Submitted: September 2, 2025 by Dr. Peter H. Gleick, member, US National Academy of Sciences.
The document “A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate” prepared by the Climate Working Group of the United States Department of Energy and released on July 23, 2025 is seriously deficient in a wide number of areas, but the focus of the following comments is on the failure to include any review or assessment of the long history of published documents from the US defense and intelligence communities on the direct and indirect threats to the United States national security from climate changes.
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. A long series of unclassified public documents highlight the ever-increasing levels of concern about these threats by the defense and intelligence communities, but this information has been entirely excluded from the July 2025 DoE Review.
Comments related to “Part III Impacts on Ecosystems and Society” (Page 103 and subsequent).
The document “A Critical Review of Impacts of Greenhouse Gas Emissions on the U.S. Climate” prepared by the Climate Working Group of the United States Department of Energy and released on July 23, 2025 is seriously deficient, omitting entirely the potential impacts to the United States of climate change on national security, defense policy, and the safety and operations of US military bases. This information should have been presented in Part III of the DoE report, beginning on page 103. Two major categories of failure are evident in the DoE report. The first is exclusion of the extensive body of evidence of the impact of climate change on international security and US national security. The second is the clearly expressed and already evident impact of climate change on US military bases, preparedness, and operations.
The evidence that climate is a security issue is clear and has been highlighted in the Fifth National Climate Assessment of the US Global Change Research Program (USGCRP). In particular, “key message” 17.2 in that assessment states:
“Climate change can contribute to political and social instability and, in some instances, to conflict (likely, high confidence). It impacts the operations and missions of defense, diplomacy, and development agencies critical to US national security (very likely, high confidence). The US Government, bilaterally and in collaboration with international partners, is increasingly addressing these implications through a range of diplomatic, development, and defense responses (very likely, high confidence.”
The report goes on to lay out the evidence for this in detail in Section 17.2, including specific threats from the document “National Intelligence Estimate “Climate Change and International Responses Increasing Challenges to US National Security Through 2040.”
Below I include additional supporting evidence for this threat, from decades of US defense and intelligence reports available as unclassified documents.
1. The Extensive Evidence of the Impact of Climate Change on US National Security Have Been Ignored by the July 23, 2025 DoE Climate Working Group Report
A wide range of published federal documents relate to this concern, none of which were addressed in the DoE Report in question. One category of assessments comes from the legislative requirement from H.R.3622 (Goldwater-Nichols Department of Defense Reorganization Act of 1986. 99th Congress (1985-1986). This Act imposes a requirement that an Annual National Security Strategy Report be prepared and transmitted to Congress.
“(1) The President shall transmit to Congress each year a comprehensive report on the national security strategy of the United States (hereinafter in this section referred to as a “national security strategy report”).”
Numerous such reports have been issued, and many of them explicitly note the threat of climate change to the US and the need to reduce emissions of greenhouse gases from burning fossil fuels. A few are summarized here, but a full list of documents is publicly available:
August 1991: The White House. The National Security Strategy of the United States. Washington, D.C. [The first explicit mention of “climate change” in the National Security Strategy.] https://history.defense.gov/Historical-Sources/National-Security-Strategy
“Global environmental concerns include such diverse but interrelated issues as stratospheric ozone depletion, climate change, food security, water supply, deforestation, biodiversity and treatment of wastes. A common ingredient in each is that they respect no international boundaries. The stress from these environmental challenges is already contributing to political conflict. Recognizing a shared responsibility for global stewardship is a necessary step for global progress. Our partners will find the United States a ready and active participant in this effort.”
January 1993: The White House. The National Security Strategy of the United States. Washington, D.C. https://history.defense.gov/Historical-Sources/National-Security-Strategy
“Environmental degradation is one of the most pressing global problems. Deforestation, climate change, air and water pollution, and depletion of water supplies have far reaching effects on the capacity of countries to sustain economic growth and ensure a healthy environment for their citizens. Environmental problems transcend national boundaries. Air and water pollution in one country can affect far distant countries as well as those nearby. Some problems, such as ozone depletion and climate change, can have a global impact. In many developing countries, environmental degradation is already causing serious health problems and limiting economic development.”
