Summary: For more than half a century, U.S.intelligence and defense communities have worked to understand the threats to national and international security from a range of environmental factors,
including pollution, population, water and energy resources, and the accelerating impacts of climate change. These assessments include both the risk that these factors will increase the potential for violence, conflict, and war, and the impacts of these issues for U.S. military forces and infrastructure. The public documents listed below comprise the unclassified reports available, which highlight ever-increasing levels of concern about these threats, with the recent exception of the administrations of President Donald Trump, who has explicitly demanded that the defense and intelligence communities delete past research,
censor specific words or concepts, cancel research and analysis efforts to identify these threats, and defund programs to prepare forces and infrastructure for environmental threats. Almost all of the past a assessments have, however, been archived by different organizations, and links to these resources are provided where possible.
January 2018: U.S. Department of Defense. Climate-Related Risk to DoD Infrastructure Initial Vulnerability Assessment Survey (SLVAS) Report. Office of the Under Secretary of Defense for Acquisition, Technology, and Logistics, as required by Senate Report 114-237 in S. 2806.
“The Department of Defense (DoD) has significant experience in planning for and managing risk and uncertainty. The effects of climate and extreme weather represent additional risks to incorporate into the Department’s various planning and risk management processes. Various studies have identified a broad range of effects that could impact our ability to fully execute the Defense mission of protecting and maintaining the security interests of the United States at home and around the world.”
February 13, 2018: Office of the Director of National Intelligence. Statement for the Record: Worldwide Threat Assessment of the U.S. Intelligence Community to the Senate Select Committee on Intelligence.
“Challenges from urbanization and migration will persist, while the effects of air pollution, inadequate water, and climate change on human health and livelihood will become more noticeable. Domestic policy responses to such issues will become more difficult—especially for democracies—as publics become less trusting of authoritative information sources.”
“The impacts of the long-term trends toward a warming climate, more air pollution, biodiversity loss, and water scarcity are likely to fuel economic and social discontent—and possibly upheaval—through 2018.
The past 115 years have been the warmest period in the history of modern civilization, and the past few years have been the warmest years on record. Extreme weather events in a warmer world have the potential for greater impacts and can compound with other drivers to raise the risk of humanitarian disasters, conflict, water and food shortages, population migration, labor shortfalls, price shocks, and power outages. Research has not identified indicators of tipping points in climate-linked earth systems, suggesting a possibility of abrupt climate change.
Worsening air pollution from forest burning, agricultural waste incineration, urbanization, and rapid industrialization—with increasing public awareness—might drive protests against authorities, such as those recently in China, India, and Iran.
Accelerating biodiversity and species loss—driven by pollution, warming, unsustainable fishing, and acidifying oceans—will jeopardize vital ecosystems that support critical human systems. Recent estimates suggest that the current extinction rate is 100 to 1,000 times the natural extinction rate.
Water scarcity, compounded by gaps in cooperative management agreements for nearly half of the world’s international river basins, and new unilateral dam development are likely to heighten tension between countries.”
February 2018: U.S. Department of Defense. The Impact of Sea-Level Rise and Climate Change on Department of Defense Installations on Atolls in the Pacific Ocean (RC-2334). Report to the U.S. Department of Defense Strategic Environmental Research and Development Program.
This study provides “basic understanding and specific information on storm ocean surface wave-driven flooding of atoll islands that house Department of Defense (DOD) installations and (2) assess the resulting impact of sea-level rise inundation and storm wave-driven flooding on infrastructure and freshwater availability under a variety of sea-level rise and climatic scenarios.
These findings have relevance not only to current or decommissioned DOD facilities on Pacific atolls (Kwajalein, Wake, Johnston, Bikini, and Enewetak Atolls), but those utilized by DOD (Diego Garcia in the British Indian Ocean Territory), US Minor Outlying Islands (Baker, Howland, and Jarvis Islands) and those under the US defense umbrella (Republic of the Marshall Islands and the Federated States of Micronesia). Together, these results provide an improved understanding of the planning and management strategies necessary to protect infrastructure and natural resources on low-lying atoll islands globally in the face of future climate change.”
November 6, 2018: Statement of the Chairman of the Joint Chiefs: Climate Change a Source of Conflict Around the World.
“When we look at, when I look at, climate change, it’s in the category of sources of conflict around the world and things we have to respond to. So it can be great devastation requiring humanitarian assistance/ disaster relief, which the U.S. military certainly conducts routinely. In fact, I can’t think of a year since I’ve been on active duty that we haven’t conducted at least one operation in the Pacific along those lines due to extreme weather in the Pacific. And then, when you look at source of conflict – shortages of water, and those kind of things – those are all sources of conflict. So, it is very much something that we take into account in our planning as we anticipate when, where and how we may be engaged in the future and what capabilities we should have.”
2018: U.S. Department of Defense. Climate-Related Risk to DoD Infrastructure Initial Vulnerability Assessment Survey (SLVAS) Report, Office of the Under Secretary of Defense for Acquisition, Technology, and Logistics.
