What does sustainability really mean, and how do we balance human needs against environmental limits?
The meaning of sustainability and sustainable development, the concepts of ecological footprint and carrying capacity, the difference between renewable and non-renewable resources, and the principles that guide sustainable resource use.
A focused answer to AQA A-Level Environmental Science 3.6 sustainability, covering the meaning of sustainability and sustainable development, ecological footprint and carrying capacity, renewable and non-renewable resources, and the principles of sustainable resource use.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
AQA wants you to explain the meaning of sustainability and sustainable development, define ecological footprint and carrying capacity, distinguish renewable from non-renewable resources, and explain the principles that guide sustainable resource use. Command words are Explain, Calculate and Discuss, so be ready to work with footprint figures as well as define the concepts.
Sustainability and sustainable development
It balances three pillars: environmental protection, economic viability and social fairness. A genuinely sustainable policy must satisfy all three, because a scheme that protects the environment but destroys livelihoods, or that grows the economy by exhausting resources, fails the test.
Ecological footprint and carrying capacity
These two concepts are complementary measures of the same imbalance: the footprint expresses human demand as an area, while carrying capacity expresses the limit as a population. When the global footprint exceeds the planet's biocapacity (ecological overshoot), humanity is drawing down natural capital faster than it regenerates.
Renewable and non-renewable resources
- Renewable resources (such as timber, fish, solar and wind energy) can be replenished naturally if used within their renewal rate. Used too fast, even renewables are exhausted: an overfished stock collapses just as surely as an emptied mine.
- Non-renewable resources (such as fossil fuels and most minerals) form over geological time and are effectively finite on a human timescale.
Principles of sustainable resource use
Sustainable use means:
- Harvesting renewables within their renewal rate (for example at or below the maximum sustainable yield).
- Conserving non-renewables through efficiency, reuse and recycling, and substituting renewables where possible.
- Minimising waste and pollution and protecting ecosystems and biodiversity for the future.
Exam-style practice questions
Practice questions written in the style of AQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AQA 20194 marksExplain the difference between ecological footprint and carrying capacity, and how each relates to sustainability.Show worked answer →
Markers award 2 marks for each concept correctly defined and linked to sustainability.
Ecological footprint: the area of productive land and sea needed to supply the resources a population uses and absorb its waste. If the footprint exceeds the biologically productive area available, the population is living unsustainably and drawing down natural capital.
Carrying capacity: the maximum population an environment can support indefinitely given its resources. Exceeding carrying capacity degrades the environment and lowers what it can support in future.
Link: sustainability requires keeping the footprint within the available biocapacity and the population within carrying capacity. The discriminating point is footprint as an area a population needs, carrying capacity as a population a place can hold.
AQA 20225 marksA country of 8 million people has an average ecological footprint of 5.2 global hectares per person, and 22 million global hectares of productive land and sea. Calculate whether the country is living within its biocapacity, and discuss what this means for sustainability.Show worked answer →
A quantitative item; markers reward the calculation and the interpretation.
Total footprint: global hectares (41.6 million).
Compare with biocapacity: the available area is only global hectares (22 million), far less than the footprint of 41.6 million. The deficit is global hectares.
Discussion: the country uses roughly times its own biocapacity, so it is living unsustainably and relies on importing resources or drawing down natural capital. Sustainability would require cutting per-person footprint or increasing biocapacity. Award the multiplication, the comparison, the deficit, and the unsustainability conclusion.
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Sources & how we know this
- AQA A-level Environmental Science (7447) specification — AQA (2017)