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Population growth is the increase in the number of people in a
population Population typically refers the number of people in a single area whether it be a city or town, region, country, or the world. Governments typically quantify the size of the resident population within their jurisdiction by a process called a ...

population
. Global human population growth amounts to around 83 million annually, or 1.1% per year. The
global population upright=1.3, Population growth graph In demographics, the world population is the total number of human Humans (''Homo sapiens'') are the most populous and widespread species of primates, characterized by bipedality, opposable thumbs, ...

global population
has grown from 1 billion in 1800 to 7.9 billion in 2020. The UN projected population to keep growing, and estimates have put the total population at 8.6 billion by mid-2030, 9.8 billion by mid-2050 and 11.2 billion by 2100. However, some academics outside the UN have increasingly developed human population models that account for additional downward pressures on population growth; in such a scenario population would peak before 2100. A popular estimate of sustainable population is 8 billion people. World human population has been growing since the end of the
Black Death The Black Death (also known as the Pestilence, the Great Mortality or the Plague) was a bubonic plague pandemic occurring in Afro-Eurasia from 1346 to 1353. It is the List of epidemics, most fatal pandemic recorded in human history, causing th ...

Black Death
, around the year 1350. A mix of technological advancement that improved
agricultural productivity Agricultural productivity is measured as the ratio of agricultural Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, where ...
and sanitation and medical advancement that reduced mortality have caused an exponential population growth. In some geographies, this has slowed through the process called the
demographic transition In demography Demography (from prefix ''demo-'' from Ancient Greek δῆμος (''dēmos'') meaning 'the people', and ''-graphy'' from γράφω (''graphō'') meaning 'writing, description or measurement') is the statistics, statistical s ...
, where many nations with high standards of living have seen a significant slowing of population growth. This is in direct contrast with less developed contexts, where population growth is still happening. However, the global human population is projected to peak during the mid-21st century and decline by 2100. Population growth alongside
overconsumption Overconsumption describes a situation where the use of a natural resource , Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, th ...
is a key driver of environmental concerns, such as
biodiversity loss Biodiversity loss includes the extinction Extinction is the termination of a kind of organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells ...
and
climate change Contemporary climate change includes both the global warming caused by humans, and its impacts on Earth's weather patterns. There have been previous periods of climate change, but the current changes are more rapid than any known even ...
, due to resource-intensive human development that exceed
planetary boundaries Planetary boundaries is a concept involving Earth system processes that contain environmental boundaries. It was proposed in 2009 by a group of Earth system and environmental scientists Environmental science is an interdisciplinary ...

planetary boundaries
. International policy focused on mitigating the impact of human population growth is concentrated in the
Sustainable Development Goals The Sustainable Development Goals (SDGs) or Global Goals are a collection of 17 interlinked global goals designed to be a "blueprint to achieve a better and more sustainable Sustainability is the capacity to endure in a relatively ongoing wa ...

Sustainable Development Goals
which seek to improve the standard of living globally while reducing the impact of society on the environment.


History

World population In demographics Demography (from prefix ''demo-'' from Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is oft ...

World population
has been rising continuously since the end of the
Black Death The Black Death (also known as the Pestilence, the Great Mortality or the Plague) was a bubonic plague pandemic occurring in Afro-Eurasia from 1346 to 1353. It is the List of epidemics, most fatal pandemic recorded in human history, causing th ...

Black Death
, around the year 1350. Population began growing rapidly in the
Western world The Western world, also known as the West, refers to various regions, nations and state (polity), states, depending on the context, most often consisting of the majority of Europe, Northern America, and Australasia.
during the
industrial revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe Continental Europe or mainland Europe is the contiguous continent A continent is any of several large landmasse ...
. The most significant increase in the world's population has been since the 1950s, mainly due to medical advancements and increases in
agricultural productivity Agricultural productivity is measured as the ratio of agricultural Agriculture is the science, art and practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, where ...
.


