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# World population

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### World population

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. In June 2013, the United Nations Department of Economic and Social Affairs, Population Division estimated that as of 2010, the world population was 6.916 billion.[1] The United States Census Bureau 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 median age of the world's population was estimated to be 29.7 years in 2014.[6]

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.[7] 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.[8] Total annual births were highest in the late 1980s at about 138 million,[9] 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.[10]

2012 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.[11][12] 2003 UN Population Division estimates for the year 2150 range between 3.2 and 24.8 billion.[13] One of many independent mathematical models supports the lower estimate,[14] while a 2014 estimate forecasts between 9.3 and 12.6 billion in 2100 and growing thereafter.[15][16] Some analysts have questioned the sustainability of further world population growth, highlighting the growing pressures on the environment, global food supplies, and energy resources.[17][18][19]

World population (millions)[20]
# Top ten most populous countries 1990 2008 2025*
1 China 1,141 1,333 1,458
2 India 849 1,140 1,398
3 United States 250 304 352
4 Indonesia 178 228 273
5 Brazil 150 192 223
6 Pakistan 108 166 226
8 Nigeria 94 151 208
9 Russia 149 143 137
10 Japan 124 128 126
World total 5,267 6,689 8,004
Top ten most populous (%) 60.0% 58.9% 57.5%
1 Asia 1,613 2,183 2,693
+ China 1,141 1,333 1,458
+ OECD Pacific* 187 202 210
2 Africa 634 984 1,365
3 Europe* 564 603 659
+ Russia 149 143 137
+ 11 Post-Soviet Republics* 134 136 146
4 Latin America 355 462 550
5 North America* 359 444 514
6 Middle East 132 199 272
Australia 17 22 28
European Union 473 499 539
US & Canada 278 338 392
Post-Soviet Union 291 286 289
Geographical definitions as in IEA Key Stats 2010 p. 66
Notes:
• 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

## Contents

• Population by region 1
• Population by continent 1.1
• History 2
• Antiquity and Middle Ages 2.1
• Modern era 2.2
• Milestones by the billions 2.3
• Global demographics 3
• Largest populations by country 4
• Most densely populated countries 4.1
• Fluctuation 5
• Projections 5.1
• Population growth by region 5.2
• Mathematical approximations 6
• Years for world population to double 6.1
• Overpopulation 7
• Predictions of scarcity 7.1
• Environmental impacts 7.2
• Population control 7.3
• Overpopulation as a "myth" 7.4
• Number of humans who have ever lived 8
• Estimation methodologies 8.1
• Notes 10
• References 11

## Population by region

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%).[21] 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.[22]

### Population by continent

Continent Density
(inhabitants/km2)
Population
(millions, 2013 estimates)
Most populous country Most populous city
Asia 96.4 4,298  China (1,361,000,000)[23] Greater Tokyo Area (35,676,000)
Africa 36.7 1,111  Nigeria (178,517,000) Lagos (21,000,000)
Europe 72.9 742  Russia (143,700,000;
approx. 110 million in Europe)
Moscow (14,837,510)
North America[24] 22.9 565  United States (317,996,000) Mexico City/Metro Area (8,851,080 / 21,163,226)
South America 22.8 407  Brazil (201,032,714) São Paulo City/Metro Area (11,316,149 / 27,640,577)
Oceania 4.5 38  Australia (23,475,992) Sydney (4,757,083)
Antarctica 0.0003
(varies)
0.004
(non-permanent, varies)[25]
N/A[note 1] McMurdo Station (1,200) (non-permanent, varies)

## History

### Antiquity and Middle Ages

The world population in 35,000 BCE is estimated to have been around 3 million people who subsisted as hunter-gatherers.[26] The population had increased to around 15 million by the time agriculture was invented around 12,000 years ago.[27] 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.[28]

The Plague of Justinian 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.[29] The population of Europe was more than 70 million in 1340.[30] 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;[31] it took 200 years for population figures to recover.[32] The population of China decreased from 123 million in 1200 to 65 million in 1393,[33] which was presumably due to a combination of Mongol invasions, famine and plague.[34]

