Show One of the big lessons from the demographic history of countries is that population explosions are temporary. For many countries the demographic transition has already ended, and as the global fertility rate has now halved we know that the world as a whole is approaching the end of rapid population growth. This visualization presents this big overview of the global demographic transition – with the 2019 data release from the UN Population Division. As we explore at the beginning of the entry on population growth, the global population grew only very slowly up to 1700 – only 0.04% per year. In the many millennia up to that point in history very high mortality of children counteracted high fertility. The world was in the first stage of the demographic transition. Once health improved and mortality declined things changed quickly. Particularly over the course of the 20th century: Over the last 100 years global population more than quadrupled. As we see in the chart, the rise of the global population got steeper and steeper and you have just lived through the steepest increase of that curve. This also means that your existence is a tiny part of the reason why that curve is so steep. The 7-fold increase of the world population over the course of two centuries amplified humanity’s impact on the natural environment. To provide space, food, and resources for a large world population in a way that is sustainable into the distant future is without question one of the large, serious challenges for our generation. We should not make the mistake of underestimating the task ahead of us. Yes, I expect new generations to contribute, but for now it is upon us to provide for them. Population growth is still fast: Every year 140 million are born and 58 million die – the difference is the number of people that we add to the world population in a year: 82 million. Where do we go from here? In red you see the annual population growth rate (that is, the percentage change in population per year) of the global population. It peaked around half a century ago. Peak population growth was reached in 1968 with an annual growth of 2.1%. Since then the increase of the world population has slowed and today grows by just over 1% per year. This slowdown of population growth was not only predictable, but predicted. Just as expected by demographers (here), the world as a whole is experiencing the closing of a massive demographic transition. This chart also shows how the United Nations envision the slow ending of the global demographic transition. As population growth continues to decline, the curve representing the world population is getting less and less steep. By the end of the century – when global population growth will have fallen to 0.1% according to the UN’s projection – the world will be very close to the end of the demographic transition. It is hard to know the population dynamics beyond 2100; it will depend upon the fertility rate and as we discuss in our entry on fertility rates here fertility is first falling with development – and then rising with development. The question will be whether it will rise above an average 2 children per woman. The world enters the last phase of the demographic transition and this means we will not repeat the past. The global population has quadrupled over the course of the 20th century, but it will not double anymore over the course of this century. The world population will reach a size, which compared to humanity’s history, will be extraordinary; if the UN projections are accurate (they have a good track record), the world population will have increased more than 10-fold over the span of 250 years. We are on the way to a new balance. The big global demographic transition that the world entered more than two centuries ago is then coming to an end: This new equilibrium is different from the one in the past when it was the very high mortality that kept population growth in check. In the new balance it will be low fertility that keeps population changes small.
Human population has grown exponentially over the past century. It has done so largely by producing large amounts of food, and learning how to control disease. Ten thousand years ago, when humans first invented agriculture, there were maybe one million humans on the planet. By about the 1300s, when the Black Death appeared, there were about 400 million. We didn’t reach a billion until the year 1800; in the late 1920s we passed the two billion mark and by 1960 we passed three billion. In 2018 there are 7.6 billion people (the world population clock gives a running total). So you have to ask, how did this happen? Normally in biology, when an organism reaches really high densities, like humans are at the moment, either disease takes hold or resources run out and the organism is wiped out. The reason why humans have increased in population so rapidly and so successfully is because we’ve sidestepped the two problems of food shortage and being knocked over by disease. That started in the industrial revolution, when there were about a billion of us, and we tapped into using fossil fuels to do large-scale agriculture. Once you’re using fuels, you can transport food, plough and harvest very large areas and manufacture pesticides. So that removes the first limitation of population – you can make essentially as much food as you want. Secondly, vast improvements in hygiene through having clean supplies of water and reticulated sewage systems to remove waste decreased the incidence of disease. As a result, life