Natural capital in ecology and economics: an overview

The Brundtland Commission report, Our Common Future, defined sustainable development as development that meets the needs of the present without compromising the ability of future generations to meet their own needs. Although the idea of sustainable development has been widely accepted, it has proved difficult to identify and implement policies and practices that promote sustainable economic growth. Some economists, environmental scientists and policy analysts believe that they can transform the consensus about sustainability into manageable practices. They propose to accomplish this feat with a set of new ideas about the relationships between the economy and the environment offered under the banner of 'natural capital'. An ideal account of natural capital would be one or more standard measures or models that would allow the direct comparison of environmental goods, like forests, fresh water and clean air, with economic goods, like money, capital and productivity. By bringing economic science and environmental science to an objective common ground, a natural capital model has the potential to provide a concrete means of comparing the economic and ecological costs and benefits of particular policies and programmes. This paper offers a survey and analysis of several new contributions to the formation of the natural capital concept from economists, ecologists, policy analysts, biometricians, foresters and a philosopher. The paper concludes that existing microeconomic theory may be 'ungreenable', if it is not reformulated. While macroeconomic approaches to natural capital have beenmore successful, they share the limitation that ecosystems and species are valued solely in monetary terms. These problems are taken to suggest that the development of a successful natural capital model may require economic theory to be recast to include non-monetary social preferences and values.