Résumé
Policy action to halt the global loss of biodiversity and ecosystems is hindered by the perception that it would be so costly as to compromise economic development, yet this assumption needs testing. Inspired by the recent Stern Review on the Economics of Climate Change, the leaders of the G8+5 nations commissioned a similar assessment of the economics of losing biodiversity, under the Potsdam Initiative on Biodiversity. Here, we propose a conceptual framework for such a global assessment which emphasizes several critical insights from the environmental economics and valuation literature: contrasting counterfactual scenarios which differ solely in whether they include specific conservation policies; identifying non-overlapping benefits; modeling the production, flow, use and value of benefits in a spatially-explicit way; and incorporating the likely costs as well as possible benefits of policy interventions. Tackling these challenges, we argue, will significantly enhance our ability to quantify how the loss of benefits derived from ecosystems and biodiversity compares with the costs incurred in retaining them. We also summarise a review of the current state of knowledge, in order to assess how quickly this framework could be operationalized for some key ecosystem services.