Deconstructing and Reconstructing the Theoretical Basis of the Ecological Scarcity Method

Abstract

The ecological scarcity method (ESM) is a widely used system for assessing the environmental impact of pollutant emissions and resource extractions in the context of life cycle assessment (LCA). Its mathematical principles have been described in various reports, but not in scientific journals, which typically only quote the ESM or challenge the numerical values of the targets. It is, therefore, appropriate to carefully dissect the method and critically reassemble the resulting fragments. Our analysis introduces a substantial number of modifications, in terms of overall formulation, detail and interpretation, while it respects most of the existing numbers and is still applicable to the full range of pollutants and resources. It also yields the conclusion that, although the developers of ESM have tried to align the approach with the ISO 14040/14044 standards for LCA, this attempt has been less successful than foreseen. We finally conclude that the reference to ESM as a “distance-to-target” method further obscures the interpretation of the method.