expectancy has increased hugely, which contributes to population size: If we all only lived to 30, there’d be half the population on the planet. Another contributor to our rapid population growth are advances in medicine which, along with the improvement in hygiene, means that mothers and children have a much greater chance of surviving childbirth, and most infants survive through childhood. And then there are two great inventions that have lowered the incidence of disease, in particular infectious disease: antibiotics and vaccination. Vaccination, for instance, has made smallpox, which used to kill millions of people, extinct. And whereas people once died from simple bacterial infections - you get scratched by a rose thorn while you’re gardening, and you’re dead in a week – with antibiotics we can now control those infections. The highest growth rate happened between 1955 and 1975. It’s known as The Great Acceleration and it corresponds to the greatest increase in welfare for the most people. Since that time, rates of reproduction, particularly in developed countries, have been dropping, so the rate of growth is starting to slow as people have less children. But we’re still going to be somewhere between 8 and 11 billion by the year 2050. In demographics, the term world population is often used to refer to the total number of humans currently living, and was estimated to have exceeded 7.9 billion as of November 2021[update].[2] It took over two million years of human prehistory and history for the human population to reach one billion[3] and only 200 years more to grow to 7 billion.[4] The human 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 370,000,000.[5] 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.[6] The growth rate declined to 1.2% between 2010 and 2015 and is projected to decline further in the course of the 21st century.[6] The global population is still increasing, but there is significant uncertainty about its long-term trajectory due to changing rates of fertility and mortality.[7] 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.[8] Other demographers predict that the human population will begin to decline in the second half of the 21st century.[9] World population estimate and projection from 10,000 BCE to 2100, by OurWorldInData, from various sources - The population grows from 2.43 million to 10.9 billion people.[clarification needed][10]Birth rates were highest in the late 1980s at about 139 million,[11] and as of 2011 were expected to remain essentially constant at a level of 135 million,[12] while the mortality rate numbered 56 million per year and were expected to increase to 80 million per year by 2040.[13] The median age of human beings as of 2020 is 31 years.[14]
Six of the Earth's seven continents are permanently inhabited on a large scale. Asia is the most populous continent, with its 4.64 billion inhabitants accounting for 60% of the world population. The world's two most populated countries, China and India, together constitute about 36% of the world's population. Africa is the second most populated continent, with around 1.34 billion people, or 17% of the world's population. Europe's 747 million people make up 10% of the world's population as of 2020, while the Latin American and Caribbean regions are home to around 653 million (8%). 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%).[16] Antarctica only has a very small, fluctuating population of about 1200 people based mainly in polar science stations.[17]
Visual comparison of the world population in past and present 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[18] 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).[19] 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.[20] 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%.[21] Ancient and post-classical historyEstimates of the population of the world at the time agriculture emerged in around 10,000 BC have ranged between 1 million and 15 million.[22][23] 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.[24] 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.[25] The population of Europe was more than 70 million in 1340.[26] From 1340 to 1400, the world's population fell from an estimated 443 million to 350-375 million,[27] with the Indian subcontinent suffering the greatest loss and Europe suffering the Black Death pandemic;[28] it took 200 years for European population figures to recover.[29] The population of China decreased from 123 million in 1200 to 65 million in 1393,[30] presumably from a combination of Mongol invasions, famine, and plague.[31] Starting in AD 2, the Han Dynasty of ancient China kept consistent family registers in order to properly assess the poll taxes and labor service duties of each household.[32] In that year, the population of Western Han was recorded as 57,671,400 individuals in 12,366,470 households, decreasing to 47,566,772 individuals in 9,348,227 households by AD 146, towards the End of the Han Dynasty.[32] From 200 to 400, the world population fell from an estimated 257 million to 206 million, with China suffering the greatest loss.[28] At the founding of the Ming Dynasty in 1368, China's population was reported to be close to 60 million; toward the end of the dynasty in 1644, it may have approached 150 million.[33] England's population reached an estimated 5.6 million in 1650, up from an estimated 2.6 million in 1500.[34] New crops that were brought to Asia and Europe from the Americas by Portuguese and Spanish colonists in the 16th century are believed to have contributed to population growth.