On October 13th, The Intercept posted a chilling video obtained from the Pentagon via the Freedom of Information Act. Shown in training courses at Joint Special Operations University, the short film portrays the world’s cities of 2030 as sprawling labyrinths that are crumbling due to overpopulation and economic inequality, exacerbated by the compounding forces of global climate change. “This is the world of our future,” the video’s narrator states. “It is one we are not prepared to operate effectively in. And it is unavoidable.” [1, 2]
Though the video has been chided by some as overly bearish and sensational, its existence signals that senior leaders in the Department of Defense and US Armed Forces are coming to realize — even as politicians remain divided on the issue — that climate change presents an absolute and inalienable risk that must be taken seriously [3, 4].
Connecting the dots
As early as 2003, the Pentagon Office of Net Assessments began exploring the potential need for a contingency plan addressing an abrupt global climate change scenario. CalTech’s Jet Propulsion Laboratory at Pasadena responded with a 23-page report arguing that the risk should be elevated “beyond a scientific debate to a U.S. national security concern.” Authors Peter Schwartz and Doug Randall found continued warming could result in a rapid fall in the planet’s human carrying capacity, setting the conditions for mass competition, an upheaval of the global political order, and the ensuing outbreak of widespread conflict .
Even if such an extreme scenario might be avoided, scientists have found strong causal evidence linking the myriad adverse effects of climate change to rising levels instability and violence across geographies. One recent study found that the frequency of intergroup conflict rises 14% for each standard deviation (1σ) change in temperature — a disturbing conclusion, as scientific consensus projects warming of 2σ to 4σ over the next 30 years [6, 7].
A changing climate is not just likely to drive higher demand for the forceful resolution of conflict, but will also complicate the military’s operational procedures and threaten its worldwide network of assets. Special operations forces and other combat arms units will have to spend more time training for defense support to civil authorities (DSCA) missions and noncombatant evacuation operations (NEOs), while simultaneously maintaining proficiency across their traditional mission profiles. National Guard units must also prepare to provide competent disaster relief and civil support services despite limited budgets and training resources.
At the same time, climate change puts countless US military installations at risk, including bases within America as well as 800-plus others around the globe. The financial value of simply maintaining these facilities under current conditions weighs in at over $85 billion per year . The majority of these bases and ports are coastal installations that are predictably vulnerable to rising sea levels. The costs of retaining the American military empire as it currently exists could grow astronomically in the coming years, complicating US efforts to project military power around the globe.
Finally, the potential impact on the military’s acquisition and supply chain requirements is obvious. Economic and resource disruptions will not only create difficulties for the production of additional military equipment in a time of need, but would also limit the ability of all services to fuel and power their vehicles, ships, planes, and bases.
The way forward
Fortunately, various departments within the US Government have at last come to focus on this emerging threat. In December 2012, the Department of Defense established a Climate Change Adaptation Working Group (CCAWG) in response to Executive Orders 13514 and 13653 . In 2014 the DoD published a comprehensive set of reports and policy letters, including the Climate Change Adaptation Roadmap and the 2014 Quadrennial Defense Review [10, 11].
Department Secretaries, the Joint Chiefs, and Combatant Commanders must now execute on the first official directive from the Pentagon . The greatest danger is that slow planning cycles will delay the start of implementation processes requiring years of aggressive and sustained effort. Planners should modify their long-term forecasts now to account for a global order and physical landscape that may severely restrict the military’s current freedom of maneuver and economic access. To reduce the risk of systemic shock, models should prioritize diversity in equipment and power sources, as well as modularity in the design of facility and infrastructure networks. Early efforts to draw more energy from sustainable sources must receive greater attention from top brass, as current over-reliance on non-renewable sources exposes the military services to heightened risk . Most importantly, field-grade officers throughout the services should be encouraged to act on their own bottom-up analysis.
A changing climate presents looming challenges to global stability and US national security in the years ahead. If it takes bold action now, the military can ensure it is ready to face our world of tomorrow.
