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January 06, 2023

The Climate–Security Nexus

By: Mark P. Nevitt
Climate Change

Climate Change

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The climate–security century is here. Our collective understanding of the linkages between climate change, energy security, and national security has grown tremendously in the last decade. See National Intelligence Council, National Intelligence Estimate: Climate Change and International Responses Increasing Challenges to US National Security Through 2040, NIC-NIE-2021-10030-A (Feb. 2022) (National Intelligence Estimate). In fact, the term “climate change” is wholly absent from the 50th Anniversary edition of this Anthology, National Security Law, Fifty Years of Transformation, An Anthology (Jill D. Rhodes ed., 2012). Indeed, climate change’s multifaceted impacts can no longer be dismissed as solely an environmental concern. Climate change has enormous security implications both at home and abroad. This new reality was reinforced in the 2022 National Security Strategy, which references “climate change” 20 times and “climate” over 60 times. National Security Strategy (Oct. 2022).

National-security intelligence experts are now in conversation with climate scientists as they assess security risk around the world. Intelligence professionals are wrestling with massive geopolitical risks if world temperature increase exceeds 1.5 degrees Celsius by 2030 or 2.0 degrees Celsius by 2050—key thresholds that may lead to irreversible and catastrophic harm. National Intelligence Estimate, supra, at 21. Climate attribution scientific advances now showcase that climate change is increasing both the scope, intensity, and frequency of extreme weather events. See generally Michael Burger, et al., The Law and Science of Climate Attribution, 45 Colum. J. Env’t L. 57 (2020). Domestically, sea level rise and extreme weather events threaten military infrastructure, impacting operational readiness and the United States’ capacity to project force abroad. Internationally, climate change aggravates environmental stressors, leading to increased competition for natural resources and violent conflict abroad—a new security reality addressed in a series of U.N. Security Council Resolutions. See S.C. Res. 2349 (Mar. 31, 2017); Int’l Comm. of the Red Cross, Seven Things You Need to Know About Climate Change and Conflict, July 9, 2020 (noting that the connection between climate and security was highlighted in U.N. Security Council Resolution 2349)

The Rise of Climate­–Security Scholarship

Climate–security studies is a wide-ranging scholarly area that cuts across numerous disciplines. It includes science, law, policy, and international relations. See, e.g., Joshua W. Busby, Beyond Internal Conflict: The Emergent Practice of Climate Security, 58 J. Peace Rsch. 186 (2020). In response to our increased understanding of climate change’s security impacts, scholarship across the interdisciplinary spectrum has exploded as scholars examine the implications of the connection between climate change and conflict. Id. Climate change and its impacts are best conceptualized as a nontraditional threat that exacerbates pre-existing environmental stressors and security risks. Climate impacts worsen underlying conditions, leading to increased food insecurity, competition over natural resources, and political instability. See, e.g., Marwa Daoudy, The Origins of the Syrian Conflict: Climate Change and Human Security (2020). A growing chorus of national security leaders, intelligence experts, and military commanders are sounding the alarm that climate change acts as both a “catalyst for conflict” and “threat accelerant.” National Intelligence Estimate, supra, at i (“We assess that climate change will increasingly exacerbate risks to US national security interests as the physical impacts increase and geopolitical tensions mount about how to respond to the challenge.”).

In recent legislation authorizing the Climate Security Advisory Council in 2020, Congress defined climate security as follows:

The term “climate security” means the effects of climate change on the following: (A) The national security of the United States, including national security infrastructure; (B) Subnational, national, and regional political stability; (C) The security of allies and partners of the United States; (D) Ongoing or potential political violence, including unrest, rioting, guerrilla warfare, insurgency, terrorism, rebellion, revolution, civil war, and interstate war.

