The notion of intertemporal h-option value is introduced to extend to environmental decision-making problems of the concept of quasi-option value, defined by Arrow and Fisher and Henry, whenever an individual faces imprecise information, or hard uncertainty, represented by a non-additive measure over events. Under hard uncertainty and irreversibility, the decision-maker faces the intertemporal h-option value, that is an uncertainty premium of preservation, which represents the gain from being able to learn about the future consequences of irreversible actions. The intertemporal h-option value is a correction factor that has to be taken into account in evaluating the total economic value of feasible actions.