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demographics Demography () is the statistical study of populations, especially human beings. Demographic analysis examines and measures the dimensions and dynamics of populations; it can cover whole societies or groups defined by criteria such as ed ...
, the world population is the total number of
human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, cultu ...
s currently living. It was estimated by the
United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmoniz ...
to have exceeded 8 billion in November 2022. It took over 200,000 years of human
prehistory Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use ...
and
history History (derived ) is the systematic study and the documentation of the human activity. The time period of event before the invention of writing systems is considered prehistory. "History" is an umbrella term comprising past events as well ...
for the human population to reach one
billion Billion is a word for a large number, and it has two distinct definitions: *1,000,000,000, i.e. one thousand million, or (ten to the ninth power), as defined on the short scale. This is its only current meaning in English. * 1,000,000,000,000, i. ...
and only 219 years more to reach 8 billion. The human population experienced continuous growth following the
Great Famine of 1315–1317 The Great Famine of 1315–1317 (occasionally dated 1315–1322) was the first of a series of large-scale crises that struck Europe early in the 14th century. Most of Europe (extending east to Russia and south to Italy) was affected. The famine ...
and the end of the Black Death in 1350, when it was nearly 370,000,000. The highest global population growth rates, with increases of over 1.8% per year, occurred between 1955 and 1975, peaking at 2.1% between 1965 and 1970. The growth rate declined to 1.1% between 2015 and 2020 and is projected to decline further in the 21st century. The global population is still increasing, but there is significant uncertainty about its long-term trajectory due to changing fertility and mortality rates. The UN Department of Economics and Social Affairs projects between 9 and 10 billion people by 2050 and gives an 80% confidence interval of 10–12 billion by the end of the 21st century, with a growth rate by then of zero. Other demographers predict that the human population will begin to decline in the second half of the 21st century. The total number of births globally is currently (2015–2020) 140 million/year, which is projected to peak during the period 2040–2045 at 141 million/year and then decline slowly to 126 million/year by 2100. The total number of deaths is currently 57 million/year and is projected to grow steadily to 121 million/year by 2100. The
median age A population pyramid (age structure diagram) or "age-sex pyramid" is a graphical illustration of the distribution of a population (typically that of a country or region of the world) by age groups and sex; it typically takes the shape of a pyramid ...
of human beings is 31 years.


