Population Change (Cambridge (CIE) IGCSE Environmental Management): Revision Note

Causes of population change

• Human populations are always changing

• Some countries grow quickly, while others grow slowly or even shrink

• These changes occur due to birth rates, death rates and migration

• These factors help to understand population growth, movement and urbanisation

Birth rates

Birth rate: children per woman

• Birth rate refers to the average number of children born to each woman

• High birth rates cause rapid population growth because more people are being added to the population

• Birth rates are often higher in low-income countries due to limited access to contraception and family planning

• Cultural and religious beliefs can encourage large families

• In many high-income countries, birth rates are low because women are more likely to work, be educated, delay marriage and have fewer children

Death rates

Death rate and life expectancy

• Death rate measures how many people die in a population over a period of time

• Life expectancy is the average number of years a person is expected to live

• Low death rates and high life expectancy increase population size

• Improved healthcare, clean water and better nutrition reduce death rates

• High death rates may be caused by disease, poor healthcare, famine or conflict

Migration

Types of migration

• Migration is the movement of people from one place to another

• Emigration is when people leave a country

• Immigration is when people enter a country

• Migration changes population size and structure, especially age and sex balance

Push and pull factors

• Push factors are negative conditions that encourage people to leave an area

• Examples include:

  • Unemployment

  • Lack of services

  • Low income

  • Environmental problems such as drought

• Pull factors are positive conditions that attract people to a new place

• Examples include:

  • Better jobs

  • Education

  • Healthcare

  • Improved living conditions

Rural–urban migration

• Rural–urban migration occurs when people move from the countryside to towns and cities

• People are pushed from rural areas by lack of jobs, poor services and mechanisation of farming

• People are pulled to cities by employment, education and healthcare opportunities

• This increases urban population size while reducing rural population

Urbanisation

Growth of urban areas

• Urbanisation is the increase in the proportion of people living in towns and cities

• It is caused by rural–urban migration and natural increase in urban populations

• Urbanisation is often rapid in low- and middle-income countries

  • Rates of urbanisation are lower in HICs, as a high percentage of the population already lives in towns and cities

  • In some HICs, rates of urbanisation may start to decrease as counter-urbanisation occurs

• Fast urban growth can lead to overcrowding, housing shortages and pressure on services

• Planned urbanisation can improve living standards and economic development

• Government policies – Some governments actively encourage urban growth by investing in cities and infrastructure

  • China, for example, has rapidly urbanised through deliberate government planning

  • Other countries might focus more on rural development