What is an ecological footprint?
The ecological footprint has been defined by Wackernagel, Mathis, and Rees (1996) as "the area of productive land and water ecosystems required to produce the resources that the population consumes and assimilate the wastes that the population produces, wherever on Earth the land and water is located."
An individual's ecological footprint is the demand that individual places on the planet. You can calculate yours here .The calculation takes into consideration factors such as how often you drive, what you drive, if you take public transportation, how often you fly, and so forth.
It's also possible to calculate the demand an organization or a country or a community puts on the planet's natural resources. The amount of land being farmed, the amount of forest being cut down, and the amount of forest needed to absorb CO2. The ecological footprint is a concept of increasing relevance as the human population grows. The World Wildlife Foundation has an extensive article that is worth checking out for more details.
Wackernagel, Mathis and W. Rees. Our Ecological Footprint. Gabriola Island, BC: New Society Publishers, 1996.