failure would create increasing opportunities for extremism or terrorism. Again, sub-Saharan Africa is often cited as the most vulnerable region.
In addition to these specific scenarios, many of the reports foresee increasingly frequent and increasingly severe natural disasters that will strain the capacity to cope with the resulting humanitarian emergencies, both in the United States and overseas (Busby, 2007; Center for Naval Analysis, 2007; Center for Climate and Energy Solutions, 2009). This is of particular concern to the U.S. military, given its expanding role in disaster assistance, although several of the reports note that helping countries prepare for and cope with disasters offers important opportunities for positive engagement.
These climate–security analyses raise concerns about several security issues beyond those of inadequate adaptation leading to humanitarian disasters, political instability, or violent conflict. One class of scenarios involves direct threats of climate change to the ability of the U.S. military to conduct its missions. An example is the threat that sea level rise, possibly in combination with more intense coastal storms, poses to naval bases in low-lying coastal areas (Busby, 2007; Center for Naval Analysis, 2007; Center for Climate and Energy Solutions, 2009; U.S. Department of Defense, 2010).2 More generally, analyses foresee climate change having broad negative effects on military organization, training, and operations—for example, by exacerbating operational difficulties for troops and equipment in already difficult locations (Busby, 2007; Center for Naval Analysis, 2007; Center for Climate and Energy Solutions, 2009; Carmen et al., 2010; U.S. Department of Defense, 2010; National Research Council, 2011b). Other concerns include the vulnerability of U.S. Department of Defense (DOD) fuel supplies to severe weather that disrupts supply lines and the possibility of droughts restricting access to water for forces and facilities overseas.
Perhaps the most frequently cited security risk from climate change is the possibility of melting Arctic sea ice leading to increased international tensions over newly accessible sea routes and natural resources in the Arctic (Busby, 2007; Center for Naval Analysis, 2007; Carmen et al., 2010). A recent NRC study (National Research Council, 2011b), addresses these and other security issues of interest to the U.S. naval forces.
It is now clear from an accumulation of scientific evidence that the risks of potentially disruptive climate events are increasing. The scientific evidence on this point is aptly summarized in this conclusion from a recent major review of the science by the NRC: “Climate change is occurring, is
2 For examples of the severe damage suffered by U.S. bases in the past from hurricanes, see Busby (2007:6).