“Senate Report 114-67 accompanying the fiscal year 2016 Military Construction, Veterans Affairs and Related Agencies appropriations bill included language directing the DoD to include an assessment of coastal erosion and potential flooding risks in the siting of proposed military construction projects. In a July 23, 2015, report to Congress regarding the security implications of climate-related risks, the Department noted that is [sic] has directed a global screening level assessment to determine installation vulnerabilities to climate-related security risks with the goal of identifying serious vulnerabilities and developing necessary adaptation strategies…
The Department of Defense (DoD) has significant experience in planning for and managing risk and uncertainty. The effects of climate and extreme weather represent additional risks to incorporate into the Department’s various planning and risk management processes. Various studies have identified a broad range of effects that could impact our ability to fully execute the Defense mission of protecting and maintaining the security interests of the United States at home and around the world.”
January 29, 2019: Office of the Director of National Intelligence. Statement for the Record: Worldwide Threat Assessment of the US Intelligence Community to the Senate Select Committee on Intelligence.
“The United States will probably have to manage the impact of global human security challenges, such as threats to public health, historic levels of human displacement, assaults on religious freedom, and the negative effects of environmental degradation and climate change.”
“Global environmental and ecological degradation, as well as climate change, are likely to fuel competition for resources, economic distress, and social discontent through 2019 and beyond. Climate hazards such as extreme weather, higher temperatures, droughts, floods, wildfires, storms, sea level rise, soil degradation, and acidifying oceans are intensifying, threatening infrastructure, health, and water and food security. Irreversible damage to ecosystems and habitats will undermine the economic benefits they provide, worsened by air, soil, water, and marine pollution.”
January 2019: U.S. Department of Defense. Report on Effects of a Changing Climate to the Department of Defense. Office of the Under Secretary of Defense for Acquisition and Sustainment.
“This report provides an assessment of the significant vulnerabilities from climate-related events in order to identify high risks to mission effectiveness on installations and to operations. This report is organized into three primary sections:
I. Summary of Climate Effects and Resulting Vulnerabilities
II. DoD Efforts to Increase Installation Resiliency & Operational Viability
III. Conclusions
The effects of a changing climate are a national security issue with potential impacts to Department of Defense (DoD or the Department) missions, operational plans, and installations. Our 2018 National Defense Strategy prioritizes long-term strategic competition with great power competitors by focusing the Department’s efforts and resources to: 1) build a more lethal force, 2) strengthen alliances and attract new partners, and 3) reform the Department’s processes.”
January 2019: Office of the Director of National Intelligence. National Intelligence Strategy of the United States of America.
“Increasing migration and urbanization of populations are also further straining the capacities of governments around the world and are likely to result in further fracturing of societies, potentially creating breeding grounds for radicalization. Pressure points include growing influxes of migrants, refugees, and internally displaced persons fleeing conflict zones; areas of intense economic or other resource scarcity; and areas threatened by climate changes, infectious disease outbreaks, or transnational criminal organizations.”
March 2019: Letter to the President of the United States: 58 Senior Military and National Security Leaders Denounce NSC Climate Panel.
In March 2019, 58 senior military and national security leaders wrote to President Trump to denounce his efforts to form a committee in the National Security Council "to dispute and undermine military and intelligence judgments on the threat posed by climate change."
Part of that letter is below:
March 5, 2019
Dear Mr. President:
We write to you as former US national security leaders to offer our support to our uniformed military, civilian national security professionals, and members of the scientific community, who across the past four Administrations have found that climate change is a threat to US national security.
Climate change is real, it is happening now, it is driven by humans, and it is accelerating. The overwhelming majority of scientists agree: less than 0.2% of peer-reviewed climate science papers dispute these facts. In this context, we are deeply concerned by reports that National Security Council officials are considering forming a committee to dispute and undermine military and intelligence judgments on the threat posed by climate change. This includes second-guessing the scientific sources used to assess the threat, such as the rigorously peer-reviewed National Climate Assessment, and applying that to national security policy. Imposing a political test on reports issued by the science agencies, and forcing a blind spot onto the national security assessments that depend on them, will erode our national security."
April 22, 2019: U.S. U.S. Coast Guard. Arctic Strategic Outlook.
"Arctic communities face increasingly frequent and severe incidents due to changing climate and growing human activity."
"Since the release of the Coast Guard Arctic Strategy in 2013, the renewal of global strategic competition has coincided with dramatic changes in the physical environment of the Arctic. The interaction of these drivers has made the Arctic a strategically competitive space for the first time since the end of the Cold War. Competition does not preclude cooperation, and the Coast Guard will always look for opportunities to collaborate to solve complex issues. However, the Service must do so within the context of the Nation’s national security interests."
June 2019: U.S. Department of Defense. Report to Congress. Department of Defense Arctic Strategy.
This 2019 Report to Congress on the Department of Defense Arctic Strategy is an update of the previous 2016 DoD Arctic Strategy as requested by Section 1071 of the John S. McCain National Defense Authorization Act for fiscal year (FY) 2019.
