Abstract

This study questions recent research [Gordon, R.B., Bertram, M., Graedel, T.E., 2006. Metal stocks and sustainability. Proc. Natl. Acad. USA 103(5), 1209-1214] that concludes that the world is likely to experience a growing scarcity of copper over this century. In particular, it focuses on the methodology used in this work that assumes the usable copper contained in the earth is a fixed amount. While the fixed-stock paradigm is intuitively appealing-after all the earth is finite so the amount of any commodity it contains must also be finite-and used with some frequency by others as well to assess long-run trends in the availability of non-renewable mineral resources, it is flawed and can lead to overly pessimistic as well as overly optimistic expectations. A more useful and appropriate approach, the opportunity-cost paradigm, assesses long-run trends in availability by real prices or alternative measures of what society has to give up or sacrifice to obtain another ton of copper or barrel of oil. This approach indicates that copper could conceivably become less scarce by the end of the century. Whether this will be the case or whether copper will be more scarce, however, depends on a number of factors, including the future course of technological change, whose influence no one can predict with any degree of certainty decades in advance. © 2007 Elsevier Ltd. All rights reserved.