The sharp rise in mineral use has revived concern about scarcity. Economist John Tilton responds by analyzing recent trends in the consumption and availability of minerals that are most integral to the needs of modern civilization. He reminds readers that, if the arguments about scarcity sound familiar, it is because the story of minerals scarcity is almost as old as human history-and so too is substitution and technological innovation. The issue at hand is the unprecedented acceleration in exploitation and use. Given global population growth, rising living standards, and environmental concerns, how seriously should today?s society take the threat of mineral exhaustion? On Borrowed Time? provides general interest and student readers with an accessible framework for understanding scarcity. Tilton defines important concepts and explores the methods used to study mineral scarcity, including physical measures of known reserves and the total resource base, and economic measures, such as extraction and end-user costs. He notes the increasing emphasis on the social and environmental costs of mineral production and use, placing the scarcity debate in context of broader concerns about sustainability and equity. He adds a history of thought about scarcity, from Malthus and Ricardo to Harold Hotelling, Donella Meadows, to the present day.