World Population: Distribution, Density, Growth and Migration

1. Patterns of population distribution and density

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• A country's people are its real wealth. Population distribution means how people are spread over the earth's surface. It is very uneven: about 90 per cent of people live on about 10 per cent of the land (NCERT).
• The 10 most populous countries hold about 60 per cent of the world's people, and six of them are in Asia (NCERT Fig. 2.1).
• George B. Cressey said: "Asia has many places where people are few and few places where people are very many." This is true of the whole world.
• Density = Population ÷ Area (persons per sq km). Example: 1,50,000 people on 100 sq km gives 1,500 per sq km. Density shows how much pressure each unit of land bears.
• Dense areas: eastern China, Japan, Korea; the Ganga-Brahmaputra plains; Java; the Mekong and Irrawaddy deltas; Europe; north-eastern USA; the Nile valley.
• Sparse areas: polar lands, the Sahara, Atacama and Gobi deserts, central Australia, the Amazon and Congo basins, and high mountains. Trap: Southeast Asia is not sparse.
• Beyond NCERT: India overtook China as the most populous country in April 2023 (UN estimate). Physiological density counts people per unit of farmland, not total land. Egypt's figure is very high because almost everyone lives in the Nile valley.

2. Factors influencing the distribution of population

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Type	Factor	Effect and example
Geographical factors of population distribution	Fresh water	River valleys are the densest areas
	Landforms	Plains attract people (Ganga plains); the Himalayas are sparse
	Climate	Very hot, very cold or very wet places push people away; Mediterranean lands were settled early
	Soils	Fertile loamy soils support intensive farming; western Rajasthan's poor soils hold few people
Economic factors of population distribution	Minerals	Mines create jobs (Katanga-Zambia copper belt)
	Urbanisation	Jobs, schools and hospitals pull people from villages to cities
	Industrialisation	Factories also bring service jobs (Kobe-Osaka region, Japan)
Social and cultural factors of population distribution	Religion and culture; unrest; government incentives	Holy places such as Varanasi and Mecca attract people; conflict drives them away; Brasilia (1960) was built to settle Brazil's interior

• Before industrialisation, physical factors mattered most. Today, economic and political factors matter more.

3. Population growth: basic concepts

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• Population growth (or change) is the change in the number of people in an area over a period. It can be positive or negative, and it can be given as a number or as a percentage. It reflects development, social progress and history.
• Growth of population example: India rose from 102.70 crore in 2001 to 121.02 crore in 2011. NCERT gives the increase as 18.15 crore, but the exact difference is about 18.3 crore. The growth rate is this change written as a percentage.
• Natural growth of population = births − deaths. Migration is ignored.
• Actual growth of population = births − deaths + in-migration − out-migration. It differs from natural growth wherever large numbers of people move in or out, as in the Gulf states.
• Positive growth of population: births exceed deaths, or people migrate permanently into the region.
• Negative growth of population: births fall below deaths, or people emigrate. Examples (verify current): Russia, Ukraine, Bulgaria, the Baltic states, Italy, Japan, South Korea, and China since 2022.
• Population doubling time (the years a population takes to double) is about 70 ÷ the annual growth rate in per cent. India's 1.64 per cent (2001-11) gives about 43 years. The world's rate of about 0.9 per cent gives about 75-80 years (verify current).

4. Components of population change: births and deaths

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• The components of population change are births, deaths and migration. Births add people, deaths remove them, and migration moves people from the origin to the destination.
• Crude birth rate: live births in a year per 1,000 people. CBR = (B ÷ P) × 1,000, where P is the mid-year population.
• Crude death rate: deaths in a year per 1,000 people. CDR = (D ÷ P) × 1,000. Population grows when deaths fall, not only when births rise. Deaths depend on age structure, social progress and economic development.
• Natural growth rate = CBR − CDR, per 1,000. Divide by 10 to get a percentage.
• These rates are called "crude" because they ignore age. An old, healthy country like Japan can have a higher CDR than a young, poor one like Niger.
• Total fertility rate (TFR): the average number of children a woman would have in her lifetime at today's birth rates. The world's TFR is about 2.2. Niger's is among the highest (above 5), and South Korea's is below 1, the lowest (verify current).
• Replacement-level fertility: the TFR at which each generation exactly replaces itself. It is about 2.1 where few children die and higher where many do. India's TFR fell to 2.0 in NFHS-5 (2019-21), below replacement.