Among the key conclusions, the report cites the latest US National Climate Assessment:
"The Arctic’s physical environment continues to change, including through diminished sea ice coverage, declining snow cover, and melting ice sheets. Temperatures across the Arctic region are increasing more than twice as fast as global average temperatures, accompanied by thawing permafrost and loss of sea ice and glacier mass. Diminishing Arctic sea ice is opening new shipping lanes and increasing access to natural resources during the summer months. If the warming trends continue at the current rate, Arcticwide sea ice loss may result in nearly ice-free late summers by the 2040s. Thawing permafrost, compounded by storm surge and coastal erosion, adversely affects infrastructure, including DoD installations, and complicates the development of new and resilient DoD infrastructure."
The report also notes that among the "Service Roles and Missions" for the military is "examining the effects of a changing climate."
June 1, 2019. U.S. Department of Defense. Indo-Pacific Strategy Report.
"The Indo-Pacific region continues to experience a myriad of security challenges from a range of transnational threats, including: terrorism; illicit arms; drug, human, and wildlife trafficking; and piracy, as well as dangerous pathogens, weapons proliferation, and natural disasters. Multiple terrorist organizations, including the Islamic State of Iraq and Syria (ISIS), operate in countries throughout the region. The heavily-traveled Indo-Pacific sea lanes are targets for pirates seeking to steal goods or hold ships and crews for ransom. Illegal, unreported, and unregulated fishing further challenges regional peace and prosperity. A region already prone to earthquakes and volcanoes as part of the Pacific Ring of Fire, the Indo-Pacific region suffers regularly from natural disasters including monsoons, hurricanes, and floods to earthquakes and volcanic activity, as well as the negative consequences of climate change."
June 1, 2019: U.S. Government Accountability Office: Climate Resilience: DOD Needs to Assess Risk and Provide Guidance on Use of Climate Projections in Installation Master Plans and Facilities Designs. (GAO-19-453.)
Conclusions: Department of Defense (DOD) installations have not consistently assessed risks from extreme weather and climate change effects or consistently used projections to anticipate future climate conditions. For example, DOD’s 2018 preliminary assessment of extreme weather and climate effects at installations was based on the installations’ reported past experiences with extreme weather rather than an analysis of future vulnerabilities based on climate projections.
Recommendations: The GAO recommends that military departments work together to update planning criteria to require an assessment of extreme weather and climate change risks and to incorporate DOD guidance on the use of climate projections into facilities design standards. GAO also recommends that DOD issue guidance on incorporating climate projections into installation master planning and facilities project designs. The DOD concurred with all eight of GAO’s recommendations.
July 2019: U.S. Army War College. Implications of Climate Change for the U.S. Army.
“The Department of Defense (DoD) is precariously unprepared for the national security implications of climate change-induced global security challenges. This study examines the implications of climate change for the United States Army. This includes national security challenges associated with or worsened by climate change, and organizational challenges arising from climate change-related issues in the domestic environment. Given that, the study’s starting point is the implications of climate change for the U.S. Army, and the Army is therefore the focus of the analysis and recommendations. That said, much of the analysis involves DoD and other elements of the government, and most of the Army-specific recommendations have parallels that apply to other military services.”
2019: Office of the U.S. Under Secretary of Defense for Acquisition. Report on Effects of a Changing Climate to the Department of Defense. As required by Section 335 of the National Defense Authorization Act for Fiscal Year 2018 (Public Law 115-91)
“The effects of a changing climate are a national security issue with potential impacts to Department of Defense (DoD or the Department) missions, operational plans, and installations. Our 2018 National Defense Strategy prioritizes long-term strategic competition with great power competitors by focusing the Department’s efforts and resources to: 1) build a more lethal force, 2) strengthen alliances and attract new partners, and 3) reform the Department’s processes.
To achieve these goals, DoD must be able to adapt current and future operations to address the impacts of a variety of threats and conditions, including those from weather and natural events. To that end, DoD factors in the effects of the environment into its mission planning and execution to build resilience.”
February 26, 2020: U.S. Congress. House Armed Services Committee hearing on The Fiscal Year 2021 National Defense Authorization Budget Request from the Department of Defense.
Statement by General Mark Milley, Chairman of the Joint Chiefs of Staff. “I think climate change is real. I think it is probably going to result in destabilization, with resource depletion, water and things like that. You’re gonna see things like increases in diseases. There are a lot of second and third order effects. And does it impact on U.S. national security? Yes it does.”
Statement by Dr. Mark Esper, Secretary of Defense: “Thank you, Mr. Langevin. I agree as I think we reported as, the Chairman and I when we were at the Army, is that climate change poses a challenge for our installations and making sure that we can make sure we can maintain installation readiness to support our forces. We discovered this in the Army the biggest challenge we face was, for example, I think when you and I spoke was desertification out west with many of our bases so it is something I’m aware of. I know we face a challenge in Norfolk with rising tides, it’s something we have to plan on to make sure we can address it so we maintain a strong installational base.”
October 15, 2020: U.S. Department of Defense. FY2021Top DOD Management Challenges, Inspector General, Department of Defense, Washington, DC.
“The recent increase in non-traditional threats, such as pandemics, changing climate, and extreme weather events, has presented the DoD with new challenges as it continues to defend and secure the Nation… Changing climate and weather patterns, including extreme and damaging weather events, have adversely impacted military infrastructure and personnel readiness. Meanwhile, droughts, water scarcity, and other natural resource limitations offer opportunities for adversaries, competitors, and violent extremist organizations to exert their influence in pursuit of their goals. These challenges require the DoD to develop long-term plans to address these non-traditional threats without compromising its ability to defend the U.S. homeland and national security interests.”
