The purpose of the concept of ‘Ecological Footprint’ is to measure how much land and water area a human population requires to produce the resource it consumes and to absorb its wastes, using prevailing technology. This can be seen as a measure of sustainable use of natural resources.

The index developed by the Global Footprint Network has been developed to track the availability of regenerative capacity within the biosphere, society’s demand on this capacity, and the difference between these two. In other words, the Ecological Footprint answers a specific research question: How much of the regenerative capacity of the Earth’s biologically productive ecosystems is occupied by human demands?

The Ecological Footprint assesses demand on the biosphere by measuring the amount of terrestrial and marine area that is required to provide the ecosystem resources and services necessary to support any defined human activity, given current technology. The Footprint of a population is a function of its size and material standard of living, including its use of energy, food, fibre and timber, and reflects the efficiency with which these resources are turned into consumption products. It also includes the area occupied by buildings, roads, dams, and other types of societal infrastructure.

The Ecological Footprint can be compared globally or locally to available biocapacity, defined anthropocentrically as the ability of biologically productive ecosystems to provide the resources and services used by humanity. Biocapacity varies each year with ecosystem management, agricultural practices (such as fertilizer use and irrigation), ecosystem degradation, and weather. Comparison of demand (Footprint) and supply (biocapacity) provides an account of the extent to which humanity’s consumption is approaching or exceeding the Earth’s ecological limits.