July 1994: The White House. A National Security Strategy of Engagement and Enlargement. Washington, D.C. https://history.defense.gov/Historical-Sources/National-Security-Strategy
“The more clearly we understand the complex interrelationships between the different parts of our world's environment, the better we can understand the regional and even global effects of local changes to the environment. Increasing competition for the dwindling reserves of uncontaminated air, arable land, fisheries and other food sources, and water, once considered "free" goods, is already a very real risk to regional stability around the world. The range of environmental risks serious enough to jeopardize international stability extends to massive population flight from man-made or natural catastrophes, such as Chernobyl or the East African drought, and to largescale ecosystem damage caused by industrial pollution, deforestation, loss of biodiversity, ozone depletion, and ultimately climate change.”
May 1997: The White House. A National Security Strategy for a New Century. Washington, D.C. https://history.defense.gov/Historical-Sources/National-Security-Strategy
“Environmental threats do not heed national borders and can pose long-term dangers to our security and well-being. Natural resource scarcities often trigger and exacerbate conflict. Environmental threats such as climate change, ozone depletion and the transnational movement of dangerous chemicals directly threaten the health of U.S. citizens. We must work closely with other countries to respond aggressively to these and other environmental threats… “Decisions today regarding the environment and natural resources can affect our security for generations; consequently, our national security planning is incorporating environmental analyses as never before. In addition, we have a full diplomatic agenda, working unilaterally, regionally and multilaterally to forge agreements to protect the global environment.”
October 1998: The White House. A National Security Strategy for a New Century. Washington, D.C. https://history.defense.gov/Historical-Sources/National-Security-Strategy
“Decisions today regarding the environment and natural resources can affect our security for generations. Environmental threats do not heed national borders and can pose long-term dangers to our security and well-being. Natural resource scarcities can trigger and exacerbate conflict. Environmental threats such as climate change, ozone depletion and the transnational movement of hazardous chemicals and waste directly threaten the health of U.S. citizens.”
December 2000: The White House. A National Security Strategy for a Global Age. Washington D.C. https://history.defense.gov/Historical-Sources/National-Security-Strategy
“Natural resource scarcities can trigger and exacerbate conflict, and phenomena such as climate change, toxic pollution, ocean dumping, and ozone depletion directly threaten the health and well-being of Americans and all other individuals on Earth.”
February 2015: The White House. National Security Strategy. Washington, D.C. https://history.defense.gov/Historical-Sources/National-Security-Strategy
“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.”
October 2022: The National Security Strategy. The White House, Washington, D.C. https://www.dau.edu/sites/default/files/Migrated/CopDocuments/Biden-Harris-Administrations-National-Security-Strategy-10.2022.pdf
“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.”
Other intelligence agency assessments also regularly highlight the threat of climate change to US security interests, including the threat of expanded migration and immigration pressures, with reports going back more than two decades. None of these assessments are addressed in the DoE report. A small selection is included below. A complete list can be found at http://www.gleick.com.
October 2003: U.S. Department of Defense. Office of Net Assessment. An Abrupt Climate Change Scenario and Its Implications for United States National Security: Jet Propulsion Laboratory Pasadena, CA. P. Schwartz and D. Randall. https://apps.dtic.mil/sti/citations/ADA469325
“The report explores how such an abrupt climate change scenario could potentially de-stabilize the geo-political environment, leading to skirmishes, battles, and even war due to resource constraints such as:
1) Food shortages due to decreases in net global agricultural production
2) Decreased availability and quality of fresh water in key regions due to shifted precipitation patterns, causing more frequent floods and droughts
3) Disrupted access to energy supplies due to extensive sea ice and storminess.”
