As the authors noted, “global climate change may cause fundamental changes in the hydrological cycle and be more severe and occur more quickly than anticipated.” They argue that the sooner the lands affected adjust their institutions and agreements, the less likely climate change will ignite a new round of water wars. There are a few hundred agreements governing water control and allocation in many of the 263 river basins that lie on either side of national boundaries. Under the surface, 269 aquifers also cross national boundaries, although there are far fewer agreements involving these fresh water reserves, where water use is often unmonitored.

The study is in large part a review and reanalysis of the existing work in this area,  and focuses on the inflexibility of existing treaties, many of which allocate water among the nations on a river’s banks but few — if any — of which account for the possibility of a river’s flow diminishing over all or at crucial times of year. Likewise, most treaties ignore the possibility of the intense floods that are expected to increase as the climate warms. Although the authors recommend that treaties or other agreements “should address how riparian states will adapt to altered timing and availability of flows,” the prospects for that kind of adjustment are poor.

Why? Simply addressing who gets what water from a river is difficult enough even when average flows are predictable. Dimensions of aquifers are hard to define and even harder to adjudicate.

Or, as the study said, “Few treaties, however, address water allocation, perhaps due to its intensely political nature. Among those that do, about a quarter require equal allocations and the rest assign specific amounts” to the lands on either bank.

One suggestion the authors offer is reworking the existing treaties and institutions. Another is setting up a transnational authority to mediate the inevitable disputes prompted by the climate-driven changes in the water cycle. “The ideal institution would have a broad scope, include all riparian nations, and have management and enforcement authority. Yet, the creation of such a supra-national authority can be perceived as a threat to more politically powerful nations for fear of losing power.”

Most of all, the study recommends that more and better treaties be produced, in part to deal with issues of water quality that could arise in, say, a delta region where sea-level rise could turn once-fresh water brackish. “A number of important elements, especially water quality and flood management, are commonly excluded” from water agreements, the study said. All that should be fixed, the authors maintain.