Haber process

Due to its dramatic impact on the human ability to grow food, the
Haber process The Haber process, also called the Haber–Bosch process, is an artificial nitrogen fixation process and is the main industrial procedure for the ammonia production, production of ammonia today. It is named after its inventors, the German chemist ...

Haber process
, named after one of its inventors, the German chemist
Fritz Haber Fritz Haber (; 9 December 1868 – 29 January 1934) was a German chemist who received the Nobel Prize in Chemistry in 1918 for his invention of the Haber process, Haber–Bosch process, a method used in industry to synthesize ammonia from nit ...

Fritz Haber
, served as the "detonator of the
population explosion Overpopulation or overabundance occurs when a species' population In biology, a population is a number of all the organisms of the same group or species In biology, a species is the basic unit of biological classification, classifica ...
", enabling the
global population upright=1.3, Population growth graph In demographics, the world population is the total number of human Humans (''Homo sapiens'') are the most populous and widespread species of primates, characterized by bipedality, opposable thumbs, ...
to increase from 1.6 billion in 1900 to 7.7 billion by November 2019.


Thomas McKeown hypotheses

Some of the reasons for the "Modern Rise of Population" were particularly investigated by the British health scientist Thomas McKeown (1912-1988). In his publications, McKeown challenged four theories about the population growth: # McKeown stated that the growth in Western population, particularly surging in the 19th century, was not so much caused by an increase in
fertility Fertility is the capability to produce through following the onset of . The is the average number of children born by a female during her lifetime and is quantified . Fertility is addressed when there is a difficulty or an inability to repro ...
, but largely by a decline of
mortality Mortality is the state of being mortal, or susceptible to death (1906) Death is the permanent, Irreversible process, irreversible cessation of all biological process, biological functions that sustain a living organism. Brain death is some ...
particularly of childhood mortality followed by
infant mortality Infant mortality is the death of young children under the age of 1. This death toll is measured by the infant mortality rate (IMR), which is the probability of deaths of children under one year of age per 1000 live births. The under-five mortalit ...

infant mortality
, # The decline of mortality could largely be attributed to rising standards of living, whereby McKeown put most emphasis on improved nutritional status, # His most controversial idea, or at least his most disputed idea, was that he questioned the effectiveness of public health measures, including sanitary reforms, vaccination and quarantine, # The sometimes fierce disputes that his publication provoked around the "McKeown thesis" have overshadowed his more important and largely unchallenged argument that
curative medicineCurative care or curative medicine is the health care Health care, health-care, or healthcare is the maintenance or improvement of health via the preventive healthcare, prevention, diagnosis, therapy, treatment, recovery, or cure of disease, illne ...
measures played little role in mortality decline, not only prior to the mid-20th century but also until well into the 20th century. Although the McKeown thesis has been heavily disputed, recent studies have confirmed the value of his ideas. His work is pivotal for present day thinking about population growth, birth control, public health and medical care. McKeown had a major influence on many population researchers, such as health economists and Nobel prize winners Robert W. Fogel (1993) and
Angus Deaton Sir Angus Stewart Deaton (born 19 October 1945) is a British-American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the United States The United States of Amer ...
(2015). The latter considered McKeown as "the founder of
social medicine The field of social medicine seeks to implement social care through # understanding how social and economic conditions impact health, disease and the practice of medicine and # fostering conditions in which this understanding can lead to a healthie ...
".