May 2008: U.S. Army War College. Global Climate Change National Security Implications. (Ed. Carolyn Pumphrey). Strategic Studies Institute, Carlisle, Pennsylvania. https://press.armywarcollege.edu/monographs/65/
“Climate change, as a security problem, needs to be addressed at multiple levels. First, there is the root problem—the changing climate. Second, there is the human misery it will engender—we are talking of such things as poverty, disease, displacement, and social
inequality. Third, there is the instability and/or changing strategic picture that will spring from all of the above. Simply put, our response needs to encompass at least three things: slowing down the rate of climate change and preparing to adapt to changes that cannot be avoided; taking steps to alleviate social distress; and preparing to cope with potential conflicts.”
June 2008: U.S. Department of Defense. National Defense Strategy: Washington, D.C.
http://nssarchive.us/national-defense-strategy-2008/
“Over the next twenty years physical pressures – population, resource, energy, climatic and environmental – could combine with rapid social, cultural, technological and geopolitical change to create greater uncertainty. This uncertainty is exacerbated by both the unprecedented speed and scale of change, as well as by the unpredictable and complex interaction among the trends themselves. Globalization and growing economic interdependence, while creating new levels of wealth and opportunity, also create a web of interrelated vulnerabilities and spread risks even further, increasing sensitivity to crises and shocks around the globe and generating more uncertainty regarding their speed and effect.
Current defense policy must account for these areas of uncertainty. As we plan, we must take account of the implications of demographic trends, particularly population growth in much of the developing world and the population deficit in much of the developed world. The interaction of these changes with existing and future resource, environmental, and climate pressures may generate new security challenges…
These risks will require managing the divergent needs of massively increasing energy demand to maintain economic development and the need to tackle climate change.”
February 12, 2009: Office of the Director of National Intelligence. Statement of Dennis C. Blair. Annual Threat Assessment of the Intelligence Community for the Senate Select Committee on Intelligence. https://www.dni.gov/files/documents/Newsroom/Testimonies/20090212_testimony.pdf
“The Intelligence Community recently completed a National Intelligence Assessment on the national security impacts of global climate change to 2030. The IC judges global climate change will have important and extensive implications for US national security interests over the next 20 years… We judge the most significant impact for the United States will be indirect and result from climate driven effects on many other countries and their potential to seriously affect US national security interests. We assess climate change alone is unlikely to trigger state failure in any state out to 2030, but the impacts will worsen existing problems such as poverty, social tensions, environmental degradation, ineffectual leadership, and weak political institutions. Climate change could threaten domestic
stability in some states, potentially contributing to intra- or, less likely, interstate conflict, particularly over access to increasingly scarce water resources. We judge economic migrants will perceive additional reasons to migrate because of harsh climates, both within nations and from disadvantaged to richer countries.”
2009: U.S. Army War College. Taking Up the Security Challenge of Climate Change. R.J. Parsons. Carlisle, Pennsylvania. https://apps.dtic.mil/dtic/tr/fulltext/u2/a508287.pdf
“Climate change, in which man-made global warming is a major factor, will likely have dramatic and long lasting consequences with profound security implications, making it a challenge the United States must urgently take up. The security implications will be most pronounced in places where the effects of climate change are greatest, particularly affecting weak states already especially vulnerable to environmental destabilization.”
2009: Institute for Defense Analyses. Climate Change Effects: Issues for International and US National Security: IDA-D3906. Alexandria, Virginia. https://apps.dtic.mil/dtic/tr/fulltext/u2/a527880.pdf
“Prior to 2006, the security implications of climate change effects received only occasional attention. The level of interest rose exponentially over the following eighteen months. Now climate change is widely recognized as a threat that is tightly interconnected with other 21st century challenges such as energy security, terrorism, proliferation of weapons of mass destruction, and organized crime. This paper provides an overview of current views on how the consequences of warming temperatures, rising sea levels, disturbances in precipitation patterns, and increases in extreme weather events might impact global stability. The purpose is to raise awareness of the full scope of climate-related security concerns. It also identifies opportunities to strengthen the U.S. in preparing to respond to the changes in security tensions that could accompany climate impacts.”
