Our Ecological Footprint: Reducing Human Impact on the Earth

by Mathis Wackernagel and William Rees. New Society Publishers, Gabriola Island, British Columbia and Philadelphia, 1996. 160 pages; hardcover $39.95, paperback $14.95.

Advocates of environmental sustainability often struggle with the challenge of assessing problems and their requisite solutions. Without quantities, it’s harder to convince people that the problem is real or that the benefits are justified. Yet most attempts at quantification either involve very complex models, or else they oversimplify the problem to the point of meaninglessness (see “Working on Green Building Assessment,”

EBN

Vol. 5, No. 1).

Our Ecological Footprint presents an exciting new approach to this problem, using productive land area rather than dollars or abstract “ecopoints” as its currency.

In effect, this approach reverses the “carrying capacity” idea biologists speak of in relation to a land area or ecosystem. Rather than: “How large a population will this area support?” it asks: “How large an area is this population (or individual) consuming?” Within this model, authors Wackernagel and Rees seem to strike a healthy balance between oversimplification and accuracy, providing a tool that can be used at many levels to enrich the discussion of options for sustainability.

Using this approach, they’ve estimated that we need at least two additional planets to support our current levels of consumption in a sustainable manner. The fact that we are currently surviving on just one planet is because we are mining and extracting nonrenewable resources, such as fossil fuels, rather than surviving on current solar income.

The basic understanding underlying this work is that “human society is a subset of the ecosphere”—our economy is contained within and dependent upon the global ecosystem, and all economic activity can be connected, either directly or indirectly, to impacts on the Earth.

Interestingly, the first place we seem to be actually feeling the global crunch is not in the area of nonrenewable resources, as many had suspected, but in the overharvesting of renewable resources, such as fish on New England’s outer banks, and forests all across the continent. And in terms of fossil fuels, we seem to be reaching a limit in the planet’s ability to assimilate our wastes (CO2 and other products of combustion) before we run out of fossil fuels to burn.

Without going into the methods themselves, it’s worth noting that their very conservative calculations suggest that in North America the average ecological footprint of each individual is about 4 to 5 hectares (10 to 12 acres) of productive land. Globally, our footprint currently exceeds the productive area of the planet by a factor of three, and this figure is rising quickly due to two factors: first, increasing per capita consumption, and second, population growth. In the short term we’re able to overtax the planet to support this level of consumption, but the long-term impacts are catching up with us.

Note: An unfortunate layout error has resulted in missing text from two of the books sidebars (pages 35 and 48). This problem will hopefully be corrected in later printings.