50 U.S.C. § 3060(f)(1). Applying this definition and conceptualizing climate change as a national security issue encompasses three lenses: climate mitigation, climate adaptation, and climate response. First, climate mitigation includes both reducing greenhouse gas emissions (mitigation) and managing geopolitical risks associated with overreliance on fossil fuels from outside nations (energy security). Second, climate adaptation is defined as the “adjustment in natural or human systems in response to a changing environment­ in a way that effectively uses beneficial opportunities ore reduces negative efforts.” Dep’t of the Army, U.S. Army Climate Strategy 2 (Feb. 2022) (Army Climate Strategy). The classic example is safeguarding military installations from sea level rise or extreme weather events through the investment in climate resilience infrastructure. Finally, climate response includes the military’s role in responding to climate-caused or -exacerbated disasters via defense support to civil authorities or humanitarian assistance. I unpack each of these three lenses—climate mitigation, climate adaptation, and climate response—below.

Climate Mitigation: Reducing Greenhouse Gas Emissions

Climate change has been aptly described as “the mother of all collective action” problems. Megan McArdle, The Mother of All Collective Action Problems, Bloomberg, Jan. 26, 2014. Climate mitigation requires affirmative steps to wean society, including national security agencies, from reliance on fossil fuels. No section of society is untouchable, as the atmosphere is agnostic about the underlying emissions source, whether coal-fired power plants, motor vehicles, or fighter jets. Moreover, emissions continue to rise and the window to avoid climate catastrophe is closing—a point reinforced by the U.N. Environment Programme:

“[T]he international community is falling far short of [its] goals, with no credible pathway to 1.5˚C in place. Only an urgent system-wide transformation can avoid climate disaster.”

U.N. Environment Programme, Emissions Gap Report 2022: The Closing Window — Climate Crisis Calls for Rapid Transformation of Societies (Oct. 27, 2022) (Emissions Gap Report). The world is well off target to reduce its greenhouse gas (GHG) emissions to avert irreversible, catastrophic harm. The GHG “emissions gap” is defined as

[T]the difference between the estimated total global GHG emissions resulting from the full implementation of the [Nationally Determined Contributions], and the total global GHG emission from least-cost scenarios that keep global warming to 2˚C, 1.8˚C or 1.5˚C, with varying levels of likelihood.

Id. at XIX. Each signatory to the Paris Agreement commits to submitting their GHG emissions via a “nationally determined contributions” or NDC process. Paris Agreement, Dec. 12, 2015, T.I.A.S. No. 16-1104. Every nation commits to reducing its emissions over time and self-reporting. Still, it remains unclear just how much is required from each nation and what enforcement mechanisms would be employed if a nation fails to follow through on its Paris commitments. These NDCs represent each individual nation’s target to reduce national emissions with the collective goal of limiting global warming to “well below” 2 degrees Celsius. Id.; Emissions Gap Report, supra, at XIII.

Meanwhile, the world continues to pump more and more emissions into the atmosphere—a reality reinforced in the Sixth Assessment report of the Intergovernmental Panel on Climate Change. Intergov’tal Panel on Climate Change, Sixth Assessment Report, Climate Change 2022: Impacts, Adaptation and Vulnerability (2022). If we fail to meet the Paris Agreement’s goals, this will result in catastrophic harm that may not be able to be reversed. Nations may even be extinguished. See Will Steffen, et. al., Trajectories of the Earth System in the Anthropocene, 115 Perspective 8257 (Aug. 14, 2018) (stating that current targets to reduce GHG emissions are off-track to “achieve the Stabilized Earth pathway … requiring a fundamental reorientation and restructuring of national and international institutions toward more effective governance at the Earth system level”). Furthermore, climate change causes disproportionate harm to the most vulnerable nations and communities, many of whom contribute a miniscule share of overall emissions. For example, Pakistan, which has emitted less than 1% of worldwide GHG emissions, suffered from a massive, climate-exacerbated flooding in September 2022. At one point, one-third of the country was underwater. Mark Nevitt, Climate Justice and Loss and Damage in the Pakistan Flood Crisis, Lawfare, Sept. 2, 2022.

