The ecological footprint from a systems perspective of sustainability

The Ecological Footprint (EF) is a method for estimating the biologically productive area necessary to support current consumption patterns, given prevailing technical and economic processes. By comparing human impact with the planet's limited bioproductive area, this method tests a basic ecological condition for sustainability. The ecological footprint has gained popularity for its pedagogical strength as it expresses the results of its analysis in spatial units that can easily be communicated. Many EF estimates have been performed on a global, national and sub-national level. In this paper, we review the method and critically assess it from a sustainability perspective based on first order principles. We examine: Which aspects of sustainability are already covered by existing EF assessments; Which further aspects of sustainability could be made accountable through the EF (such as areas needed to assimilate waste streams that are not yet accounted for in present assessments); and Those aspects of sustainability that cannot be accountable through the EF, thereby needing complimentary auditing tools. Since the EF is a measure of renewable biocapacity, we argue that some dimensions of ecological sustainability should not be included in the EF. These include human activities that should be phased out to obtain sustainability, such as emissions of persistent compounds foreign to nature and qualitative aspects that represent secondary uses of ecological areas and do not, therefore, occupy a clearly identifiable additional ecological space. We also conclude that the EF is useful for documenting the overall human use or abuse of the potentially renewable functions and services of nature. Particularly, by aggregating in a consistent way a variety of human impacts, it can effectively identify the scale of the human economy by comparison with the size of the biosphere.