stations. [16]

### Population by continent

Population by continent (2020 estimates)
ContinentDensity
(inhabitants/km2)
Population
(millions)
Most populous countryMost populous city (metropolitan area)
Asia104.14,6411,439,323,000 [note 1]   China 37,393,000/13,929,000 Greater Tokyo Area/Tokyo Metropolis
Africa44.41,340206,139,000   Nigeria 20,900,000 Cairo [17]
Europe73.4747145,934,000   Russia;
approx. 110 million in Europe
16,855,000/12,537,000 Moscow metropolitan area/Moscow [18]
Latin America 24.1653212,559,000   Brazil 22,043,000/12,176,000 São Paulo Metro Area/São Paulo City
Northern America [note 2] 14.9368331,002,000   United States 23,724,000/8,323,000 New York metropolitan area/New York City
Oceania 54225,499,000   Australia 4,925,000 Sydney
Antarctica ~00.004 [16] N/A [note 3] 1,258 McMurdo Station

## History

Estimates of world population by their nature are an aspect of modernity, possible only since the Age of Discovery. Early estimates for the population of the world [19] date to the 17th century: William Petty in 1682 estimated world population at 320 million (modern estimates ranging close to twice this number); by the late 18th century, estimates ranged close to one billion (consistent with modern estimates). [20] More refined estimates, broken down by continents, were published in the first half of the 19th century, at 600 million to 1 billion in the early 1800s and at 800 million to 1 billion in the 1840s. [21]

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]

### Ancient and post-classical history

Estimates of the population of the world at the time agriculture emerged in around 10,000 BC have ranged between 1 million and 15 million. [23] [24] Even earlier, genetic evidence suggests humans may have gone through a population bottleneck of between 1,000 and 10,000 people about 70,000 BC, according to the Toba catastrophe theory. 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 of Justinian, which first emerged during the reign of the Roman 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 200 years for population figures to recover. [29] The population of China decreased from 123 million in 1200 to 65 million in 1393, [30] presumably from a combination of Mongol invasions, famine, and plague. [31]

Starting in AD 2, the Han Dynasty of ancient China kept consistent family registers in order to properly assess the poll taxes and labor service duties of each household. [32] In that year, the population of Western Han was recorded as 57,671,400 individuals in 12,366,470 households, decreasing to 47,566,772 individuals in 9,348,227 households by AD 146, towards the End of the Han Dynasty. [32] 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. [33] England's population reached an estimated 5.6 million in 1650, up from an estimated 2.6 million in 1500. [34] New crops that were brought to Asia and Europe from the Americas by Portuguese and Spanish colonists in the 16th century are believed to have contributed to population growth. [35] [36] [37] Since their introduction to Africa by Portuguese traders in the 16th century, [38] maize and cassava have similarly replaced traditional African crops as the most important staple food crops grown on the continent. [39]

The pre-Columbian population of the Americas is uncertain; historian David Henige called it "the most unanswerable question in the world." [40] By the end of the 20th century, scholarly consensus favored an estimate of roughly 55 million people, but numbers from various sources have ranged from 10 million to 100 million. [41] Encounters between European explorers and populations in the rest of the world often introduced local epidemics of extraordinary virulence. [42] According to the most extreme scholarly claims, as many as 90% of the Native American population of the New World died of 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 history

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 populated by people of European descent comprised 36% of the world's population in 1900. [51]

Population growth in the West became more rapid after the introduction of vaccination and other improvements in medicine and sanitation. [52] Improved material conditions led to the population of Britain increasing from 10 million to 40 million in the 19th century. [53] 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 Imperial Russia and the Soviet Union was marked by a succession of major wars, famines and other disasters which caused large-scale population losses (approximately 60 million excess deaths). [56] [57] After the collapse of the Soviet Union, Russia's population declined significantly – from 150 million in 1991 to 143 million in 2012 [58] – but by 2013 this decline appeared to have halted. [59]

Many countries in the developing world have experienced extremely rapid population growth since the early 20th century, due to economic development and improvements in public health. China's population rose from approximately 430 million in 1850 to 580 million in 1953, [60] and now stands at over 1.3 billion. The population of the Indian subcontinent, which was about 125 million in 1750, increased to 389 million in 1941; [61] today, India, Pakistan and Bangladesh are collectively home to about 1.63 billion people. [62] Java had about 5 million inhabitants in 1815; its present-day successor, Indonesia, now has a population of over 140 million. [63] In just one hundred years, the population of Brazil decupled (x10), from about 17 million in 1900, or about 1% of the world population in that year, to about 176 million in 2000, or almost 3% of the global population in the very early 21st century. Mexico's population grew from 13.6 million in 1900 to about 112 million in 2010. [64] [65] Between the 1920s and 2000s, Kenya's population grew from 2.9 million to 37 million. [66]

### Milestones by the billions

World population milestones in billions (Worldometers estimates)
Population12345678910
Year1804192719601974198719992011202320372057
Years elapsed1233314131212121420

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. [67] 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. [68] The United Nations, however, estimated that the world population reached seven billion in October 2011. [69] [70] [71]

According to current projections, the global population will reach eight billion by 2024, and is likely to reach around nine billion by 2042. Alternative scenarios for 2050 range from a low of 7.4 billion to a high of more than 10.6 billion. [72] 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. [72] 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. [73] [74]

There is no estimation for the exact day or month the world's population surpassed one or two billion. The points at which it reached three and four billion were not officially noted, but the International Database of the United States Census Bureau placed them in July 1959 and April 1974 respectively. The United Nations did determine, and commemorate, the "Day of 5 Billion" on 11 July 1987, and the "Day of 6 Billion" on 12 October 1999. The Population Division of the United Nations declared the "Day of 7 Billion" to be 31 October 2011. [75] [ needs update ]

## Global demographics

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 sex imbalances evident in the Indian and Chinese populations. [77] [78] 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. [77] The median age of the world's population was estimated to be 29.7 years in 2014, [79] and is expected to rise to 37.9 years by 2050. [80]

According to the World Health Organization, the global average life expectancy is 71.4 years as of 2015, with women living an average of 74 years and men approximately 69 years. [76] In 2010, the global fertility rate was estimated at 2.52 children per woman. [74] In June 2012, British researchers calculated the total weight of Earth's human population as approximately 287 million tonnes, with the average person weighing around 62 kilograms (137 lb). [81]