February 2, 2010: Office of the Director of National Intelligence. Statement for the Record. Dennis C. Blair. Annual Threat Assessment of the Intelligence Community for the Senate Select Committee on Intelligence. https://www.dni.gov/files/documents/Newsroom/Testimonies/20100202_testimony.pdf
“We continue to assess that global climate change will have wide-ranging implications for US national security interests over the next 20 years because it will aggravate existing world problems—such as poverty, social tensions, environmental degradation, ineffectual leadership, and weak political institutions—that threaten state stability.”
October 2011: U.S. Department of Defense. Defense Science Board Task Force Report: Trends and Implications of Climate Change for National and International Security. http://www.fas.org/irp/agency/dod/dsb/climate.pdf
“Changes in climate patterns and their impact on the physical environment can create profound effects on populations in parts of the world and present new challenges to global security and stability. Failure to anticipate and mitigate these changes increases the threat of more failed states with the instabilities and potential for conflict inherent in such failures.”
2013: Central Intelligence Agency and the U.S. National Research Council. Climate and Social Stress: Implications for Security Analysis. National Research Council. The National Academies Press, Washington, D.C. https://doi.org/10.17226/14682.
“Climate change can reasonably be expected to increase the frequency and intensity of a variety of potentially disruptive environmental events--slowly at first, but then more quickly. It is prudent to expect to be surprised by the way in which these events may cascade, or have far-reaching effects. During the coming decade, certain climate-related events will produce consequences that exceed the capacity of the affected societies or global systems to manage; these may have global security implications.”
2014: U.S. Department of Defense. Climate Change Adaptation Roadmap. https://www.usni.org/sites/default/files/inline-files/242845848-Read-DoD-report-2014-Climate-Change-Adaptation-Roadmap.pdf
“Among the future trends that will impact our national security is climate change. Rising global temperatures, changing precipitation patterns, climbing sea levels, and more extreme weather events will intensify the challenges of global instability, hunger, poverty, and conflict. They will likely lead to food and water shortages, pandemic disease, disputes over refugees and resources, and destruction by natural disasters in regions across the globe.
“In our defense strategy, we refer to climate change as a “threat multiplier” because it has the potential to exacerbate many of the challenges we are dealing with today – from infectious disease to terrorism. We are already beginning to see some of these impacts.”
2014: U.S. Department of Defense. Quadrennial Defense Review. https://history.defense.gov/Historical-Sources/Quadrennial-Defense-Review/
“The impacts of climate change may increase the frequency, scale, and complexity of future missions, including defense support to civil authorities, while at the same time undermining the capacity of our domestic installations to support training activities. Our actions to increase energy and water security, including investments in energy efficiency, new technologies, and renewable energy sources, will increase the resiliency of our installations and help mitigate these effects.
"Climate change poses another significant challenge for the United States and the world at large. As greenhouse gas emissions increase, sea levels are rising, average global temperatures are increasing, and severe weather patterns are accelerating. These changes, coupled with other global dynamics, including growing, urbanizing, more affluent populations, and substantial economic growth in India, China, Brazil, and other nations, will devastate homes, land, and infrastructure. Climate change may exacerbate water scarcity and lead to sharp increases in food costs. The pressures caused by climate change will influence resource competition while placing additional burdens on economies, societies, and governance institutions around the world. These effects are threat multipliers that will aggravate stressors abroad such as poverty, environmental degradation, political instability, and social tensions – conditions that can enable terrorist activity and other forms of violence.”