November 6, 2020: Office of the Director of National Intelligence. Water Insecurity Threatening Economic Growth, Political Stability. (National Intelligence Council Memorandum NICM-2020-05949)
“Countries that are unable to adequately address water challenges probably will face health and disease problems, growing inequality, poor economic growth, and a greater risk of internal political instability. Shared water resources among states are increasingly likely to become flashpoints as water security diminishes and geopolitical competition grows.”
“More frequent and severe water security problems during the next 20 to 30 years are likely to touch almost all elements of global life, including personal security, economic growth, political stability, and interstate conflict.”
“During the next two decades, declining water security is likely to exacerbate existing social grievances and divisions, potentially triggering conflict between societal groups and industry sectors and increase the risk of political instability.”
This report concludes that “Governments, industry, and civil society are facing an increasing risk of water insecurity as demand grows and supply is increasingly strained.” It attributes these increased risks to “development practices, agriculture, and environmental degradation” and to “poor governance and resource management” that affect both water availability and quality.
It also notes that while most of these risks will be experienced in developing countries, “some developed countries will also experience water strains” and the countries that experience water problems will suffer health and disease problems, growing economic and social inequality, reduced economic growth, and “a greater risk of internal political instability.” For countries that share water resources, water is likely to become a flashpoint for geopolitical competition.
January 27, 2021: The White House. Presidential Executive Order on Tackling the Climate Crisis at Home and Abroad.
“Prioritizing Climate in Foreign Policy and National Security. To ensure that climate change considerations are central to United States foreign policy and national security:
(a) Agencies that engage in extensive international work shall develop, in coordination with the Special Presidential Envoy for Climate, and submit to the President, through the Assistant to the President for National Security Affairs, within 90 days of the date of this order, strategies and implementation plans for integrating climate considerations into their international work, as appropriate and consistent with applicable law.”
Agencies required to prepare assessments of climate and security include:
• The Director of National Intelligence.
• The Secretary of Defense, in coordination with the Secretary of Commerce, through the Administrator of the National Oceanic and Atmospheric Administration, the Chair of the Council on Environmental Quality, the Administrator of the Environmental Protection Agency, the Director of National Intelligence, the Director of the Office of Science and Technology Policy, the Administrator of the National Aeronautics and Space Administration, and the heads of other agencies as appropriate.
• The Secretary of Defense and the Chairman of the Joint Chiefs of Staff shall consider the security implications of climate change in developing a National Defense Strategy, Defense Planning Guidance, Chairman's Risk Assessment, and other relevant strategy, planning, and programming documents and processes.
• The Secretary of Homeland Security shall consider the implications of climate change in the Arctic, along our Nation's borders, and to National Critical Functions.
March 2021: U.S. National Intelligence Council. Global Trends 2040: A More Contested World.
This report contains an extensive discussion of global environmental trends, including especially climate change and threat to U.S. security interests. Among the key observations:
“Shared global challenges—including climate change, disease, financial crises, and technology disruptions—are likely to manifest more frequently and intensely in almost every region and country. These challenges—which often lack a direct human agent or perpetrator—will produce widespread strains on states and societies as well as shocks that could be catastrophic.”
“Rarely is climate change the sole or even primary driver of instability and conflict; however, certain socio-political and economic contexts are more vulnerable to climate sparks that ignite conflict.”
“While militaries will continue to adapt and fight in the changing world, climate effects will strain readiness and compound fiscal pressures on many militaries.”
“Shared global challenges—including climate change, disease, financial crises, and technology disruptions—are likely to manifest more frequently and intensely in almost every region and country. These challenges—which often lack a direct human agent or perpetrator—will produce widespread strains on states and societies as well as shocks that could be catastrophic.”
April 9, 2021: Office of the Director of National Intelligence. Annual Threat Assessment of the U.S. Intelligence Community.
“We assess that the effects of a changing climate and environmental degradation will create a mix of direct and indirect threats, including risks to the economy, heightened political volatility, human displacement, and new venues for geopolitical competition that will play out during the next decade and beyond. Scientists also warn that warming air, land, and sea temperatures create more frequent and variable extreme weather events, including heat waves, droughts, and floods that directly threaten the United States and US interests, although adaptation measures could help manage the impact of these threats. The degradation and depletion of soil, water, and biodiversity resources almost certainly will threaten infrastructure, health, water, food, and security, especially in many developing countries that lack the capacity to adapt quickly to change, and increase the potential for conflict over competition for scarce natural resources.”
April 22, 2021. U.S. Department of Defense. Remarks of Secretary of Defense Lloyd Austin at Climate Change Summit.
“Today, no nation can find lasting security without addressing the climate crisis. We face all kinds of threats in our line of work, but few of them truly deserve to be called existential. The climate crisis does. As NATO Secretary General Stoltenberg has said: Our core task is to keep our people safe. Climate change is making the world more unsafe and we need to act.
