Suppose you eat 50 pounds of pasta a year. To make this pasta, grain must be planted, harvested, transformed into spaghetti (or linguine or macaroni elbows), packaged, and transported to your table. The entire process from planting the grain to boiling the pasta uses natural resources such as land, oil, and water. It is not hard to find out how many acres of farmland are needed to grow the grain. You can also figure out how many acres of forest are needed to absorb the tailpipe emissions from all the vehicles used in transporting the grain and pasta. If you do the same type of calculation for each step of production, you can estimate the total amount of land needed to generate the natural resources used in producing the pasta and the amount of land needed to absorb the by-products. Do the same for all the food you consume during a year, and you’ve just discovered your “food footprint.” This is the amount of land needed to sustainably generate your food for a year. A sustainable harvest from a piece of land is one that can be taken year after year without degrading the productivity of the land and without generating substances that cannot be reabsorbed.

Now, think about all the other ways in which you affect the natural world. Your “ecological footprint” is one way of measuring this impact. Ecological footprinting is an elegant concept developed in the 1990s by Mathis Wackernagel and William Rees. The basic idea is that you can quantify the amount of land area needed to sustain yourself without depleting the earth’s resources for future generations. A typical ecological footprint calculation measures impacts from food production, transportation, consumption of goods and services, and shelter requirements.

Calculating an ecological footprint is not an exact science. Different calculators include different elements and make different assumptions about the impact of each element. I tried a number of footprint calculators and found my personal footprint spanned a large range from 14 to 25 acres. However, all footprint calculators agree that most citizens of developed countries have relatively big feet. The United States has the largest per capita footprint of any nation–approximately 31 acres per person. Living more lightly on the planet doesn’t have to mean freezing in the dark without doughnuts. Other industrialized nations with similarly high standards of living use significantly less than we do: Sweden’s citizens have 20 acre footprints while Germany’s citizens have just 15. The average world citizen has a footprint of 7.1 acres.

The problem is that the amount of biologically productive area available per person (leaving little for any other species) is only 5.3 acres. The environmental group Redefining Progress estimates that we are currently exceeding the biological capacity of the earth by approximately 35 percent. In other words, we are using resources much faster than they can be replenished. The reason that some citizens of the world are not yet suffering unduly from this situation (although many already are) is because the earth’s resources are so vast. If we think of these resources as a giant bank account, we are currently living off the principle rather than the interest. We are eating breeding stock from our fisheries and paving over our farmland.

We can still live pretty well for a while, but when we eat the last chicken we’re not going to get any more eggs. Of course, we can’t tell hungry people not to eat the last chicken. People in the developing world have a right to food, health care, education, and opportunities to thrive. What does this mean for the planet? You guessed it folks: it’s up to us fat cats to cut back a bit. Interested in finding out what your ecological footprint is? Try one of the footprint calculators listed at the end of this article. Seemingly small changes can have a big impact; you may be surprised to find that you can shave an entire acre off your footprint simply by switching to vegetarian fare two days per week. Please pass the pasta!

http://www.myfootprint.org

http://www.environ.sc.edu/sui/ecofootprint.htm

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