Growth rate models

The "population growth rate" is the rate at which the number of individuals in a population increases in a given time period, expressed as a fraction of the initial population. Specifically, population growth rate refers to the change in population over a unit time period, often expressed as a percentage of the number of individuals in the population at the beginning of that period. This can be written as the formula, valid for a sufficiently small time interval: :Population\ growth\ rate = \frac A positive growth rate indicates that the population is increasing, while a negative growth rate indicates that the population is decreasing. A growth ratio of zero indicates that there were the same number of individuals at the beginning and end of the period—a growth rate may be zero even when there are significant changes in the
birth rate The crude birth rate (CBR) in a period is the total number of live 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; population ...
s,
death rate Mortality rate, or death rate, is a measure of the number of death (1906) Death is the permanent, Irreversible process, irreversible cessation of all biological process, biological functions that sustain a living organism. Brain death is ...
s,
immigration rate Immigration is the international movement of people to a destination country A country is a distinct territory, territorial body or political entity. It is often referred to as the land of an individual's birth, residence or citizenship ...
s, and age distribution between the two times. A related measure is the
net reproduction rate In population ecology and demography, the net reproduction rate, ''R''0, is the average number of offspring (often specifically daughters) that would be born to a female if she passed through her lifetime conforming to the age-specific fertility ...
. In the absence of migration, a net reproduction rate of more than 1 indicates that the population of females is increasing, while a net reproduction rate less than one (
sub-replacement fertility Sub-replacement fertility is a total fertility rate (TFR) that (if sustained) leads to each new generation A generation is "all of the people born and living Living or The Living may refer to: Common meanings *Life, a condition that disti ...
) indicates that the population of females is decreasing. Most populations do not grow exponentially, rather they follow a logistic model. Once the population has reached its
carrying capacity The carrying capacity of an environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical ...
, it will stabilize and the exponential curve will level off towards the carrying capacity, which is usually when a population has depleted most its
natural resource Natural resources are resource Resource refers to all the materials available in our environment which help us to satisfy our needs and wants. Resources can broadly be classified upon their availability — they are classified into renewabl ...
s.


Logistic equation

The growth of a population can often be modelled by the logistic equation :\frac=rP\left(1-\frac\right), where * P(t) = the population after time t; * t = time a population grows; * r = the relative growth rate coefficient; * K = the carrying capacity of the population; defined by ecologists as the maximum population size that a particular environment can sustain. As it is a separable differential equation, the population may be solved explicitly, producing a
logistic function A logistic function or logistic curve is a common S-shaped curve (sigmoid curve A sigmoid function is a function (mathematics), mathematical function having a characteristic "S"-shaped curve or sigmoid curve. A common example of a sigmoid f ...
: :P(t)=\frac, where A=\frac and P_0 is the initial population at time 0.


Population growth rate

In 2017, the estimated annual growth rate was 1.1%. The
CIA World Factbook ''The World Factbook'', also known as the ''CIA World Factbook'', is a reference resource produced by the Central Intelligence Agency The Central Intelligence Agency (CIA; ), known informally as the Agency and the Company, is a civilian ...
gives the world annual birthrate, mortality rate, and growth rate as 1.86%, 0.78%, and 1.08% respectively. The last 100 years have seen a massive fourfold increase in the population, due to
medical advances Medicine is the Art (skill), art, science, and Praxis (process) , practice of caring for a patient and managing the diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment or Palliative care , palliation of their injury or dise ...
, lower mortality rates, and an increase in agricultural productivity made possible by the
Green Revolution The Green Revolution, or the Third Agricultural Revolution, is the set of research technology transfer initiatives occurring between 1950 and the late 1960s, that increased agricultural production worldwide, beginning most markedly in the late ...

Green Revolution
. The annual increase in the number of living humans peaked at 88.0 million in 1989, then slowly declined to 73.9 million in 2003, after which it rose again to 75.2 million in 2006. In 2017, the human population increased by 83 million. Generally, developed nations have seen a decline in their growth rates in recent decades, though annual growth rates remain above 2% in poverty-stricken countries of the
Middle East The Middle East ( ar, الشرق الأوسط, ISO 233 The international standard An international standard is a technical standard A technical standard is an established norm (social), norm or requirement for a repeatable technical task whi ...

Middle East
and
Sub-Saharan Africa Sub-Saharan Africa (commonly called Black Africa) is, geographically, the area of the continent of Africa that lies south of the Sahara. According to the United Nations, it consists of all list of sovereign states and dependent territories i ...