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.[35] England's population reached an estimated 5.6 million in 1650, up from an estimated 2.6 million in 1500.[36] 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.[37][38] Since their introduction by Portuguese traders from Brazil to Africa in the 16th century,[39] maize and cassava have replaced traditional African crops as the most important staple food crops grown on the continent.[40]

Around 300 BC, the population of India was between 100 million and 140 million.[41] The population of India in 1600 was around 100 million. Hence, from 300 BC to 1600, India's population was more or less stable.[42]

The pre-Columbian North American population probably numbered somewhere between 2 million and 18 million.[43] Encounters between European explorers and populations in the rest of the world often introduced local epidemics of extraordinary virulence.[44] 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.[45] Over the centuries, the Europeans had developed high degrees of immunity to these diseases, while the indigenous peoples had no such immunity.[46]

### Modern era

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.[47] By 2050, the proportion may reach 70%.[48]

During the European Agricultural and Industrial Revolutions, the life expectancy of children increased dramatically.[49] 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.[50][51] Between 1700 and 1900, Europe’s population increased from about 100 million to over 400 million.[52] Altogether, the areas populated by people of European descent comprised 36% of the world's population in 1900.[53]

Population growth in the West became more rapid after the introduction of vaccination and improvements in medicine and sanitation.[54] Improved conditions led to the population of Britain increasing from 10 million to 40 million in the 1800s.[55] The population of the United Kingdom reached 60 million in 2006.[56] The United States saw its population grow from around 5.3 million in 1800 to 106 million in 1920, exceeding 307 million in 2010.[57]

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.[58] In recent decades, Russia's population has declined significantly – from 150 million in 1991 to 143 million in 2012[59] – but as of 2013 this decline appears to have halted.[60]

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,[61] 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;[62] today, India, Pakistan and Bangladesh are collectively home to about 1.5 billion people.[63] Java had about five million inhabitants in 1815, and now has over 140 million people.[64] Mexico's population grew from 13.6 million in 1900 to about 112 million in 2010.[65][66] Between the 1920s and 2000s, Kenya's population grew from 2.9 million to 37 million.[67]

### Milestones by the billions

World population milestones (USCB estimates)[68]
Population
(in billions)
1 2 3 4 5 6 7 8 9
Year 1804 1927 1959 1974 1987 1999 2012 2026 2042
Years elapsed between milestones 123 32 15 13 12 13 14 16

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.[69] 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.[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.[70] 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.[70] 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.[13][71]

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.[72]

## Global demographics

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.[73][74] 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.[73] The global median age was 30.4 years in 2012, and is expected to rise to 37.9 years by 2050.[75]

The global average life expectancy is 67.07 years,[73] with women living an average of 69 years and men approximately 65 years.[73] In 2010, the global fertility rate was estimated at 2.52 children per woman.[71] 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).[76]

