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 Template:As of, the world population was 6.916 billion. The United States Census Bureau estimates that the world population exceeded 7 billion on March 12, 2012. According to a separate estimate by the United Nations Population Fund, it reached this milestone on October 31, 2011. The median age of the world's population was estimated to be 29.7 years in 2014.

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. 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 1.1% Template:As of. Total annual births were highest in the late 1980s at about 138 million, 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.

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

World population (millions)
#	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
7	Bangladesh	116	160	198
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

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%). 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.

Population by continent

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

History

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Antiquity and Middle Ages

{{#invoke:main|main}} The world population in 35,000 BCE is estimated to have been around 3 million people who subsisted as hunter-gatherers. The population had increased to around 15 million by the time agriculture was invented around 12,000 years ago. 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.

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. The population of Europe was more than 70 million in 1340. 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; it took 200 years for population figures to recover. The population of China decreased from 123 million in 1200 to 65 million in 1393, which was presumably due to a combination of Mongol invasions, famine and plague.

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

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

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

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. By 2050, the proportion may reach 70%.

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

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

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

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

Milestones by the billions

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World population milestones (USCB estimates)

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. 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. The United Nations, however, estimated that the world population reached seven billion in October 2011.

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. 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. 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.

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.

Global demographics

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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. 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. The global median age was 30.4 years in 2012, and is expected to rise to 37.9 years by 2050.

The global average life expectancy is 67.07 years, with women living an average of 69 years and men approximately 65 years. In 2010, the global fertility rate was estimated at 2.52 children per woman. In June 2012, British researchers calculated the total weight of Earth's human population as 287 million tonnes, with the average person weighing Template:Convert.

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. Around 1.29 billion people (18.4% of the world population) live in extreme poverty, subsisting on less than US$1.25 per day; approximately 870 million people (12.25%) are undernourished. 83% of the world's over-15s are considered literate. In June 2012, there were around 2.4 billion global Internet users, constituting 34.2% of the world population.

The Han Chinese are the world's largest single ethnic group, constituting over 19% of the global population in 2011. 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%). 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%. In 2005, around 16% of the global population were reported to be non-religious.

Largest populations by country

File:World population.svg

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	Template:Country data China	Template:Data China
2	Template:Country data India	Template:Data India
3	Template:Country data United States	Template:Data United States
4	Template:Country data Indonesia	252,164,800	July 1, 2014	%
5	Template:Country data Brazil	Template:Data Brazil
6	Template:Country data Pakistan	Template:Data Pakistan
7	Template:Country data Nigeria	178,517,000	July 1, 2014	%
8	Template:Country data Bangladesh	Template:Data Bangladesh
9	Template:Country data Russia	146,068,400	June 1, 2014	%
10	Template:Country data Japan	127,130,000	August 1, 2014	%

Approximately 4.185 billion people live in these ten countries, representing around % of the world's population as of August 2014.

Most densely populated countries

Template:Rellink 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	Template:Country data Singapore	5,399,200	710	7605
2	Template:Country data Bahrain	1,234,571	750	1646
3	Template:Country data Bangladesh	149,772,364	147,570	1101
4	Template:Country data Taiwan	23,361,147	36,190	645
5	Template:Country data Mauritius	1,257,900	2,040	617
6	Template:Country data South Korea	50,219,669	99,538	505
7	Template:Country data Lebanon	4,822,000	10,452	461
8	Template:Country data Netherlands	16,911,719	41,526	407
9	Template:Country data Rwanda	10,537,222	26,338	400
10	Template:Country data 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
Template:Country data India	Template:Data India	Growing country
Template:Country data Bangladesh	149,772,364	147,570	1101	Growing country
Template:Country data Japan	127,180,000	377,873	337	Declining in population
Template:Country data Philippines	98,698,000	300,076	329	Growing country
Template:Country data Vietnam	90,388,000	331,689	268	Growing country
Template:Country data United Kingdom	63,705,000	243,610	262	Growing country
Template:Country data South Korea	50,219,669	99,538	505	Slowly growing country
Template:Country data Taiwan	23,361,147	36,190	645	Steady in population
Template:Country data Sri Lanka	20,328,597	65,610	309	Slowly growing country
Template:Country data Netherlands	16,848,208	41,526	406	Steady in population

Fluctuation

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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.

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), 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.{{ safesubst:#invoke:Unsubst||date=__DATE__ |$B= {{#invoke:Category handler|main}}{{#invoke:Category handler|main}} }} 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. Template:Col-begin Template:Col-break Template:Legend Template:Legend Template:Col-break Template:Legend Template:Legend Template:Col-break Template:Legend Template:Legend Template:Col-break Template:Legend Template:Legend Template:Col-end

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.

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.

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. 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. An alternative scenario is given by Jorgen Randers, who argues that traditional projections insufficiently take into account the downward impact of global urbanization on fertility. Randers' "most likely scenario" reveals a peak in the world population in the early 2040s at about 8.1 billion people, followed by decline.

