Many existing water-sharing treaties should be re-assessed in the context of climate change, write Shlomi Dinar, David Katz, Lucia De Stefano, and Brian Blakespoor in a World Bank working paper.

While “water wars” have historically been incredibly rare, the changes to water systems wrought by climate change may change things. “Environmental changes may aggravate political tensions, especially in regions that are not equipped with an appropriate institutional apparatus,” the authors say.

The working paper analyzes water bodies that cross state borders and the treaties that govern them. Contrary to popular belief, Dinar et al. find that cooperation between states increases as water variability rises, but only to a point. Widespread changes in rainfall amount and predictability may cause increased water stress and/or flooding that affect core national interests and force states to take defensive postures over who controls their water sources. “Once variability increases beyond a certain threshold, cooperative behavior is negatively affected,” write the authors.

Well-defined, yet flexible treaties and strong institutional mechanisms are needed to decrease the likelihood of conflict as societies adjust.

Strong But Flexible Treaties Make a Difference

The authors cite the Jordan, Tigris-Euphrates, and Indus rivers as examples of volatile trans-national waterways. Changes in flow for these rivers will severely test already unstable borders and relationships, they warn. “Whether in the form of heightened political tensions or the more extreme violent exchange, the projected increase in water variability may further complicate existing shared water management strategies.”

Building on existing research, the authors suggest that the presence of strong, clear, and flexible mechanisms for water allocation will impact the capacity of treaties to deal with major changes. Allocative mechanisms, which govern water distribution, particularly benefit from direct, flexible stipulations. “Allocative mechanisms that are either too vague or too rigid do not bode well for sustained cooperation,” they write.

Specific, direct mechanisms “ensure credibility and action,” they say. “Treaties that codify side-payments and issue linkage, direct enforcement measures, and adaptability to water variability provisos may be of particular importance for achieving higher levels of cooperation.”

Due to their scale and unpredictability, climate-induced changes to transboundary water bodies have the potential to test governments in ways that previous changes have not. Yet, treaties can diminish that threat, Dinar et al. conclude, so long as they include proven techniques for conflict mitigation.