The CIA estimated nominal 2013 gross world product at US$74.31 trillion, giving an annual global per capita figure of around US$10,500. [82] Around 1.29 billion people (18.4% of the world population) live in extreme poverty, subsisting on less than US$1.25 per day; [83] approximately 870 million people (12.3%) are undernourished. [84] 83% of the world's over-15s are considered literate. [77] In June 2014, there were around 3.03 billion global Internet users, constituting 42.3% of the world population. [85] The Han Chinese are the world's largest single ethnic group, constituting over 19% of the global population in 2011. [86] The world's most-spoken first languages are Mandarin Chinese (spoken by 12.4% of the world's population), Spanish (4.9%), English (4.8%), Arabic (3.3%) and Hindi (2.7%). [77] The world's largest religion is Christianity, whose adherents account for 31.4% of the global population; [87] Islam is the second-largest religion, accounting for 24.1%, and Hinduism the third, accounting for 13.8%. [77] In 2005, around 16% of the global population were reported to be non-religious. [88] ## Largest populations by country ### 10 most populous countries RankCountryPopulation % of worldDateSource (official or UN) 1 China 1,407,751,0401 May 2021National population clock [89] 2 India 1,376,399,0541 May 2021National population clock [90] 3 United States 331,594,3361 May 2021National population clock [91] 4 Indonesia 269,603,4001 Jul 2020National annual projection [92] 5 Pakistan 220,892,3311 Jul 2020UN Projection [93] 6 Brazil 213,075,4351 May 2021National population clock [94] 7 Nigeria 206,139,5871 Jul 2020UN Projection [93] 8 Bangladesh 170,588,5641 May 2021National population clock [95] 9 Russia 146,748,5901 Jan 2020National annual estimate [96] 10 Mexico 127,792,2861 Jul 2020National annual projection [97] Approximately 4.45 billion people live in these ten countries, representing around 57% of the world's population as of September 2020. ### Most densely populated countries The tables below list the world's most densely populated countries, both in absolute terms and in comparison to their total populations. 10 most densely populated countries (with population above 5 million) RankCountryPopulationArea (km2) Density (pop/km2) 1 Singapore 5,704,0007108,033 2 Bangladesh 170,590,000143,9981,185 3 Lebanon 6,856,00010,452656 4 Taiwan 23,604,00036,193652 5 South Korea 51,781,00099,538520 6 Rwanda 12,374,00026,338470 7 Haiti 11,578,00027,065428 8 Netherlands 17,590,00041,526424 9 Israel 9,340,00022,072423 10 India 1,376,400,0003,287,240419 Countries ranking highly in both total population (more than 20 million people) and population density (more than 250 people per square kilometer): RankCountryPopulationArea (km2) Density (pop/km2) Population trend 1 India 1,376,400,0003,287,240419Growing 2 Pakistan 223,480,000803,940278Growing 3 Bangladesh 170,590,000143,9981,185Rapidly growing 4 Japan 126,010,000377,873333Declining [98] 5 Philippines 110,160,000300,000367Growing 6 Vietnam 96,209,000331,689290Growing 7 United Kingdom 66,436,000243,610273Steady 8 South Korea 51,781,00099,538520Steady 9 Taiwan 23,604,00036,193652Steady 10 Sri Lanka 21,803,00065,610332Growing ## Fluctuation 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. 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. A number of factors contributed to this increase, 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. [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] ### Annual population growth Global annual population growth [108] YearPopulationYearly changeDensity (pop/km2) Urban population %NumberNumber% 19512,584,034,2611.88%47,603,11217775,067,69730% 19522,630,861,5621.81%46,827,30118799,282,53330% 19532,677,608,9601.78%46,747,39818824,289,98931% 19542,724,846,7411.76%47,237,78118850,179,10631% 19552,773,019,9361.77%48,173,19519877,008,84232% 19562,822,443,2821.78%49,423,34619904,685,16432% 19572,873,306,0901.80%50,862,80819933,113,16832% 19582,925,686,7051.82%52,380,61520962,537,11333% 19592,979,576,1851.84%53,889,48020992,820,54633% 19603,034,949,7481.86%55,373,563201,023,845,51734% 19613,091,843,5071.87%56,893,759211,055,435,64834% 19623,150,420,7951.89%58,577,288211,088,376,70335% 19633,211,001,0091.92%60,580,214221,122,561,94035% 19643,273,978,3381.96%62,977,329221,157,813,35535% 19653,339,583,5972.00%65,605,259221,188,469,22436% 19663,407,922,6302.05%68,339,033231,219,993,03236% 19673,478,769,9622.08%70,847,332231,252,566,56536% 19683,551,599,1272.09%72,829,165241,285,933,43236% 19693,625,680,6272.09%74,081,500241,319,833,47436% 19703,700,437,0462.06%74,756,419251,354,215,49637% 19713,775,759,6172.04%75,322,571251,388,834,09937% 19723,851,650,2452.01%75,890,628261,424,734,78137% 19733,927,780,2381.98%76,129,993261,462,178,37037% 19744,003,794,1721.94%76,013,934271,501,134,65537% 19754,079,480,6061.89%75,686,434271,538,624,99438% 19764,154,666,8641.84%75,186,258281,577,376,14138% 19774,229,506,0601.80%74,839,196281,616,419,30838% 19784,304,533,5011.77%75,027,441291,659,306,11739% 19794,380,506,1001.76%75,972,599291,706,021,63839% 19804,458,003,5141.77%77,497,414301,754,201,02939% 19814,536,996,7621.77%78,993,248301,804,215,20340% 19824,617,386,5421.77%80,389,780311,854,134,22940% 19834,699,569,3041.78%82,182,762321,903,822,43641% 19844,784,011,6211.80%84,442,317321,955,106,43341% 19854,870,921,7401.82%86,910,119332,007,939,06341% 19864,960,567,9121.84%89,646,172332,062,604,39442% 19875,052,522,1471.85%91,954,235342,118,882,55142% 19885,145,426,0081.84%92,903,861352,176,126,53742% 19895,237,441,5581.79%92,015,550352,233,140,50243% 19905,327,231,0611.71%89,789,503362,290,228,09643% 19915,414,289,4441.63%87,058,383362,347,462,33643% 19925,498,919,8091.56%84,630,365372,404,337,29744% 19935,581,597,5461.50%82,677,737372,461,223,52844% 19945,663,150,4271.46%81,552,881382,518,254,11144% 19955,744,212,9791.43%81,062,552392,575,505,23545% 19965,824,891,9511.40%80,678,972392,632,941,58345% 19975,905,045,7881.38%80,153,837402,690,813,54146% 19985,984,793,9421.35%79,748,154402,749,213,59846% 19996,064,239,0551.33%79,445,113412,808,231,65546% 20006,143,494,0001.31%79,255,000412,868,308,00046% 20016,222,627,0001.29%79,133,000422,933,079,00047% 20026,301,773,0001.27%79,147,000423,001,808,00047% 20036,381,185,0001.26%79,412,000433,071,744,00048% 20046,461,159,0001.25%79,974,000433,143,045,00048% 20056,541,907,0001.25%80,748,000443,215,906,00049% 20066,623,518,0001.25%81,611,000443,289,446,00050% 20076,705,947,0001.24%82,429,000453,363,610,00050% 20086,789,089,0001.24%83,142,000463,439,719,00050% 20096,872,767,0001.23%83,678,000473,516,830,00051% 20106,956,824,0001.22%84,057,000473,594,868,00051% 20117,041,194,0001.21%84,371,000473,671,424,00052% 20127,125,828,0001.20%84,634,000483,747,843,00052% 20137,210,582,0001.19%84,754,000483,824,990,00053% 20147,295,291,0001.17%84,709,000493,902,832,00053% 20157,379,797,0001.16%84,506,000503,981,498,00054% 20167,464,022,0001.14%84,225,000504,060,653,00054% 20177,547,859,0001.12%83,837,000514,140,189,00055% 20187,631,091,0001.10%83,232,000514,219,817,00055% 20197,713,468,0001.08%82,377,000524,299,439,00056% 20207,795,000,0001.05%81,331,000524,378,900,00056% ### 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] Region15001600170017501800185019001950199920082010201220502150 World5856607107919781,2621,6502,5216,0086,7076,8967,0529,7259,746 Africa861141061061071111332217839731,0221,0522,4782,308 Asia2823504115026358099471,4023,7004,0544,1644,2505,2675,561 Europe168170178190203276408547675732738740734517 Latin America [Note 1] 40201016243874167508577590603784912 Northern America [Note 1] 632272682172312337345351433398 Oceania333222613303437385751 World historical and predicted populations by percentage distribution [112] [113] Region15001600170017501800185019001950199920082010201220502150 Africa14.717.314.913.410.98.88.18.813.014.514.815.225.523.7 Asia48.253.057.963.564.964.157.455.661.660.460.460.354.257.1 Europe28.725.825.120.620.821.924.721.711.210.910.710.57.65.3 Latin America [Note 1] 6.83.01.42.02.53.04.56.68.58.68.68.68.19.4 Northern America [Note 1] 1.00.50.30.30.72.15.06.85.25.05.05.04.54.1 Oceania0.50.50.40.30.20.20.40.50.50.50.50.50.60.5 ### Past population 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] YearWorldAfricaAsiaEuropeLatin America & Carib. [Note 1] North America [Note 1] OceaniaNotes 70,000 BC< 0.01500 [116] 10,000 BC4 [117] 8000 BC5 6500 BC5 5000 BC5 4000 BC7 3000 BC14 2000 BC27 1000 BC507339[ citation needed ] 500 BC100146616 AD 12002314128 10004007026950812 150045886243843933 16005801143391111033 17006821064361251023 17507911065021631622 18001,0001076562032473 18501,26211180927638262 19001,65013394740874826 19502,5252291,39454916917212.7 [118] 19552,7582541,53457719318714.2 19603,0182851,68760622120415.8 19653,3223221,87563525421917.5 19703,6823662,12065728823119.7 19754,0614162,37867732624221.5 19804,4404782,62669436525423.0 19854,8535502,89770840626724.9 19905,3106323,20272144728127.0 19955,7357203,47572848729629.1 20006,1278143,71472652731431.1 20056,5209203,94572956432933.4 20106,9301,0444,17073560034436.4 20157,3491,1864,39373863435839.3 Using the above figures, the change in population from 2010 to 2015 was: • World: +420 million • Africa: +142 million • Asia: +223 million • Europe: +3 million • Latin America and Caribbean: +35 million • Northern America: +14 million • Oceania: +2.9 million 1. North America is here defined to include 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. [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] UN (medium variant – 2019 revision) and US Census Bureau (June 2015) estimates [132] [133] YearUN est. (millions) DifferenceUSCB est. (millions) Difference 20056,5426,473 20106,9574156,866393 20157,3804237,256390 20207,7954157,643380 20258,1843908,007363 20308,5493648,341334 20358,8883398,646306 20409,1993118,926280 20459,4822839,180254 20509,7352539,408228 UN 2019 estimates and medium variant projections (in millions) [132] YearWorldAsiaAfricaEuropeLatin America/CaribbeanNorthern AmericaOceania 20006,1443,741 (60.9%)811 (13.2%)726 (11.8%)522 (8.5%)312 (5.1%)31 (0.5%) 20056,5423,978 (60.8%)916 (14.0%)729 (11.2%)558 (8.5%)327 (5.0%)34 (0.5%) 20106,9574,210 (60.5%)1,039 (14.9%)736 (10.6%)591 (8.5%)343 (4.9%)37 (0.5%) 20157,3804,434 (60.1%)1,182 (16.0%)743 (10.1%)624 (8.5%)357 (4.8%)40 (0.5%) 20207,7954,641 (59.5%)1,341 (17.2%)748 (9.6%)654 (8.4%)369 (4.7%)43 (0.6%) 20258,1844,823 (58.9%)1,509 (18.4%)746 (9.1%)682 (8.3%)380 (4.6%)45 (0.6%) 20308,5494,974 (58.2%)1,688 (19.8%)741 (8.7%)706 (8.3%)391 (4.6%)48 (0.6%) 20358,8885,096 (57.3%)1,878 (21.1%)735 (8.3%)726 (8.2%)401 (4.5%)50 (0.6%) 20409,1995,189 (56.4%)2,077 (22.6%)728 (7.9%)742 (8.1%)410 (4.5%)53 (0.6%) 20459,4825,253 (55.4%)2,282 (24.1%)720 (7.6%)754 (8.0%)418 (4.4%)55 (0.6%) 20509,7355,290 (54.3%)2,489 (25.6%)711 (7.3%)762 (7.8%)425 (4.4%)57 (0.6%) 20559,9585,302 (53.2%)2,698 (27.1%)700 (7.0%)767 (7.7%)432 (4.3%)60 (0.6%) 206010,1525,289 (52.1%)2,905 (28.6%)689 (6.8%)768 (7.6%)439 (4.3%)62 (0.6%) 206510,3185,256 (51.0%)3,109 (30.1%)677 (6.6%)765 (7.4%)447 (4.3%)64 (0.6%) 207010,4595,207 (49.8%)3,308 (31.6%)667 (6.4%)759 (7.3%)454 (4.3%)66 (0.6%) 207510,5775,143 (48.6%)3,499 (33.1%)657 (6.2%)750 (7.1%)461 (4.4%)67 (0.6%) 208010,6745,068 (47.5%)3,681 (34.5%)650 (6.1%)739 (6.9%)468 (4.4%)69 (0.7%) 208510,7504,987 (46.4%)3,851 (35.8%)643 (6.0%)726 (6.8%)474 (4.4%)71 (0.7%) 209010,8104,901 (45.3%)4,008 (37.1%)638 (5.9%)711 (6.6%)479 (4.4%)72 (0.7%) 209510,8524,812 (44.3%)4,152 (38.3%)634 (5.8%)696 (6.4%)485 (4.5%)74 (0.7%) 210010,8754,719 (43.4%)4,280 (39.4%)630 (5.8%)680 (6.3%)491 (4.5%)75 (0.7%) ## Mathematical approximations 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: ${\displaystyle N={\frac {C}{\tau }}\operatorname {arccot} {\frac {T_{0}-T}{\tau }}}$ where • N is current population • T is the current year • C = (1.86±0.01)·1011 • T0 = 2007±1 • ${\displaystyle \tau }$ = 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] Starting at 500 million Population (in billions) 0.51248 Year15001804192719742024 Years elapsed3041234750 Starting at 375 million Population (in billions) 0.3750.751.536 Year11711715188119601999 Years elapsed5441667939 ## Overshoot ### Predictions of scarcity 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, 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]

