You’ve probably heard of the carbon footprint – the amount of carbon being emitted by an activity or organization – but what about the Ecological Footprint? The Ecological Footprint is the measure of human demand on the Earth's ecosystems. It compares planet Earth's ecological capacity to regenerate compared to all of the resources we humans use. With this model, we can see how much of our planet it takes to support us while we live a certain lifestyle (i.e.: staying on our current track of waste, or mending our ways and becoming more resourceful).
For 2005, humanity's total Ecological Footprint was estimated at 1.3 planet Earths, which means that we'd need another Earth plus almost a third of another one just to be able to provide us with the natural resources we currently use, or that the Earth needs a year and four months to regain the resources we use in one year. This number is recalculated every year, but is 3 years behind because of the amount of time it takes the UN to collect and publish the statistics. UN scenarios show that if our current consumption trends continue, by 2030 we'll need two Earths to support humanity. That's more than one too many. (See these charts for the Ecological Footprint of the US.)
This article appears in Jul 15-21, 2009.