Implementing a Precautionary Principle can mean different things to different people. Policy analysts may believe that finding a quantitative approach to the Principle would remove ambiguity over fundamental issues. We demonstrate that one approach to quantifying the Precautionary Principle does not necessarily solve what we call the ‘continuation framing problem’. That problem is based in the competing perspectives of stakeholders when they view their own activity as the status quo and a change in that activity as causing irreversible costs. Even a shared analytic framework, here that of real options analysis, does not remove the need for political decisions about property rights in differing uses of the atmosphere.

The notion of residual obligations can be used as a tool to overcome, at least in part, the conflict between the individual's prima facie right not to be exposed to involuntary risks, and the rights of industries and other large organisations to carry out activities that are associated with risks. A typology of residual obligations is developed, and it is applied in a discussion of the moral obligations of those who impose risks on others. The major types are obligations to compensate, to communicate, to improve, to search for knowledge, and to have an appropriate attitude. It is argued that conscientious compliance with risk-related residual obligations is an essential component of what makes it morally acceptable to expose others to risk.

Recent droughts in Spain have triggered interest in behavioural responses to drought risk due to climate change. This paper models the sharing of irrigation water from a joint reservoir as a game between farmers, since farmers' demand comprises the major share of water demands. Empirical data from a dynamic recursive mathematical programming model for three case studies are used to test the hypothesis that the present institutional structure provides farmers proper incentives to minimise their water requirement for irrigation.

The analysis with both an estimated static game and an empirically calibrated repeated game shows that most farmers are unlikely to conserve water used for irrigation purposes. In the case where climate change induces a higher drought risk, incentives emerge for farmers to become conservative in their demand for irrigation water, provided that proper institutional arrangements emerge which protect the share of the water saved by farmers for future use.

A Simplified Conjoint Expected Risk (SCER: Holtgrave and Weber, 1993) model-based approach was used to explore differences in the perceived risk of a variety of financial and health activities among Caucasians, African-Americans, Mexican-Americans, and Taiwanese-Americans. The SCER model postulates that the perceived risk of an activity is a function of five dimensions: the subjective probability of harm, benefit, and status quo, and the subjective expected harm and benefit. This model offers a framework in which to apply qualitative and quantitative approaches in order to identify and to assess the generality of ethnic group differences in the relative weight attached to probability and expected outcome information, the subjective valuation of probabilities and expected outcomes, and the perceived harms and benefits. Results demonstrated that the primary and most generalised locus of ethnic group perceived risk differences is the relative importance attached to probability and expected outcome information. As predicted, these differences tended to mirror ethnic group differences in orientation toward uncertainty. By decomposing differences in terms of the elements of the SCER model, these results demonstrate that risk communication and policy efforts in ethnically diverse countries should recognise the role of the relative weight attached to the likelihood and magnitude of harm and benefit in risk perception. Clarifying the bases for differences in perceived risk among ethnic groups may provide a better understanding of conflict over environmental or other issues and aid in the development of effective strategies for communicating about risk and negotiating solutions to important policy problems.