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.[77] Around 1.29 billion people (18.4% of the world population) live in extreme poverty, subsisting on less than US$1.25 per day;[78] approximately 870 million people (12.25%) are undernourished.[79] 83% of the world's over-15s are considered literate.[73] In June 2012, there were around 2.4 billion global Internet users, constituting 34.2% of the world population.[80] The Han Chinese are the world's largest single ethnic group, constituting over 19% of the global population in 2011.[81] 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%).[73] 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%.[73] In 2005, around 16% of the global population were reported to be non-religious.[82] ## Largest populations by country A map of the world's countries by total population, with darker shading indicating larger populations. 10 most populous countries Rank Country / Territory Population Date Approx. % of world population Source 1 China[note 2] 1,368,420,000 February 25, 2015 18.9% [83] 2 India 1,267,400,000 February 25, 2015 17.5% [84] 3 United States 319,669,000 February 25, 2015 4.42% [85] 4 Indonesia 252,164,800 July 1, 2014 3.49% [86] 5 Brazil 203,932,000 February 25, 2015 2.82% [87] 6 Pakistan 189,068,000 February 25, 2015 2.62% [88] 7 Nigeria 178,517,000 July 1, 2014 2.47% [89] 8 Bangladesh 157,891,000 February 25, 2015 2.18% [90] 9 Russia 146,068,400 June 1, 2014 2.02% [91] 10 Japan 127,130,000 August 1, 2014 1.76% [92] Approximately 4.185 billion people live in these ten countries, representing around 58% of the world's population as of August 2014. ### 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. 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) Rank Country/Region Population Area (km2) Density (Pop. per km2) 1 Singapore 5,399,200 710 7605 2 Bahrain 1,234,571 750 1646 3 Bangladesh 149,772,364 147,570 1101 4 Taiwan 23,361,147 36,190 645 5 Mauritius 1,257,900 2,040 617 6 South Korea 50,219,669 99,538 505 7 Lebanon 4,822,000 10,452 461 8 Netherlands 16,911,719[93] 41,526 407 9 Rwanda 10,537,222 26,338 400 10 Haiti 10,413,211 27,065 385 Countries ranking highly in terms of both total population (more than 15 million people) and population density (more than 250 people per square kilometer): Country Population Area (km2) Density (Pop. per km2) Notes India 1,267,400,000 3,287,240 386 Growing country Bangladesh 149,772,364 147,570 1101 Growing country Japan 127,180,000 377,873 337 Declining in population[94] Philippines 98,698,000 300,076 329 Growing country Vietnam 90,388,000 331,689 268 Growing country United Kingdom 63,705,000 243,610 262 Growing country South Korea 50,219,669 99,538 505 Slowly growing country[95] Taiwan 23,361,147 36,190 645 Steady in population Sri Lanka 20,328,597 65,610 309 Slowly growing country Netherlands 16,848,208 41,526 406 Steady in population[96] ## Fluctuation 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: • 228 million in Asia; • 92 million in Africa; • 38 million in Latin America; • 16 million in Northern America; • −3.3 million in Europe; • 2.0 million in Oceania; • 383 million overall. 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.[97][98][99] 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),[100] 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. 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.[101] 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.[94] In 2006, the United Nations stated that the rate of population growth was visibly diminishing due to the ongoing global [104] ### 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 latter, the world population reached seven billion in March 2012,[105] while the UN asserted that this occurred in late 2011.[106] 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[107][108] Year UN est. (millions) Difference USCB est. (millions) Difference 2005 6,514 6,474 2010 6,916 402 6,864 390 2015 7,324 408 7,250 386 2020 7,717 393 7,628 378 2025 8,083 366 7,984 356 2030 8,425 342 8,315 331 2035 8,743 318 8,619 304 2040 9,039 296 8,899 280 2045 9,308 269 9,154 255 2050 9,551 243 9,383 229 UN 2012 estimates and medium variant projections (in millions)[107] Year World Asia Africa Europe Latin America/Caribbean Northern America Oceania 2010 6,916 4,165 (60.2%) 1,031 (14.9%) 740 (10.7%) 596 (8.6%) 347 (5.0%) 37 (0.5%) 2015 7,324 4,385 (59.9%) 1,166 (15.9%) 743 (10.1%) 630 (8.6%) 361 (4.9%) 39 (0.5%) 2020 7,717 4,582 (59.4%) 1,312 (17.0%) 744 (9.6%) 662 (8.6%) 376 (4.9%) 42 (0.5%) 2025 8,083 4,749 (58.8%) 