U.S. Environmental Protection Agency


Date of this Version



Published in Social-Ecological Resilience and Law, ed. Ahjond S. Garmestani and Craig R. Allen (New York: Columbia University Press, 2014).


U.S. government work.


Of all the expected impacts of climate change, the most significant is likely to be the change in the availability of freshwater associated with changing precipitation. The most recent Intergovernmental Panel on Climate Change (IPCC) report notes that all regions of the world are expected to experience a net negative impact on water resources and freshwater ecosystems. The impact is likely to be highly variable, with some regions experiencing declining runoff and others experiencing increasing runoff. Many areas are projected to experience increased variability in precipitation and hence. in water supply, water quality, and flood risks (IPCC 2007). Individual countries are already developing strategies to adapt to or to mitigate the consequences of changes in water availability, including the adoption of water conservation measures and water conservation and adaptive management practices, together with the development of novel institutions-including water markets. Internationally, however, there are fewer options. Transboundary water resources are typically governed by international treaties and by the mechanisms established under those treaties (e.g., transboundary water commissions).