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    examBoard: Cambridge
    examType: IGCSE
    lessonTitle: Population Growth and Decline Factors
Geography - Human Geography - Changing Populations - Population Growth and Decline Factors - BrainyLemons
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Changing Populations » Population Growth and Decline Factors

What you'll learn this session

Study time: 30 minutes

  • The key factors that influence population growth and decline
  • How birth rates, death rates and migration affect population change
  • The demographic transition model and its stages
  • Population policies and their impacts in different countries
  • Case studies of countries experiencing population growth and decline

Population Growth and Decline: Understanding the Factors

Population change is one of the most significant geographical processes affecting our world today. Some countries are experiencing rapid growth while others face declining populations. But what causes these changes?

Key Definitions:

  • Population growth: An increase in the number of people living in an area.
  • Population decline: A decrease in the number of people living in an area.
  • Natural increase/decrease: The difference between births and deaths in a population.
  • Net migration: The difference between immigration (people moving in) and emigration (people moving out).

The Population Equation

Population change can be expressed using this simple equation:

Population Change = (Births - Deaths) + (Immigration - Emigration)

Or more simply: Natural Change + Net Migration

👶 Birth Rate Factors

Birth rates are influenced by:

  • Access to contraception - When contraception is available, birth rates tend to be lower
  • Cultural and religious beliefs - Some cultures value large families
  • Women's education and careers - Higher education levels often lead to lower birth rates
  • Government policies - Some countries have policies to encourage or discourage births
  • Economic development - More developed countries typically have lower birth rates

🕊 Death Rate Factors

Death rates are influenced by:

  • Healthcare quality - Better healthcare reduces death rates
  • Sanitation and clean water - Reduces disease spread
  • Food security - Reliable food supply improves life expectancy
  • War and conflict - Increases death rates
  • Natural disasters - Can cause temporary spikes in death rates
  • Age structure - Older populations have higher death rates

Migration: The Third Factor

Migration can dramatically change a country's population size and structure. People move for many reasons, which geographers classify as 'push' and 'pull' factors.

👉 Push Factors

Reasons people leave a place:

  • War and conflict
  • Poverty
  • Unemployment
  • Natural disasters
  • Political persecution
👈 Pull Factors

Reasons people move to a place:

  • Job opportunities
  • Better healthcare
  • Education access
  • Political freedom
  • Family connections
👥 Migration Effects

How migration changes populations:

  • Changes age structure
  • Affects dependency ratios
  • Influences cultural diversity
  • Impacts labour markets
  • Changes population distribution

The Demographic Transition Model

The Demographic Transition Model (DTM) shows how populations change as countries develop economically. It helps us understand why some countries have high growth rates while others have low or negative growth.

The Five Stages of the DTM

Each stage represents different patterns of birth rates, death rates and total population:

📊 Stages 1-3: Growth Phases

  • Stage 1: High birth rates and high death rates. Population stable but with fluctuations. (Example: Pre-industrial societies)
  • Stage 2: High birth rates but falling death rates. Rapid population growth. (Example: Many developing countries in the 20th century)
  • Stage 3: Declining birth rates and low death rates. Population still growing but at a slower rate. (Example: India, Brazil)

📉 Stages 4-5: Stabilisation and Decline

  • Stage 4: Low birth rates and low death rates. Population stable or growing slowly. (Example: UK, USA)
  • Stage 5: Birth rates below death rates. Natural decrease in population. (Example: Japan, Italy)

Did You Know?

It took 127 years for the world population to grow from 1 billion to 2 billion (1804-1931), but only 12 years to grow from 6 billion to 7 billion (1999-2011)!

Population Policies

Governments sometimes introduce policies to influence population growth or decline:

👇 Anti-Natalist Policies

Policies to reduce birth rates:

  • China's former One-Child Policy (1979-2015)
  • India's family planning programme
  • Educational campaigns about contraception
  • Financial incentives for smaller families

👆 Pro-Natalist Policies

Policies to increase birth rates:

  • Singapore's "Have Three or More" campaign
  • Russia's baby bonus payments
  • Sweden's generous parental leave
  • Tax benefits for families with children

Case Studies: Population Growth and Decline

Case Study: Nigeria - Rapid Population Growth

Nigeria is Africa's most populous country with about 200 million people. It has:

  • High birth rate (5.3 children per woman)
  • Declining but still significant death rate
  • Young population (median age of 18.1 years)
  • Projected to become the world's third most populous country by 2050

Challenges: Providing education, healthcare and jobs for a rapidly growing population; urban infrastructure struggles to keep pace with growth.

Case Study: Japan - Population Decline

Japan is experiencing population decline due to:

  • Very low birth rate (1.4 children per woman)
  • Minimal immigration
  • Ageing population (median age of 48.4 years)
  • Population projected to fall from 126 million to below 100 million by 2050

Challenges: Supporting an ageing population; declining workforce; empty rural areas; maintaining economic growth with fewer workers.

The Impacts of Population Change

Effects of Rapid Population Growth

Countries with high growth rates often face:

  • Resource pressure: Strain on food, water and energy supplies
  • Youth bulge: Large proportion of young people needing education and jobs
  • Urbanisation: Rapid growth of cities, often with informal settlements
  • Environmental impacts: Deforestation, pollution and habitat loss
  • Development challenges: Difficulty providing infrastructure and services

Effects of Population Decline

Countries with declining populations often face:

  • Ageing population: Increasing proportion of elderly people
  • Labour shortages: Fewer working-age people
  • Pension pressures: Fewer workers supporting more retirees
  • Rural abandonment: Declining rural communities and services
  • Economic challenges: Shrinking domestic markets and tax base

Sustainable Population Growth

The UN Sustainable Development Goals recognise that balanced population growth is essential for sustainable development. This means:

  • Access to family planning and reproductive healthcare
  • Education for girls and women
  • Reducing child mortality
  • Supporting ageing populations
  • Managing migration humanely and effectively

Summary: Key Factors Affecting Population Change

Population growth and decline are influenced by a complex mix of factors:

  • Natural factors: Birth rates and death rates
  • Social factors: Education, gender equality, cultural norms
  • Economic factors: Development level, job opportunities, cost of raising children
  • Political factors: Population policies, conflict, political stability
  • Environmental factors: Resource availability, climate change, natural disasters
  • Technological factors: Healthcare advances, contraception, agricultural technology

Understanding these factors helps geographers explain why populations change and predict future trends. This knowledge is crucial for planning sustainable development and addressing the challenges of both population growth and decline.

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