Population Change (SL IB Geography)

• Since the Industrial Revolution (1850s), no two country's population have changed in the same way
• However, some similarities can be seen in population growth
• These similarities are shown by the demographic transition model (DTM)
• The model illustrates 5 generalised stages of population change that countries pass through as they industrialise
• It shows how birth and death rates change over time and its effects on the overall population 
• The gap between the birth rate and death rate is called natural change (either an increase or decrease in population)

Demographic transition model

The demographic transition model shows the transition of the population from high birth and death rates to lower rates over time

Description of DTM

• The strengths of the model include:
  • It can be applied to different settings 
  • It can help demographers plan for predicted future changes
• The limitations of the model include:
  • Developed in 1929, when many countries were still under colonial rule. The model assumes all countries will follow the same pathway through the stages
  • It fails to take into account the effects of globalisation, migration, natural disasters, pandemics, wars and government policies that impact birth rates, e.g. China’s one-child policy
  • It fails to take into account the decline in fertility rates
  • It is too Euro-centric. The model is based on data from 3 countries (England, Wales and Sweden) that industrialised between the 18th and 20th centuries
  • It is difficult to apply to LICs that are currently industrialising in a shorter time frame due to globalisation

• Current LICs population change has differences:
  • Birth rates in stages 1 and 2 are generally higher in LICs
    • Currently only 1 African country (Niger) has a birth rate of 45 /1000 or more
    • In 2000, 14 African countries were in this situation
  • Death rates have fallen quickly for different reasons
    • Availability and use of modern medicine, particularly vaccinations, has lowered mortality rates significantly
    • However, AIDS has caused the death rate to rise in some countries, particularly sub-Saharan Africa
  • Base populations are different
    • With the overall global growth in population, LICs have a much bigger base population to start with, making the impact of high growth bigger in stage 2 and early stage 3 
    • When India and China entered stage 2, no developed country had a population close to that size
  • Fall in fertility rates have been steeper for countries in stage 3 
    • Mainly due to the availability, reliability and education of modern contraception

Differences in demographic transitions

• Not all countries follow the classic model of transition
  • France essentially skipped stage 2, as their birth rate declined in line with death rates
  • Mexico saw an increase in births in stage 2 as maternal health care improved
  • Ireland saw falling birth rates and rising death rates in stage 2 because of emigration after the Great Famine of 1845-9

Types of demographic transition

• Natural population change occurs when birth and death rates differ in a place
  • If birth rates are higher than death rates then there will be a natural increase
  • If death rates are higher than birth rates there will be a natural decrease
• The crude birth rate is heavily influenced by the age structure of a population
  • For instance, in 2022 the crude birth rate varied globally
  • The overall global crude rate was 17/1000
  • Highest was Niger with 46.86/1000
  • Lowest was South Korea and Hong Kong with 5/1000
• Natural change is calculated as a % by subtracting the crude death rate from the crude birth rate 

• Population also changes when people migrate into and out of an area
• Population change is also influenced by the following key vital rates:
  • Fertility rate
  • Infant mortality rate 
  • Replacement level
  • Net production rate

Fertility rate

• For more accurate measures of fertility, the fertility rate and the total fertility rate (TFR) are used
• These rates apply to women within the main reproductive age range of 15-49 years, rather than to the whole population
• This makes for a more accurate measure of fertility than just the birth rate
• Fertility rate is:
  • The number of live births per 1000 women aged 15-49 years in a given year
• Total fertility rate is:
  • The average number of children that would be born alive to a woman during her lifetime - total family size
    • This assumes that she passes through her child-bearing years conforming to the age-specific fertility rates of a given year
• Factors affecting fertility can be grouped into four main categories:

Categories Affecting Fertility Rates

• The United Nations has predicted that:

The world's population is expected to increase by nearly 2 billion persons in the next 30 years, from the current 8 billion to 9.7 billion in 2050 and could peak at nearly 10.4 billion by 2100

• Generally, as health improves the mortality rate in the population decreases, and typically there is an accelerated population growth
• However, fertility levels have been falling faster than expected:
  • The global average fertility rate is around 2.3 children per woman today
  • Yet 50 years ago, the global fertility rate was double, with rates of 4.5 to 7 children per woman across the globe
  • Since then, LICs and MICs have seen rapid falls in fertility, partly due to:
    • Increased status and well-being of children
    • Empowerment of women within society and relationships through strengthening: 
      • Access to education
      • Recognition and participation in the labour force
      • Improved women's rights 

Declining global fertility rates over time

• Replacement level fertility is the level at which those in every generation have just enough children to replace themselves in the population
• A total fertility rate of 2.1 children is usually considered a replacement level, below this, and countries see a population decline 

Life expectancy

• This measure indicates the average age of death in a population
• In the past, life expectancy was around 30 years in all regions of the world
• Since the 17th century, life expectancy has steadily increased, although it is unevenly spread
• Industrialising countries saw the largest increase through improved health and access to medicines
• Since the 1900s, average, global life expectancy has risen to above 70 years, although it still varies within and between countries
• in 2021, Japan had the highest life expectancy at close to 85 years and Chad was the lowest at 52.5 years
• Globally, the African continent has the lowest average life expectancy at 61.7 years and Oceania the highest at 79.9 years
• Countries with a life expectancy of below 60 years are found in Sub-Saharan Africa due to conflict, poverty and the AIDS virus
• Yemen, Haiti and Afghanistan have life expectancies of over 62 years, yet in 1950 they were below 37.5 years

Women live longer

• Before the 19th century, this wasn't the case, as many women died in childbirth or complications from childbirth
• In fact, the death rate between men and women was fairly equal
• As countries developed, men became more vulnerable to cardiovascular diseases such as strokes and heart disease, through self-destructive lifestyles such as drinking and smoking
• Men became less active as job roles changed from manual to desk work 
• Men are more likely to be involved in conflict and take bigger risks with their lives
• Biologically, women are more resistant to disease and fat is laid down in the body differently than men
• Environmental changes due to the reduction or eradication of infectious diseases