### Environmental impacts

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]

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] According to said study, having one less child would save 24 times more CO
2
e
than living car free.

### Population control

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 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]

## Number of humans who have ever lived

Estimates of the total number of humans who have ever lived range is estimated to be of the order of 100 billion. Such estimates can only be rough approximations; as even modern population estimates are subject to uncertainty of around 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 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. [186] Thus, there is a significant margin of error when estimating ancient global populations. Pre-modern infant mortality rates are another critical factor for such an estimate; these rates 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.

## Notes

1. Excluding its Special Administrative Regions (SARs) of Hong Kong and Macau.
2. Excluding Central America and the Caribbean.
3. 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.

## Related Research Articles

Extreme poverty, deep poverty, abject poverty, absolute poverty, destitution, or penury, is the most severe type of poverty, defined by the United Nations (UN) as "a condition characterized by severe deprivation of basic human needs, including food, safe drinking water, sanitation facilities, health, shelter, education and information. It depends not only on income but also on access to services" Historically, other definitions have been proposed within the United Nations.

India is the second most populated country in the world with nearly a fifth of the world's population. According to the 2019 revision of the World Population Prospects the population stood at 1,352,642,280.

Nigeria is one of the most densely populated countries in Africa, with approximately 200 million people in an area of 923,768 km2 (356,669 sq mi), and is also the country with the largest population in Africa and the seventh largest population in the world.

In biology, a population is a number of all the organisms of the same group or species who live in a particular geographical area and are capable of interbreeding. The area of a sexual population is the area where inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals from other areas.

The United States had an official resident population of 331,449,281 on April 1, 2020, according to the U.S. Census Bureau. This figure includes the 50 states and the District of Columbia but excludes the population of five self-governing U.S. territories as well as several minor island possessions. The United States is the third most populous country in the world. The Census Bureau showed a population increase of 0.75% for the twelve-month period ending in July 2012. Though high by industrialized country standards, this is below the world average annual rate of 1.1%. The total fertility rate in the United States estimated for 2019 is 1.706 children per woman, which is below the replacement fertility rate of approximately 2.1.