History

Estimates of world population by their nature are an aspect of
modernity Modernity, a topic in the humanities and social sciences, is both a historical period (the modern era) and the ensemble of particular socio-cultural norms, attitudes and practices that arose in the wake of the Renaissancein the "Age of Reas ...
, possible only since the
Age of Discovery The Age of Discovery (or the Age of Exploration), also known as the early modern period, was a period largely overlapping with the Age of Sail, approximately from the 15th century to the 17th century in European history, during which seafarin ...
. Early estimates for the population of the world date to the 17th century:
William Petty Sir William Petty FRS (26 May 1623 – 16 December 1687) was an English economist, physician, scientist and philosopher. He first became prominent serving Oliver Cromwell and the Commonwealth in Ireland. He developed efficient methods to s ...
, in 1682, estimated the world population at 320 million (current estimates ranging close to twice this number); by the late 18th century, estimates ranged close to one billion (consistent with current 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 800 million to 1 billion in the 1840s. It is difficult for estimates to be better than rough approximations, as even current population estimates are fraught with uncertainties from 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 now largely discredited
Toba catastrophe theory The Youngest Toba eruption was a supervolcano eruption that occurred around 74,000 years ago at the site of present-day Lake Toba in Sumatra, Indonesia. It is one of the Earth's largest known explosive eruptions. The Toba catastrophe theory ho ...
. By contrast, it is estimated that around 50–60 million people lived in the combined eastern and western
Roman Empire The Roman Empire ( la, Imperium Romanum ; grc-gre, Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn) was the post- Republican period of ancient Rome. As a polity, it included large territorial holdings around the Mediter ...
in the 4th century AD. The
Plague of Justinian The plague of Justinian or Justinianic plague (541–549 AD) was the first recorded major outbreak of the first plague pandemic, the first Old World pandemic of plague, the contagious disease caused by the bacterium ''Yersinia pestis''. The dis ...
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. From 1340 to 1400, the world's population fell from an estimated 443 million to 350–375 million, with the
Indian subcontinent The Indian subcontinent is a list of the physiographic regions of the world, physiographical region in United Nations geoscheme for Asia#Southern Asia, Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian O ...
suffering the most tremendous loss and Europe suffering the Black Death pandemic; it took 200 years for European 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 The Mongols ( mn, Монголчууд, , , ; ; russian: Монголы) are an East Asian ethnic group native to Mongolia, Inner Mongolia in China and the Buryatia Republic of the Russian Federation. The Mongols are the principal member ...
invasions, famine, and plague. Starting in AD 2, the
Han dynasty The Han dynasty (, ; ) was an imperial dynasty of China (202 BC – 9 AD, 25–220 AD), established by Liu Bang (Emperor Gao) and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–207 BC) and a warr ...
of ancient China kept consistent family registers 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 The Han dynasty (, ; ) was an imperial dynasty of China (202 BC – 9 AD, 25–220 AD), established by Liu Bang (Emperor Gao) and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–207 BC) and a war ...
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. From 200 to 400, the world population fell from an estimated 257 million to 206 million, with China suffering the greatest loss. At the founding of the
Ming dynasty The Ming dynasty (), officially the Great Ming, was an imperial dynasty of China, ruling from 1368 to 1644 following the collapse of the Mongol-led Yuan dynasty. The Ming dynasty was the last orthodox dynasty of China ruled by the Han peo ...
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 Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...
and
cassava ''Manihot esculenta'', commonly called cassava (), manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America. Although a perennial plant, cassava is extensively cultivated ...
have similarly replaced traditional African crops as the most important staple food crops grown on the continent. The
pre-Columbian In the history of the Americas, the pre-Columbian era spans from the original settlement of North and South America in the Upper Paleolithic period through European colonization, which began with Christopher Columbus's voyage of 1492. Usually, ...
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 The term ''New World'' is often used to mean the majority of Earth's Western Hemisphere, specifically the Americas."America." ''The Oxford Companion to the English Language'' (). McArthur, Tom, ed., 1992. New York: Oxford University Press, p. ...
died of Old World diseases such as
smallpox Smallpox was an infectious disease caused by variola virus (often called smallpox virus) which belongs to the genus Orthopoxvirus. The last naturally occurring case was diagnosed in October 1977, and the World Health Organization (WHO) c ...
, 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 Revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
s, the
life expectancy Life expectancy is a statistical measure of the average time an organism is expected to live, based on the year of its birth, current age, and other demographic factors like sex. The most commonly used measure is life expectancy at birth ...
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
Western world The Western world, also known as the West, primarily refers to the various nations and states in the regions of Europe, North America, and Oceania.
became more rapid after the introduction of
vaccination Vaccination is the administration of a vaccine to help the immune system develop immunity from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating ...
and other improvements in medicine and
sanitation Sanitation refers to public health conditions related to clean drinking water and treatment and disposal of human excreta and sewage. Preventing human contact with feces is part of sanitation, as is hand washing with soap. Sanitation syste ...
. 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 The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
was marked by a succession of major wars,
famine A famine is a widespread scarcity of food, caused by several factors including war, natural disasters, crop failure, population imbalance, widespread poverty, an economic catastrophe or government policies. This phenomenon is usually accompani ...
s 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 The Indian subcontinent is a list of the physiographic regions of the world, physiographical region in United Nations geoscheme for Asia#Southern Asia, Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian O ...
, 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 Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mos ...
, an island in
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
, had about 5 million inhabitants in 1815; it had a population of over 139 million in 2020. 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

The UN 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, it took 14 years for the global population to reach four billion in 1974, 13 years to reach five billion in 1987, 12 years to reach six billion in 1999 and, according to the United States Census Bureau, 13 years to reach 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 the UN, the global population reached eight billion in November 2022, but because the growth rate is slowing, it will take another 15 years to reach around 9 billion by 2037 and 20 years to reach 10 billion by 2057. 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 Fertility is the capability to produce offspring through reproduction following the onset of sexual maturity. The fertility rate is the average number of children born by a female during her lifetime and is quantified demographically. Fertili ...
and mortality variables. 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 Seven Billion" to be 31 October 2011. The United Nations marked the birth of the eight billionth person on 15 November 2022.


