Footprints to nowhere

Crisp numbers make it to the headlines. However, it is unlikely that a single crisp number can capture a complex issue, such as the analysis of the sustainability of human progress both at the local and the global scale. This paper tackles this standard epistemological predicament in relation to a media-friendly model of man's impact on Nature: the Ecological Footprint (EF). The claim made by the proponents of this analytical tool is that EF makes it possible to check how much is taken by the economic process versus how much could be taken according to ecological processes. In this paper we argue that the ecological footprint assessment - purportedly useful as an argument against the idea of perpetual growth - is fraught with internal contradictions. Our critical appraisal is based on the lack of correspondence between the semantics - the claim about what the EF accounting does - and the syntax - the EF protocol of accounting that should deliver the purported output. We critically examine the various assumptions used in the approach, showing that the EF is in contradiction with its stated purposes and would lead to paradoxes if its prescriptions were used for policy making. We also contend that the laboriousness of EF computation protocols contrasts with its ultimate fragility. In fact the estimate of carbon footprint due to energy production is what determines the assessment of the planet's deficit of virtual land. We show that this estimate cannot be defended in light of the assumptions and simplifications used for its construction. Our conclusion is that the EF does not serve a meaningful discussion on the modeling of sustainability, and that the same media-friendly narrative about the Earth Overshot day is in the end reassuring and complacent when considering other aspects on man's pressure on the planet and its ecosystems. (C) 2014 Elsevier Ltd. All rights reserved.