The risks climate change may hold for national security more broadly are connected to the relationships between climate-related stresses on societies and conflict. Direct linkages between climate-related stress and conflict are unclear, but climate variability has been shown to affect conflict through intermediate processes, including resource competition, commodity price shocks, and food insecurity. The potential for conflict increases where there is a history of civil violence, conflict elsewhere in the region, low GDP or economic growth, economic shocks, weak governance, and lack of access to basic needs. For example, droughts around the world in 2010 contributed to a doubling of global wheat prices in 2011 and a tripling of bread prices in Egypt. This and other factors, including national trade policy and poverty, contributed to the civil unrest that ultimately resulted in the 2011 Egyptian revolution. While the 2010 droughts were not the sole cause of the revolution, they contributed to destabilization of an already unstable region. …

Human migration is another potential national security issue. Extreme weather events can in some cases result in population displacement. For example, in 1999 the United States granted Temporary Protected Status to 57,000 Honduran and 2,550 Nicaraguan nationals in response to Hurricane Mitch. In 2013, more than 4 million people were internally displaced by Typhoon Haiyan in the Philippines, and the United States committed 13,400 military personnel to the relief effort. Six months after Typhoon Haiyan, more than 200,000 people remained without adequate shelter. While neither Hurricane Mitch nor Typhoon Haiyan was solely attributable to climate change, tropical cyclones are projected to increase in intensity, which would increase the risk of forced migration. Slower changes, including sea level rise and reduced agricultural productivity related to changes in temperature and precipitation patterns, could also affect migration patterns.