Abstract

Mineral depletion is a perennial concern in natural resources management. Despite a multiplicity of perspectives, most analyses fall largely into one of two groups. Studies in the first group take the fixed quantity of any material in the earth as the starting point for analysis, focus primarily on physical stocks and flows of mineral resources, and assess when society will run out of a resource or when production and use will peak (the fixed-stock viewpoint). Studies in the second group start by noting the heterogeneous nature of mineral resources and our incomplete knowledge of the quantity and quality of minerals in the earth, focus on the dynamic nature of mineral availability, and assess the ability of society to adjust to mineral depletion at existing mines though mineral exploration and mine development, technological innovation, and substitution (the opportunity-cost viewpoint). This paper seeks to reconcile these diverging perspectives by developing a modified cumulative availability curve (CAC) - which combines physical stocks and flows (from the fixed-stock perspective) with geologic stock uncertainty, different demand scenarios and extraction costs (from the opportunity-cost perspective). When applied to copper resources, the modified CAC suggests that copper demand is likely to be satisfied from known deposits until about 2075. Thereafter, society's ability to discover and develop previously unknown deposits and improve the efficiency of their production - as well as efforts at substitution and improving recycling and re-use of copper - will importantly influence whether copper demand is satisfied and at what copper price.