Explain how human population growth and patterns of consumption drive environmental impact, and describe how the ecological footprint measures the demand humans place on the biosphere.

What this dot point is asking

This dot point asks you to explain why the size and behaviour of the human population is central to environmental impact, and to describe how scientists measure that impact using the ecological footprint. You should be able to link population growth and per-person consumption to demand on ecosystems, and use the footprint to compare nations and judge whether humanity is living within the planet's limits.

Why population size matters

Every human needs food, water, energy, shelter and materials, and every human produces waste. As the population grows, the total demand placed on ecosystems rises. The global human population reached about one billion around 1800, but improvements in food production, sanitation and medicine drove rapid growth through the twentieth century, passing eight billion people in 2022. Australia's population has likewise grown strongly, passing twenty-six million, driven largely by immigration rather than natural increase.

Population growth is not even or unlimited. The same logistic principles that govern other species apply: finite resources eventually limit growth. Demographers describe how nations move through the demographic transition, a shift from high birth and death rates to low birth and death rates as living standards, education and healthcare improve. Wealthy countries such as Australia now have low birth rates and slowing natural growth, while some developing regions still grow quickly.

Impact depends on consumption, not just numbers

Population size alone does not determine impact. A useful idea is that impact depends on the number of people multiplied by how much each person consumes and the technology used to supply it. A person in a high-income country such as Australia typically consumes far more energy, food, water and manufactured goods than a person in a low-income country, and so has a much larger individual impact. This is why a relatively small, wealthy population can place enormous demands on global ecosystems.

This distinction matters for fairness and for policy. Slowing population growth helps, but reducing the impact of high consumption in wealthy nations is at least as important. Australians, with high rates of car use, meat consumption, air travel and household energy use, have one of the larger per-person footprints in the world.

The ecological footprint

The ecological footprint is a way of putting human demand into a single, comparable measure. It estimates the area of biologically productive land and sea required to provide everything a population consumes and to absorb the waste it generates, especially the carbon dioxide from burning fossil fuels. It is usually expressed in global hectares per person.

The footprint is compared against biocapacity, the area actually available to supply those resources and absorb that waste. When humanity's total footprint exceeds Earth's biocapacity, we are in ecological overshoot, drawing down natural capital faster than it can regenerate, much as overspending runs down a bank balance. Globally, humanity now uses the resources of well over one planet each year, with the date of overshoot tracked each year as Earth Overshoot Day.

Tasmanian and Australian context

Tasmania has a small population of around half a million but a large area of forest, ocean and other productive land, so at a state level its biocapacity is high relative to its population. This can make per-person footprints look favourable, but it does not mean consumption is sustainable, because much of what Tasmanians consume is produced elsewhere and the carbon component of the footprint is global. Tasmania's largely hydro-electric and wind electricity supply does, however, lower the energy part of its footprint compared with mainland states that burn more coal and gas.

Bringing it together

To answer this dot point well, explain that environmental impact is the product of population size and per-person consumption, describe how the human population has grown and how the demographic transition is now slowing that growth, and define the ecological footprint as the productive area needed to supply a population and absorb its waste. Conclude by comparing footprint with biocapacity to explain ecological overshoot, using Australian high consumption as a concrete example.