Ever since American security analysts began to consider the impact of global warming on international security, water has been viewed as an especially critical factor. In many parts of the developing world, water supplies are already insufficient to meet societal requirements, and, by shrinking these supplies further, climate change will cause widespread hardship, unrest, and conflict. But exactly what role water plays in this equation has been the subject of considerable reassessment over time. When analysts first examined warming’s impacts, they largely assumed that climate-related water scarcities would most likely provoke conflict within nations; only later did analysts look closely at the possibility of conflicts arising between states, typically in the context of shared river systems. This risk appears particularly acute in South Asia, where several highly-populated countries, including China, India, and Pakistan, rely on river systems which depend for part of their flow on meltwater from the Himalayan glaciers, which are contracting as a result of climate change. In the absence of greater efforts by these countries to address this peril in a collaborative, equitable manner, looming water shortages could combine with other antagonisms to trigger armed conflict, possibly entailing the use of nuclear weapons.
Thermal extremes in regulated river systems under climate change: an application to the southeastern U.S. rivers