The climate crisis is a profoundly destabilizing force for our world. As the Arctic melts, competition for resources and influence in the region increases. Closer to the equator, rising temperatures and more frequent and intense extreme weather events in Africa and Central America threaten millions with drought, hunger, and displacement.
As families risk their lives in search of safety and security, mass migration leaves them vulnerable to exploitation and radicalization, all of which undermine stability. And in the far reaches of the Pacific, rising sea levels and more frequent and intense storms put individuals, families, and whole communities at risk – while pushing the limits of our collective capacity to respond.”
May 14, 2021: U.S. Army. Addressing Climate Change Threats.
“Climate change is a serious threat to U.S. National security interests and defense objectives. The effects of climate change can cause humanitarian disasters, undermine weak governments and contribute to long-term social and economic disruptions.
Warming temperatures open new theaters of operations for military and commercial use, while extreme weather events and rising sea levels threaten infrastructure and economic output, trigger large-scale population displacement, migration and exacerbate food and water insecurity. In line with the President and the Secretary of Defense’s direction, the Army is prioritizing climate change considerations in its threat picture, strategic plans, operations and installations.”
May 17, 2021: U.S. Department of Defense. DOD Exercise Highlights Need to Address Climate Change.
The Defense Department's first climate and environmental security "tabletop" exercise, dubbed Elliptic Thunder, highlighted the growing security threats posed by climate and environmental change, while illustrating that prevention activities today are essential to avoiding dire consequences in the future. The main takeaways of the Elliptic Thunder exercise included:
• Climate and environmental change will exacerbate existing threats and security challenges via increased frequency and severity of environmental stressors and extreme events. Compounding and cascading events are likely to be particularly disruptive.
• Environmental changes have implications across the department with respect to great power competition, counterterrorism, our alliances and partners, basing, access to ports and landing sites, infrastructure investments and more.
• DOD will need to develop and/or refine policies, authorities and organizations — as well as processes, budget and funding to best prepare for and respond to climate threats.
• Improved understanding of emerging threats will help prevent and prepare for future environmental and climate security challenges. Enabling a shift to prevention activities will help avoid simply responding to crises.
September 1, 2021: U.S. Department of Defense. Climate Adaptation Plan
“The Department of Defense (DOD) has identified climate change as a critical national security issue and threat multiplier (DOD 2014a) and top management challenge (DOD 2020a). Climate change will continue to amplify operational demands on the force, degrade installations and infrastructure, increase health risks to our service members, and could require modifications to existing and planned equipment. Extreme weather events are already costing the Department billions of dollars and are degrading mission capabilities. These effects and costs are likely to increase as climate change accelerates. Not adapting to climate change will be even more consequential with failure measured in terms of lost military capability, weakened alliances, enfeebled international stature, degraded infrastructure, and missed opportunities for technical innovation and economic growth.
The Department must take bold steps to accelerate adaptation to reduce the adverse impacts of climate change. These adaptation efforts must align with our strategic objectives and mission requirements, ensuring that our military can deter aggression and defend the nation under all conditions.”
September 23, 2021: Comments by Secretary of State Antony J. Blinken at UN Security Council Meeting on Climate and Security, UN Headquarters.
“From day one, President Biden has made addressing the climate crisis a top priority of our administration, including by directing me – and every one of our diplomats – to ensure it’s a core element of U.S. foreign policy. We’re taking into account how every bilateral and multilateral engagement we have – every policy decision we make – will impact our goal of putting the world on a safer, more sustainable path.
Look at any one of our countries, you will see record-breaking extreme weather events like this. The climate crisis isn’t coming. It’s already here. And clear patterns are emerging in its impact. The consequences are falling disproportionately on vulnerable and low-income populations. And they’re worsening conditions and human suffering in places already afflicted by conflict, high levels of violence, instability.
Look at almost every place where you see threats to international peace and security today – and you’ll find that climate change is making things less peaceful, less secure, and rendering our response even more challenging. That’s the story of Syria, Mali, Yemen, South Sudan, Ethiopia, many other places beset by strife. By agreeing that the issue belongs here in the Security Council, we’ll also send a clear message to the international community of the serious implications that climate change has for our collective security.”
October 2021: U.S. Department of Defense. Climate Risk Analysis to the National Security Council.
Climate change is reshaping the geostrategic, operational, and tactical environments with significant implications for U.S. national security and defense. Increasing temperatures; changing precipitation patterns; and more frequent, intense, and unpredictable extreme weather conditions caused by climate change are exacerbating existing risks and creating new security challenges for U.S. interests. The risks of climate change to Department of Defense (DoD) strategies, plans, capabilities, missions, and equipment, as well as those of U.S. allies and partners, are growing. Global efforts to address climate change – including actions to address the causes as well as the effects – will influence DoD strategic interests, relationships, competition, and priorities. To train, fight, and win in this increasingly complex environment, DoD will consider the effects of climate change at every level of the DoD enterprise.
October 21, 2021: Office of the Director of National Intelligence. Climate Change and International Responses Increasing Challenges to US National Security Through 2040. NIC-NIE-2021-10030-A.
