Stephen Faris in Foreign Policy:
Until now, the two sides had been able to relegate the water issue to the back burner. In 1960, India and Pakistan agreed to divide the six tributaries that form the Indus River. India claimed the three eastern branches, which flow through Punjab. The water in the other three, which pass through Jammu and Kashmir, became Pakistan's. The countries set a cap on how much land Kashmir could irrigate and agreed to strict regulations on how and where water could be stored. The resulting Indus Waters Treaty has survived three wars and nearly 50 years. It's often cited as an example of how resource scarcity can lead to cooperation rather than conflict.
But the treaty's success depends on the maintenance of a status quo that will be disrupted as the world warms. Traditionally, Kashmir's waters have been naturally regulated by the glaciers in the Himalayas. Precipitation freezes during the coldest months and then melts during the agricultural season. But if global warming continues at its current rate, the Intergovernmental Panel on Climate Change estimates, the glaciers could be mostly gone from the mountains by 2035. Water that once flowed for the planting will flush away in winter floods.