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Interdisciplinary Sciences
Sustainability Science
1996
Beginner

Ecological Footprint Equation

EF=N×efEF = N \times e_f

Total human demand on nature equals population times per-capita ecological footprint.

By William Rees, Mathis Wackernagel

Interdisciplinary Sciences
Ecological Footprint Equation
1996 · William Rees
Why it matters: Made sustainability measurable—Earth Overshoot Day annually.

Discoverers: William Rees, Mathis Wackernagel (1996)

What does it mean?

Total human demand on nature equals population times per-capita ecological footprint.

Why should I care?

Made sustainability measurable—Earth Overshoot Day annually.

Variables & Units

SymbolNameUnitMeaning
EFEFEcological footprint—Global hectares
NNPopulation—Number of people
efe_fPer capita footprint—gha per person

Worked Example

Humanity uses ~1.7 Earths worth of biocapacity annually.

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Sources & further reading

Search WikipediaSearch Wolfram MathWorldOpen in Wolfram|AlphaWatch explainers on YouTube

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Equation Universe

Ecological Footprint Equation

EF=N×efEF = N \times e_f

Real-world impact

Planetary stewardship

Dynamics equations inform sustainability.

Photo: Unsplash — forest ecosystem

Total human demand on nature equals population times per-capita ecological footprint.

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