Population Growth & Decline (Cambridge (CIE) IGCSE Geography) : Revision Note

Patterns and trends in population change

• Nearly 80 million people are added to the world's population each year

• Population growth was steady and low until 1804, when the world population reached 1 billion 

• After 1804, it took just over 100 years for the population to double to 2 billion

• The rate of increase after 1930 was more rapid and led to a population explosion

• The fastest increase in population happened during the 1980s and 1990s

• Population growth rate is the average annual change of the population size during a set period of time, usually a year  

  • The population is still increasing but at a slower rate

    • In 1970, the growth rate was 2% 

    • In 2022, the growth rate is under 1%

• It is predicted by the UN that the population will stabilise at around 11 billion in 2100 

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• This rapid global population increase has been caused by a 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

  • clean 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 low-income countries (LICs) 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 

Reasons for the growth and decline of population

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)

• Both LICs and high income countries (HICs) experience migration

  • Most emigration is from LICs

  • Most immigration is to HICs

Natural population change

• Natural population change occurs due to changes in the birth rates and death rates

  • 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 negative rate of natural increase happens when the birth rate is lower than the death rate

Birth rate

• The birth rate is the number of live babies born per 1000 people

• This figure is calculated by:

  • dividing the total number of births by the total population and multiplying by 1000

• In HICs, the birth rate tends to be low whereas in LICs the birth rate tends to be high

Fertility rate

• Fertility rate is the number of live births per 1000 women aged 15-49 years in a given year

• These rates apply to women within the main reproductive age range of 15-49 years (some sources use 15-44 years), rather than to the whole population

• This makes for a more accurate measure of fertility than just the birth rate

• Total fertility rate (TFR) is:

  • The average number of children that would be born alive to a woman during her lifetime – total family size

• The global fertility rate has fallen rapidly since 1950

Death rate

• The death rate is the number of deaths per 1000 people

• This figure is calculated by:

  • dividing the total number of deaths by the total population and multiplying by 1000

• In HICs, the death rate tends to be low whereas in LICs the death rate tends to be high