“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. Global momentum is growing for more ambitious greenhouse gas emissions reductions, but current policies and pledges are insufficient to meet the Paris Agreement goals. Countries are arguing about who should act sooner and competing to control the growing clean energy transition. Intensifying physical effects will exacerbate geopolitical flashpoints, particularly after 2030, and key countries and regions will face increasing risks of instability and need for humanitarian assistance.”
Key Judgment 1: Geopolitical tensions are likely to grow as countries increasingly argue about how to accelerate the reductions in net greenhouse gas emissions that will be needed to meet the Paris Agreement goals.
Key Judgment 2: The increasing physical effects of climate change are likely to exacerbate cross-border geopolitical flashpoints as states take steps to secure their interests.
Key Judgment 3: Scientific forecasts indicate that intensifying physical effects of climate change out to 2040 and beyond will be most acutely felt in developing countries, which we assess are also the least able to adapt to such changes. These physical effects will increase the potential for instability and possibly internal conflict in these countries, in some cases creating additional demands on US diplomatic, economic, humanitarian, and military resources.
October 21, 2021: U.S. Department of Homeland Security (DHS). Strategic Framework to Address Climate Change for the Department of Homeland Security.
“The impacts of climate change pose both an acute and a systemic threat to the safety, security, and prosperity of the United States. This human-induced warming has already led to changes in the environment, such as rising ocean temperatures, shrinking sea ice, rising sea levels, and ocean acidification. As our climate continues to warm, the Nation will experience even more extreme climate change related disasters, such as heat waves, droughts, wildfires, coastal storms, and inland flooding. These hazards often disproportionately affect the Nation’s most vulnerable communities.
“As the Department of Homeland Security (DHS) continues to support and coordinate across the homeland security enterprise to address impacts of climate change, the Department will also model best practices to mitigate our own carbon footprint and build resilient capacity to adapt to a rapidly changing environment. This Framework provides the overarching goals, principles, and lines of effort for the Department to counter the effects of climate change on the homeland and join in the global effort to mitigate climate change.”
October 2021. The White House. Report on the Impact of Climate Change on Migration. Washington, D.C.
“As the effects of climate change intensify, it is important to understand the underlying factors that may mitigate or exacerbate migration, and develop strategies to both proactively and humanely manage these impacts and be considered in the context of any geographic or environmental factors that would contribute disproportionately to the destabilization of economically or politically important regions.
“Climate-related migration has potentially significant implications for international security, instability, conflict, and geopolitics. Disaggregating climate change from the many other factors influencing individuals’ decisions to migrate is difficult, as is the ability to understand indirect links between climate change and other drivers. To frame the discussion, the focus of this section is on the direct and indirect geopolitical security implications of climate-related migration and not the consequences of migration more generally or the non-migration implications of climate change.”
2021: U.S. Department of Defense. Tackling the Climate Crisis (website page).
General portal for the U.S. Department of Defense climate works. Website deleted March 2025.
February 8, 2022: U.S. Army. U.S. Army Climate Strategy.
“Climate change poses an immediate and serious threat to U.S. national security and affects how and where the Army trains and operates. As the Secretary of the Army (SecArmy) stated in the United States Army Climate Strategy (ACS), "For today's Soldiers operating in extreme temperature environments, fighting wildfires, and supporting hurricane recovery, climate change isn't a distant future, it is a reality." The Total Army must train, modernize, and remain ready to deploy, fight, and win the nation's wars. Extreme weather events, soaring average temperatures, and other hazards caused by climate change are increasing the risk to military operations and forces at home and in many parts of the world. Adapting the Army to climate change will return significant, lasting advantages in training, readiness, and capabilities at strategic and operational levels.”
February 2022. Office of the Director of National Intelligence. Annual Threat Assessment of the U.S. Intelligence Community.
“We assess that climate change will increasingly exacerbate risks to U.S. national security interests as the physical impacts increase and geopolitical tensions mount about how to respond to the challenge. Meanwhile, environmental degradation will increasingly intersect with and worsen climate change effects in many countries, particularly low-income countries.”
“The increasing physical effects of climate change are likely to exacerbate domestic and cross-border geopolitical flashpoints producing additional instability… These physical effects will increase the potential for instability and possibly internal conflict in some countries, in some cases creating additional demands on U.S. diplomatic, economic, humanitarian, and military resources. Despite geographic and financial resource advantages, the United States and its partners face costly challenges that will become more difficult to manage without concerted effort to reduce emissions and cap warming.
Unsustainable land use, poor water governance, and pollution will intersect with and worsen the effects of climate change, primarily but not exclusively in low-income countries in the near term. The combination of environmental degradation, rising temperatures, changing precipitation patterns, and other climate effects is likely to lead to an array of human challenges such as food and water insecurity and threats to human health.”
April 1, 2022: U.S. Department of State. Bureau of Conflict and Stabilization Operations. 2022 Prologue to the United States Strategy to Prevent Conflict and Promote Stability.
“Climate and environmental crises or hazards are reshaping our world. The Earth’s climate is now changing faster than at any point in the history of modern civilization and will exacerbate most physical, social, economic, and/or preexisting environmental vulnerabilities. Secondary effects of environmental degradation, vulnerabilities to natural weather and geologic disasters, and climate change include displacement, loss of livelihoods, weakened governments, and in some cases political instability and conflict. We will consider and address the risks posed by the impacts of climate change and other environmental security risks and test new ways of building climate resilience and deepen our understanding of the connections between fragility, peacebuilding and the environment.
