Measuring population change
Population growth is the change in the number of people over time. It is controlled by the birth rate, the death rate and migration. The birth rate is the number of live births per 1,000 people per year, and the death rate is the number of deaths per 1,000 people per year.
Key idea
Natural increase = birth rate − death rate. When births are greater than deaths, the population grows naturally. Overall change also depends on net migration.
Factors affecting growth
- Raising birth rate — early marriage, desire for large families, limited family planning, need for farm labour.
- Lowering death rate — better medical care, clean water, more food, improved sanitation.
- Rapid growth often occurs when death rates fall quickly but birth rates stay high.
Demographic transition
Many countries pass through stages of change: high birth and death rates (slow growth), then falling death rates (rapid growth), then falling birth rates (slowing growth), and finally low birth and death rates (stable or falling population). Developed countries such as Japan now face ageing and slow or negative growth, while some developing countries still grow quickly.
Example
World population passed 8 billion in 2022. Growth has been fastest in parts of Africa and South Asia, while countries such as Japan have low birth rates and an ageing population.
Remember
- Natural increase = birth rate − death rate.
- Growth is affected by births, deaths and migration.
- Falling death rates with high birth rates cause rapid growth.