[35][36][37] Since their introduction to Africa by Portuguese traders in the 16th century,[38] maize and cassava have similarly replaced traditional African crops as the most important staple food crops grown on the continent.[39] The pre-Columbian population of the Americas is uncertain; historian David Henige called it "the most unanswerable question in the world."[40] By the end of the 20th century, scholarly consensus favored an estimate of roughly 55 million people, but numbers from various sources have ranged from 10 million to 100 million.[41] Encounters between European explorers and populations in the rest of the world often introduced local epidemics of extraordinary virulence.[42] According to the most extreme scholarly claims, as many as 90% of the Native American population of the New World died of Old World diseases such as smallpox, measles, and influenza.[43] Over the centuries, the Europeans had developed high degrees of immunity to these diseases, while the indigenous peoples had no such immunity.[44] Modern historyMap showing urban areas with at least one million inhabitants in 2006. Only 3% of the world's population lived in urban areas in 1800; this proportion had risen to 47% by 2000, and reached 50.5% by 2010.[45] By 2050, the proportion may reach 70%.[46] During the European Agricultural and Industrial Revolutions, the life expectancy of children increased dramatically.[47] The percentage of the children born in London who died before the age of five decreased from 74.5% in 1730–1749 to 31.8% in 1810–1829.[48][49] Between 1700 and 1900, Europe's population increased from about 100 million to over 400 million.[50] Altogether, the areas populated by people of European descent comprised 36% of the world's population in 1900.[51] Population growth in the West became more rapid after the introduction of vaccination and other improvements in medicine and sanitation.[52] Improved material conditions led to the population of Britain increasing from 10 million to 40 million in the 19th century.[53] The population of the United Kingdom reached 60 million in 2006.[54] The United States saw its population grow from around 5.3 million in 1800 to 106 million in 1920, exceeding 307 million in 2010.[55] The first half of the 20th century in Imperial Russia and the Soviet Union was marked by a succession of major wars, famines and other disasters which caused large-scale population losses (approximately 60 million excess deaths).[56][57] After the collapse of the Soviet Union, Russia's population declined significantly – from 150 million in 1991 to 143 million in 2012[58] – but by 2013 this decline appeared to have halted.[59] Many countries in the developing world have experienced extremely rapid population growth since the early 20th century, due to economic development and improvements in public health. China's population rose from approximately 430 million in 1850 to 580 million in 1953,[60] and now stands at over 1.3 billion. The population of the Indian subcontinent, which was about 125 million in 1750, increased to 389 million in 1941;[61] today, India, Pakistan and Bangladesh are collectively home to about 1.63 billion people.[62] Java had about 5 million inhabitants in 1815; its present-day successor, Indonesia, now has a population of over 140 million.[63] In just one hundred years, the population of Brazil decupled (x10), from about 17 million in 1900, or about 1% of the world population in that year, to about 176 million in 2000, or almost 3% of the global population in the very early 21st century. Mexico's population grew from 13.6 million in 1900 to about 112 million in 2010.[64][65] Between the 1920s and 2000s, Kenya's population grew from 2.9 million to 37 million.[66] Milestones by the billions
It is estimated that the world population reached one billion for the first time in 1804. It was another 123 years before it reached two billion in 1927, but it took only 33 years to reach three billion in 1960.[67] Thereafter, the global population reached four billion in 1974, five billion in 1987, six billion in 1999 and, according to the United States Census Bureau, seven billion in March 2012.[68] The United Nations, however, estimated that the world population reached seven billion in October 2011.[69][70][71] According to current projections, the global population will reach eight billion by 2024, and is likely to reach around nine billion by 2042. Alternative scenarios for 2050 range from a low of 7.4 billion to a high of more than 10.6 billion.[72] Projected figures vary depending on underlying statistical assumptions and the variables used in projection calculations, especially the fertility variable. Long-range predictions to 2150 range from a population decline to 3.2 billion in the "low scenario", to "high scenarios" of 24.8 billion.[72] One extreme scenario predicted a massive increase to 256 billion by 2150, assuming the global fertility rate remained at its 1995 level of 3.04 children per woman; however, by 2010 the global fertility rate had declined to 2.52.[73][74] There is no estimation for the exact day or month the world's population surpassed one or two billion. The points at which it reached three and four billion were not officially noted, but the International Database of the United States Census Bureau placed them in July 1959 and April 1974 respectively. The United Nations did determine, and commemorate, the "Day of 5 Billion" on 11 July 1987, and the "Day of 6 Billion" on 12 October 1999. The Population Division of the United Nations declared the "Day of 7 Billion" to be 31 October 2011.[75][needs update]