1,468 (18.2%) 741 (10.1%) 691 (9.2%) 390 (4.8%) 45 (0.6%) 2030 8,425 4,887 (58.0%) 1,634 (19.4%) 736 (8.7%) 717 (8.5%) 403 (4.8%) 47 (0.6%) 2035 8,743 4,997 (57.2%) 1,812 (20.7%) 730 (8.3%) 739 (8.5%) 415 (4.8%) 50 (0.6%) 2040 9,039 5,080 (56.2%) 1,999 (22.1%) 724 (8.0%) 757 (8.4%) 426 (4.8%) 52 (0.6%) 2045 9,308 5,136 (55.2%) 2,194 (23.6%) 717 (7.7%) 771 (8.3%) 436 (4.7%) 55 (0.6%) 2050 9,551 5,164 (54.1%) 2,393 (25.1%) 709 (7.4%) 782 (8.2%) 446 (4.7%) 57 (0.6%) 2055 9,766 5,168 (52.9%) 2,595 (26.6%) 700 (7.2%) 788 (8.1%) 456 (4.7%) 59 (0.6%) 2060 9,957 5,152 (51.7%) 2,797 (28.1%) 691 (6.9%) 791 (7.9%) 465 (4.7%) 61 (0.6%) 2065 10,127 5,120 (50.6%) 2,998 (29.6%) 681 (6.7%) 791 (7.8%) 474 (4.7%) 63 (0.6%) 2070 10,277 5,075 (49.4%) 3,195 (31.1%) 673 (6.5%) 788 (7.6%) 482 (4.7%) 64 (0.6%) 2075 10,409 5,019 (48.2%) 3,387 (32.5%) 665 (6.4%) 783 (7.5%) 490 (4.7%) 66 (0.6%) 2080 10,524 4,957 (47.1%) 3,570 (33.9%) 659 (6.3%) 776 (7.4%) 496 (4.7%) 67 (0.6%) 2085 10,626 4,894 (46.1%) 3,742 (35.2%) 653 (6.1%) 767 (7.2%) 502 (4.7%) 68 (0.6%) 2090 10,717 4,833 (45.1%) 3,903 (36.4%) 649 (6.1%) 757 (7.1%) 506 (4.7%) 69 (0.6%) 2095 10,794 4,773 (44.2%) 4,051 (37.6%) 644 (6.0%) 747 (6.9%) 510 (4.7%) 69 (0.6%) 2100 10,854 4,712 (43.4%) 4,185 (38.6%) 639 (5.9%) 736 (6.8%) 513 (4.7%) 70 (0.6%) ### Population growth by region The table below shows historical and predicted regional population figures in millions.[106][109][110] The availability of historical population figures varies by region. World historical and predicted populations (in millions)[111][112] Region 1500 1600 1700 1750 1800 1850 1900 1950 1999 2008 2010 2012 2050 2150 World 458 580 682 791 978 1,262 1,650 2,521 5,978 6,707 6,896 7,052 8,909 9,746 Africa 86 114 106 106 107 111 133 221 767 973 1,022 1,052 1,766 2,308 Asia 243 339 436 502 635 809 947 1,402 3,634 4,054 4,164 4,250 5,268 5,561 Europe 84 111 125 163 203 276 408 547 729 732 738 740 628 517 Latin America[Note 1] 39 10 10 16 24 38 74 167 511 577 590 603 809 912 Northern America[Note 1] 3 3 2 2 7 26 82 172 307 337 345 351 392 398 Oceania 3 3 3 2 2 2 6 13 30 34 37 38 46 51 World historical and predicted populations by percentage distribution[111][112] Region 1500 1600 1700 1750 1800 1850 1900 1950 1999 2008 2010 2012 2050 2150 World 100 100 100 100 100 100 100 100 100 100 100 100 100 100 Africa 18.8 19.7 15.5 13.4 10.9 8.8 8.1 8.8 12.8 14.5 14.8 15.2 19.8 23.7 Asia 53.1 58.4 63.9 63.5 64.9 64.1 57.4 55.6 60.8 60.4 60.4 60.3 59.1 57.1 Europe 18.3 19.1 18.3 20.6 20.8 21.9 24.7 21.7 12.2 10.9 10.7 10.5 7.0 5.3 Latin America[Note 1] 8.5 1.7 1.5 2.0 2.5 3.0 4.5 6.6 8.5 8.6 8.6 8.6 9.1 9.4 Northern America[Note 1] 0.7 0.5 0.3 0.3 0.7 2.1 5.0 6.8 5.1 5.0 5.0 5.0 4.4 4.1 Oceania 0.7 0.5 0.4 0.3 0.2 0.2 0.4 0.5 0.5 0.5 0.5 0.5 0.5 0.5 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) Year World Africa Asia Europe Latin America[Note 1] Northern America[Note 1] Oceania Notes 70,000 BC < 0.015 [113] 10,000 BC 4 [114] 8000 BC 5 6500 BC 5 5000 BC 5 4000 BC 7 3000 BC 14 2000 BC 27 1000 BC 50 7 33 9 500 BC 100 14 66 16 AD 1 200 23 141 28 1000 265 1750 791 106 502 163 16 2 2 1800 978 107 635 203 24 7 2 1850 1,262 111 809 276 38 26 2 1900 1,650 133 947 408 74 82 6 1950 2,519 221 1,398 547 167 172 12.8 [115] 1955 2,756 247 1,542 575 191 187 14.3 1960 2,982 277 1,674 601 209 204 15.9 1965 3,335 314 1,899 634 250 219 17.6 1970 3,692 357 2,143 656 285 232 19.4 1975 4,068 408 2,397 675 322 243 21.5 1980 4,435 470 2,632 692 361 256 22.8 1985 4,831 542 2,887 706 401 269 24.7 1990 5,263 622 3,168 721 441 283 26.7 1995 5,674 707 3,430 727 481 299 28.9 2000 6,070 796 3,680 728 520 316 31.0 2005 6,454 888 3,917 725 558 332 32.9 2010 6,972 1,022 4,252 732 580 351 35.6 1. ^ a b c d e f 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 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 Sergey 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} where • N is current population • T is the current year • C = (1.86±0.01)·1011 • T0 = 2007±1 • \tau = 42±1 ### Years for world population to double 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 Population (in billions) 0.5 1 2 4 8 Year 1500 1804 1927 1974 2025 Years elapsed 304 123 47 51 Starting at 375 million Population (in billions) 0.375 0.75 1.5 3 6 Year 1171 1715 1881 1960 1999 Years elapsed 544 166 79 39 ## Overpopulation ### Predictions of scarcity Greater Los Angeles lies on a coastal mediterranean savannah with a small watershed 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, 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

