Uncertainty and sustainability

Uncertainties pertinent to the environmental context of economies and its s ustainability have implications for precautionary policies. Three types of uncertainty are acknowledged: uncertainty due to ignorance, model uncertain ty and parameter uncertainty. Parameter uncertainty may be met by using saf ety factors or by responses based on running large numbers of model simulat ions. Model uncertainties may be met by model adaptation or by responses th at are robust to such uncertainties. In case of ignorance precautionary pol icies should be guided by the potential seriousness of the threats to susta inability involved. (C) 1999 Elsevier Science B.V. All rights reserved.