= Our human footprint consists of our annual consumption of renewables and non-renewables.
"A footprint has a size and a weight. Together they determine the impact on the area that supports the footprint. The footprint represents the consumption of resources per year.
If our consumption of renewables is higher than their rate of regeneration, we will run out of food and fibre.
If our depletion rate of non-renewables is low in comparison to the available stocks, we can carry on for a relatively long period of time.
Renewable resources are products made of plant and animal material, water, etc.. They are regenerated by the interactive functioning of nature, that is the balances of living beings and non-living material on Earth.
Non-renewable resources, such as fossil fuels, uranium, metals and minerals, are finite stocks, that are not renewed by nature." (http://ecoglobe.ch/sustain/e/footprint.htm)