 Joint Special Operations University (JSOU) offers numerous courses ranging from days to months for US and international military students. Most classes are intended to train officers and non-commissioned officers to work in staff assignments within US Special Operations Command (SOCOM). JSOU’s public website can be accessed at [https://jsou.socom.mil/Pages/Default.aspx].
 Nick Turse, “Pentagon video warns of ‘unavoidable’ dystopian future for the world’s biggest cities,” The Intercept, 13 Oct 2016. Online: accessed Nov 2016 at [http://theintercept.com/2016/10/13/pentagon-video-warns-of-unavoidable-dystopian-future-for-worlds-biggest-cities/].
 Annalee Newitz, “Bizarre leaked Pentagon video is a science fiction story about the future of cities,” Ars Technica, 28 Oct 2016. Online: accessed Nov 2016 at [http://arstechnica.com/tech-policy/2016/10/bizarre-leaked-pentagon-video-is-a-science-fiction-story-about-the-future-of-cities/].
 Even Lehmann, “Republic platform rejects Paris Climate Agreement,” Scientific American, 19 July 2016. Online: accessed Nov 2016 at [https://www.scientificamerican.com/article/republican-platform-rejects-paris-climate-agreement/].
 Peter Schwartz and Doug Randall, “An Abrupt Climate Change Scenario and its Implications for United States National Security,” Pentagon Office of Net Assessments, October 2003. Online: accessed Nov 2016 at [http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA469325].
 The range of 2-to-4 standard deviations includes projections for nearly all regions and locations in the world; specific locations are expected to land within different parts of the band.
 Salomon Hsiang, Marshall Burke, and Edward Miguel, “Quantifying the Influence of Climate on Human Conflict,” Science, Vol. 341 Iss. 6151, 13 Sep 2013. Online: accessed Nov 2016 at [http://science.sciencemag.org/content/341/6151/1235367].
 David Vine, “Where in the world is the US military?” Politico, August 2015. Online: accessed Nov 2016 at [http://www.politico.com/magazine/story/2015/06/us-military-bases-around-the-world-119321].
 Executive Orders [EOs] are legally binding orders issued by the President to Federal Administrative Agencies. EO 13514 and 13653 dictated that each Department and Agency evaluate the impact of climate change on their mission and operations, and begin developing a plan of action to confront all identified challenges.
 “2014 Climate Change Adaptation Roadmap,” US Department of Defense, FY 2014. Online: accessed Nov 2016 at [http://ppec.asme.org/wp-content/uploads/2014/10/CCARprint.pdf].
 “2014 Quadrennial Defense Review,” US Department of Defense, FY 2014. Online: accessed Nov 2016 at [http://archive.defense.gov/pubs/2014_Quadrennial_Defense_Review.pdf].
 DoD Directive 4715.21, “Climate Change Adaptation and Resilience,” effective 14 Jan 2016. Online: accessed Nov 2016 at [http://www.defense.gov/Portals/1/Documents/pubs/471521p.pdf].
 Camille von Kaenel, “Energy security drives U.S. military to renewables,” Scientific American, 16 Mar 2016. Online: accessed Nov 2016 at [https://www.scientificamerican.com/article/energy-security-drives-u-s-military-to-renewables/].
“The National Security Implications of a Changing Climate,” The White House of the United States, May 2015. Online: accessed Nov 2016 at [https://www.whitehouse.gov/sites/default/files/docs/National_Security_Implications_of_Changing_Climate_Final_051915.pdf].
Marshall Burke, Solomon Hsiang, and Edward Miguel, “Climate and Conflict,” Annual Review of Economics, Vol. 7: 577-617, Aug 2015. Online: accessed Nov 2016 at [http://www.annualreviews.org/doi/10.1146/annurev-economics-080614-115430].
Herbert Carmen, Christine Parthemore, and Will Rogers, “Broadening Horizons: Climate Change and the U.S. Armed Forces,” Center for a New American Security, April 2010. Online: accessed Nov 2016 at [https://s3.amazonaws.com/files.cnas.org/documents/CNAS_Broadening-Horizons_Carmen-Parthemore-Rogers.pdf].