5. Migration: types, push and pull, and the displaced

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• Migration is the movement of people from a place of origin, which loses people, to a place of destination, which gains them. It can be permanent, temporary or seasonal, and rural-rural, rural-urban, urban-urban or urban-rural. NCERT calls it "a spontaneous effort to achieve a better balance between population and resources".
• Emigration means moving out (emigrants). Immigration means moving in (immigrants). The same person is both: a Kerala worker in the UAE is an emigrant from India and an immigrant in the UAE.
• Push and pull factors: push factors make the origin unattractive (unemployment, poor living conditions, political turmoil, bad climate, disasters, epidemics). Pull factors make the destination attractive (jobs, peace, security, pleasant climate). Trap: medical and educational facilities are a pull factor.
• International migrant stock: people living outside their country of birth. The IOM's World Migration Report 2024 put it at about 281 million in 2020 (3.6 per cent of the world's people). India is the largest country of origin (verify current).
• Refugee: a person outside their own country who has a well-founded fear of persecution (1951 Convention and 1967 Protocol). India has signed neither.
• Internally displaced person: someone forced from home who stays inside their own country. The IDMC counts them in its annual Global Report on Internal Displacement.
• Climate migration: movement caused by sea-level rise, drought, floods or storms. "Climate refugee" has no legal status. The World Bank's Groundswell report (2021) projected up to 216 million internal climate migrants by 2050.

6. Trends in world population growth

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• World population growth trend: human numbers grew more than 10 times in the last 500 years, and about 4 times in the 20th century alone. NCERT says the world had "over 6 billion" at the start of the 21st century.
• Milestones (UN estimates): 1 billion around 1804, 2 billion in 1927, 3 billion in 1960, 4 billion in 1974, 5 billion in 1987, 6 billion in 1999 and 7 billion in 2011.
• World population of 8 billion: reached on 15 November 2022, about 12 years after 7 billion.
• Why numbers surged after 1750:
• Farming and industrial revolutions, better food and better transport.
• Vaccines and sanitation, and later antibiotics and the Green Revolution.

• As a result, deaths fell long before births did.

• Spatial pattern: Africa grows fastest (NCERT exercise). Europe and East Asia are shrinking.

• World Population Prospects (UN DESA, usually every two years): the 2024 revision gives about 8.2 billion in 2024 and a peak of about 10.3 billion in the mid-2080s (verify current).
• Population momentum: a young population keeps growing for decades even after fertility falls to replacement, because many people are still entering child-bearing age.
• State of World Population report (UNFPA, every year): the 2025 edition, "The Real Fertility Crisis", says the bigger problem is people who cannot have the number of children they want.
• Impact: fast growth strains food, water, jobs and the environment. Decline brings labour shortages and empty villages, as in Japan.

7. Demographic transition theory

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• Demographic transition theory: as a society moves from rural, farming and illiterate to urban, industrial and literate, it shifts from high births and deaths to low births and deaths. These stages together are called the demographic cycle (NCERT Fig. 2.2).

Stage	Births and deaths	Growth	Features
First stage of demographic transition	Both high	Slow	Epidemics and uncertain food supply; large farm families; low life expectancy; all countries were here 200 years ago
Second stage of demographic transition	Deaths fall; births high at first, then decline	Highest (population explosion)	Better sanitation and health care
Third stage of demographic transition	Both low	Stable or slow	Urban, literate, skilled people who choose small families

• Beyond NCERT: the idea comes from Warren Thompson (1929) and Frank Notestein (1945). The five-stage version adds a fifth stage of decline, where births fall below deaths (Japan, Italy). Critique: the theory is based on Europe, and fertility fell in Bangladesh and Kerala without industrialisation.
• Youth bulge: a large share of people aged 15-24 or 15-29 (sub-Saharan Africa, Pakistan). It speeds up growth if there are jobs and can cause unrest if there are not.
• Population ageing: the share of old people rises as births and deaths fall. Japan, Italy and South Korea are among the oldest societies (verify current).

8. Population and resources: Malthus and after

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• Malthusian theory of population (Thomas Malthus, 1798): population grows geometrically (1, 2, 4, 8) and food grows arithmetically (1, 2, 3, 4). Unchecked growth ends in a crash through famine, disease and war.
• Preventive and positive checks:
• Preventive checks lower births (late marriage, moral restraint).
• Positive checks raise deaths (famine, disease, war).

• Malthus said preventive checks are better. NCERT: the world must control rapid growth to keep resources sustainable.