• 

  Estimated world population figures, 10,000 BC–2000 AD.

• 

  Estimated world population figures, 10,000 BC–2000 AD (in log y scale).

• 

  World population figures, 1950–2000.

• 

  Estimated global growth rates, 1950–2050.

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  Estimated and projected populations of the world and its continents (except Antarctica) from 1950 to 2100. The shaded regions correspond to the range of projections by the United Nations Department of Economic and Social Affairs.

Projections

{{#invoke:main|main}} 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, while the UN asserted that this occurred in late 2011. 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

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)

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. The availability of historical population figures varies by region.

World historical and predicted populations (in millions)

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 AmericaTemplate:R	39	10	10	16	24	38	74	167	511	577	590	603	809	912
Northern AmericaTemplate:R	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

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 AmericaTemplate:R	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 AmericaTemplate:R	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 AmericaTemplate:R	Northern AmericaTemplate:R	Oceania	Notes
70,000 BC	< 0.015
10,000 BC	4
8000 BC	5
6500 BC	5
5000 BC	5
4000 BC	7
3000 BC	14
2000 BC	27
1000 BC	50	7	33	9				{{ safesubst:#invoke:Unsubst	$B= {{#invoke:Category handler|main}}{{#invoke:Category handler|main}} }}
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
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

Mathematical approximations

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

According to Sergey Kapitsa, the world population grew between 67,000 BC and 1965 according to the following formula:

$N={\frac {C}{\tau }}\operatorname {arccot} {\frac {T_{0}-T}{\tau }}$

where

• N is current population
• T is the current year
• C = (1.86±0.01)·10¹¹
• T₀ = 2007±1
• $\tau$ = 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.

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

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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. 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%. 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. 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.

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), global population growth, the effects of climate change, the loss of agricultural land to residential and industrial development, and growing consumer demand in the population centres of China and India. Food riots subsequently occurred in some countries. 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.

David Pimentel, professor of ecology and agriculture at Cornell University, estimates that the sustainable agricultural carrying capacity for the United States is about 200 million people; its population as of 2013 is over 310 million. 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. According to a 2009 report by the United Nations Food and Agriculture Organisation (FAO), the world will have to produce 70% more food by 2050 to feed a projected extra 2.3 billion people.

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. The 2009 FAO estimates showed an even more dramatic increase, to 1.02 billion.

Environmental impacts

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

A number of scientists have argued that the current global population expansion and accompanying increase in resource consumption threatens the world's ecosystem, as well as straining humanity's ability to feed itself. The InterAcademy Panel Statement on Population Growth, which was ratified by 58 member national academies in 1994, called the growth in human numbers "unprecedented", and stated that many environmental problems, such as rising levels of atmospheric carbon dioxide, global warming, and pollution, were aggravated by the population expansion. Indeed, some analysts claim that overpopulation's most serious impact is its effect on the environment. At the time of the 1994 IAP statement, the world population stood at 5.5 billion, and lower-bound scenarios predicted a peak of 7.8 billion by 2050, a number that current estimates state will be reached in the late 2020s.

Population control

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

Human population control is the practice of intervening to alter the rate of population growth. Historically, human population control has been implemented by limiting a region's birth rate, by voluntary contraception or by government mandate. It has been undertaken as a response to factors including high or increasing levels of poverty, environmental concerns, and religious reasons. The use of abortion in some population control strategies has caused controversy, with religious organizations such as the Roman Catholic Church explicitly opposing any intervention in the human reproductive process.

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." 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.

Overpopulation as a myth

Some scientists, religious commentators and public policy analysts have criticised predictions of overpopulation and attendant resource scarcity, with some describing overpopulation as a myth. The Population Research Institute argues that advances in agricultural, medical and industrial technology have allowed global economic productivity to keep pace with rising populations despite Malthusian predictions to the contrary, and point out that family sizes are naturally declining worldwide due to higher living standards and better economic opportunities for women. PRI's stance on overpopulation and the arguments for "Overpopulation is a Myth" have been described as deceptive.

Ten Million Club Foundation further adds to criticism, accusing PRI of having a religious hidden agenda (against family planning and contraception) that motivates its (allegedly) deceiving claims, stating that those are not backed up by any original research. PRI hasn't as yet published a single peer review paper in any scientific journal.

Number of humans who have ever lived

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

Estimation methodologies

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

More importantly, robust population data only exist for the last two or three centuries. Until the late 18th century, few governments had ever performed an accurate census. In many early attempts, such as in Ancient Egypt and the Persian Empire, the focus was on counting merely a subset of the population for purposes of taxation or military service. Thus, there is a significant margin of error when estimating ancient global populations.

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

External links

Further reading

• {{#invoke:citation/CS1|citation

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• "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.

Organizations

• 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

Statistics and maps

• 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

Population clocks

• U.S. and World Population Clock (US Census Bureau)
• People in the world
• Live World Population

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