Global demographics

As of 2012, the global
sex ratio The sex ratio (or gender ratio) is usually defined as the ratio of males to females in a population. As explained by Fisher's principle, for evolutionary reasons this is typically about 1:1 in species which reproduce sexually. Many species d ...
is approximately 1.01 males to 1 female. 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 is estimated to be 31 years in 2020, and is expected to rise to 37.9 years by 2050. According to the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of ...
, the global average
life expectancy Life expectancy is a statistical measure of the average time an organism is expected to live, based on the year of its birth, current age, and other demographic factors like sex. The most commonly used measure is life expectancy at birth ...
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 The total fertility rate (TFR) of a population is the average number of children that would be born to a woman over her lifetime if: # she were to experience the exact current age-specific fertility rates (ASFRs) through her lifetime # she were ...
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 The gross world product (GWP) is the combined gross national income of all the countries in the world. Because imports and exports balance exactly when considering the whole world, this also equals the total global gross domestic product (GDP).Se ...
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
malnourished Malnutrition occurs when an organism gets too few or too many nutrients, resulting in health problems. Specifically, it is "a deficiency, excess, or imbalance of energy, protein and other nutrients" which adversely affects the body's tissues ...
. 87% of the world's over-15s are considered
literate Literacy in its broadest sense describes "particular ways of thinking about and doing reading and writing" with the purpose of understanding or expressing thoughts or ideas in written form in some specific context of use. In other words, hum ...
. As of April 2022, there were about 5 billion global Internet users, constituting 63% of the world population. The
Han Chinese The Han Chinese () or Han people (), are an East Asian ethnic group native to China. They constitute the world's largest ethnic group, making up about 18% of the global population and consisting of various subgroups speaking distinctiv ...
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 English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ide ...
(1.132B),
Mandarin Chinese Mandarin (; ) is a group of Chinese (Sinitic) dialects that are natively spoken across most of northern and southwestern China. The group includes the Beijing dialect, the basis of the phonology of Standard Chinese, the official language ...
(1.117B),
Hindi Hindi ( Devanāgarī: or , ), or more precisely Modern Standard Hindi (Devanagari: ), is an Indo-Aryan language spoken chiefly in the Hindi Belt region encompassing parts of northern, central, eastern, and western India. Hindi has been ...
(615M),
Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many Latin American countries **Spanish cuisine Other places * Spanish, Ontario, Can ...
(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 largest religious categories in the world as of 2020 are estimated as follows:
Christianity Christianity is an Abrahamic monotheistic religion based on the life and teachings of Jesus of Nazareth. It is the world's largest and most widespread religion with roughly 2.38 billion followers representing one-third of the global pop ...
(31%), Islam (25%), Unaffiliated (16%) and
Hinduism Hinduism () is an Indian religion or '' dharma'', a religious and universal order or way of life by which followers abide. As a religion, it is the world's third-largest, with over 1.2–1.35 billion followers, or 15–16% of the global p ...
(15%).


Population by region

Six of the Earth's seven
continent A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions In geography, regions, otherwise referred to as zones, lands or territories, are areas t ...
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 Latin Americans ( es, Latinoamericanos; pt, Latino-americanos; ) are the citizens of Latin American countries (or people with cultural, ancestral or national origins in Latin America). Latin American countries and their diasporas are multi-eth ...
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 Oceania (, , ) is a geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern and Western hemispheres, Oceania is estimated to have a land area of and a population of around 44.5 million ...
, the least populated region, has about 42 million inhabitants (0.5%).
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...
only has a very small, fluctuating population of about 1200 people based mainly in polar science stations.


Largest populations by country


10 most populous countries

Approximately 4.49 billion people live in these ten countries, representing around 56% of the world's population as of July 2022.


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, as of November 2022. All areas and populations are from
The World Factbook ''The World Factbook'', also known as the ''CIA World Factbook'', is a reference resource produced by the Central Intelligence Agency (CIA) with almanac-style information about the countries of the world. The official print version is availabl ...
, unless otherwise noted.


