Population growth: basic concepts

Detail

1. What population growth means

• Population growth (also called population change) is the change in the number of people living in an area between two points in time.
• It can be positive (numbers go up) or negative (numbers go down).

• It can be given in absolute numbers (for example, "18 crore more people") or as a percentage.

• Why geographers study it: it shows a region's:

• economic development, because richer societies usually have lower birth and death rates;
• social progress, through literacy, health care and the status of women;
• history and culture, through wars, famines, migrations and religious or social customs.

2. Growth of population and growth rate: the India example

• Growth of population is the change in the number of people between two dates, given as a plain number.
• India's population was 102.70 crore in 2001 (Census 2001) and 121.02 crore in 2011 (Census 2011).

• NCERT gives the increase as 18.15 crore. Subtracting the two figures directly gives about 18.3 crore. The gap comes from rounding and from revisions to the census figures.

• Growth rate of population is the same change written as a percentage of the starting population.

• India's decadal growth rate (growth over ten years) was 17.7 per cent for 2001-2011, down from 21.5 per cent for 1991-2001 [2].

• India's average annual growth rate fell from 1.95 per cent (2001) to about 1.63-1.64 per cent (2011) [2].

• Exam point: a growth rate can fall while the population still adds very large absolute numbers each year, because the base keeps getting bigger.

3. Natural growth and actual growth

Concept	Formula	What it counts	Where it matters most
Natural growth of population	Births − Deaths	Only what happens inside the population; migration is ignored	Closed or low-migration countries, e.g. most of rural India and sub-Saharan Africa
Actual growth of population	Births − Deaths + In-migration − Out-migration	Natural change plus people moving in and out	Gulf states (large in-migration of workers); Kerala's emigrant districts (large out-migration)

• Natural growth of population: births minus deaths in an area over a period. It shows what the population would do without any migration.
• Actual growth of population: natural growth plus net migration (people who moved in minus people who moved out).
• How migration separates the two (Gulf example):
• Oil wealth creates many jobs in construction and services.
• Large numbers of workers come from South Asia, including India, so in-migration is very high.

• As a result, actual growth is much higher than natural growth.

• The opposite case (Kerala example):

• Many working-age people emigrate to the Gulf.
• Out-migration lowers actual growth, so the population grows more slowly than births and deaths alone would suggest.

4. Positive and negative growth

• Positive growth of population happens when:
• births are more than deaths, or

• people migrate permanently into the region.

• Negative growth of population happens when:

• births fall below deaths, which is common where fertility is very low and the population is old, or

• people emigrate (leave the country to live elsewhere) in large numbers.

• Countries in Europe and Asia with negative or near-negative growth (NCERT asks for these as a map skill). These are the examples to mark on the map:

• Europe: Russia, Ukraine (also falling because of the war), Belarus, Bulgaria, Romania, Serbia, the Baltic states (Estonia, Latvia, Lithuania), Italy, Greece, Poland.

• Asia: Japan, South Korea, and China. China's population peaked and fell during 2022 [6].

• Current position (UN World Population Prospects 2024):

• In 63 countries and areas, with 28 per cent of the world's population in 2024, the population had already peaked before 2024. These include China, Germany, Japan and the Russian Federation [3].
• The total population of this group is projected to fall by 14 per cent over the next 30 years [4].
• Brazil, Iran, Türkiye and Viet Nam are projected to reach their peak between 2025 and 2054 [3].

• About one-fifth of countries, including China, Italy, South Korea and Spain, have ultra-low fertility (below 1.4 births per woman) [4].

• Why China declined: its fertility was 1.2 births per woman in 2022, one of the lowest in the world. India's was 2.0, just below the replacement level of 2.1 [6].

• Replacement level is the average number of children each woman must have for the population to replace itself over time, without migration.

• India overtook China as the world's most populous country around the end of April 2023, with about 142.58 crore (1,425,775,850) people [6].

5. Population doubling time

• Population doubling time is the number of years a population takes to become twice its present size at its current growth rate.
• Rule of 70: doubling time ≈ 70 ÷ annual growth rate (in per cent). The number 70 comes from the natural log of 2 (about 0.693), which is used in compound-growth calculations.

