parties) or outside it (insurgent, separatist, or revolutionary movements) that are capable of leading, organizing, and engaging in or increasing already existing anti-government or anti-regime violence.

The scenarios in which climate events are most likely to lead to risks to U.S. national security are in countries of security concern that have a significant likelihood of exposure to particular climate events combined with susceptible populations and life-supporting systems, weak response capacity, and underlying sources of potential political instability. Pakistan offers a case that illustrates these points particularly well, as described below. Another potential case, Egypt, is presented in Box 5-2.

BOX 5-2
Egypt

Of the many places in the world where climate dynamics might induce globally consequential disruption within a decade, Egypt is a principal possibility. Egypt’s population of some 80 million people consumes 18 million tons of wheat annually as a dietary staple, half of which is imported, with virtually all the rest dependent on water from the Nile River. The Nile flows through Sudan and Ethiopia before entering Egypt and accumulates nearly all of its volume upstream. The production of wheat and other food crops supported by the river is being burdened by population increases in all three countries. The countries’ current combined total of 208 million people is projected to reach 272 million by 2025, presumably generating an increase in agricultural production demand on the order of 30 percent or more within the watershed. In addition South Korea and Saudi Arabia have purchased large tracts of land in the watershed to assure imports for their own populations, and that will also add to the demand for water (Brown, 2011).

At the moment there is no broadly agreed projection of water flow in the Nile over the next decade and hence no widely accepted basis for estimating the risk of climate-induced disruption. There are historical reasons for acknowledging the possibility, however. In particular, between 1961 and 1964 there was a sharp increase in annual rainfall over Lake Victoria, adding a substantial amount of water to the White Nile branch of the watershed. Annual rainfall over the lake has receded in the intervening years, but it has not yet returned to the levels that generally prevailed from the time that annual records were initiated in 1869 up until 1961 (Sutcliffe, 2009). If that were to occur on a sustained basis, the three countries primarily affected would encounter very serious water management problems with no agreement in place to organize their respective responses. Their populations would encounter a threat to their food supply that no allocational arrangement would likely remove. In the past the existence of the Aswan Dam has buffered Egypt against fluctuations in river flow, but the continued increases in water demand, plus the potential loss of flow noted in the second paragraph, increase the potential that such buffering will be insufficient in the future.



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