It is often difficult to measure the degrees to which our consumption choices affect our immediate and extended ecosystems. However, William Rees, director of the School of Community and Regional Planning at the University of British Columbia, and Mathis Wackernagel one of Rees's former students, have developed a useful methodology for doing just that. Summing the natural resource requirements for all significant categories of consumption and waste, Rees and Wackernagel use a new instrument, “ecological footprint analysis,” to determine the ecological impacts various human populations have on the environment.

Rees and Wackernagel work from the premise that energy, material consumption, and waste assimilation require the continuing support of a measurable area of land and water. Ecological footprinting yields an area-based estimate of the natural resource requirements of any given human population, from an individual to an entire country. Rees and Wackernagel add up factors such as physical occupancy of land, types of construction materials, share of city streets and intercity highways, and carbon dioxide production to determine the size of a household's eco-footprint. For example, they converted amounts of forest products consumed in constructing and maintaining a house into an equivalent area of productive forest land. The larger the household's footprint, the more resources (in spatial units of land and water) required to sustain its current level of consumption.

Wackernagel recently estimated the housing and commuting component of the footprint of a person living in a high-rise or walk-up apartment would be 0.7 acres; a person living in a modest cohousing community would use about 1.1 acres, and a person living in a large, suburban home would use about 5.6 acres. Each estimates assumes the person is living as part of a family of four. These housing estimates do not include other impacts on the environment, including furnishings, recreation, food, and clothing.

The average American has a total ecological footprint of about 25 acres, meaning that if everyone consumed like an average American, we would need several additional Earths to live on. There are about 5.5 acres of biologically productive land per capita in the world.


For more information, see: William E. Rees and Mathis Wackernagel. “Our Ecological Footprint: Reducing Human Impact on the Earth,”New Society: Gabriola Island, 1996

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