Extractable global resources and the future availability of metal stocks: “Known Unknowns” for the foreseeable future

The primary purpose of this article is to suggest that estimates of extractable global resources (EGRs) of metals made using current methodologies are so uncertain as to render them generally unfit for guiding policy with regard to resource depletion and governance. This situation is unlikely to change much for the foreseeable future, as the expensive geochemical sampling programs required to define metal ore deposits are driven by the short to medium term operational considerations of mining companies, with the determination of EGR being of little to no concern. Furthermore, it is shown that even if it became possible to estimate EGRs quite accurately, this in the absence of a detailed understanding of the post-mining disposition of metal stocks, and the feasible recovery and recycling rates for those stocks over the long term, would leave us little better positioned to determine the long-term availability of metals. Given this, trying to design policies for international governance of the extraction of metal ores, on the premise of extending their availability to future generations, is unlikely to be a productive investment of research effort. Meeting the challenge of maintaining metal supplies for future generations will be better served by continuing to improve our understanding the impacts of ever-increasing mining activity on natural systems, how improved mining practices might reduce this, and by following the fate of metals post-mining, and the implications for metals recoverability and recycling potential.