July 23, 2015: U.S. Department of Defense. National Security Implications of Climate-Related Risks and a Changing Climate: Report to Congress. Submitted in response to a request contained in Senate Report 113-211, H.R. 4870, the Department of Defense Appropriations Bill, 2015. https://man.fas.org/eprint/dod-climate.pdf
“DoD recognizes the reality of climate change and the significant risk it poses to U.S. interests globally. The National Security Strategy, issued in February 2015, is clear that climate change is an urgent and growing threat to our national security, contributing to increased natural disasters, refugee flows, and conflicts over basic resources such as food and water. These impacts are already occurring, and the scope, scale, and intensity of these impacts are projected to increase over time.”
September 21, 2016: U.S. National Intelligence Council. Implications for U.S. National Security of Anticipated Climate Change. NIC WP 2016-01. https://www.dni.gov/files/documents/Newsroom/Reports%20and%20Pubs/NIC_White_Paper_Climate_Change.pdf
“Long-term changes in climate will produce more extreme weather events and put greater stress on critical Earth systems like oceans, freshwater, and biodiversity. These in turn will almost certainly have significant effects, both direct and indirect, across social, economic, political, and security realms during the next 20 years. These effects will be all the more pronounced as people continue to concentrate in climate-vulnerable locations, such as coastal areas, water-stressed regions, and ever-growing cities… “Climate change and its resulting effects are likely to pose wide-ranging national security challenges for the United States and other countries over the next 20 years.”
July 23, 2015: U.S. Department of Defense. National Security Implications of Climate-Related Risks and a Changing Climate: Report to Congress. Submitted in response to a request contained in Senate Report 113-211, H.R. 4870, the Department of Defense Appropriations Bill, 2015. https://man.fas.org/eprint/dod-climate.pdf
“This report responds to the Congressional request to the Department of Defense to identify the most serious and likely climate-related security risks for each Combatant Command, the ways in which the Combatant Commands are integrating mitigation of these risks into their planning processes, and a description of the resources required for an effective response.”
“DoD recognizes the reality of climate change and the significant risk it poses to U.S. interests globally. The National Security Strategy, issued in February 2015, is clear that climate change is an urgent and growing threat to our national security, contributing to increased natural disasters, refugee flows, and conflicts over basic resources such as food and water. These impacts are already occurring, and the scope, scale, and intensity of these impacts are projected to increase over time.”
November 6, 2018: Statement of the Chairman of the Joint Chiefs: Climate Change a Source of Conflict Around the World. https://climateandsecurity.org/2018/11/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.”
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. https://climateandsecurity.org/2020/03/u-s-secretary-of-defense-and-chairman-of-the-joint-chiefs-climate-change-impacts-national-security/
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.”
March 2021: U.S. National Intelligence Council. Global Trends 2040: A More Contested World. https://climateandsecurity.org/wp-content/uploads/2025/01/GlobalTrends_2040_for_web1.pdf
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.”
April 9, 2021: Office of the Director of National Intelligence. Annual Threat Assessment of the U.S. Intelligence Community. https://www.globalsecurity.org/jhtml/jframe.html#https://www.globalsecurity.org/intell/library/reports/2021/us-ic_annual-threat-assessment_odni_20210409.pdf|||Annual%20Threat%20Assessment%20of%20the%20Intelligence%20Community
“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.”
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. https://www.dni.gov/files/ODNI/documents/assessments/NIE_Climate_Change_and_National_Security.pdf
“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 2021. The White House. Report on the Impact of Climate Change on Migration. Washington, D.C. https://bidenwhitehouse.archives.gov/wp-content/uploads/2021/10/Report-on-the-Impact-of-Climate-Change-on-Migration.pdf
“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.
February 2022. Office of the Director of National Intelligence. Annual Threat Assessment of the U.S. Intelligence Community. https://climateandsecurity.org/wp-content/uploads/2025/01/ATA-2022-Unclassified-Report.pdf
“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.
February 6, 2023. Office of the Director of National Intelligence. Annual Threat Assessment of the U.S. Intelligence Community https://www.dni.gov/files/ODNI/documents/assessments/ATA-2023-Unclassified-Report.pdf
“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.”
