Does the Shoe Fit? Real versus Imagined Ecological Footprints
Despite its relative youth (less than two decades), the ecological footprint (EF) is a commonly used term in environmental science, policy discussions, and popular discourse. The motivation behind the concept is sound—we must account for, and quantify, the impacts of humanity on Earth’s ecosystems if we are to manage the planet sustainably for the benefit of both human well-being and our natural heritage. The EF seeks to measure humanity’s use of renewable biological resources, which can then be compared to the planet’s capacity to regenerate these resources. The result of EF calculations that is quoted most widely is that humanity currently uses the equivalent of 1.5 Earths to support human needs. Therefore, we are already exceeding the planet’s carrying capacity in what amounts to “ecological overshoot”
http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001700