Annual growth rate	Doubling time (approx.)	Example
3.0 %	~23 years	Fastest-growing African countries
1.64 %	~43 years	India, 2001-2011
1.0 %	~70 years	—
~0.9 %	~75-80 years	World, early 2020s
0 % or negative	Never doubles	Japan, Italy, China (shrinking)

• Fast growth is still happening: the populations of Angola, Central African Republic, DR Congo, Niger and Somalia are projected to double between 2024 and 2054 [4].
• How growth sped up over history:
• Before 1650, the world population took about 1,500 years to double.
• Doubling time then fell steadily, to about 35 years in the 1960s, when world growth was at its peak.
• Reasons: the Agricultural and Industrial Revolutions, better food supply, sanitation and medicine all cut the death rate, while birth rates stayed high.

• This is the demographic transition (the shift from high birth and death rates to low birth and death rates as a society develops), at its stage of rapid growth.

• Slowing again:

• The world reached 8 billion on 15 November 2022 [5].
• Going from 7 to 8 billion took 12 years. Reaching 9 billion is expected to take about 15 years (around 2037). This shows the growth rate is falling [5].

• Half of the 8th billion came from Asia, and Africa added almost 400 million [5].

• The long-term outlook:

• The world population was 8.2 billion in 2024 [3].
• It is projected to peak at about 10.3 billion in the mid-2080s [3].
• It is then projected to fall slightly, to 10.2 billion by 2100. This is about 700 million fewer than the UN projected a decade earlier [3][4].

Prelims Hooks

• Natural growth = births − deaths. Actual growth = births − deaths + in-migration − out-migration. A common trap: natural growth ignores migration.
• Rule of 70: India's 1.64 per cent a year (2001-11) gives a doubling time of about 43 years. The world's ~0.9 per cent gives about 75-80 years.
• India's decadal growth: 21.5 per cent (1991-2001) → 17.7 per cent (2001-2011) [2].
• World population passed 8 billion on 15 November 2022. 7 → 8 billion took 12 years; 8 → 9 billion is expected around 2037 [5].
• India passed China as the most populous country around end-April 2023. China's population fell in 2022 [6].
• UN WPP 2024: the world will peak at about 10.3 billion in the mid-2080s. 63 countries had already peaked, including China, Germany, Japan and Russia [3].
• Ultra-low fertility (below 1.4 births per woman) is found in China, Italy, South Korea and Spain [4]. Replacement level is 2.1.
• Gulf states are a textbook case where actual growth is much higher than natural growth, because of labour in-migration.
• Doubling time fell from about 1,500 years (before 1650) to about 35 years (1960s). It is now rising again as growth slows.

Mains Points

• Negative growth in Europe and East Asia:
• Causes: ultra-low fertility, ageing, emigration (Eastern Europe, the Baltic states) and conflict (Ukraine).
• Effects: labour shortages, pension and health-care strain, and depopulated villages.

• Responses: pro-natal incentives (Japan, South Korea, China's relaxation of birth limits) and managed immigration (Germany) [3][4].

• Migration can outweigh natural change:

• Gulf economies depend on migrant labour, so actual growth is far above natural growth.
• Kerala's emigrant districts grow more slowly but gain from remittances.

• Planners therefore need actual-growth figures, not just natural-growth figures, for housing, jobs and services.

• India's demographic position:

• Growth slowed to 17.7 per cent (2001-11) and 1.63 per cent a year [2], and fertility fell to about 2.0 [6].
• Even so, India keeps adding large absolute numbers because of population momentum (growth that continues because many young people are entering child-bearing age). This makes the demographic dividend (the extra economic growth possible when the working-age share of the population is large) a time-bound chance.

• The dividend depends on spending on skills, health and jobs.

• Global imbalance:

• Populations in parts of sub-Saharan Africa (Niger, DR Congo, Angola, Somalia) are projected to double by 2054 [4], while 63 countries have already peaked [3].
• This gap will drive future international migration, food-security pressure and SDG (Sustainable Development Goal) priorities.