The big idea: Everything we consume uses up natural resources. Two ideas measure that demand:
- Ecological footprint — the area of land and water needed to supply one person (or place) with resources and to absorb their waste. - Embedded (virtual) water — the hidden water used to produce a good or service, not the water you drink or see.
Both turn invisible consumption into a number you can compare.
Key terms
- Ecological footprint — the area of productive land and sea (in global hectares) needed to provide a person's resources and absorb their waste.
- Embedded water — the total water used along the whole supply chain to make a product (also called virtual water).
- Biocapacity — how much productive land and sea is actually available to supply those resources.
Embedded water in everyday goods: A single cotton T-shirt takes roughly 2,700 litres of water to grow and process the cotton.
One beef burger carries about 2,400 litres. You never see this water, but it was used somewhere to make the product.
How the footprint measures consumption
- It adds up the land you use — for food, timber, fibres and built-up space — into one comparable area.
- It includes the waste you create — especially the forest area needed to absorb your carbon emissions.
- More consumption = a bigger area — wealthier, high-consuming lifestyles need far more land per person.
- It is per person — so it can be compared fairly between rich and poor countries.
Explain one way the ecological footprint captures how much an individual consumes in resources.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
Explain needs the link: Explain wants the mechanism, not just a definition. Say how the footprint reflects consumption (it turns resource use into a land area) and that more consumption means a bigger footprint.
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Embedded water is not fixed: The embedded water in the goods a country consumes rises or falls over time. Diets, technology and trade all shift it.
| Driver | Pushes embedded water UP | Pushes embedded water DOWN |
|---|---|---|
| Diet | More meat and dairy (water-thirsty) | More plant-based, less meat |
| Technology | Old, wasteful irrigation | Efficient drip irrigation and recycling |
| Trade | Importing water-heavy goods | Sourcing goods grown in wetter places |
| Wealth | Richer consumers buy more goods | Falling waste and smaller portions |
A real shift — China's rising meat demand: As incomes rose in China, average meat consumption climbed sharply since the 1990s.
Meat carries far more embedded water than grain, so the embedded water locked into the country's food has increased over time.
How this is tested: A bar graph of daily water use per person is a common stimulus here: you State one country's value straight off the bars, then Estimate the range (highest minus lowest).
For an ecological-footprint map (global hectares per person), the task switches to Describe the spatial pattern using the figures shown.
Read the scale first. Find the tallest and shortest bars before you State or Estimate.
Interactive diagram
Explore the labelled diagram, charts and maps for this topic in full study mode.
Using the bar graph: state the daily water use for Mexico [1], then estimate the range of the values shown [1].
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.
| Country | Daily water use per person (litres) |
|---|---|
| United States | 575 |
| Australia | 490 |
| Italy | 385 |
| Mexico | 365 |
| Dominican Republic | 315 |
| United Kingdom | 150 |
| Bangladesh | 45 |
IB-style question — read the data
Using the table above: (a) state the daily per-person water use for the Dominican Republic [1]; (b) work out the range (highest minus lowest) of the values shown [1]; (c) describe the pattern in water use across the countries [2].
How to answer each part
- (a) State the value. Read the Dominican Republic row straight off — 315 litres per person per day.
- (b) Estimate the range. Range = highest minus lowest = 575 (United States) - 45 (Bangladesh) = 530 litres.
- (c) Describe the pattern. Water use is far higher in high-income countries (United States 575, Australia 490) than in lower-income ones (Bangladesh 45), with a large gap of over 500 litres between them.
Final answer
(a) 315 litres; (b) 530 litres (575 - 45); (c) much higher in wealthy countries than poorer ones, a gap of 500+ litres.
Describe the spatial pattern of ecological footprint shown on a world map, using map data.
Model answer plan
See the mark-by-mark plan — for / against / judgement, with marking guidance — in study mode.