On the Inexhaustibility of Exhaustible Resources

Many forms of natural capital, such as fossil fuels, are best described as 'exhaustible' or 'non-renewable' because they do not renew themselves on human timescales. As these exhaustible resources can appear to be essential inputs in many production processes, it is not unreasonable to ask how soon we will run out of them, and what might happen when we do. These concerns about resource limits and scarcity fuelled publications such as the Limits to Growth and motivated the now famous bet between Ehrlich and Simon about whether the price of a bundle of natural resources would fall or rise over a corresponding decade. We analyse publicly-available data from the United States Geological Survey, along with further historical data requested from USGS, which provides (annual) US prices, US consumption and the best estimates of worldwide production and economically extractible reserves/resources for over 45 different commodities since 1957. Using econometric methods for the detection of breaks in trends in Reserve-Production Ratios, we find that past concerns about minerals depletion have not been well founded — there is little evidence that we're running out of anything. In contrast, production of most minerals continues to grow, suggesting that we are some way from 'peak minerals'. Of course, the persistent errors of past pessimistic forecasts does not necessarily imply that current pessimistic forecasts won't turn out to be correct, and it is logically true that indefinite resource consumption will eventually exhaust any finite stock of resources. However, humans rarely appropriate minerals more than a few kilometres into Earth's crust (which is up to 70 km deep depending on the precise location), and the evidence strongly suggests that market and price dynamics have provided, and will continue to provide, incentives for innovation and substitution. Concerns about natural resource depletion in the near future appear misplaced.