Closer to home, the Department of Defense (DOD) is an enormous consumer of fossil fuels. One study estimated that the U.S. military is the world’s 55th largest GHG emitter when compared against other nations. DOD emits more GHG than many European countries. See Neta C. Crawford, Pentagon Fuel Use, Climate Change, and the Costs of War, Costs of War (Nov. 13, 2019). As the United States works to reduce its national GHG emissions and follow through on its Paris Agreement commitments, there is no automatic opt-out for military emissions. Therefore, each nation must take into account all of its emissions sources, and the United States cannot ignore DOD contributions to aggregate U.S. GHG emissions. In 2021, the DOD issued a Climate Adaptation Plan, and each service detailed its own Climate Action Plan with the goal of achieving net-zero emissions by 2050. See, e.g., Emma Newburger, U.S. Navy Climate Plan Calls to Curb Emissions, Electrify Vehicle Fleet, CNBC, May 24, 2022.

Energy Security and Geopolitical Tensions

China is, by far, the world’s largest GHG emitter on an annual basis today. It accounts for over 30% of worldwide emissions. (The United States is the second largest emitter on an annualized basis and the largest historic emitter.) Statista, Distribution of Carbon Dioxide Emissions Worldwide in 2021, By Select Country. While emissions from Europe and the United States are falling, China’s emissions—as well as GHG emissions from India and many developing nations—continue to rise. The United States and China already have a fraught relationship on a host of issues: trade, intellectual property theft, and South China Sea claims. Add climate change to this fraught geopolitical cocktail. Climate change, its impacts, and the need to rapidly transition away from carbon sources further stress the U.S.-Chinese relationship. China and India’s reliance on coal and other fossil fuels was highlighted at the UN Climate Change Conference UK 2021 in Glasgow, Scotland when India argued that parties should phase–down coal power and fossil fuel subsidies. Mark Nevitt, Key Takeaways from the Glasgow Climate Pact, Lawfare (Nov. 17, 2021). The initial draft of the text used the term “phase–out.” China and India insisted that the language be softened to “phase–down.” Id.

Tragically, our collective failure to close the emissions gap sets the stage for massive global destabilization. Complicating matters, several “petrostate” economies’ (e.g., Russia and most of the nations in the Middle East) are overly reliant on fossil fuel extraction. Not surprisingly, these petrostates are poised to fight broader decarbonization efforts—a point reinforced in recent intelligence reports. See National Intelligence Estimate, supra, at 7.

Many petrostates view these decarbonization efforts as a threat to their economic well-being. The National Intelligence Estimate defines petrostates as nations that rely on the production and export of fossil fuels for greater than 50% of their economies, identifies twenty such nations, and makes the point:

[M]ost countries that rely on fossil fuel exports to support their budgets will continue to resist a quick transition to a zero–carbon world because they fear the economic, political, and geopolitical costs of doing so.

Id. Because the global economy depends so heavily on fossil fuels, petrostates wield disproportionate political and economic influence. And many petrostates, such as Russia, have authoritarian regimes that thumb their nose at the international community. Russia in particular has resisted measures to reduce GHG emissions because of its economic dependence on fossil fuels. Id. Meanwhile, nations that rely on fossil fuels from petrostates are exposing their own economies to further energy-security risk. While the international community can and must continue to transition away from fossil fuels, it must recognize that the consequences to petrostates’ economies exacerbate geopolitical stability. Id.

Consider the role fossil fuels play in the ongoing Russia–Ukraine conflict. Germany and much of Europe rely on Russia for oil and gas. A project for a pipeline from Russia to Germany was abruptly halted in response to the February 2022 Russian invasion of Ukraine, forcing Germany to devise immediate and longer-term alternatives. See Putin’s War and European Energy Security: A German Perspective on Decoupling From Russian Fossil Fuels: Testimony Before U.S. Comm’n on Sec. & Coop. in Eur. (June 7, 2022) (testimony of Constanze Stelzenmüller).

