Authors:

Brad Ewing, Anders Reed, Sarah M. Rizk, Alessandro Galli, Mathis Wackernagel, Justin Kitzes

ABSTRACT

Human demand on ecosystem services continues to increase, and there are indications that thisdemand may be outpacing the regenerative and absorptive capacity of the biosphere. Theproductivity of natural capital may increasingly become a limiting factor for the humanendeavour. Therefore, metrics tracking human demand on, and availability of, regenerative andwaste absorptive capacity within the biosphere are needed. The Ecological Footprint is one suchmetric; it measures human appropriation of ecosystem products and services in terms of theamount of bioproductive land and sea area needed to supply these services. The area of land orsea available to serve a particular use is called biocapacity, and represents the biosphere’s abilityto meet human demand for material consumption and waste disposal. The Ecological Footprintand biocapacity accounts cover six land use types: cropland, grazing land, fishing ground, forestland, built-up land and carbon uptake land (to accommodate the Carbon Footprint). For eachcomponent, the demand for ecological services is divided by the yield for those ecologicalservices to arrive at the Footprint of each land use type. Ecological Footprint and biocapacity arescaled with yield factors and equivalence factors to convert this physical land demanded to worldaverage biologically productive land called global hectares. This allows for comparisons betweenvarious land use types with differing productivities. The National Footprint Accounts calculatethe Ecological Footprint and biocapacity of individual countries and of the world. According tothe 2008 edition of the National Footprint Accounts, humanity demanded the resources andservices of 1.31 planets in 2005. This situation, in which total demand for ecological goods andservices exceeds the available supply, is known as overshoot. On the global scale, overshootindicates that stocks of ecological capital are depleting or that waste is accumulating.