“That country is living unsustainably” is an opinion until you can put a number on it. Indicators do exactly that — and the UK’s ecological footprint being roughly two and a half times its biocapacity is the number worth memorising.
📘 What you need to know
Sustainability indicators are quantitative measures used to assess aspects of sustainability.
The three named footprints: ecological, carbon and water.
Ecological footprint (EF): the area of land and water needed to support a population at a given standard of living, in global hectares (gha) per capita per year.
Biocapacity: the resources the land available can provide sustainably.
If EF exceeds biocapacity, the lifestyle or country is not sustainable.
UK figures: EF about 4.2 gha per person against a biocapacity of about 1.7 gha.
GDP ignores resource depletion and environmental degradation. Green GDP subtracts those costs.
What sustainability indicators are
Sustainability indicators are quantitative measures used to assess various aspects of sustainability. They can be specific to biodiversity, pollution, human population, climate change and many other factors, and they can be applied at any scale from local to global to evaluate the environmental, social and economic dimensions of sustainability — whether something is environmentally sound, socially fair and economically viable.
Ecological footprint
An ecological footprint (EF) is a theoretical concept used to assess the environmental impact of human populations. It quantifies the area of land and water required to support a specific population at a particular standard of living, measured in global hectares (gha) per capita per unit time.
Two definitions to keep apartEcological footprint — the area of land and water needed to support a population at a given standard of living, in gha per person per year. Biocapacity — the amount of resources the available land can provide sustainably.
The EF accounts for the resources individuals consume — food, energy, water, materials — as well as the waste generated and the ecosystem services required to absorb that waste. Taken together, this makes it a comprehensive measure of the demands a population places on the environment.
The 2.5 gha gap is made up by importing resources and exporting waste — which is exactly the mechanism behind the environmental injustice on the previous page.
EFs can be used to compare the sustainability of different lifestyles, businesses and whole countries. If the EF exceeds the biocapacity available to that population, the lifestyle or country is not sustainable in the long term.
In the UK, the ecological footprint is estimated at about 4.2 gha per person per year, while biocapacity is only around 1.7 gha per person per year — so the UK population is living unsustainably.
What changes an ecological footprint
Lifestyle choices, including diet and consumption patterns, affect the size of a region’s EF. Countries with very high consumption of highly processed foods have large footprints, both because of the resources needed to sustain that diet and because of the volume of solid domestic waste it produces.
To reduce an EF, the standard measures are reducing meat consumption, using renewable energy, and walking, cycling or using public transport instead of driving. EFs are a useful tool for promoting sustainable development and raising awareness of human impact.
The other two footprints
What it measures
Units
Example figure
Ecological footprint
Area of land and water needed to support a population at a given standard of living
global hectares (gha) per person per year
UK: about 4.2 gha
Carbon footprint
Greenhouse gases produced by a person, activity, business or country
tonnes of carbon dioxide equivalent per year
UK citizen: about 5.5 tonnes CO2
Water footprint
Water used directly or indirectly to produce goods and services, such as crop irrigation or manufacturing
cubic metres per year
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You need to be able to interpret data and compare results for all three footprints, but you do not need to know how any of them are calculated. Spend your revision time on the definitions, the units, and what the numbers mean — not on the arithmetic behind them.
Economic indicators and their limits
Traditional economic indicators such as gross domestic product (GDP) give a limited view of progress. GDP measures the value of goods and services produced within a country’s borders, but it does not account for the depletion of natural resources or the costs of environmental degradation. That can encourage patterns of unsustainable development which prioritise short-term economic gain over long-term sustainability.
This is the measurement version of the weak-versus-strong sustainability argument from the first page in this sub-topic.
Green GDP adjusts traditional GDP by accounting for environmental costs and the depletion of natural resources. By subtracting those costs, it gives a more accurate measure of economic progress that reflects both long-term economic and environmental sustainability. In China, policymakers have begun incorporating environmental considerations into economic planning through measures such as Green GDP, showing growing recognition that sustainability underpins long-term prosperity.
Worked examples
WE 1
Footprint and biocapacity
Define ecological footprint and explain how it is used to judge sustainability. (4 marks)
Step 1: the definition
An ecological footprint is the area of land and water required to support a population at a particular standard of living, measured in global hectares per person per year.
Step 2: what it includes
It accounts for resources consumed — food, energy, water, materials — plus the waste generated and the ecosystem services needed to absorb it.
Step 3: the comparison
It is compared against biocapacity, the resources the available land can provide sustainably.
Step 4: the judgement
If the footprint exceeds biocapacity, the population is living unsustainably. The UK’s EF of about 4.2 gha against a biocapacity of about 1.7 gha shows this.
Demand above supply means unsustainable, by definitionquoting the two UK figures secures the application mark
WE 2
Reducing a footprint
Suggest three ways an individual could reduce their ecological footprint. (3 marks)
Way 1: diet
Reduce meat consumption, since producing meat requires far more land and resources per unit of food energy.
Way 2: energy
Use renewable energy sources rather than fossil fuels, cutting the land and absorptive capacity needed to deal with emissions.
Way 3: transport
Walk, cycle or use public transport instead of driving.
Why these work
Each reduces either the resources consumed or the waste that ecosystems must absorb, the two components of the footprint.
Consume fewer resources, or generate less waste to absorbexplaining why each works lifts a list into an answer
WE 3
Limits of GDP
Explain why GDP is a poor indicator of sustainability, and how Green GDP improves on it. (4 marks)
Step 1: what GDP measures
GDP measures the value of goods and services produced within a country’s borders.
Step 2: what it omits
It does not account for the depletion of natural resources or the costs of environmental degradation.
Step 3: the consequence
This encourages unsustainable development, because short-term economic gains are recorded while long-term environmental costs are invisible.
Step 4: the improvement
Green GDP subtracts the environmental costs of economic activity, giving a more accurate measure that reflects both economic and environmental sustainability. China has begun using it in planning.
GDP counts the income and ignores the depreciationquestion whether any indicator reflects true costs — that scepticism earns evaluation marks
💡 Exam tips
Learn ecological footprint and biocapacity as two separate definitions.
Memorise the units: gha per person per year, tonnes CO2 per year, cubic metres per year.
Keep the UK figures ready: 4.2 gha footprint against 1.7 gha biocapacity.
You do not need to know how footprints are calculated, only how to interpret them.
Always state the rule: EF above biocapacity means unsustainable.
Be ready to criticise indicators for their limitations and biases.
⚠ Common mistakes
Confusing footprint with biocapacity. One is demand, the other is supply.
Giving footprints without units. The unit is part of the answer.
Trying to calculate an ecological footprint. Not required, and a waste of revision time.
Forgetting waste. The EF covers waste absorption as well as resource consumption.
Treating GDP as simply wrong. It measures output accurately; it just omits environmental cost.
Assuming Green GDP is exact. Environmental costs are difficult to value in money.
Up next: Citizen Science and Public Data. Indicators need data, and there is far more environment than there are professional scientists. The next page is about who else can collect it.
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