Military operations on the battlefield offer another example where the military’s outsized fossil-fuel dependence is felt. General James Mattis, then commander of the 1st Marine Division, once exclaimed that the U.S. military in Afghanistan must be “unleashed from the tether of fuel.” Greg Douquet, ”Unleash Us from the Tether of Fuel”, Atlantic Council (Jan. 11, 2017). The U.S. military is actively engaged in solving challenges associated with “operational energy,” or “the energy required for training, moving, and sustaining military forces and weapons platforms for military operations.” Off. of Assistant Sec’y of Def. for Sustainment, Operational Energy. The need to make progress on operational energy was highlighted in the 2022 Army Climate Strategy, which set the objective to “significantly reduce operational energy and water use by 2035.” Army Climate Strategy, supra, at 13.

Climate Adaptation: Investing in Climate Resilient Infrastructure

Climate adaptation focuses on safeguarding national security infrastructure, particularly at military bases. Consider the climate challenges facing Norfolk Naval Station, home to the largest naval base in the world. It is also uniquely vulnerable to climate impacts; the seas are rising and the soil is sinking, exposing the base to debilitating climate impacts. See Jeff Goodell, The Pentagon & Climate Change: How Deniers Put National Security at Risk, Rolling Stone, Feb. 12, 2015. In response to climate vulnerabilities facing bases like Norfolk, military leaders and national security policymakers have focused attention on adaptation measures for military installations vulnerable to climate impacts. This includes sea level rise, flooding, extreme heat, and drought. See U.S. Gov’t Accountability Off., Budget Issues: Opportunities to Reduce Federal Fiscal Exposure Through Greater Resilience to Climate Change and Extreme Weather, GAO-14-504T, 4 (July 29, 2014) (noting that the DOD “manages a global real–estate portfolio that includes over 555,000 facilities and 28 million acres of land with a replacement value of close to $850 billion.”). Climate’s role in exacerbating extreme weather events is of particular concern. In 2018, Hurricane Michael devastated Tyndall Air Force Base and the surrounding community. The recovery and rebuilding continued beyond 2019 and into 2022. See Staff Sgt. Magen M. Reeves, Tyndall AFB Continues Rebuild Effort One Year After Hurricane Michael, Oct. 10, 2019; Airman 1st Class Tiffany Price, Surviving Hurricane Michael in Building 909, Mar. 9, 2022.

In the past decade, the DOD has issued several reports on climate adaptation, and Congress has passed legislation with provisions addressing climate adaptation on military installations. For example, in 2014, the DOD released a Climate Change Adaptation Roadmap, focused on “actions and planning … to increase its resilience to the impacts of climate change.” Release, U.S. Dep’t of Def., DoD Releases 2014 Climate Change Adaptation Roadmap (Oct. 13, 2014). The 2018 defense spending bill required the DOD to provide a report ranking the military installations most vulnerable to climate change. National Defense Authorization Act of 2018, Pub. L. No. 115–91, § 335, 131 Stat. 1283, 1357 (2017). See Jordan Brunner, Congress Adapts to Calamity: The FY 2018 NDAA’s Climate Change Provisions, Lawfare, Dec. 11, 2017. While this reporting provision was a small step, it was a step forward in the U.S. military’s climate adaptation efforts.

Climate Response: Reacting to Climate Disasters at Home and Abroad

Climate response is the third climate-security lens. It addresses how nations’ militaries respond to an increase in humanitarian assistance missions due to climate-exacerbated disasters at home and abroad. Climate response includes both international and domestic elements. Climate change disproportionately affects low-income countries, which lack the resources to respond to and adapt to crisis—a point reinforced by the National Intelligence Estimate. National Intelligence Estimate, supra, at 21 (“Scientific forecasts indicate that intensifying physical effects of climate change out to 2040 and beyond will be most acutely felt in low–income countries, which we assess are also the least able to adapt to such changes.”). The Estimate further notes that geopolitical conflict will escalate as there is a growing risk of conflict over water and migration. Id. at 7. Within the United States, President Joe Biden’s executive order on resettling refugees represents a maturation in the national understanding that human migration is inextricably linked to climate change. Exec. Order No. 14,013, 86 Fed. Reg. 8839 (Feb. 4, 2021).