A population decline in humans is a reduction in a human population size caused by short term events such as pandemics, wars, famines or other catastrophes, or by long-term demographic trends, as in sub-replacement fertility rate, or persistent emigration. Even though short-term population shocks have caused terrible loss of life and human misery, sometimes lasting several centuries, over the long-term, stretching from prehistory to the present, this planet's human population has continued to grow. However, current events suggest that this long-term trend may be coming to an end. Up until the beginning of the industrial revolution, global population grew very slowly. After about 1800 the growth rate accelerated to a peak of 2.1% annually in 1968; but since then, due to the world-wide collapse of the total fertility rate, it has declined to 1.1% today (2020).

Population ageing is an increasing median age in a population due to declining fertility rates and rising life expectancy. Most countries have rising life expectancy and an ageing population. This is the case for every country in the world except the 18 countries designated as "demographic outliers" by the UN. The aged population is currently at its highest level in human history. The UN predicts the rate of population ageing in the twenty-first century will exceed that of the previous century. The number of people aged 60 years and over has tripled since 1950, reaching 600 million in 2000 and surpassing 700 million in 2006. It is projected that the combined senior and geriatric population will reach 2.1 billion by 2050. Countries vary significantly in terms of the degree and pace of ageing, and the UN expects populations that began ageing later will have less time to adapt to its implications.

An urban area, or built-up area, is a human settlement with a high population density and infrastructure of built environment. Urban areas are created through urbanization and are categorized by urban morphology as cities, towns, conurbations or suburbs. In urbanism, the term contrasts to rural areas such as villages and hamlets; in urban sociology or urban anthropology it contrasts with natural environment. The creation of early predecessors of urban areas during the urban revolution led to the creation of human civilization with modern urban planning, which along with other human activities such as exploitation of natural resources led to a human impact on the environment. "Agglomeration effects" are in the list of the main consequences of increased rates of firm creation since. This is due to conditions created by a greater level of industrial activity in a given region. However, a favorable environment for human capital development would also be generated simultaneously.

Population growth is the increase in the number of individuals in a population. 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.

Figures for the population of Europe vary according to the particular definition of Europe's boundaries. As of 2018, Europe has a total population of over 741 million people. Russia is the most populous country in Europe, with a population of 146 million.

Human overpopulation refers to a human population that is too large to be sustained by its environment in the long term. The idea is usually discussed in the context of world population, though it may also concern regions. Human population growth has in recent centuries become exponential due to changes in technology that reduce mortality. Experts concerned by this trend argue that it results in a level of resource consumption which exceeds the environment's carrying capacity, leading to population overshoot. The subject is often discussed in relation to other population concerns such as demographic push, depopulation, ecological or societal collapse, and human extinction.

The population of Africa has grown rapidly over the past century and consequently shows a large youth bulge, further reinforced by a low life expectancy of below 50 years in some African countries. Total population as of 2020 is estimated at more than 1.341 billion, with a growth rate of more than 2.5% p.a. The total fertility rate for Sub-Saharan Africa is 4.7 as of 2018, the highest in the world according to the World Bank. The most populous African country is Nigeria with over 206 million inhabitants as of 2020 and a growth rate of 2.6% p.a.

Growth of religion is the spread of religions and the increase of religious adherents around the world. Statistics commonly measure the absolute number of adherents, the percentage of the absolute growth per year, and the growth of the number of converts in the world. Such forecasts cannot be validated empirically and remain contentious.

This article lists current estimates of the world population in history. In summary, estimates for the progression of world population since the late medieval period are in the following ranges:

Water scarcity is the lack of fresh water resources to meet the standard water demand. Humanity is facing a water crisis, due to unequal distribution resulting in some very wet and some very dry geographic locations, plus a sharp rise in global freshwater demand in recent decades driven by industry. Water scarcity can also be caused by droughts, lack of rainfall, or pollution. This was listed in 2019 by the World Economic Forum as one of the largest global risks in terms of potential impact over the next decade. It is manifested by partial or no satisfaction of expressed demand, economic competition for water quantity or quality, disputes between users, irreversible depletion of groundwater, and negative impacts on the environment. Two-thirds of the global population live under conditions of severe water scarcity at least 1 month of the year. Half a billion people in the world face severe water scarcity all year round. Half of the world's largest cities experience water scarcity.

Christian population growth is the population growth of the global Christian community. According to a 2011 Pew Research Center survey, there were more than 2.2 billion Christians around the world in 2010, more than three times as many as the 600 million recorded in 1910. However, this rate of growth is slower than the overall population growth over the same time period.

The Earth has a population of 7.8 billion, with an overall population density of .01 people per km2, excluding Antarctica. Nearly two-thirds of the world's population lives in Asia, with more than 2.7 billion in the countries of China and India combined. The world's literacy rate has increased dramatically in the last 40 years, from 66.7% in 1979 to 86.3% today. Lower literacy levels are mostly attributable to poverty. Lower literacy rates are mostly found in South Asia and Sub-Saharan Africa. The world's largest ethnic group is Han Chinese, with Mandarin being the world's most spoken language in terms of native speakers.

Population projections are attempts to show how the human population living today will 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 effect fertility and mortality, and thus population growth.

World population milestones went unnoticed until the 20th century, since there was no reliable data on global population dynamics.