Sub-Saharan Africa
, and also in
South Asia South Asia is the southern region of Asia Asia () is 's largest and most populous , located primarily in the and . It shares the continental of with the continent of and the continental landmass of with both Europe and . Asia cov ...

South Asia
,
Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern subregion of Asia, consisting of the regions ...

Southeast Asia
, and
Latin America * ht, Amerik Latin, link=no * pt, América Latina, link=no , image = Latin America (orthographic projection).svg , area = , population = ( est.) , density = , ethnic_groups = , ethnic_groups_year = 2018 , ethnic ...

Latin America
. In some countries the population is declining, especially in
Eastern Europe Eastern Europe is the eastern region of Europe Europe is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven geographical reg ...

Eastern Europe
, mainly due to low
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 was to experience the exact current age-specific rates (ASFRs) through her lifetime # she was to live from ...
s, high death rates and
emigration Emigration is the act of leaving a resident country or place of residence with the intent to settle elsewhere (to permanently leave a country). Conversely, immigration Immigration is the international movement of people to a destination ...
. In
Southern Africa Southern Africa is the south South is one of the cardinal directions or compass points. South is the opposite of north and is perpendicular to the east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Pr ...
, growth is slowing due to the high number of AIDS-related deaths. Some
Western Europe Western Europe is the western region of Europe Europe is a continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven geographical r ...

Western Europe
countries might also experience population decline. Japan's population began decreasing in 2005. The
United Nations Population Division The United Nations Department of Economic and Social Affairs (UN DESA) is part of the United Nations Secretariat The United Nations Secretariat (french: link=no, Secrétariat des Nations unies) is one of the six major organs of the United N ...
projects world population to reach 11.2 billion by the end of the 21st century. 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, ...
projects that the global population will peak in 2064 at 9.73 billion and decline to 8.89 billion in 2100. A 2014 study in ''
Science Science () is a systematic enterprise that builds and organizes knowledge Knowledge is a familiarity or awareness, of someone or something, such as facts A fact is something that is truth, true. The usual test for a statement of ...
'' concludes that the global population will reach 11 billion by 2100, with a 70% chance of continued growth into the 22nd century. The German Foundation for World Population reported in December 2019 that the global human population grows by 2.6 people every second, and could reach 8 billion by 2023.


Growth by country

According to
United Nations The United Nations (UN) is an intergovernmental organization aiming to maintain international peace and international security, security, develop friendly relations among nations, achieve international cooperation, and be a centre for harm ...

United Nations
population statistics, the world population grew by 30%, or 1.6 billion humans, between 1990 and 2010. In number of people the increase was highest in India (350 million) and China (196 million). Population growth rate was among highest in the
United Arab Emirates The United Arab Emirates (UAE; ar, الإمارات العربية المتحدة ) or the Emirates ( ar, الإمارات ), is a country in Western Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion A subregio ...

United Arab Emirates
(315%) and
Qatar Qatar (, , or ; ar, قطر, Qaṭar ; local vernacular pronunciation: ), officially the State of Qatar,) is a country in Western Asia. It occupies the small Qatar Peninsula on the northeastern coast of the Arabian Peninsula, and shares it ...

Qatar
(271%). Many of the world's countries, including many in
Sub-Saharan Africa Sub-Saharan Africa (commonly called Black Africa) is, geographically, the area of the continent of Africa that lies south of the Sahara. According to the United Nations, it consists of all list of sovereign states and dependent territories i ...

Sub-Saharan Africa
, the
Middle East The Middle East ( ar, الشرق الأوسط, ISO 233 The international standard An international standard is a technical standard A technical standard is an established norm (social), norm or requirement for a repeatable technical task whi ...

Middle East
,
South Asia South Asia is the southern region of Asia Asia () is 's largest and most populous , located primarily in the and . It shares the continental of with the continent of and the continental landmass of with both Europe and . Asia cov ...