Fluctuation

Population size fluctuates at differing rates in differing regions. Nonetheless, population growth has been 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 as the whole world entered the early phases of what has come to be called the "
demographic transition In demography, demographic transition is a phenomenon and theory which refers to the historical shift from high birth rates and high death rates in societies with minimal technology, education (especially of women) and economic development, to l ...
". Some of the key factors contributing to this increase included the lessening of the
mortality rate Mortality rate, or death rate, is a measure of the number of deaths (in general, or due to a specific cause) in a particular population, scaled to the size of that population, per unit of time. Mortality rate is typically expressed in units of d ...
in many countries by improved sanitation and medical advances, and a massive increase in agricultural productivity attributed to the
Green Revolution The Green Revolution, also known as the Third Agricultural Revolution, was a period of technology transfer initiatives that saw greatly increased crop yields and agricultural production. These changes in agriculture began in developed countrie ...
. By 2000, there were approximately ten times as many people on Earth as there had been in 1700. However, this rapid growth did not last. During the period 2000–2005, the United Nations estimates that the world's population was growing at an annual rate of 1.3% (equivalent to around 80 million people), down from a peak of 2.1% during the period 1965–1970. Globally, although the population growth rate has been steadily declining from its peak in 1968, growth still remains high in Sub-Saharan Africa. In fact, during the 2010s, Japan and some countries in Europe began to reduce in population, due to
sub-replacement fertility Sub-replacement fertility is a total fertility rate (TFR) that (if sustained) leads to each new generation being less populous than the older, previous one in a given area. The United Nations Population Division defines sub-replacement fertilit ...
rates. In 2019, the United Nations reported that the rate of population growth continues to decline due to the ongoing global demographic transition. If this trend continues, the rate of growth may diminish to zero by 2100, concurrent with a world population plateau of 10.9 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 The University of Washington (UW, simply Washington, or informally U-Dub) is a public research university in Seattle, Washington. Founded in 1861, Washington is one of the oldest universities on the West Coast; it was established in Seattl ...
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. Since 1951 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. Complicating the UN's and others’ attempts to project future populations is the fact that average global
birth rate The birth rate for a given period is the total number of live human births per 1,000 population divided by the length of the period in years. The number of live births is normally taken from a universal registration system for births; populati ...
s, as well as
mortality rate Mortality rate, or death rate, is a measure of the number of deaths (in general, or due to a specific cause) in a particular population, scaled to the size of that population, per unit of time. Mortality rate is typically expressed in units of d ...
s, are declining rapidly, as the nations of the world progress through the stages of the demographic transition, but both vary greatly between developed countries (where birth rates and mortality rates are often low) and developing countries (where birth and mortality rates typically remain high). Different ethnicities also display varying birth rates. Both of these can change rapidly due to disease epidemics,
wars War is an intense armed conflict between states, governments, societies, or paramilitary groups such as mercenaries, insurgents, and militias. It is generally characterized by extreme violence, destruction, and mortality, using regular ...
and other mass catastrophes, or advances in medicine and
public health Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the det ...
. The UN's first report in 1951 showed that during the period 1950–55 the
crude birth rate The birth rate for a given period is the total number of live human births per 1,000 population divided by the length of the period in years. The number of live births is normally taken from a universal registration system for births; populati ...
was 36.9/1,000 population and the crude death rate was 19.1/1,000.  By the period 2015–20 both numbers had dropped significantly to 18.5/1,000 for the crude birth rate and 7.5/1,000 for the crude death rate.  UN projections for 2100 show a further decline in the crude birth rate to 11.6/1,000 and an increase in the crude death rate to 11.2/1,000., The total number of births globally is currently (2015–20) 140 million/year, is projected to peak during the period 2040–45 at 141 million/year and thereafter decline slowly to 126 million/year by 2100. The total number of deaths is currently 57 million/year and is projected to grow steadily to 121 million/year by 2100. 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 DSW (german: Deutsche Stiftung Weltbevölkerung) is an international non-governmental organisation addressing Sexual & Reproductive Health (SRH) and population dynamics. DSW funds its project and advocacy work from private donations and the finan ...
projected that the global population will reach 8 billion by 2023 as it increases by 156 every minute. In a modeled future projection by the
Institute for Health Metrics and Evaluation The Institute for Health Metrics and Evaluation (IHME) is a research institute working in the area of global health statistics and impact evaluation at the University of Washington in Seattle. The Institute is headed by Christopher J.L. Murray ...
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 When a quantity grows towards a singularity under a finite variation (a "finite-time singularity") it is said to undergo hyperbolic growth. More precisely, the reciprocal function 1/x has a hyperbola as a graph, and has a singularity at 0, meani ...
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

The total number of humans who have ever lived is estimated to be approximately 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 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 Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from that which does not, and is defined by the capacity for growth, reaction to stimuli, metabolism, energy t ...
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


Sources

*


Further reading

*
"World Population Prospects, the 2012 Revision"
United Nations Population Division The United Nations Department of Economic and Social Affairs (UN DESA) is part of the United Nations Secretariat and is responsible for the follow-up to major United Nations Summits and Conferences, as well as services to the United Nations Ec ...
. Retrieved 19 May 2014.
"World Population Prospects, the 2010 Revision"
United Nations Population Division The United Nations Department of Economic and Social Affairs (UN DESA) is part of the United Nations Secretariat and is responsible for the follow-up to major United Nations Summits and Conferences, as well as services to the United Nations Ec ...
. 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 ''The World Factbook'', also known as the ''CIA World Factbook'', is a reference resource produced by the Central Intelligence Agency (CIA) with almanac-style information about the countries of the world. The official print version is availabl ...
''. US
Central Intelligence Agency The Central Intelligence Agency (CIA ), known informally as the Agency and historically as the Company, is a civilian foreign intelligence service of the federal government of the United States, officially tasked with gathering, processing, ...
(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 The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant u ...
. 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 BBC News is an operational business division of the British Broadcasting Corporation (BBC) responsible for the gathering and broadcasting of news and current affairs in the UK and around the world. The department is the world's largest broad ...
. 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)

World Population Clock – Worldometer
{{DEFAULTSORT:World Population Cultural globalization Human overpopulation