Population Growth Dynamics (AQA A Level Geography)

Balancing Population and Resources

• The concept of population ecology refers to how humans interact with their environment to change in number over space and time
• Also known as population growth dynamics
• Global population has grown exponentially over the past 200 years
• In 1800 it was 1 billion
• In November 2022 it reached 8 billion
• Due to humans’ ability to resist the limiting environmental factors
• E.g.s of limiting factors are disease and food supply
• Humans have overcome these by finding
• Medicines and vaccines to reduce or control rates of disease
• Technology to increase food supply to allow for population growth
• Continued population growth puts pressure on scarce resources
• The balance between population and resource use determines a place’s standard of living
• Careful management of population and resources is needed to maximise income per capita
• Countries aim to achieve a perfect balance between population and resources, known as optimum population 
• An imbalance between population and resources leads to overpopulation or underpopulation

The Relationship between Population, Resources and Standard of Living

• Population structure can also impact the population and resource balance
• Countries with a low dependency ratio are more likely to develop resources efficiently and so:
• Achieve economic growth
• Have an increased standard of living
• Allow a rise in population to be supported
• Countries with a high dependency ratio will spend precious resources on looking after the elderly or young dependents and so will struggle to:
• Grow the economy
• Support a population increase without negative social and economic issues

Concepts of Carrying Capacity and Ecological Footprint

• The maximum stable population size that an environment can support is known as the carrying capacity
• The size of the Earth’s carrying capacity is determined by:
  • Size of the population
  • Level of resource consumption
  • Technological innovation
  • Level of wealth

• If resources are consumed at sustainable rates, a larger population may be supported
• Countries going through industrialisation tend to consume and waste resources at unsustainable levels which leads to a lower carrying capacity
• Technological innovation can either lead to:
• Increases in supply of resources such as energy and minerals, lowering carrying capacity
• Or:
• Improved resource use efficiency and a higher carrying capacity
• Wealthier countries usually have a larger carrying capacity than poorer countries because:
• They export waste to poorer countries
• They import products from poorer countries
• This means that although poorer countries use fewer resources, they are supporting the resource use of the richer countries

Two different scenarios showing population response to carrying capacity

• An ecological footprint is a measure of a person’s or group’s use of natural resources
  • It is the amount of global heactares (gha) available for use by each person on the planet
  • It also shows the demand each person puts on the Earth’s biosphere
  • It forms a part of a person’s carbon footprint
  • Ecological footprints are hugely uneven around the world
    • Much higher in developed countries - USA 15.5 gha per person
    • In developing countries they are lower - Haiti 0.7gha per person
• As global demand for resources increases, so the planet’s ecological footprint gets bigger and its carrying capacity gets smaller
• Calculations suggest the world is in a state of overshoot, using the equivalent of 1.6 Earth’s worth of resources
• With population predicted to increase to around 9-10 billion by 2050 even more ‘Earths’ will be required unless more sustainable resource use strategies are put in place
  • This may act as a natural ‘check’ on global population growth 
• Other implications of changes to the carrying capacity and ecological footprint include:
  • Destruction of ecosystems such as forests and coral reefs with knock-on effects of extinction of plant and animal species 
  • Climate change
  • Deforestation and changes of land use for growing urban areas, transport and industrial development
  • Reduction of availability and quality of fresh water
  • Reduction in soil quality through erosion leading to crop and food shortages