South Asia
and
South East Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern subregion of Asia, consisting of the regions ...
, have seen a sharp rise in population since the end of the
Cold War The Cold War was a period of geopolitical Geopolitics (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country loc ...
. The fear is that high population numbers are putting further strain on natural resources, food supplies, fuel supplies, employment, housing, etc. in some of the less fortunate countries. For example, the population of
Chad Chad (; ar, تشاد , ; french: Tchad, ), officially known as the Republic of Chad ( ar, جمهورية تْشَاد, link=no '; ), is a landlocked A landlocked country is a country that does not have territory connected to an oce ...

Chad
has ultimately grown from 6,279,921 in 1993 to 10,329,208 in 2009, further straining its resources.
Vietnam Vietnam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,, group="n" is a country in Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia or SEA, is the ...

Vietnam
,
Mexico Mexico, officially the United Mexican States, is a country A country is a distinct territorial body or political entity A polity is an identifiable political entity—any group of people who have a collective identity, who are organi ...

Mexico
,
Nigeria Nigeria (), officially the Federal Republic of Nigeria, is a country in West Africa West Africa or Western Africa is the westernmost region of . The defines Western Africa as the 17 countries of , , , , , , , , , , , , , , , and as we ...

Nigeria
,
Egypt Egypt ( ar, مِصر, Miṣr), officially the Arab Republic of Egypt, is a transcontinental country This is a list of countries located on more than one continent A continent is one of several large landmasses. Generally identi ...

Egypt
,
Ethiopia Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country A landlocked country is a country A country is a distinct territory, territorial body or political entity. It is often referred to as the ...

Ethiopia
, and the
DRC The Democratic Republic of the Congo ( french: République démocratique du Congo (RDC) ), also known as Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly Zaire Zaire (, ), officially the Republic of Zaire (french ...

DRC
are witnessing a similar growth in population. The following table gives some example countries: ;Notes :* Eritrea left Ethiopia in 1991. : Split into the nations of Sudan and
South Sudan South Sudan (), officially known as the Republic of South Sudan, is a landlocked country in East Africa, east/central Africa. It is bordered to the east by Ethiopia, to the north by Sudan, to the west by the Central African Republic, to th ...

South Sudan
during 2011. : Japan and the Ryukyu Islands merged in 1972. :# India and Sikkim merged in 1975.


Future population


See also

*
Demographic historyDemographics, Demographic history is the reconstructed record of human population in the past. Given the lack of population records prior to the 1950s, there are many gaps in our record of demographic history. Historical demographers must make do wit ...
*
Demographic transition In demography Demography (from prefix ''demo-'' from Ancient Greek δῆμος (''dēmos'') meaning 'the people', and ''-graphy'' from γράφω (''graphō'') meaning 'writing, description or measurement') is the statistics, statistical s ...
*
Density dependenceIn population ecology Population ecology is a sub-field of ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their p ...
* Epidemiological transition *
Human population planning Human reproduction planning is the practice of intentionally controlling the rate of growth of a human population. Historically, human population planning has been implemented with the goal of increasing the rate of human population growth. Howe ...
*
Irruptive growth Irruptive growth is a growth pattern over time, defined by a sudden rapid growth in the population of an organism. Irruptive growth is studied in population ecology. Population cycles often display irruptive growth, but with a predictable pattern su ...
*
List of countries by population growth rate This article includes a table of countries and by annual rate. __TOC__ Methodology The table below shows annual population growth rate history and projections for various areas, countries, regions and sub-regions from various sources for variou ...
*
Population dynamics Population dynamics is the type of mathematics used to model and study the size and age composition of populations as dynamical systems. History Population dynamics has traditionally been the dominant branch of mathematical biology, which has a ...
*
World population In demographics Demography (from prefix ''demo-'' from Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is oft ...

World population
* Estimates of historical world population


References


External links

* * * * * {{Authority control Ecological metrics Population ecology Human overpopulation Environmental controversies