From the liberal tree huggers at the DoD:

DoD recognizes the reality of climate change and the significant risk it poses to U.S.
interests globally. The National Security Strategy, issued in February 2015, is clear that climate
change is an urgent and growing threat to our national security, contributing to increased natural
disasters, refugee flows, and conflicts over basic resources such as food and water.1 These
impacts are already occurring, and the scope, scale, and intensity of these impacts are projected
to increase over time.

Persistently recurring conditions such as flooding, drought, and higher
temperatures increase the strain on fragile states and vulnerable populations by
dampening economic activity and burdening public health through loss of agriculture and
electricity production, the change in known infectious disease patterns and the rise of new
ones, and increases in respiratory and cardiovascular diseases. This could result in
increased intra- and inter-state migration, and generate other negative effects on human
security. For example, from 2006-2011, a severe multi-year drought affected Syria and
contributed to massive agriculture failures and population displacements. Large
movements of rural dwellers to city centers coincided with the presence of large numbers
of Iraqi refugees in Syrian cities, effectively overwhelming institutional capacity to
respond constructively to the changing service demands. These kinds of impacts in
regions around the world could necessitate greater DoD involvement in the provision of
humanitarian assistance and other aid.

 More frequent and/or more severe extreme weather events that may require
substantial involvement of DoD units, personnel, and assets in humanitarian assistance
and disaster relief (HA/DR) abroad and in Defense Support of Civil Authorities (DSCA)
at home. Massive flooding in Pakistan in 2010 was the country’s worst in recorded
history, killing more than 2,000 people and affecting 18 million; DoD delivered
humanitarian relief to otherwise inaccessible areas. Super Storm Sandy in New York and
New Jersey in 2012 resulted in over 14,000 DoD personnel mobilized to provide direct
support, and at least an additional 10,000 who supported the operation in various
capacities in the areas of power restoration, fuel resupply, transportation infrastructure
repair, water and meal distribution, temporary housing and sheltering, and debris
removal. The need for HADR and DSCA will likely rise as cities expand to encompass
the majority of the global population and because flood risk threatens more people than any other natural hazard, especially in urban areas.
Many growing cities are located in
low- and middle-income countries with limited resources. Building partner nation
capacity for HA/DR capabilities and civilian-military partnerships for DSCA are
important parts of GCC security cooperation efforts. The Office of U.S. Foreign Disaster
Assistance (OFDA) is responsible for leading and coordinating the U.S. Government’s
response to disasters overseas.

 Sea level rise and temperature changes lead to greater chance of flooding in coastal
communities and increase adverse impacts to navigation safety, damages to port facilities
and cooperative security locations, and displaced populations. Sea level rise may require
more frequent or larger-scale DoD involvement in HADR and DSCA. Measures will
also likely be required to protect military installations, both in the United States and
abroad, and to work with partner nations that support DoD operations and activities. Sea
level rise, increased ocean acidification, and increased ocean warming pose threats to fish
stocks, coral, mangroves, recreation and tourism, and the control of disease affecting the
economies, and ultimately stability, of DoD’s partner nations. Some Pacific island
nations face the risk of being entirely submerged by rising seas, and most island nations’
freshwater supplies will be threatened by saltwater intrusion well before then. Loss of
land, especially highly populated and agriculturally rich coastal land, also poses secondorder
effects on human displacement and economic and food stability, and may further
exacerbate challenges associated with disease vectors.4

 Decreases in Arctic ice cover, type, and thickness will lead to greater access for
tourism, shipping, resource exploration and extraction, and military activities. Land
access—which depends on frozen ground in the Arctic—will diminish as permafrost
thaws. These factors may increase the need for search and rescue (SAR) capabilities,
monitoring of increased shipping and other human activity, and the capability to respond
to crises or contingencies in the region. Difficult and unpredictable weather conditions,
large distances, and scarce resources make emergency response in the Arctic difficult.
Arctic operations are expensive and dangerous for military forces that are unprepared for
the austere operating environment. DoD continues to evaluate the need for specific
Arctic capabilities.