## References

1. "World Development Indicators – Google Public Data Explorer". google.com. Archived from the original on 26 May 2015. Retrieved 4 October 2019.
2. "World Population to Hit Milestone With Birth of 7 Billionth Person". PBS NewsHour. 27 October 2011. Archived from the original on 24 September 2017. Retrieved 11 February 2018.
3. "World population hits 6 billion". 4 March 2004. Archived from the original on 22 February 2018. Retrieved 11 February 2018.
4. 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.
5. "World Population Prospects". esa.un.org. Population Division – United Nations. Archived from the original on 19 September 2016. Retrieved 15 September 2016.
6. Ortiz-Ospina, Esteban; Roser, Max (9 May 2013). "World Population Growth". Our World in Data. Archived from the original on 13 October 2016. Retrieved 13 October 2016.
7. "World Population Prospects". UN.org. 2019. Archived from the original on 11 December 2020. Retrieved 19 January 2021.
8. "World Population Prospects, 2012 revision (697 million births from 1985–1990)". United Nations. 2012. Archived from the original on 27 August 2014. Retrieved 11 May 2015.
9. "Annual number of births – World". United Nations Population Division. 2011. Archived from the original on 3 April 2015. Retrieved 27 March 2015.
10. "World Population estimates by the US Census Bureau". USCB. Archived from the original on 11 January 2012. Retrieved 22 May 2012.
11. male 29.6, female 31.1 years. "CIA, The World Factbook: Field Listing: Median Age". cia.gov. Archived from the original on 5 February 2016. Retrieved 13 May 2018.
12. "World Population Prospects: The 2015 Revision". UN Population Division. Archived from the original on 22 December 2015. Retrieved 19 January 2016.. Linked to at Download Files, where it states that the figures are for 1 July of the given year.
13. "Regions in the world by population (2020)" . Retrieved 5 October 2020.
14. "Antarctica". CIA World Factbook. 19 June 2014. Retrieved 18 March 2015.
15. "World City Populations". Archived from the original on 20 February 2020. Retrieved 26 September 2020.
16. "World City Populations" . Retrieved 26 September 2020.
17. the compound "world population" becomes common from c. the 1930s, adapted from early 20th-century "world's population"; pre-20th century authors use "population of the world".
18. "The population of the world, which Sir W. P. in 1682, stated at only 320 millions, has been estimated by some writers at about 730 millions, by others, at upwards of 900 millions; Mr. Wallace, of Edinburgh, conjectured it might amount to 1 billion, and this number has since generally been adopted who have noticed the subject;" The Monthly Magazine 4 (July–December 1797), p. 167.
19. 600 million: Simon Gray, The Happiness of States (1818), p. 356 Archived 6 June 2019 at the Wayback Machine . 800 million: Gordon Hall, Samuel Newell, The Conversion of the World (1818), p. 10 Archived 6 June 2019 at the Wayback Machine . 800 to 1000 million: John Redman Coxe, Considerations Respecting the Recognition of Friends in Another World (1845), p. 21 (footnote with references).
20. "even recent demographic data is accurate only from 3 to 5%, although in demography traditionally more digits are indicated than those having a meaning. This is partially due to the ethical difficulty in rounding off numbers that supposedly represent real people, officially counted during a census." Sergei P Kapitza, 'The phenomenological theory of world population growth', Physics-Uspekhi 39(1) 57-71 (1996).
21. Luc-Normand Tellier (2009). Urban world history: an economic and geographical perspective. p. 26. ISBN   978-2-7605-1588-8.
22. Ralph Thomlinson, 1975, Demographic Problems: Controversy over population control, 2nd Ed., Dickenson Publishing Company, Ecino, CA, ISBN   0-8221-0166-1.
23. Dr. Kenneth W. Harl (1998). "Population estimates of the Roman Empire". Tulane.edu. Archived from the original on 7 May 2016. Retrieved 8 December 2012.
24. "Plague, Plague Information, Black Death Facts, News, Photos". National Geographic. Archived from the original on 26 June 2013. Retrieved 3 November 2008.
25. "History of Europe – Demographic and agricultural growth". Encyclopædia Britannica. 2012. Archived from the original on 20 December 2012. Retrieved 17 December 2012.
26. "Historical Estimates of World Population". Census.gov. Archived from the original on 9 July 2012. Retrieved 12 November 2016.
27. Jay, Peter (17 July 2000). "A Distant Mirror". TIME Europe. 156 (3). Archived from the original on 25 July 2008. Retrieved 9 August 2014.
28. Horst R. Thieme (2003). Mathematics in population biology. p. 285. ISBN   978-0-691-09291-1.
29. Graziella Caselli; Gillaume Wunsch & Jacques Vallin (2005). Demography: Analysis and Synthesis, Four Volume Set: A Treatise in Population. p. 34. ISBN   978-0-12-765660-1.
30. Nishijima, Sadao (1986), "The economic and social history of Former Han", in Twitchett, Denis; Loewe, Michael, Cambridge History of China: Volume I: the Ch'in and Han Empires, 221 B.C. – A.D. 220, Cambridge: Cambridge University Press, pp 595-96.
31. "Qing China's Internal Crisis: Land Shortage, Famine, Rural Poverty". Columbia University: Asia for Educators. 2009. Archived from the original on 8 July 2011. Retrieved 9 July 2013.
32. "History of Europe – Demographics". Encyclopædia Britannica. Archived from the original on 23 July 2013. Retrieved 9 July 2013.
33. "China's Population: Readings and Maps". Columbia University: East Asian Curriculum Project. Archived from the original on 19 July 2011. Retrieved 18 December 2012.
34. "The Columbian Exchange". University of North Carolina. Archived from the original on July 26, 2011. Retrieved December 18, 2012.
35. Collingham, Lizzie (2006). Vindaloo: the Portuguese and the chilli pepper. Curry: A Tale of Cooks and Conquerors. Oxford: Oxford University Press. pp. 47–73. ISBN   978-0-19-988381-3.
36. "Super-Sized Cassava Plants May Help Fight Hunger in Africa". Ohio State University. May 24, 2006. Archived from the original on December 8, 2013. Retrieved July 9, 2013.
37. James Brabazon (2000). . Syracuse University Press. p.  242. ISBN   978-0-8156-0675-8.
38. "U.S. News & World Report: How many people were here before Columbus? Pick a number". 18 August 1997. Archived from the original on 5 March 2008. Retrieved 9 August 2019.
39. Snow, D. R (16 June 1995). "Microchronology and Demographic Evidence Relating to the Size of Pre-Columbian North American Indian Populations". Science . 268 (5217): 1601–1604. Bibcode:1995Sci...268.1601S. doi:10.1126/science.268.5217.1601. PMID   17754613. S2CID   8512954.
40. Arthur C. Aufderheide; Conrado Rodríguez-Martín & Odin Langsjoen (1998). . Cambridge University Press. p.  205. ISBN   978-0-521-55203-5.
41. "The Story Of... Smallpox – and other Deadly Eurasian Germs". Public Broadcasting Service. 2005. Archived from the original on 29 January 2018. Retrieved 24 April 2013.
42. Austin Alchon, Suzanne (2003). A pest in the land: new world epidemics in a global perspective. University of New Mexico Press. p. 31. ISBN   978-0-8263-2871-7. Archived from the original on 18 May 2016. Retrieved 15 November 2015.
43. "World Demographics Profile 2012". Index Mundi. Archived from the original on 7 June 2012. Retrieved 22 May 2012.
44. "By 2050, 70% of the world's population will be urban. Is that a good thing?". Fast Co. Design. 2012. Archived from the original on 12 May 2012. Retrieved 1 May 2012.
45. Population crises and cycles in history – A review by Claire Russell and W.M.S. Russell, Vicnet.net.au, archived from the original on April 5, 2011, retrieved March 26, 2015
46. Buer, Mabel C. (1926). Health, Wealth and Population in the Early Days of the Industrial Revolution. London: George Routledge & Sons. p.  30. ISBN   978-0-415-38218-2.
47. "The Foundling Hospital". BBC History. 5 October 2012. Archived from the original on 17 June 2013. Retrieved 22 April 2013.
