Conventional economic accounts, which measure Gross National Product (GNP)and related indicators of national performance, do not fully allow for the damages caused to the environment in the course of producing and consuming goods and services. Nor do they fully account for the fact that some resources are being depleted in achieving the living standards that we enjoy today. This failure is important, because policy-makers are guided by the changes in macroeconomic indicators such as GNP. Moreover such indicators are not a good guide to the sustainability of present practices of consumption...