February 5, 2024. Office of the Director of National Intelligence. Annual Threat Assessment of the U.S. Intelligence Community. https://climateandsecurity.org/wp-content/uploads/2025/01/ATA-2024-Unclassified-Report.pdf
“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.”
2. Impacts of Climate Change on US Military Forces, Bases, and Operations Have Been Ignored by the July 23, 2025 DoE Climate Working Group Report
The second major category of security threats of climate change ignored by the 2025 DoE Climate report is the impact of climate change on US military forces, bases, and operations. Again, these threats have long been recognized and reported, with reports going back to 1990. Below is a subset of key documents and references that any honest assessment of climate change impacts should have considered. A full annotated list of documents is available at www.gleick.com.
May 1990: U.S. Navy War College. Global Climate Change: Implications for the United States: Newport, RI (T.P. Kelley). http://documents.theblackvault.com/documents/weather/climatechange/globalclimatechange-navy.pdf
“Naval operations in the coming half century may be drastically affected by the impact of global climate change. For the Navy to be fully prepared for operations in this future climate environment, resources of both mind and money must be committed to the problem. The Navy’s research and analysis efforts are required to support the sound planning evolution necessary to insure the Navy’s capabilities in this future climate environment.”
October 2007: U.S. Departments of the Navy, the Marine Corps and the Coast Guard. A Cooperative Strategy for 21st Century Sea Power. https://www.revolvy.com/topic/A%20Cooperative%20Strategy%20for%2021st%20Century%20Seapower
“Climate change is gradually opening up the waters of the Arctic, not only to new resource development, but also to new shipping routes that may reshape the global transport system. While these developments offer opportunities for growth, they are potential sources of competition and conflict for access and natural resources.
The effects of climate change may also amplify human suffering through catastrophic storms, loss of arable lands, and coastal flooding, could lead to loss of life, involuntary migration, social instability, and regional crises.”
November 10, 2009: U.S. Department of the Navy. Arctic Roadmap. http://purl.fdlp.gov/GPO/gpo7867
From transmittal memo, Vice Chief of Naval Operations. “Scientific evidence indicates that the Earth’s climate is changing, and the most rapid changes are occurring in the Arctic. Because the Arctic is primarily a maritime environment, the Navy must consider the changing Arctic in developing future policy, strategy, force structure, and investment.”
February 18, 2010: United States Joint Forces Command. The Joint Operating Environment (JOE), Ready for Today, Preparing for Tomorrow, Norfolk, Virginia. https://fas.org/man/eprint/joe2010.pdf
The impact of climate change, specifically global warming and its potential to cause natural disasters and other harmful phenomena such as rising sea levels, has become a concern… Climate change is included as one of the ten trends most likely to impact the Joint Force.
2010: U.S. Department of the Navy. Climate Change Road Map: Task Force Climate Change. http://www.navy.mil/navydata/documents/CCR.pdf
“Climate change is a national security challenge with strategic implications for the Navy. Climate change will lead to increased tensions in nations with weak economies and political institutions. While climate change alone is not likely to lead to future conflict, it may be a contributing factor. Climate change is affecting, and will continue to affect, U.S. military installations and access to natural resources worldwide. It will affect the type, scope, and location of future Navy missions. The Navy Climate Change Roadmap outlines the Navy’s approach to observing, predicting, and adapting to climate change.
A preponderance of global observational evidence shows the Arctic Ocean is losing sea ice, global temperatures are warming, sea level is rising, large landfast ice sheets (Greenland and Antarctic) are losing ice mass, and precipitation patterns are changing. While there has been criticism on the details of the methods and results found in reports published by the IPCC and other entities, the Navy acknowledges that climate change is a national security challenge with strategic implications for the Navy. Climate change may influence the type, scope, and location of future Navy missions through its effects on the distribution and availability of natural resources (e.g., water, agriculture, fisheries, coastal areas, etc.). Economically unstable regions will be more vulnerable to the effects of climate change, and climate change will be one of several factors that may increase instability. Climate change is affecting, and will continue to affect, U.S. military installations worldwide. Melting permafrost is degrading roads, foundations, and structures on DoD and USCG installations in Alaska. Droughts in the southeast and southwest U.S. are challenging water resource management. Sea level rise and storm surge will lead to an
increased likelihood of inundation of coastal infrastructure, and may limit the availability of overseas bases.”