48. "Modernization – Population Change". Encyclopædia Britannica. Archived from the original on 6 April 2009. Retrieved 6 February 2013.
49. Graziella Caselli; Gillaume Wunsch & Jacques Vallin (2005). Demography: Analysis and Synthesis, Four Volume Set: A Treatise in Population. p. 42. ISBN   978-0-12-765660-1.
50. "Victorian Medicine – From Fluke to Theory". BBC History. 1 February 2002. Archived from the original on 5 March 2013. Retrieved 17 February 2013.
51. "A portrait of Britain in 2031". The Independent. 24 October 2007. Archived from the original on 9 December 2017. Retrieved 17 February 2013.
52. "UK population breaks through 60m". BBC News. 24 August 2006. Archived from the original on 8 February 2009. Retrieved 14 April 2012.
53. "US population through history". About.com. Archived from the original on 13 January 2012. Retrieved 14 April 2012.
54. Jay Winter, Emmanuel Sivan (2000). War and Remembrance in the Twentieth Century. Cambridge University Press. p. 64. ISBN   978-0521794367. Archived from the original on 4 September 2015. Retrieved 20 July 2015.
55. Mark Harrison (2002). Accounting for War: Soviet Production, Employment, and the Defence Burden, 1940–1945. p. 167. ISBN   978-0-521-89424-1.
56. "Vladimir Putin vows to reverse Russian population decline". The Daily Telegraph . 13 February 2012. Archived from the original on 24 April 2012. Retrieved 13 April 2012.
57. "Russia's Population Decline Said To Have 'Stopped'". Radio Free Europe. 27 May 2013. Retrieved 15 June 2013.
58. Schran, Peter (1978). "China's demographic evolution 1850–1953 reconsidered". The China Quarterly. 75 (75): 639–646. doi:10.1017/S0305741000042594. JSTOR   652987.
59. "Reintegrating India with the World Economy" (PDF). Peterson Institute for International Economics. 2003. Archived (PDF) from the original on 4 March 2012. Retrieved 8 November 2012.
60. "The World Factbook – Central Intelligence Agency". cia.gov. Archived from the original on 27 September 2011. Retrieved 8 January 2017.
61. "Java (island, Indonesia)". Encyclopædia Britannica. Archived from the original on 9 July 2013. Retrieved 7 July 2013.
62. Jorge Durand (March 2004). "From Traitors to Heroes: 100 Years of Mexican Migration Policies". University of Guadalajara. Archived from the original on 5 May 2011. Retrieved 16 July 2013.
63. "Population and Housing Census: Mexico 2010" (PDF). University of Minnesota. 3 March 2011. Archived (PDF) from the original on 3 November 2013. Retrieved 16 July 2013.
64. Gunnar Heinsohn (7 January 2008). "Kenya's Violence: Exploding population". The New York Times. Archived from the original on 15 July 2014. Retrieved 7 July 2013.
65. "The World at Six Billion: Introduction" (PDF). United Nations. 1999. Archived from the original (PDF) on 5 February 2016. Retrieved 14 July 2013.
66. "U.S. Census Bureau – World POPClock Projection". July 2013. Archived from the original on 18 November 2011. Retrieved 18 February 2018. The number on this page is automatically updated daily.
67. "Population seven billion: UN sets out challenges". BBC News. 26 October 2011. Archived from the original on 26 October 2011. Retrieved 27 October 2011.
68. Coleman, Jasmine (31 October 2011). "World's 'seven billionth baby' is born". The Guardian. London. Archived from the original on 30 September 2013. Retrieved 31 October 2011.
69. "7 billion people is a 'serious challenge". UPI. 31 October 2011. Archived from the original on 3 November 2011. Retrieved 9 November 2011.
70. "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 3 July 2010.
71. "Total fertility estimates, 1950–2010". UN Population Division. April 2011. Archived from the original on 7 June 2012. Retrieved 14 June 2012.
72. "World Population Prospects, the 2008 Revision – Frequently Asked Questions". Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat. 10 November 2010. Archived from the original on 24 February 2015. Retrieved 26 March 2015.
73. "World Health Statistics 2016: Monitoring health for the SDGs Annex B: tables of health statistics by country, WHO region and globally" (PDF). World Health Organization. 2016. p. 110. Archived (PDF) from the original on 17 May 2018. Retrieved 3 August 2018.
74. "World Demographics Profile 2011". Index Mundi. Archived from the original on 30 November 2011. Retrieved 18 November 2011.
75. "Sex-ratio imbalance in Asia: Trends, consequences and policy responses" (PDF). UNFPA. 2007. Archived (PDF) from the original on 4 June 2012. Retrieved 20 May 2012.
76. "World Demographics Profile 2014". Index Mundi. Archived from the original on 6 October 2014. Retrieved 4 October 2014.
77. Janneh, Abdoulie (April 2012). "General debate on national experience in population matters: adolescents and youth" (PDF). United Nations Economic Commission for Africa. Archived (PDF) from the original on 10 November 2013. Retrieved 19 February 2014.
78. "Global weight gain more damaging than rising numbers". BBC. 18 June 2012. Archived from the original on 4 February 2013. Retrieved 12 February 2013.
79. "World". CIA World Factbook . 2015. Retrieved 17 January 2015.
80. "What It Will Take to 'Graduate' 1.2 Billion People Out of Extreme Poverty". The Huffington Post . 4 April 2012. Archived from the original on 18 April 2012. Retrieved 26 April 2012.
81. Food and Agriculture Organization of the United Nations, The State of Food Insecurity in the World Archived 11 June 2014 at the Wayback Machine . WorldHunger.org. 2012. Retrieved 26 April 2012.
82. "Statistics". Internet World Stats. 30 June 2014. Archived from the original on 24 November 2017. Retrieved 5 March 2015.
83. "World’s Most Typical Person: Han Chinese Man" Archived 6 June 2019 at the Wayback Machine . Wall Street Journal. 4 March 2011. Retrieved 18 November 2011.
84. "Religious Composition by Country, 2010-2050". Pew Research Center. 2 April 2015.
85. Religions by adherents Archived 15 June 2008 at the Wayback Machine . Adherents.com. 2005 data. Retrieved 19 December 2011.
86. "National Data". data.stats.gov.cn. Archived from the original on 14 June 2018. Retrieved 22 November 2019.
87. "data.gov.in". data.gov.in. Archived from the original on 19 June 2016. Retrieved 22 November 2019.
88. "Population Clock". www.census.gov. Archived from the original on 17 November 2015. Retrieved 18 April 2020.
89. "Badan Pusat Statistik". www.bps.go.id. Archived from the original on 17 July 2018. Retrieved 8 August 2017.
90. United Nations. "World Population Prospects 2019".
91. "IBGE | Projeção da população". www.ibge.gov.br. Archived from the original on 4 February 2020. Retrieved 22 November 2019.
92. "Bangladesh Bureau of Statistics". 4 September 2011. Archived from the original on 4 September 2011.
93. "Федеральная служба государственной статистики". www.gks.ru. Archived from the original on 4 January 2020. Retrieved 5 January 2020.
94. "Indicadores demográficos de México de 1950 a 2050 - Selecciona un año para la República Mexicana - Indicadores demográficos de la República Mexicana en el año". Archived from the original on 3 January 2019. Retrieved 18 April 2020.
95. Demetriou, Danielle (17 April 2013). "Japan's population suffers biggest fall in history". The Daily Telegraph. London. Archived from the original on 21 May 2013. Retrieved 22 July 2013.
96. "The limits of a Green Revolution?". BBC News. 29 March 2007. Archived from the original on 28 July 2011. Retrieved 1 August 2010.
97. "The Real Green Revolution". Energybulletin.net. Archived from the original on 22 April 2008. Retrieved 1 August 2010.
98. "World Population to 2300" (PDF). United Nations Department of Economic and Social Affairs. 2004. Archived (PDF) from the original on 19 September 2018. Retrieved 16 June 2013.
99. "International Programs". USCB. 7 January 2009. Archived from the original on 23 August 2010. Retrieved 16 December 2012.
100. Ron Nielsen (2006). The Little Green Handbook. New York: Picador. ISBN   978-0-312-42581-4.
101. "2006 report highlights" (PDF). United Nations. Archived (PDF) from the original on 12 October 2018. Retrieved 1 August 2010.
