Ecological footprint is a term commonly used in sustainable building practice as a measure of our demand on earth’s resources. More specifically, it represents the amount of biologically productive land and sea area necessary to supply the resources necessary to a given population. Since resource utilization is dependent on personal lifestyle, the ecological footprint can be considered to be a quantification of the demand for natural capital needed to support a given lifestyle.
This unit of measure was first conceptualized in the PhD dissertation of Mathis Wackernagel under the supervision of William Rees at the University of British Columbia in Vancouver in 1988. Originally the two men called their concept “appropriated carrying capacity”. The revised term, “ecological footprint”, was coined in their book, “Our Ecological Footprint: Reducing Human Impact on the Earth” in 1996.
When calculated at the level of cities and countries, the measure provides a useful indicator of the relative demand on resources for any given population base. An ecological footprint calculation indicates that, for example the Dutch need a land are 15 times the physical footprint of the Netherlands to support their population. The population of London requires a land area 125 times greater than its physical footprint. William Rees’ ecological footprint analysis of his home city of Vancouver, Canada indicates that Vancouver appropriates the productive output of a land area nearly 174 times larger than the city’s physical area to support its lifestyle.
When considering the ecological footprint on the individual level, given Earth’s 8.9 billion hectares of productive land and its 6 billion human inhabitants, the average ecological footprint comes to roughly 1.5 hectares per person. This per-capita footprint provides a benchmark from which to assess the long-term sustainability of material consumption. Accordingly, individual footprints below 1.5 hectares are sustainable and footprints above 1.5 hectares are not. Wackernagel and Rees’ original calculations indicate that inhabitants of industrialized countries often have footprints as large as four (4) to ten (10) hectares, i.e. up to six times the carrying capacity of the planet.
What is your personal ecological footprint? A number of non-governmental agencies (NGOs) offer online ecological footprint calculators. One of them is at Footprint Calculator.
Some resources available for further reading include Wackernagel’s original thesis “Ecological Footprint and Appropriated Carrying Capacity: A Tool for Planning Toward Sustainability” and William Rees’ 1992 paper, “Ecological Footprints And Appropriated Carrying Capacity: What Urban Economics Leaves Out“.