• Critiques:

• Technology, including the Green Revolution, raised food supply far beyond his forecast.
• Fertility fell on its own as countries developed.
• Ester Boserup (1965) argued that population pressure itself drives farming innovation.

• Amartya Sen showed that famines such as Bengal 1943 come from people losing the ability to buy or grow food, not just from food shortage.

• Neo-Malthusianism: a revival of Malthus's fear, in Ehrlich's The Population Bomb (1968) and The Limits to Growth (1972). It favours birth control. The mass famines these books predicted did not happen, but the idea of planetary limits lives on in climate debates.

• Optimum population: the population size at which output per person is highest for given resources and technology. Fewer people means underpopulation and more people means overpopulation. The optimum changes as technology changes.
• Opposite view: Julian Simon (1981) called human ingenuity the "ultimate resource".

9. Population policies: from control to choice

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• Family planning: spacing or preventing births through informed choice and contraception. It limits growth and improves women's health. India started the world's first national programme in 1952.
• Population control measures (NCERT): propaganda, free contraceptives and tax disincentives for large families. Coercion backfired, as India's forced sterilisations during the Emergency (1975-77) showed.
• International Conference on Population and Development (Cairo, 1994): it shifted policy from numerical targets to reproductive health, rights and women's empowerment. India dropped method-specific targets in 1996 in line with it. An earlier slogan from Bucharest (1974): "development is the best contraceptive".
• One-child policy (China, from 1980): it cut births sharply but skewed the sex ratio and sped up ageing. China moved to a two-child policy in 2016 and a three-child policy in 2021.
• Pronatalist policy: steps to raise births, such as baby bonuses, paid parental leave, tax breaks and childcare. France, Hungary, Russia, South Korea, Japan and China use them. Results are modest, and South Korea's TFR stays the lowest (verify current).
• Today's policy map: anti-natalist policies in parts of Africa and South Asia, pronatalist policies in Europe and East Asia. Migration is a third lever (Canada, Germany).

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Exam angles

Prelims — high-yield facts and traps

• About 90 per cent of people live on about 10 per cent of land. The top 10 countries hold about 60 per cent, six of them in Asia. India has been the most populous country since April 2023 (UN estimate).
• Factor-example pairs: Katanga-Zambia copper belt (minerals); Kobe-Osaka (industry); Mediterranean (climate); Ganga plains (landform and soil).
• "Southeast Asia is a sparse area": FALSE. The Atacama, polar lands and equatorial forests are sparse.
• Formulas: density = P ÷ A; CBR = B ÷ P × 1,000; CDR = D ÷ P × 1,000; natural growth = B − D; actual growth = B − D + in-migration − out-migration; doubling time ≈ 70 ÷ growth rate (in per cent).
• "Medical and educational facilities are a push factor": FALSE (they pull). Epidemics and water shortage push.
• "Growth is high in the first stage of demographic transition": FALSE. Growth is highest in stage two.
• Milestones: 7 billion (2011); 8 billion (15 November 2022). Projected peak about 10.3 billion in the mid-2080s (verify current). Africa grows fastest.
• Replacement TFR is about 2.1. India's TFR is 2.0 (NFHS-5, 2019-21). Lowest is South Korea and highest is Niger (verify current).
• Malthus (1798): geometric vs arithmetic growth; preventive vs positive checks. Ehrlich (1968); The Limits to Growth (1972).
• ICPD was held in Cairo (1994). China: one-child (1980), two-child (2016), three-child (2021). India is not party to the 1951 Refugee Convention. IDPs stay within their own country.

Mains — GS-I themes

1. Factors influencing the distribution and density of world population, with examples and a sketch map.
2. Demographic transition theory and how well it fits developing countries today.
3. Is Malthus still relevant in the age of climate change? Discuss neo-Malthusian and cornucopian views.
4. Ageing societies vs youth bulges: where they are, and what they mean for labour migration.
5. Climate-induced migration: should "climate refugees" get legal protection?
6. From population control to reproductive rights: how policy has changed since Cairo 1994.

Current-affairs hooks

• New UN World Population Prospects revisions and World Population Day (11 July) themes (verify current).
• UNFPA State of World Population reports and the debate on low fertility and pronatalism.
• China's population decline and East Asian pronatalist packages (verify current).
• IOM, UNHCR and IDMC displacement figures for crises in Sudan, Gaza, Ukraine and Myanmar (verify current).
• India's record remittances and rules for Gulf labour migration (verify current).
• Climate migration from Pacific islands and the Bangladesh delta, and loss-and-damage debates at COPs.