Metal Resources Indicators in LCA : From depletion of the geosphere to recoverability from the anthroposphere

Abiotic resource depletion (Guinée and Heijungs, 1995) is still a popular indicator of resource use in many lifecycle analyses, despite the fact that it has been regularly criticized for considering resources as a fixed stock. Authors have suggested alternative methods including the increase in energy required to mine future stocks (Vieira et al., 2012) or the notion of ultimate resource in the Earth crust to overcome this problem (Arfvidsson, 2020). However, mineral resource specialists have insisted that these approaches are not consistent with our current understanding of future resources (Ericsson et al., 2019) and have suggested to take into account that resources are not consumed but essentially stockpiled into the anthroposphere. A recent paper summarizes different approaches (Berger, 2020) and, even more recently (Dewulf, 2021), the notion of accessibility is being suggested to better take into account compromising human actions in the use of metals. In this paper, we will suggest pathways to better estimate recoverability of metals from the anthropogenic stocks by developing quality indicators to complement the current mass flow analysis.