The U.N. Security Council was begun to address climate security in earnest, although Russia, a permanent member of the Council, has pushed back on the Council’s attempts to declare climate change a “threat to the peace” under Article 39. See, e.g., Mark Nevitt, Is It Time to “Climatize” the UN Security Council?, Ctr. For Climate & Sec., Dec. 17, 2021. Since 2007, the Security Council has sponsored four Climate Security open forums and several more informal “Arria–formula” climate meetings. See, e.g., Security Council Report, Energy, Climate and Natural Resources. In 2017, the Security Council took the historic step of referencing climate change as having a destabilizing impact within a Security Council Resolution. In addressing the deteriorating security situation in Africa’s Lake Chad Basin, the Security Council highlighted that the “adverse effects of climate change and ecological change” played a role in destabilizing the security situation in the region. S.C. Res. 2349, ¶ 26 (Oct. 14, 2017).

Under the U.N. Charter, Chapter V, Article 27, June 26, 1945, any Security Council Resolution requires “an affirmative vote of nine members including the concurring votes of the permanent members”: Russia plus the United States, France, China, and the United Kingdom. In December 2021, Ireland and Niger introduced a Security Council resolution that would have defined climate change as a “threat to peace” within Article 39 of the U.N. Charter. Id. See Nevitt, Is it Time to “Climatize” the UN Security Council?, supra. Declaring climate change a “threat to peace” would have served as a powerful signal of climate change’s importance as a security issue from the institution entrusted with the maintenance of international peace and security. It also would have opened the door for the Security Council to activate legal authorities and tackle the climate crisis. Russia vetoed the resolution. With the ongoing Russia–Ukraine conflict, it is highly unlikely that the Security Council will take up any similar measure in the foreseeable future.

Meanwhile, climate change is re-shaping the Arctic as an operational environment with geopolitical and security implications. As climate change warms the Arctic, it creates opportunities and risks, particularly for the region’s militaries. The Northern Sea Route that hugs the Russian coastline is of particular concern, with Russia asserting that international transit passage rights do not apply. For further discussion of the Arctic and national security, see Stanley Fields & Kevin Lunday, The Arctic: Shrinking Ice, Growing Importance, An Anthology: 60 Years of Transformation, Dec. 5, 2022.

The Next Decade: Climate Challenges Ahead

In the last ten years, the U.S. executive branch has shown an increased interest in climate–security matters. President Barack Obama’s 2015 National Security Strategy, for example, mentioned climate change nineteen times and stated:

Climate change is an urgent and growing threat to our national security, contributing to increased natural disasters, refugee flows, and conflicts over basic resources like food and water. The present–day effects of climate change are being felt from the Arctic to the Midwest. Increased sea levels and storm surges threaten coastal regions, infrastructure, and property. In turn, the global economy suffers, compounding the growing costs of preparing and restoring infrastructure.

National Security Strategy 12 (Feb. 2015). Although President Donald Trump did not address climate change in his national security strategy, that was an aberration. Indeed, his was the first National Security Strategy since 1991 to omit the word “climate” altogether. President Biden’s Interim National Security Strategy highlighted the existential nature of the climate challenge, stating that our collective failure to act on climate now will have “dire consequences for the health of our people, our economy, our security, and our planet.” Interim National Security Strategic Guidance 12 (Mar. 2021).

