Why current assessments of ‘future efforts’ are no basis for establishing policies on material use—a response to research on ore grades

The concept of declining availability due to declining primary resource quality has been investigated for various resource categories to try to determine the effort needed in future to either extract the resource or to treat it for intended use. The concept of ‘future efforts’ due to declining primary resource quality is explored by Vieira et al. (2016, 2017). They suggest that a specific burden associated with the production of each primary material should be taken into account and that this can be done by studying the costs of production or ore requirements of the material and by projecting forward likely costs into the future. For the purpose of the analysis, they employ mine cost data for 2000–2013 and reserve data published by the US Geological Survey. We will argue below that this approach is not correct and, with this comment, we wish to make it clear that—contrary to what is suggested in much of the Life Cycle Assessment literature—the future efforts concept is not an established rule of natural resource extraction. For mineral resources, it is quite impossible to proceed with extraction in the ordered way that this approach suggests because nobody has a comprehensive view of the entire natural resource. Secondly, there is no evidence available to support the idea that extracting a mineral resource today causes a decrease in availability of that mineral tomorrow. On the contrary, the weight of evidence suggests that where declines in ore grades have been observed, they are overwhelmingly due to technology development in response to high demand and have been accompanied by increased mining efficiency and increased availability of the resource to successive generations. Grade is a rather arbitrary measure since the grade of mined ore ultimately has to do with the relationship of costs and revenues. It is not only the technology employed which matters but also how smartly this technology is applied. Thirdly, the future efforts approach entirely overlooks the potential availability of mineral materials from secondary (scrap) sources, sources which are expected to become increasingly important to mineral supply in the future. Our conclusion from the discussion is that we as humans have been able to economically access ever-increasing amounts of material from often lower and lower-grade sources. What is impossible to conclude from this is that the environment no longer contains any of the higher-grade sources. In fact, all the available evidence suggests that higher-grade deposits are still out there. We remain critical optimists.