102. "UN population estimates and projections, database query, August 2009". United Nations. 11 March 2009. Archived from the original on 19 August 2010. Retrieved 1 August 2010.
103. Randers, Jorgen (2012). 2052: A Global Forecast for the Next Forty Years. Vermont: Chelsea Green Publishing. p. 62.
104. World population to keep growing this century, hit 11 billion by 2100 Archived 4 December 2016 at the Wayback Machine . UWToday. 18 September 2014
105. "World Population by Year". www.worldometers.info. Retrieved 30 May 2020.
106. "World Population Prospects: The 2008 Revision" (PDF). Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat. June 2009. Archived (PDF) from the original on 19 March 2013. Retrieved 20 June 2013.
107. "The World at Six Billion". United Nations. 12 October 1999. Archived from the original on 9 July 2013. Retrieved 1 August 2010.
108. "Population Growth over Human History". University of Michigan. January 4, 2006. Archived from the original on July 24, 2011. Retrieved March 9, 2013.
109. Figures include the former Soviet countries in Europe. Caselli, Graziella; Gillaume Wunsch; Jacques Vallin (20 December 2005). Demography: Analysis and Synthesis, Four Volume Set: A Treatise in Population. Academic Press. p. 42. ISBN   978-0-12-765660-1.
110. "UN report – 2004 data" (PDF). Archived from the original (PDF) on 5 February 2016. Retrieved 1 August 2010.
111. "World Population Prospects The 2015 Revision". Archived from the original (PDF) on 20 March 2014.
112. "The World at Six Billion". UN Population Division. Archived from the original on 5 March 2016.
113. Fewer than 15,000 individuals, according to the Toba catastrophe theory, though this theory has been criticized by some scientists. See: "Toba super-volcano catastrophe idea "dismissed"". BBC News. 30 April 2013. Archived from the original on 7 January 2015. Retrieved 21 March 2015.
114. An approximation based on figures from different sources as listed at the US Census Bureau's Historical Estimates of World Population Archived 2 May 2019 at the Wayback Machine ; see also * Kremer, Michael (1993). "Population Growth and Technological Change: One Million B.C. to 1990". The Quarterly Journal of Economics. 108 (3): 681–716. doi:10.2307/2118405. JSTOR   2118405.
115. An approximation based on figures from different sources as listed at the US Census Bureau's Total Midyear Population for the World: 1950-2050 Archived 21 May 2017 at the Wayback Machine
116. "Notes on the World POPClock and World Vital Events". US Census Bureau. Archived from the original on 2 October 2013. Retrieved 12 February 2013.
117. "World Population Prospects, the 2012 Revision – "Low variant" and "High variant" values". UN. 2012. Archived from the original on 1 July 2014. Retrieved 15 June 2013.
118. "World population projected to reach 9.6 billion by 2050 – UN report". UN News Centre. 14 June 2013. Archived from the original on 23 August 2013. Retrieved 16 June 2013.
119. "A model predicts that the world's populations will stop growing in 2050". ScienceDaily.com. 4 April 2013. Archived from the original on 2 January 2020. Retrieved 3 June 2013.
120. Carrington, Damien (18 September 2014). "World population to hit 12bn in 2100 – with 70% chance of continuous rise". The Guardian. Archived from the original on 20 September 2014. Retrieved 21 September 2014.
121. Gerland, P.; Raftery, A. E.; Ev Ikova, H.; Li, N.; Gu, D.; Spoorenberg, T.; Alkema, L.; Fosdick, B. K.; Chunn, J.; Lalic, N.; Bay, G.; Buettner, T.; Heilig, G. K.; Wilmoth, J. (14 September 2014). "World population stabilization unlikely this century". Science. AAAS. 346 (6206): 234–7. Bibcode:2014Sci...346..234G. doi:10.1126/science.1257469. ISSN   1095-9203. PMC  . PMID   25301627.
122. "World Population Prospects 2019: Highlights" (PDF). Archived (PDF) from the original on 3 July 2019. Retrieved 8 July 2019.
123. Silk, John (21 December 2019). "World's population to hit 7.75 billion in 2019". Deutsche Welle . Retrieved 17 July 2020.
124. "World population in 2100 could be 2 billion below UN forecasts, study suggests". The Guardian. 15 July 2020. Retrieved 15 July 2020.
125. Stokstad, Erik (5 May 2019). "Landmark analysis documents the alarming global decline of nature". Science . AAAS . Retrieved 19 July 2020. Driving these threats are the growing human population, which has doubled since 1970 to 7.6 billion, and consumption. (Per capita of use of materials is up 15% over the past 5 decades.)
126. Peter P. Rogers; Kazi F. Jalal & John A. Boyd (2008). An Introduction To Sustainable Development. p. 53. ISBN   978-1849770477.
127. "Overpopulation's Real Victim Will Be the Environment". TIME. 26 October 2011. Archived from the original on 18 February 2013. Retrieved 18 February 2013.
128. Zehner, Ozzie (2012). Green Illusions. Lincoln and London: University of Nebraska Press. pp. 187–331. Archived from the original on 29 November 2019. Retrieved 10 April 2020.
129. "World Population Prospects: The 2019 Revision" (XLS). Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat. June 2019. Retrieved 8 July 2019.
130. "World Population – Total Midyear Population for the World: 1950–2050". Census.gov. July 2015. Archived from the original on 21 May 2017. Retrieved 7 March 2016.
131. Sebastien von Hoerner (1975). "Population Explosion and Interstellar Expansion". Journal of the British Interplanetary Society. 28 (28): 691–712. Bibcode:1975JBIS...28..691V.
132. Introduction to Social Macrodynamics Archived 10 February 2012 at the Wayback Machine . 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" Archived 17 February 2019 at the Wayback Machine .
133. Kapitsa, Sergei P. (1996). "The phenomenological theory of world population growth". Physics-Uspekhi. 39 (1): 57–71. Bibcode:1996PhyU...39...57K. doi:10.1070/pu1996v039n01abeh000127. Archived from the original on 11 May 2009. Retrieved 26 July 2013.
134. Lutz, Wolfgang; Sanderson, Warren; Scherbov, Sergei (19 June 1997). "Doubling of world population unlikely" (PDF). Nature. 387 (6635): 803–805. Bibcode:1997Natur.387..803L. doi:10.1038/42935. PMID   9194559. S2CID   4306159.
135. "World faces 'perfect storm' of problems by 2030, chief scientist to warn". The Guardian. 18 March 2009. Archived from the original on 14 November 2016. Retrieved 18 February 2013.
136. Jowit, Juliette (23 October 2011). "Paul Ehrlich, a prophet of global population doom who is gloomier than ever". The Guardian. London. Archived from the original on 1 October 2013. Retrieved 22 July 2013.
137. Kindall, Henery W & Pimentel, David (May 1994). "Constraints on the Expansion of the Global Food Supply". Ambio. 23 (3). Archived from the original on 11 October 2018. Retrieved 10 August 2009.
138. "The limits of a Green Revolution?". BBC News. 29 March 2007. Archived from the original on 28 July 2011. Retrieved 18 February 2013.
139. "Host Plant Resistance and Conservation of Genetic Diversity". Radcliffe's IPM World Textbook. University of Minnesota. March 2013. Archived from the original on 3 November 2013. Retrieved 20 July 2013.
140. van den Bergh, Jeroen C. J. M.; Rietveld, Piet (2004). "Reconsidering the Limits to World Population: Meta-analysis and Meta-prediction". BioScience. 54 (3): 195. doi:. ISSN   0006-3568.
141. "The global grain bubble". The Christian Science Monitor. 18 January 2008. Archived from the original on 30 November 2009. Retrieved 18 February 2013.
142. James Randerson, science correspondent (7 March 2008). "Food crisis will take hold before climate change, warns chief scientist". The Guardian. London. Archived from the original on 2 September 2013. Retrieved 18 February 2013.
143. John Vidal, environment editor (3 November 2007). "Global food crisis looms as climate change and fuel shortages bite". The Guardian. London. Archived from the original on 30 September 2013. Retrieved 18 February 2013.
144. Walsoft (22 February 2008). "Experts: Global Food Shortages Could 'Continue for Decades'". Marketoracle.co.uk. Archived from the original on 21 February 2013. Retrieved 18 February 2013.
