Level: SL and HL
Subtopic: 1.3 Sustainability
Sustainability measures the extent to which practices maintain the long-term viability of a system without diminishing conditions for future generations. It is measured using quantitative indicators and models that compare human demands with environmental and social limits.
Sustainability has three interconnected pillars: environmental, social and economic. A practice is not fully sustainable if it protects ecosystems but creates severe inequality, or if it supports economic production by depleting natural resources.
Sustainable development applies sustainability to social and economic development: it meets present needs without compromising the ability of future generations to meet their own needs.
| Measure or model | What it shows |
|---|---|
| Sustainability indicators | Quantitative data on biodiversity, pollution, population, climate change and resource use |
| Ecological footprint | The biologically productive area needed to supply resources and absorb wastes |
| Biocapacity | The capacity of an area to produce renewable resources and absorb resulting wastes |
| Carbon footprint | Greenhouse gas emissions expressed as carbon dioxide equivalents |
| Water footprint | Water use, normally measured in cubic metres per year |
| Planetary boundaries | Limits to human disturbance of nine Earth-system processes |
| Doughnut economics | Whether human needs are met within ecological limits |
If a population’s ecological footprint exceeds available biocapacity, this indicates ecological overshoot and therefore unsustainability. However, no single indicator provides a complete judgment: national averages can conceal unequal access to water, food and energy.
This links sustainability to environmental justice, which concerns equitable access to resources and a pollution-free environment. Amsterdam, for example, has used the doughnut economics framework to connect ecological limits with housing, health and social equity.
A common misconception is that “renewable” automatically means “sustainable.” A renewable resource can still be harvested faster than it regenerates or processed using polluting methods.
Exam technique: For an explain question, define sustainability and show how a named indicator measures it. For evaluate, discuss both the indicator’s usefulness and limitations, include a named example, and reach a supported conclusion.
