Climate Change Poses Serious National Security Threat

After years of debate, there is growing awareness within the DAF, DoD, and the U.S. government more broadly that climate change has the potential to pose a serious national security threat, and some efforts to cope with this challenge are underway. As summarized in the Department of Defense Climate Adaptation Plan, published in 2021, there are an array of ongoing military adaptation and resilience efforts, from building a climate-ready force to improving supply chain resilience.1 The DAF published its own Climate Action Plan in 2022 and an implementation-focused Climate Campaign Plan in 2023, with three priorities: maintaining air and space dominance in the face of climate risks, making climate-informed decisions, and optimizing energy use and pursuing alternative energy sources.2 The first and third priorities reflect the emphasis that DoD has placed on adapting to physical challenges and further reductions in greenhouse gas emissions. However, the second priority—the need to make climate-informed decisions and, in particular, incorporate climate considerations into operational and campaign plans—highlights the need for broader research on potential climate effects.

These reports represent only some of the U.S. government’s recent attempts to better understand and identify ways to respond to the problems that climate change may pose for the military.3 Perhaps the broadest U.S. government assessment of the national security implications of climate change can be found in the 2021 National Intelligence Estimate (NIE) on this topic.4 The NIE makes the case for a wide variety of possible future effects of climate change on U.S. national security, including through effects on resources and the physical environment, as well as through effects on geopolitical issues. Although, by design, the NIE does not provide detailed evidence or arguments for its conclusions, it represents a good starting point for further investigations into these issues. However, many of the geopolitical implications that the NIE highlights have not become part of subsequent DoD strategies and assessments, which remain focused on efforts to enhance DAF and DoD operating resilience. Therefore, questions remain: Which climate-related issues should the DAF and DoD focus on? To what extent will broader geopolitical concerns require more-fundamental shifts in DAF or DoD missions, posture, or investments?

This paper argues that, in order to answer these questions, there is still an enormous amount to be learned about how climate change may affect U.S. national security and whether the United States and the DAF may, as a result, be missing important opportunities to respond. To make this case, this paper first summarizes scientific projections on the ways in which the earth’s climate is likely to change in the years to come. Second, it summarizes recent or ongoing research on the ways in which climate change is currently assessed to affect U.S. national security interests. Third, it lays out an argument for why several important gaps remain in current research and maps out how future research could address those gaps in ways that would leave the United States better prepared for the future. Specifically, building on the literature and integrating additional potential insights, this paper explores how political and social systems might attempt to adapt to or mitigate climate change in ways that could affect U.S. national security interests.5 It also addresses the possibility that states and individuals will increasingly assign blame to past or ongoing polluters in ways that could alter geopolitical relationships or generate novel security concerns. These currently under-investigated ways in which climate change might affect U.S. national security interests could, in turn, have substantial nearer-term implications for the DAF and DoD, potentially altering investment and posture decisions that are being made today.


This concept paper makes the case that the burgeoning research into the national security implications of climate change remains too narrowly focused on the physical effects of climate change, paying short shrift to many plausible social or political implications that may affect the broader future operating environment faced by DoD and the DAF. It is important to acknowledge that researchers have only just begun to think seriously about the full scope and scale of effects that climate change may have on U.S. national security. Climate change is not reshaping just a handful of discrete events, or the next few years; it is reshaping the map of the world. Therefore, we should expect it to affect many aspects of national security, potentially in transformative ways

While climate change is, by definition, a long-term process, with many of its effects in the physical and environmental realm arriving gradually, political and social systems may behave much less predictably, not showing signs of change until a certain threshold is reached and more-dramatic effects can be seen. Therefore, researchers should not assume that political and social changes will move at the same pace as environmental ones. Identifying where the pressures for political and social changes might be building up and where the effects of these pressures are likely to be felt is a critical issue for U.S. national security and a necessary area for research to better inform decisions.

DoD and the DAF are increasingly focused on making investments to enhance both capabilities and readiness in the 2030 to 2040 time frame and pursuing relationships and agreements to enhance forward posture options in the Indo-Pacific. As discussed above, climate change could complicate these plans, although in ways that might take time to come to fruition. The potential for physical effects on U.S. bases or operations in the region is increasingly well appreciated and studied. But it is unlikely that the effects of climate change will be confined to these direct physical effects. Some allies and partners that are considered vital for U.S. basing and access might be disproportionately likely to be negatively affected by climate change, and, as a result, the politics regarding partnering with the United States or appearing to oppose China might shift. Long-term plans for managing protracted conflicts might not reflect the possibility that the United States or its adversaries might develop alternative energy sources, reducing the effectiveness of some tools of statecraft, such as blockades. The political stability of U.S. allies, partners, and adversaries might also be affected by climate change, in ways that should be reflected in DoD’s planning for contingencies. In short, climate change might cause additional and more-fundamental changes to the Indo-Pacific operating environment that might, in turn, require morefundamental shifts in DAF or DoD missions, posture, or investments to address. To better understand these and many other potential changes and how they should inform DAF and DoD policy choices, from security cooperation and posture decisions to investment priorities, the time to both widen the scope of issues under investigation and deepen the attention paid to them is now

1. DoD, Department of Defense Climate Adaptation Plan; DoD, Department of Defense Climate Risk Analysis.

2. DAF, Office of the Assistant Secretary for Energy, Installations, and Environment, Department of the Air Force Climate Action Plan; DAF, Office of the Assistant Secretary for Energy, Installations, and Environment, Department of the Air Force Climate Campaign Plan.

3. Others include Schwartz and Randall, An Abrupt Climate Change Scenario and Its Implications for United States National Security; DoD, National Defense Strategy and Its Implications for United States National Security; DoD, Department of Defense Climate Change Adaptation Roadmap; DoD, 2014 Climate Change Adaptation Roadmap; DoD, National Security Implications of Climate-Related Risks and a Changing Climate; Office of the Under Secretary of Defense for Acquisition, Technology, and Logistics, Climate-Related Risk to DoD Infrastructure Initial Vulnerability Assessment Survey (SLVAS) Report; DoD, Report on Effects of a Changing Climate to the Department of Defense; the Office of Management and Budget Sustainability Scorecards; DoD Directive 4715.21, Climate Change Adaptation and Resilience; Government Accountability Office, Climate Change Adaptation; 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; Government Accountability Office, Climate Resilience: DOD Coordinates with Communities, but Needs to Assess the Performance of Related Grant Programs; Government Accountability Office, “National Security Snapshot”; and White House, National Security Strategy.

4. Office of the Director of National Intelligence, National Intelligence Estimate.

5. Adaptation is defined as altering human behavior, systems, and ways of life to protect humanity from the impacts of climate change. Mitigation is defined as efforts to reduce or prevent emission of greenhouse gases in order to limit climate change.