Population Change

• There are two ways in which a population can change:

  • Migration 

  • Natural population change

Migration

• Migration can cause the population to either increase or decrease

• This occurs as the result of emigration or immigration

• Net migration is the difference between the number of people moving into a country (immigrants) and the number of people leaving the country (emigrants)

  
  

Remember, immigration and emigration are not the same. Immigration is the inward movement of people into a country. Emigration is the outward movement of people from a country.

Natural Population Change

Natural causes of population change

• Rapid global population increase has been the combination of numerous factors, including improvements in:

  • agriculture, particularly during the agricultural revolution, led to higher yields and more varied diets

  • medicine and medical care, which reduces the death rate

  • technology and transport led to a wealthier population, which increased life expectancy

  • water supply and sewage disposal leading to a reduction in disease

• All these factors also led to a decrease in the death rate 

• The birth rate has remained high mainly in LEDCs due to:

  • lack of access to family planning and contraception 

  • an increase in women surviving childbirth

  • families continuing to have large numbers of children to look after their parents in old age and to help support the family

  • the culture of having larger families, which takes many years to change

  • religious reasons 

• Natural change in population is calculated by subtracting the death rate from the birth rate

• The combination of a decreasing death rate and high birth rate led to rapid natural increase and population explosion

• A natural decrease happens when the birth rate is lower than the death rate

• Population also changes as a result of migration into and out of a country/area but this is not part of the natural increase

Demographic Transition Model

• The demographic transition model shows the five generalised stages of population change that countries pass through as they develop

• It shows how birth and death rates change over time and how this affects the overall population as the country 

Stage 1

• The total population is low 

• High birth rates due to lack of contraception/family planning 

• High death rates due to poor healthcare, poor diet and famine

• High infant mortality leads people to have more children so that some children survive to adulthood

Stage 2

• The total population starts to rise rapidly

• Birth rates remain high as people continue to have large families

• Death rates decrease as a result of improved diets, better healthcare, lower infant mortality and increased access to clean water

Stage 3

• The total population continues to increase but the rate of growth begins to slow

• The birth rate begins to fall rapidly due to increased birth control, family planning, increased cost of raising children and low infant mortality rate 

• The death rate is still decreasing but at a slower rate as improvements in medicine, hygiene, diet and water quality continue

Stage 4

• The total population is high and is increasing slowly 

• The birth rate is low and fluctuating due to accessible birth control and the choice of having fewerchildren, as well as delaying the age women start to have children

• The death rate is low and fluctuates 

Stage 5

• The total population starts to slowly decline as the death rate exceeds the birth rate 

• The birth rate is low and slowly decreasing

• The death rate is low and fluctuates

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Population Change

• All countries have different rates of population change

• Population growth rates are currently highest in LEDCs such as Niger, Mali and Zambia

• Population growth rates are lowest in MEDCs 

  • In someMEDCs, such as Italy and Japan, the population is decreasing as the number of deaths is higher than the number of births

• These changes are dependent on three factors:

  • fertility

  • mortality

  • migration

Fertility

• As well as the birth rate, fertility can also be measured by the fertility rate

• There are several factors affecting fertility which can be categorised as social, economic or political

Social

• Infant mortality rate

  • When this is high, the fertility rate also tends to be high as women have more children to ensure some survive to adulthood

• Education

  • Higher levels of education lead to lower fertility rates as more women are in formal employment

• Religion

  • Religious beliefs can influence how many children a woman has

• Healthcare

  • The availability of contraception and family planning 

Economic

• Cost of having children

  • In MEDCs the cost of raising children may reduce the number of children a woman has

• Lack of pensions

  • In LEDCs, children are needed to care for elderly parents as there are no pensions. This increases the fertility rate

• Contribution to family income

  • In LEDCs, children often work to contribute to family income so more children are needed, increasing the fertility rate

Political

• Pronatalist policies

  • Encourage women to have children and increase the fertility rate

• Anti-natalist policies

  • Encourage women to have fewer children, which decreases the fertility rate

Mortality

• The death rate is affected by a range of factors:

  • Quality of, and access to, healthcare

  • Natural disasters: famine, drought, etc.

  • Diseases such as HIV/AIDS

  • War/conflict