A method for valuing global ecosystem services

The goal of this paper is to provide an investigation of several approaches to valuing ecosystem services and to contribute additional techniques whic h may be used in evaluating 'green' GDP accounts. Our estimates focus on th e ecosystem as a productive economic input, not a stock which is depreciate d or depleted over time; as such, it differs with other concepts more frequ ently employed in green GDP accounting. Most of our results are derived fro m the analytical fiction that a single owner of the biosphere establishes a market for all ecological resources. This monopolist then appropriates all rents from the human population. The maximum amount the monopolist charges is first assumed to be world gross product less the global human subsisten ce level. In addition, we examine the excess rents available in factor mark ets using the assumption of weak complementarity between factor inputs and ecosystem services. We also provide more conservative estimates of the valu e of ecosystem services by investigating the sustainable price the monopoli st could charge the global population and by exploring the effects of compe nsating wage differentials and a non-monopolist owner of the ecosystem. (C) 1998 Elsevier Science B.V. All rights reserved.