• U.S. and World Population Clock (US Census Bureau)
• People in the world
• Live World Population
Population clocks
• HiveGroup.com – World population statistics presented in a treemap interface
• PopulationLabs.com – World population map and graph
• PopulationData.net – Information and maps about populations around the world
• GeoHive.com – World statistics including population and future predictions
• Win.tue.nl – World countries mapped by population size
• World-statistics.org – World statistics including population and projections
Statistics and maps
• Optimum Population Trust
• The Day of 6 Billion and 7 Billion – Official homepages maintained by UNFPA
• Population Reference Bureau – News and issues related to population
• Berlin Institute for Population and Development
Organizations
• Cohen, Joel E. (1995). How Many People Can The Earth Support?. New York: W. W. Norton.
• "World Population Prospects, the 2012 Revision". United Nations Population Division. Retrieved May 19, 2014.
• "World Population Prospects, the 2010 Revision". United Nations Population Division. Retrieved June 25, 2013.
• "Symptoms of The Global Demographic Decline". Demographia.ru. Retrieved June 25, 2013.
• Central Intelligence Agency (2012). World Factbook 2012. CIA. Retrieved November 6, 2012.
• "The World in Balance" (transcript). Two-part PBS Nova on world population. April 20, 2004. Retrieved July 19, 2013.
• "The Environmental Politics of Population and Overpopulation". University of California, Berkeley. 2012. Retrieved July 19, 2013.
• "Global population: Faces of the future". The Economist. June 22, 2013. Retrieved June 25, 2013.
• "Creating new life – and other ways to feed the world". BBC. July 23, 2013. Retrieved July 23, 2013.