Geography · Ch 2 — The World Population: Distribution, Density and Growth
Population Growth
Population Growth
Population Growth: The Big Picture
Population growth — or population change — simply means the change in the number of people living in a given area over a specific period of time. That change can be positive (the population increases) or negative (the population decreases). It is usually measured in two ways: as an absolute number (how many more or fewer people) or as a percentage (the rate of change).
Why does this matter? Because how a population changes tells us a great deal about that region's economic development, social progress, and even its historical and cultural background. A rapidly growing population might signal a young, developing economy; a shrinking one might point to an ageing society or out-migration.
Key Concepts in Population Geography
The textbook introduces several precise terms that you must know:
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Growth of Population: This is simply the difference in population between two points in time. For example, India's population in 2001 was 102.70 crore; in 2011 it was 121.02 crore. The growth in absolute numbers = 121.02 – 102.70 = 18.15 crore.
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Growth Rate of Population: This is the same change, but expressed as a percentage rather than an absolute number.
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Natural Growth of Population: This is the increase (or decrease) that comes only from the difference between births and deaths in a region, over a given period. It ignores migration entirely.
Natural Growth = Births – Deaths
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Actual Growth of Population: This is the real change, which includes migration.
Actual Growth = Births – Deaths + In-Migration – Out-Migration
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Positive Growth of Population: This happens when the population increases. It occurs when the birth rate is higher than the death rate, or when more people move into the region (immigrate) than leave it.
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Negative Growth of Population: This happens when the population decreases. It occurs when the death rate exceeds the birth rate, or when more people emigrate out of the region than immigrate into it.
The Three Components of Population Change
Population size changes because of three factors: births, deaths, and migration. Each is measured in a standard way.
1. Births: The Crude Birth Rate (CBR)
The Crude Birth Rate is the number of live births in a year per 1,000 people in the population. It is called "crude" because it does not account for the age or sex structure of the population — it is a simple, overall rate.
CBR = (Number of live births in a year / Estimated mid-year population) × 1000
2. Deaths: The Crude Death Rate (CDR)
The Crude Death Rate is the number of deaths in a year per 1,000 people. It is a straightforward measure of mortality in an area.
CDR = (Number of deaths in a year / Estimated mid-year population) × 1000
Mortality rates are not random. They are strongly influenced by a region's demographic structure (e.g., how many elderly people there are), its social advancement (e.g., healthcare, education), and its level of economic development (e.g., poverty, nutrition).
3. Migration
Migration is the third major component. When people move, the place they leave is called the Place of Origin, and the place they go to is called the Place of Destination. The origin loses population; the destination gains it.
- Immigrants: People who move into a new place.
- Emigrants: People who move out of a place.
The same person is both an immigrant (from the destination's perspective) and an emigrant (from the origin's perspective).
Migration can be permanent, temporary, or seasonal. It can happen between any combination of rural and urban areas: rural-to-rural, rural-to-urban, urban-to-urban, or urban-to-rural.
Why do people migrate? The textbook gives two sets of forces:
- Push Factors: These make the place of origin less attractive. Examples include unemployment, poor living conditions, political turmoil, unpleasant climate, natural disasters, epidemics, and socio-economic backwardness. …