Biocapacity and earthshares

One of the most powerful uses of the ecological footprint approach is in the assessment of sustainability. By comparing the ecological footprint (demand on natural resources) with biocapacity (the available supply of natural resources) it is possible to assess the ecological sustainability of current consumption - if demand is greater than supply, the level of consumption is not sustainable.

Biocapacity can be expressed as local biocapacity or as global average biocapacity - the latter is referred to as the average earthshare. If everyone lived within their earthshare, this would give an environmentally sustainable human existence on earth. Earthshare is calculated by dividing the total amount of bioproductive land and sea on Earth by the current population. This gives the average amount of bioproductive land and sea available globally per person. The latest calculations estimate the earthshare to be 1.9 gha per person (Loh, 2002).