World population

In

demographics

, the world population is the total number of

human

s currently living, and was estimated to have exceeded 7.9 billion people . It took over 2 million years of human prehistory and history for the world's population to reach 1

billion

and only 200 years more to grow to 7 billion.

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.
The highest global population growth rates, with increases of over 1.8% per year, occurred between 1955 and 1975peaking at 2.1% between 1965 and 1970. The growth rate declined to 1.2% between 2010 and 2015 and is projected to decline further in the course of the 21st century. The global population is still increasing, but there is significant uncertainty about its long-term trajectory due to changing rates of fertility and mortality. 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. Other demographers predict that world population will begin to decline in the second half of the 21st century.

Birth rates were highest in the late 1980s at about 139 million, and as of 2011 were expected to remain essentially constant at a level of 135 million, while the mortality rate numbered 56 million per year and were expected to increase to 80 million per year by 2040.
The

median age

of human beings as of 2020 is 31 years.

Population by region

Six of the Earth's seven

continent

s 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%). Northern 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%).

Antarctica

only has a very small, fluctuating population of about 1200 people based mainly in polar science stations.

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 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). 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.

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%.

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. 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.

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. 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, presumably from a combination of Mongol invasions, famine, and plague.

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.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. 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. 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 Portuguese and Spanish colonists in the 16th century are believed to have contributed to population growth. Since their introduction to Africa by Portuguese traders in the 16th century,

maize

and

cassava

have similarly replaced traditional African crops as the most important

staple food

crops grown on the continent.

The pre-Columbian population of the Americas is uncertain; historian David Henige called it "the most unanswerable question in the world." 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. Encounters between European explorers and populations in the rest of the world often introduced local epidemics of extraordinary virulence. 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

. Over the centuries, the Europeans had developed high degrees of immunity to these diseases, while the indigenous peoples had no such immunity.

Modern history

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 other improvements in medicine and

sanitation

. Improved material conditions led to the population of Britain increasing from 10 million to 40 million in the 19th century. 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 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). After the collapse of the Soviet Union, Russia's population declined significantly – from 150 million in 1991 to 143 million in 2012 – but by 2013 this decline appeared to have halted.

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, 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 billion people.

Java

had about 5 million inhabitants in 1815; its present-day successor,

Indonesia

, now has a population of over 140 million. 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. Between the 1920s and 2000s, Kenya's population grew from 2.9 million to 37 million.

Milestones by the billions

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 number on this page is automatically updated daily. 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 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.*
*
*
*
* 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 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.

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. 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 median age of the world's population was estimated to be 29.7 years in 2014, and is expected to rise to 37.9 years by 2050.

According to the World Health Organization, the global average life expectancy is 73.3 years as of 2020, with women living an average of 75.9 years and men approximately 70.8 years. In 2010, the global

fertility rate

was estimated at 2.44 children per woman. In June 2012, British researchers calculated the total weight of Earth's human population as approximately , with the average person weighing around .

The

IMF

estimated nominal 2021 gross world product at US$94.94 trillion, giving an annual global per capita figure of around US$12,290. Around 9.3% of the world population live in extreme poverty, subsisting on less than US$1.9 per day; around 8.9% are undernourished. 83% of the world's over-15s are considered literate. In June 2014, there were around 3.03 billion global Internet users, constituting 42.3% 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 languages are

English

(1,132M), Mandarin Chinese (1,117M),

Hindi

(615M),

Spanish

(534M) and

French

(280M). More than three billion people speak an Indo-European language, which is the largest language family by number of speakers. Standard Arabic is a language with no native speakers, but the total number of speakers is estimated at 274 million people.

The 2020 religious composition of the world is estimated to be as follows:

Christianity

(31.1%), Islam (24.9%), Unaffliated ( and

Hinduism

the third, accounting for 15.2%.

Largest populations by country

10 most populous countries

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.

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

.

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), 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

.

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.

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 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. 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."

File:Population curve.svg, Estimated world population figures, 10,000 BC–AD 2000
File:World population growth (lin-log scale).png, Estimated world population figures, 10,000 BC–AD 2000 (in

log y scale

)
File:World population history.svg, World population figures, 1950–2017

Annual population growth

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.

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" whereas the data from 1950 to 2015 are from a UN data sheet.. Linked to a
Download Files
where it states that the figures are for 1 July of the given year.

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

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, while the USCB asserted that this occurred in March 2012. 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. 2003 UN Population Division population projections 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 continued growth thereafter. 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. 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. 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. Some analysts have questioned the sustainability of further world population growth, highlighting the growing pressures on the environment, global food supplies, and energy resources.

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 the Russian demographer

Sergey Kapitsa

, the world population grew between 67,000 BC and 1965 according to the following formula:
: $N = \frac \arccot \frac,$
where
: ''N'' is current population,
: ''T'' is the current year,
: ''C'' = (1.86 ± 0.01)·10¹¹,
: ''T''₀ = 2007 ± 1,
: $\tau$ = 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.

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%." en 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). Kapitsa (1996) cites estimates ranging between 80 and 150 billion. The PRB puts the figure at 117 billion as of 2020, estimating that the current world population is 6.7% of the all the humans who have ever lived. Haub (1995) prepared another figure, updated in 2002 and 2011; the 2011 figure was approximately 107 billion. ''Note: text of paper publication slightly different from text of on-line publication''. 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".

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.Kuhrt, A. (1995). ''The Ancient Near East, c. 3000–330 BCE''. Vol. 2. London: Routledge. p. 695. 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", 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.

See also

Explanatory notes

References

Further reading

*

"World Population Prospects, the 2012 Revision"
United Nations Population Division. Retrieved 19 May 2014.

"World Population Prospects, the 2010 Revision"
United Nations Population Division. Retrieved 25 June 2013.

"World Population History Graph"
World population graph 10000 BC – AD 1950.


Demographia.ru. Retrieved 25 June 2013.
*
World
. ''The World Factbook''. US Central Intelligence Agency (CIA). Retrieved 6 November 2012.

"The World in Balance"
(transcript). Two-part PBS ''Nova'' episode on world population. 20 April 2004. Retrieved 19 July 2013.

"The Environmental Politics of Population and Overpopulation"
University of California, Berkeley. 2012. Retrieved 19 July 2013.

"Global population: Faces of the future"
''The Economist''. 22 June 2013. Retrieved 25 June 2013.

"Creating new life – and other ways to feed the world"
BBC News. 23 July 2013. Retrieved 23 July 2013.

World Population Growth
(Oct 2016), Esteban Ortiz-Ospina and Max Roser, OurWorldInData.org
*

External links

Organizations

The Day of 6 Billion
an
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



Population clocks

U.S. and World Population Clock (US Census Bureau)

{{DEFAULTSORT:World Population
World population,
Cultural globalization
Human overpopulation