March 14, 2017: Statement to the U.S. Senate Armed Forces Committee by Secretary of Defense, James Mattis. https://climateandsecurity.org/2018/11/21/update-chronology-of-u-s-military-statements-and-actions-on-climate-change-and-security-2017-2018/ https://www.propublica.org/article/trumps-defense-secretary-cites-climate-change-national-security-challenge?utm_campaign=bt_twitter&utm_source=twitter&utm_medium=social
“Climate change is impacting stability in areas of the world where our troops are operating today. It is appropriate for the Combatant Commands to incorporate drivers of instability that impact the security environment in their areas into their planning… “Climate change can be a driver of instability and the Department of Defense must pay attention to potential adverse impacts generated by this phenomenon.”
July 26, 2017: U.S. Department of Defense. Statement by Assistant Secretary of Defense Niemeyer: Climate Plays Pivotal Role in Military Mission. https://climateandsecurity.org/2017/07/assistant-secretary-niemeyer-climate-plays-a-pivotal-role-in-dods-ability-to-execute-our-missions/
“Yes, the climate plays a pivotal role in DoD’s ability to execute our missions. The Department has always considered risks from climate related effects such as high winds, precipitation, extreme temperatures and drought to mission readiness and execution. As Secretary Mattis has stated “the Department should be prepared to mitigate any consequences of a changing climate, including ensuring that our shipyards and installations will continue to function as required… I agree that the Department must be prepared for extreme weather, but in the long run DoD must plan now to ensure it can meet future mission requirements to remain a ready and resilient fighting force.
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.) https://www.gao.gov/products/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. https://climateandsecurity.org/wp-content/uploads/2019/07/implications-of-climate-change-for-us-army_army-war-college_2019.pdf
“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.”
May 14, 2021: U.S. Army. Addressing Climate Change Threats. https://www.army.mil/standto/archive/2021/05/14/
“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.”
September 1, 2021: U.S. Department of Defense. Climate Adaptation Plan https://www.esd.whs.mil/Portals/54/Documents/FOID/Reading%20Room/Other/22-F-1350_Climate_Action_Plan_01.pdf
“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.”
February 8, 2022: U.S. Army. U.S. Army Climate Strategy. https://www.army.mil/e2/downloads/rv7/about/2022_Army_Climate_Strategy_Implementation_Plan_FY23-FY27.pdf
“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.”.
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 https://media.defense.gov/2022/Apr/15/2002977604/-1/-1/1/DODIG-2022-083.PDF
“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. https://www.secnav.navy.mil/Climate/Shared%20Documents/Climate%20Action%202030.pdf
“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.”
January 2023. U.S. Coast Guard. Climate Framework. https://climateandsecurity.org/wp-content/uploads/2025/01/USCG-CLIMATE-FRAMEWORK_JAN2023_FINAL.pdf
“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.”
July 2023. U.S. Department of the Air Force. Climate Campaign Plan. https://www.af.mil/Portals/1/documents/2023SAF/DAF_Climate_Campaign_Plan.pdf
“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.”
3. Summary Comment
The failure of the July 2025 DoE Climate Working Group report to include the science and assessments of the threats of climate change for US national security and the effectiveness of US military forces and operations is inexcusable, given the long and extensive publicly available evidence of these threats, but it reflects the narrow perspectives of the authors, their “cherry-picking” of evidence that only includes information favorable to their pre-selected conclusions and excludes the vast body of information on the adverse consequences of greenhouse gas emissions, and the shoddy analysis of the overall report.
Submitted: September 2, 2025 by Dr. Peter H. Gleick, member, US National Academy of Sciences.