President Biden’s executive order, Tackling the Climate Crisis at Home and Abroad, placed climate change squarely on the national security agenda and elevated the roles that senior personnel play in tackling the climate crisis. Exec. Order 14,008, 86 Fed. Reg. 7619 (Jan. 27, 2021). Former Environmental Protection Agency Administrator Gina McCarthy and former Secretary of State John Kerry were named to senior positions in the Biden Administration. Coral Davenport & Lisa Friedman, Biden’s Twin Climate Chiefs, McCarthy and Kerry, Face a Monumental Task, N.Y. Times, Dec. 21, 2020. Mr. Kerry’s role as global climate envoy also included a seat on the National Security Council—a historic first. Id. Following the executive order, the DOD, Office of the Director of National Intelligence, Department of Homeland Security, and National Security Council each released reports on climate change’s national security impacts. See, e.g., National Intelligence Estimate, supra. The Army released its climate strategy, Army Climate Strategy, supra, which was followed by plans from the Navy and Air Force. See John Conger, And Air Force Makes Three … Comparing the U.S. Army, Navy and Air Force Climate Plans, Center for Climate & Security, Oct. 5, 2022.

As the GHG emissions gap continues to grow, climate change will have greater impacts that will be felt throughout the world. Political leaders may come under increased pressure to use all legal tools at their disposal to tackle the climate crisis. In the summer of 2022, there were reports that President Biden was considering declaring climate change a national emergency and use the powers granted in the National Emergencies Act, 50 U.S.C. §§ 1601, 1621, 1622 (NEA). In the NEA, Congress grants the president wide discretion to determine what constitutes an emergency under the statutory scheme.

Declaring a climate emergency could operationalize the International Emergency Economic Powers Act, Pub. L. No. 95-223, 91 Stat. 1625 (1977) (IEEPA), which is the emergency authority most often used by the executive branch and one that could be employed to address the climate crisis. In 2020, President Trump relied on the IEEPA and declared that “the unrestricted foreign supply of bulk–power system electric equipment constitutes an unusual and extraordinary threat to the national security, foreign policy, and economy of the United States.” Exec. Order No. 13,920, 85 Fed. Reg. 26,595 (May 1, 2020). But see Dep’t of Energy, Off. of Cybersec., Energy Sec., and Emergency Response, Securing the United States Bulk-Power System Executive Order (Apr. 20, 2021). And in 2022, President Biden used his emergency authority under the IEEPA to ban the importation of Russian oil and gas into the United States following Russia’s invasion of Ukraine. See Fact Sheet, The White House, United States Bans Imports of Russian Oil, Liquefied Natural Gas, and Coal (Mar. 8, 2022). The IEEPA could potentially be used to address issues with climate consequences, such as the importation of products from the Amazon rain forest or products that damage the environment, e.g., nitrous oxide. Mark Nevitt, Is Climate Change a National Emergency? 55 U.C. Davis L. Rev. 591 (Dec. 2021).

What does the next decade portend for climate–security challenges? Climate impacts will be dictated by our global progress on closing the emissions gap, with 2030 being a key year to assess our work. Climate change is shifting the geopolitical landscape and “transforming the context” of national security. U.S. Dep’t of Def., Fact Sheet: 2022 National Defense Strategy (2022). The extent of this shift will be determined by the world’s collective ability to reduce our GHG emissions and adapt to a climate-destabilized future. Indeed, how the United States responds to the climate crisis will increasingly define our national security posture this century and truly demonstrate the undeniable nexus between climate and security.

Mark P. Nevitt

Associate Professor of Law at Emory University School

Mark Nevitt is an Associate Professor of Law at Emory University School of Law in Atlanta, Georgia. He served for twenty years as both a tactical jet aviator and attorney (judge advocate) in the U.S. Navy, retiring in the rank of commander in 2017. He received his J.D. and LL.M. (with distinction) from the Georgetown University Law Center and B.S.E. from the Wharton School, University of Pennsylvania. 

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The material in all ABA publications is copyrighted and may be reprinted by permission only. Request reprint permission here.