As of 2012, the global sex ratio is approximately 1.01 males to 1 female. The greater number of men is possibly due to the significant sex imbalances evident in the Indian and Chinese populations.[77][78] Approximately 26.3% of the global population is aged under 15, while 65.9% is aged 15–64 and 7.9% is aged 65 or over.[77] The median age of the world's population was estimated to be 29.7 years in 2014,[79] and is expected to rise to 37.9 years by 2050.[80] According to the World Health Organization, the global average life expectancy is 73.3 years as of 2020, with women living an average of 75.9 years and men approximately 70.8 years.[81] In 2010, the global fertility rate was estimated at 2.44 children per woman.[82] In June 2012, British researchers calculated the total weight of Earth's human population as approximately 287 million tonnes (630 billion pounds), with the average person weighing around 62 kilograms (137 lb).[83] 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.[84] Around 9.3% of the world population live in extreme poverty, subsisting on less than US$1.9 per day;[85] around 8.9% are undernourished.[86] 83% of the world's over-15s are considered literate.[77] In June 2014, there were around 3.03 billion global Internet users, constituting 42.3% of the world population.[87] The Han Chinese are the world's largest single ethnic group, constituting over 19% of the global population in 2011.[88] The world's most-spoken languages are English (1.132B), Mandarin Chinese (1.117B), 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.[89] The religious composition of the world as of 2020 is estimated as follows: Christianity (31.1%), Islam (24.9%), Unaffiliated (15.6%) and Hinduism (15.2%).[90] A map of world population in 2019 Most populous countries, previous decade[needs update]
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 countriesThe 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. Purple and pink areas denote regions of highest population density.
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.[101][102][103] 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),[104] 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.[105] Map of countries by fertility rate (2020), according to the Population Reference Bureau 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.[100] 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.[106] 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.[107] 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.[108] 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."[109]
Annual population growth
Population growth by regionThe table below shows historical and predicted regional population figures in millions.[111][112][113] The availability of historical population figures varies by region.
Past populationThe 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"[117] whereas the data from 1950 to 2015 are from a UN data sheet.[15]
Using the above figures, the change in population from 2010 to 2015 was:
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,[111] while the USCB asserted that this occurred in March 2012.[121] 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.[122][123] 2003 UN Population Division population projections for the year 2150 range between 3.2 and 24.8 billion.[73] One of many independent mathematical models supports the lower estimate,[124] while a 2014 estimate forecasts between 9.3 and 12.6 billion in 2100, and continued growth thereafter.[125][126] 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.[127] 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.[128] 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.[129] Some analysts have questioned the sustainability of further world population growth, highlighting the growing pressures on the environment,[130] global food supplies, and energy resources.[131][132][133]
In 1975, Sebastian von Hoerner proposed a formula for population growth which represented hyperbolic growth with an infinite population in 2025.[136] 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.[137] The transition from hyperbolic growth to slower rates of growth is related to the demographic transition. According to the Russian demographer Sergey Kapitsa,[138] the world population grew between 67,000 BC and 1965 according to the following formula: N = C τ arccot T 0 − T τ , {\displaystyle N={\frac {C}{\tau }}\operatorname {arccot} {\frac {T_{0}-T}{\tau }},}where N is current population, T is the current year, C = (1.86 ± 0.01)·1011, T0 = 2007 ± 1, τ {\displaystyle \tau } = 42 ± 1.Years for world population to doubleAccording 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.[139] Historic chart showing the periods of time the world population has taken to double, from 1700 to 2000
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%.[21] Kapitsa (1996) cites estimates ranging between 80 and 150 billion.[140] 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.[141] Haub (1995) prepared another figure, updated in 2002 and 2011; the 2011 figure was approximately 107 billion.[142][143][144] 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".[143] 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.[145] 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",[143] 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.
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