The establishment of international environmental institutions is often predicated on the assumption that cooperation is politically feasible and that regime formation is viable. However, the provision of many environmental services remains vulnerable to asymmetries in interests that impede both cooperation and adaptation. We examine governance structures that internalize externalities under asymmetrical conditions aggravated by abrupt and/or significant changes in political circumstances (in this context, the eruption of political violence which, in this article, we refer to as political variability). We analyze the change over time in Israel's strategies for stream and river rehabilitation undertaken as a response to continued runoff of wastewater from Palestinian territories. We find that abrupt political changes that negatively affect relations among the parties undermine the foundations for cooperative solutions. In the Israeli-Palestinian case, Israel has responded by adopting a position of “unilateral environmentalism.” Such a non-cooperative policy was deemed the best possible option for addressing the transboundary pollution problems, in stark contrast to the model of cooperation that underlies most IEAs. Yet, we find that while unilateral environmentalism may safeguard a country's immediate political and environmental interests, it also entails various risks in the medium and long term.

Ambiguity has a clear role in facilitating closure in negotiations to regulate natural resources. However, there are no empirical studies that examine whether such “constructive ambiguity” can in fact become destructive. The aim of the present study is thus to determine when ambiguity becomes destructive during the management phase of environmental regimes. The implementation of the Israeli-Jordanian water agreement is used as a case study. It was found that when political and hydrological conditions are unstable, the parties see the process of clarifying the ambiguities in a water agreement as broader than simply a question of bilateral relations over resource allocation. As a result, the cost of clarifying ambiguity at the implementation phase dramatically increases. The anatomy of resolving ambiguous agreements teaches us that there are early signs that indicate when ambiguity becomes destructive. Tracing these signals is crucial, since the cost of ambiguity is not linear. Rather, when a disagreement around ambiguity passes a threshold, it can escalate into a conflict in a very short time.