April 2022: U.S. Department of Defense. Inspector General’s Office. Evaluation of the Department of Defense’s Efforts to Address the Climate Resilience of U.S. Military Installations in the Arctic and Sub-Arctic
“In the past 5 years, extreme weather and changing climate have caused hundreds of billions of dollars’ worth of damage in the United States. In 2019, a DoD report to Congress on the effects of climate change on military installations called the effects of a changing climate a national security issue, with potential impacts to DoD missions, operational plans, and installations. Public law, DoD directives, and recently released DoD Facilities Criteria require DoD installations to address climate and energy risks and threats to installation infrastructure, assets, and missions.
“The extent of climate change is more significant in the Arctic than in most other parts of the world. The DoD’s Arctic Strategy recognizes that the Arctic has direct implications for U.S. national security interests. The DoD is investing in resilient installation infrastructure and assets in the Arctic and sub-Arctic regions to support increased Arctic operations and enhanced Arctic awareness.”
May 2022: U.S. Department of the Navy. Climate Action 2030.
“Climate change is one of the most destabilizing forces of our time, exacerbating other national security concerns and posing serious readiness challenges. Our naval forces, the United States Navy and Marine Corps, are in the crosshairs of the climate crisis: the threat increases instability and demands on our forces while simultaneously impacting our capacity to respond to those demands.
“Climate change is an existential threat that impacts not only our operations and readiness but also our infrastructure, our forces, and their families. Rising sea levels, recurring flooding, and more frequent and destructive hurricanes threaten our coastal installations. Changes in global climate and other dangerous trans-boundary threats, including pandemics, are only expected to worsen, posing increasing challenges for our forces, platforms, infrastructure, and supporting communities, and driving or intensifying conflict and humanitarian disasters around the world. The DON will adapt to these challenges that are increasingly putting pressure on our force and the systems that support it.
“To combat these impacts, the Department of the Navy has an urgent charge: to build a climate-ready force.”
October 2022: U.S. Department of Defense. Climate Adaptation Plan Progress Report.
“Every day, climate change affects the work we do at the Department of Defense. Rising temperatures, changing precipitation patterns, and more frequent, extreme, and unpredictable weather conditions caused by climate change are worsening existing security risks and creating new challenges for the United States and our allies and partners. Climate change is increasing the demand and scope for military operations at home and around the world. At the same time, it is undermining military readiness and imposing increasingly unsustainable costs on the Department of Defense… No country can find lasting security without tackling the climate crisis. Climate change will continue to shape the context for military operations—for the United States and for our competitors—which is why we must ensure that our combat forces are ready to respond to future risks and equipped to operate superbly no matter the changing conditions. The 2022 Climate Adaptation Plan Progress Report describes some of our recent efforts to respond to this crisis, but we know that we have much more work to do. In the years ahead, the countries that are the most resilient and best prepared to manage the effects of climate change will gain significant security advantages.”
October 2022: The National Security Strategy. The White House, Washington, D.C.
“Of all of the shared problems we face, climate change is the greatest and potentially existential for all nations. Without immediate global action during this crucial decade, global temperatures will cross the critical warming threshold of 1.5 degrees Celsius after which scientists have warned some of the most catastrophic climate impacts will be irreversible.
“We are enhancing Federal, state, and local preparedness against and resilience to growing extreme weather threats, and we’re integrating climate change into our national security planning and policies.”
October 2022: U.S. Department of the Air Force. Climate Action Plan.
“Climate change matters first and foremost to the Department of the Air Force because it impacts our mission capabilities and those impacts are projected to increase over time. The department is composed of two military services—the Air Force and the Space Force. While both services have distinct missions, the role of both services is consistent: to deter conflict and if necessary, defeat adversaries across the air and space domains. Climate change has introduced acute challenges to achieving air and space dominance; climate change impacts our ability to maintain operational readiness, access strategic locations globally, and execute the operational mission.”
“Increasing temperatures, changing precipitation patterns, and more frequent, severe weather conditions driven by climate change pose increasing risks to our installations and operational readiness.”
“Climate change is aggravating geopolitical unrest and acting as a threat multiplier, which is leading to new and expanded mission requirements for the department. Food insecurity, water scarcity, economic dislocation, and natural disasters perpetuate regional instability and test the capacity of governments around the world to protect their citizens. Violent extremist organizations take advantage of these conditions to increase their influence and power. We may be called upon to respond to increasing numbers of natural disasters or to spiraling regional conflicts driven by instability.”
October 2022: U.S. Department of Defense. DoD Climate Resilience Portal.
Broad web portal to access Department of Defense climate resources. Website deleted in March 2025.
October 2022. U.S. Department of Defense. Climate Assessment Tool
A CAC-accessible geospatial tool supporting climate change exposure assessments for Department of Defense sites and installations both domestic and overseas... The Climate Assessment Tool enables integration of screening-level climate exposure assessments into military installation planning processes consistently across the Department’s warfighting missions. DCAT provides important information for understanding an installation’s vulnerability to climate-related hazards.