145. Moya K. Mason. "Has Urbanization Caused a Loss to Agricultural Land?". Moyak.com. Archived from the original on 24 September 2013. Retrieved 9 July 2013.
146. Walt, Vivienne (27 February 2008). "The World's Growing Food-Price Crisis". Time. Archived from the original on 29 November 2011. Retrieved 18 February 2013.
147. "The cost of food: Facts and figures" Archived 20 January 2009 at the Wayback Machine . BBC. 16 October 2008. Retrieved 18 February 2013.
148. Julian Borger (26 February 2008). "Feed the world? We are fighting a losing battle, UN admits". The Guardian. London. Archived from the original on 25 December 2016. Retrieved 18 February 2013.
149. Buchanan, Emily (22 April 2008). "Assessing the global food crisis". BBC News. Archived from the original on 15 January 2009. Retrieved 6 April 2010.
150. "Half of all food 'wasted' report claims". BBC. 10 January 2013. Archived from the original on 10 January 2013. Retrieved 10 January 2013.
151. "Oil shock could push world food prices higher". CNN Money. 3 March 2011. Archived from the original on 9 March 2013. Retrieved 18 February 2013.
152. P. Crabbè (2000). Implementing ecological integrity: restoring regional and global environmental and human health. North Atlantic Treaty Organization Scientific Affairs Division/Springer. p. 411. ISBN   978-0-7923-6351-4.
153. "Global crisis 'to strike by 2030". BBC News. 19 March 2009. Archived from the original on 15 November 2016. Retrieved 18 February 2013.
154. "Global food production will have to increase 70% for additional 2.3 billion people by 2050". Finfacts.com. 24 September 2009. Archived from the original on 10 March 2016. Retrieved 18 February 2013.
155. "The State of Food Insecurity in the World, 2008: High food prices and food security – threats and opportunities". UN Food and Agriculture Organization – Economic and Social Development Department. 2008. p. 2. Archived from the original on 13 June 2018. Retrieved 8 December 2012.
156. "One sixth of humanity undernourished – more than ever before". Food and Agriculture Organization of the United Nations. 2009. Archived from the original on 17 November 2012. Retrieved 8 December 2012.
157. "Ecological Debt Day". Archived from the original on December 17, 2008. Retrieved February 18, 2013.
158. "Planetary Boundaries: Specials". Nature. 23 September 2009. Archived from the original on 12 February 2013. Retrieved 18 February 2013.
159. "IAP (login required)". InterAcademies.net. Archived from the original on 10 February 2010. Retrieved 18 February 2013.
160. Pimm, S.L.; Jenkins, C.N.; Abell, R.; Brooks, T.M.; Gittleman, J.L.; Joppa, L.N.; Raven, P. H.; Roberts, C. M.; Sexton, J. O. (30 May 2014). "The biodiversity of species and their rates of extinction, distribution, and protection" (PDF). Science . 344 (6187): 1246752. doi:10.1126/science.1246752. PMID   24876501. S2CID   206552746. Archived (PDF) from the original on 31 August 2019. Retrieved 15 December 2016. The overarching driver of species extinction is human population growth and increasing per capita consumption.
161. Ceballos, Gerardo; Ehrlich, Paul R.; Barnosky, Anthony D.; García, Andrés; Pringle, Robert M.; Palmer, Todd M. (2015). "Accelerated modern human–induced species losses: Entering the sixth mass extinction". Science Advances . 1 (5): e1400253. Bibcode:2015SciA....1E0253C. doi:10.1126/sciadv.1400253. PMC  . PMID   26601195.
162. Sutter, John D. (12 December 2016). "How to stop the sixth mass extinction". CNN. Archived from the original on 12 January 2017. Retrieved 19 December 2016.
163. Ceballos, Gerardo; Ehrlich, Paul R; Dirzo, Rodolfo (23 May 2017). "Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines". PNAS . 114 (30): E6089–E6096. doi:10.1073/pnas.1704949114. PMC  . PMID   28696295. Much less frequently mentioned are, however, the ultimate drivers of those immediate causes of biotic destruction, namely, human overpopulation and continued population growth, and overconsumption, especially by the rich. These drivers, all of which trace to the fiction that perpetual growth can occur on a finite planet, are themselves increasing rapidly.
164. Ripple WJ, Wolf C, Newsome TM, Galetti M, Alamgir M, Crist E, Mahmoud MI, Laurance WF (13 November 2017). "World Scientists' Warning to Humanity: A Second Notice". BioScience . 67 (12): 1026–1028. doi:.
165. Cockburn, Harry (29 March 2019). "Population explosion fuelling rapid reduction of wildlife on African savannah, study shows". The Independent . Archived from the original on 22 May 2019. Retrieved 1 April 2019.
166. Watts, Jonathan (6 May 2019). "Human society under urgent threat from loss of Earth's natural life". The Guardian . Archived from the original on 18 May 2019. Retrieved 23 June 2019.
167. Greenfield, Patrick (9 September 2020). "Humans exploiting and destroying nature on unprecedented scale – report". The Guardian . Retrieved 10 September 2020.
168. Lewis, Sophie (9 September 2020). "Animal populations worldwide have declined by almost 70% in just 50 years, new report says". CBS News . Retrieved 10 September 2020. The report blames humans alone for the "dire" state of the planet. It points to the exponential growth of human consumption, population, global trade and urbanization over the last 50 years as key reasons for the unprecedented decline of Earth's resources – which it says the planet is incapable of replenishing.
169. Perkins, Sid (11 July 2017). "The best way to reduce your carbon footprint is one the government isn't telling you about". Science . Archived from the original on 1 December 2017. Retrieved 9 December 2017.
170. 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 . 15 June 2012. Archived from the original on 29 August 2012. Retrieved 29 August 2012.
171. "Fighting poverty to build peace". Vatican. 1 January 2009. Archived from the original on 11 October 2011. Retrieved 24 October 2011.
172. Zehner, Ozzie (2012). Green lllusions. Lincoln and London: University of Nebraska. p. 188. Archived from the original on 29 November 2019. Retrieved 10 April 2020.
173. Connelly, Matthew (2008). Fatal Misconception: The Struggle to Control World Population. ISBN   978-0674029835.
174. Carrington, Damian (22 March 2018). "Paul Ehrlich: 'Collapse of civilisation is a near certainty within decades'". The Guardian . Retrieved 23 August 2020.
175. Cite Warren, Stephen G. "Did agriculture cause the population explosion?." Nature 397.6715 (1999): 101.
176. "Morgan Freeman on the 'Tyranny of Agriculture' and the Doomed Human Race". ecorazzi. 19 February 2014.
177. Armelagos, George J.; Goodman, Alan H.; Jacobs, Kenneth H. (1 September 1991). "The origins of agriculture: Population growth during a period of declining health". Population and Environment. 13 (1): 9–22. doi:10.1007/BF01256568. ISSN   1573-7810. S2CID   153470610.
178. Sergei P Kapitza, 'The phenomenological theory of world population growth', Physics-Uspekhi 39(1) 57-71 (1996), citing K. M. Weiss, Human Biology 56637 (1984) and N. Keyfitz, Applied Mathematical Demography (New York: Wiley, 1977).
179. Curtin, Ciara (1 March 2007). "Fact or Fiction?: Living People Outnumber the Dead". Scientific American. Scientific American, Inc. (published September 2007). 297 (3): 126. Bibcode:2007SciAm.297c.126C. doi:10.1038/scientificamerican0907-126. PMID   17784634 . Retrieved 4 August 2008.Note: text of paper publication slightly different from text of on-line publication
180. Haub, Carl (November–December 2002). "How Many People Have Ever Lived on Earth?" (PDF). Population Today. Population Reference Bureau. 30 (8): 3–4. Archived (PDF) from the original on 12 August 2011. Retrieved 4 August 2008.
181. Haub, Carl (October 2011). "How Many People Have Ever Lived on Earth?". Population Reference Bureau. Archived from the original on 24 April 2013. Retrieved 29 April 2013.
182. Kuhrt, A. (1995). The Ancient Near East, c. 3000–330 BCE. Vol. 2. London: Routledge. p. 695.

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