December 23, 2022: U.S. Congress. H.R.7776 - James M. Inhofe National Defense Authorization Act for Fiscal Year 2023
In December 2022, President Biden signed the Fiscal Year 2023 National Defense Authorization Act (NDAA), a $858 billion measure authorizing defense spending for next year. The bill includes support for climate security In the Fiscal Year 2023 budget DoD requested $3.1 billion in climate investments, focused on installation resilience and increasing operational efficiencies. The FY23 NDAA largely approved those requests, and even included modest increases in some resilience programs like the Defense Community Investment Program, the Energy Resilience and Conservation Investment Program and the Readiness and Environmental Protection Integration Program.
January 2023. U.S. Coast Guard. Climate Framework
“The world is changing. Rising sea levels, more frequent severe weather, retreating Polar ice, migrating fish stocks, and coastal infrastructure damage are creating challenges for people around the globe. Increasing pressure to reduce environmental impact is driving change in energy generation and the global economy. These impacts of climate change will influence every Coast Guard mission. To uphold our tradition of service to the Nation, the Coast Guard must apply strategic foresight to prepare for the challenges ahead. This Climate Framework charts the first waypoint of our journey as we move forward at best speed.”
February 6, 2023. Office of the Director of National Intelligence. Annual Threat Assessment of the U.S. Intelligence Community
“In every region of the world, challenges from climate change, demographic trends, human and health security, and economic disruptions caused by energy and food insecurity and technology proliferation will combine and interact in specific and unique ways to trigger events ranging from political instability, to terrorist threats, to mass migration, and potential humanitarian emergencies.”
“Climate change will increasingly exacerbate risks to U.S. national security interests as the physical impacts increase and geopolitical tensions mount about the global response to the challenge. The increasing physical effects of climate change also are likely to intensify or cause domestic and cross-border geopolitical flashpoints.”
“Climate-related disasters in low-income countries will deepen economic challenges, raise the risk of inter-communal conflict over scarce resources, and increase the need for humanitarian and financial assistance. The growing gap between the provision of basic needs and what governments and the international community can provide raises the likelihood of domestic protests, broader instability, extremist recruitment, and migration.”
April 2023: U.S. Department of Defense. DoD Plan to Reduce GHG Emissions.
“This report is the Department’s inaugural enterprise-wide greenhouse gas (GHG) emissions reduction plan and describes strategies for both military installations and operations. The Department’s focus is to enhance capability and lethality while increasing the readiness and resilience of the force. Initiatives that reduce GHG emissions can also create warfighting advantage. For example, improving efficiency and deploying clean distributed generation and storage can strengthen the resilience of critical missions housed on military installations in the face of extreme weather, cyber attacks, and even kinetic attacks impacting electric grids. Improving the efficiency of combat platforms and operations can enable freedom of maneuver and mitigate risk, while increasing operational reach and endurance in contested logistics environments.”
April 2023. U.S. Department of Homeland Security. The Third Quadrennial Homeland Security Review.
“We face more serious threats from nation states now than at any time in the Department's history. DHS is bringing together its authorities and capabilities across Operational Components to counter those threats, including enforcing U.S. trade laws banning the importation of goods made, wholly or in part, with forced labor, strengthening maritime governance, and increasing awareness of nation state threats with our federal, state, local, tribal, territorial, and private sector partners.
“Even with significant interventions, the planet will continue to warm, causing increasingly serious impacts on the American people and on DHS’s missions and its workforce. Severe and frequent natural disasters, rising ocean temperatures, shrinking sea ice, rising sea levels, wildfires, heatwaves, droughts, and ocean acidification all produce serious threats.”
July 2023. U.S. Department of the Air Force. Climate Campaign Plan.
“In the past two decades, our natural environment has become more dynamic due to the effects of global climate change. Extreme weather events such as hurricanes, drought, flooding, and other natural disasters have shaped the international security environment and created humanitarian crises in greater numbers. Our installations have also been impacted by these changes. We cannot launch or recover aircraft on a flooded runway, nor can we operate from installations devastated by hurricanes and wildfires. Our bases are our power projection platforms and as those bases are increasingly impacted by the effects of climate change, adapting to these challenges will be critical to meet our national security obligations. This Climate Campaign Plan implements our Climate Action Plan.”
February 5, 2024. Office of the Director of National Intelligence. Annual Threat Assessment of the U.S. Intelligence Community.
“The risks to U.S. national security interests are increasing as the physical effects of climate and environmental change intersect with geopolitical tension and vulnerabilities of some global systems. Climate-related disasters in low-income countries will deepen economic challenges, raise the risk of inter-communal conflict over scarce resources, and increase the need for humanitarian and financial assistance.”
March 2025: Office of the Director of National Intelligence. Annual Threat Assessment of the U.S. Intelligence Community.
For the first time since 2008, the annual Worldwide Threat Assessments from the Office of the Director of National Intelligence has been purged of any references at all to environmental, water, or climate, threats to U.S. security or the effectiveness or operations of the U.S. military. (Note: No report was published in 2020 by the first Trump administration – the only year when ODNI didn’t release an assessment since 2006.)
For earlier documents, see Parts 1 and 2 of this Review
