Is Climate Change a National Security Issue?

The case for linking climate change and national security is robust but imperfect, and today there is a serious debate about whether it makes sense.

Around the planet there is growing momentum to define climate change as a security issue and hence as an agenda-topping problem that deserves significant attention and resources. In December 2010, for example, while poised to start a two-year term on the United Nations Security Council, Germany announced its intention to push to have climate change considered as a security issue in the broadest sense of the term. Germany’s objective captures a sentiment that has been expressed in many venues, including several recent high-level U.S. national security documents. The May 2010 version of the National Security Strategy repeatedly groups together violent extremism, nuclear weapons, climate change, pandemic disease, and economic instability as security threats that require strength at home and international cooperation to address adequately. The February 2010 Quadrennial Defense Review links climate change to future conflict and identifies it as one of four issues in which reform is “imperative” to ensure national security. This sentiment has met resistance, however, and today there is a serious debate about whether linking climate change to security, and especially to national security, makes sense.

The case in support of this linkage integrates three strands of argument. The first builds on efforts to expand a very narrow definition of the term “national security” that was dominant during the 20th century. The narrow meaning was shaped by a specific set of events. After World Wars I and II, a third major war involving nuclear weapons was widely regarded as the single greatest threat to the survival of the United States and indeed to much of the world. In response to this perception, the National Security Act of 1947 sought “to provide for the establishment of integrated policies and procedures for the departments, agencies, and functions of the Government relating to the national security.” Its focus was on strengthening the country’s military and intelligence capabilities, and the government was supported in this effort through the rapid buildup of independent think tanks and security studies programs at colleges and universities throughout the country. National security was seen by most experts as a condition that depended on many factors, and hence the broadest goals of the national security community were to build and maintain good allies, a strong economy, social cohesion and trust in government, democratic processes, civil preparedness, a skilled diplomatic corps, and powerful, forward-looking military and intelligence agencies. For more than four decades after World War II, however, efforts to improve national security were assessed against estimates of the threats of nuclear war and communist expansion, and invariably emphasized the paramount importance of military and intelligence assets. National security was largely about the military and intelligence capabilities necessary for preventing or winning a major war.

Because some resources are becoming increasingly scarce and others increasingly valuable, the prospects for environmental factors gaining weight in the security arena appear robust.

In the 1990s, this powerful architecture was challenged in several ways. First, with the rapid and largely unexpected collapse of the Soviet Union came the question: Since there were no other countries likely to launch a full-scale nuclear attack against us, could we now reduce our large military and intelligence expenditures and invest in other areas? Second, as the 20th century drew to a close, it became evident that the nature of violent conflict had changed from short, brutal, and decisive interstate wars to long, somewhat less brutal, and frequently inconclusive civil wars. Under the quagmire conditions of this new generation of warfare, superior military capability did not translate inexorably into victory.

Finally, having spent so much time focused on the particular threat of military-to-military conflict, analysts asked if we should now be looking at threats more broadly and even considering alternative ways of thinking about security. By mid-decade, human security and some variant of global security had gained support as alternative or complementary ways of thinking about security. Further, in the United States and abroad, conceptions of security threats expanded to include issues such as terrorism, disease, and global economic crisis.

As the era of great wars receded, some observers concluded that violence was now mainly structural, a fact hidden or ignored during the Cold War, when the threat of large-scale violence was linked to an ideologically based power struggle. From the structuralist perspective, victory and defeat were unproductive ways of thinking about security. Instead, improvements in security depended on extensive reform of the global economy, the international system of states, the divide between nature and civilization, and entrenched patterns of gender and ethnic inequality. Many others agreed that our new era of security underscored the limits of military force, which had been the centerpiece of much 20th-century security policy. Hence, at the very least, we needed to carefully rethink security and reconsider what was needed to provide it, a reflection that would certainly lead to important, if not necessarily structural, change.

One of the issues invigorating all of these challenges to Cold War security thinking (challenges that, incidentally, were not entirely new and had been voiced at various times throughout the 20th century) was a growing concern about environmental degradation and stress. Indeed, just as the Cold War ended, the Rio Summit on Environment and Development catalyzed global attention around climate change, biodiversity loss, and deforestation; underscored the need for national, regional, and global conservation strategies; and introduced a transformative vision that involved shifting the entire planet onto the path of sustainable development. In this context, a handful of observers argued that, in light of the trends observed by scientists from multiple disciplines, the Cold War peace dividend should be redirected toward environmental rescue, and that failing to do this could push the world toward higher and higher levels of insecurity.

The second strand woven into the case for integration picks up on this latter intuition. A central question of this strand of analysis is: What could happen if we fail to act to promote sustainable development and allow alarming environmental trends to continue more or less unchecked? Building on arguments that extend at least as far back as 18th-century demographer Thomas Malthus, who worried that population growth would outstrip increases in food production, leading to a period of intense famine, war, and disease, a contemporary generation of scholars used case studies and other methodologies to explore linkages between environmental stress and two national security challenges: violent conflict and state failure. Although simple, causal relationships have proved elusive—a generic problem in the study of war and peace—patterns have been identified that many have found compelling. To simplify what is becoming a rich field of inquiry, certain natural resources, especially when they suddenly become scarce (water or arable land) or acquire high value (diamonds or timber) can become a significant factor affecting government behavior, development prospects, population flows, and forms of competition. Under certain conditions, such challenges trigger innovation and adaptation, but under other conditions they contribute to violent conflict and other types of insecurity. Because some resources are becoming increasingly scarce and others increasingly valuable, the prospects for environmental factors gaining weight in the security arena appear robust.


Climate change and national security

National security concerns Weakening of elements of national power State failure Disruption and violent conflict
Climate change impacts
Changes in water distribution Job loss in rural areas Reduce agricultural outputs, basic needs unmet Increased competition for water

Severe weather events Undermine economic strength Funds diverted to disaster relief, away from infrastructure, etc. Displace people into areas where they are not welcome

Heat waves Pandemics Greater demands to meet basic needs Riots in urban areas

Drought Undermine economic development Deepen social inequality as some groups control food and water Displace people into areas where they are not welcome

Sea-level rise Destroy coastal military bases Increase inequality and promote extremism as some people lose land Put the survival of states such as the Maldives and Bangladesh at risk

Flooding Reduce military effectiveness in the field Destroy critical infrastructure Increase urban strife

The examples in Table 1 are not meant to be definitive but rather to indicate how climate effects could affect national security. Clearly many of these examples could be reiterated in many boxes.

Scholars such as Thomas Homer-Dixon, for example, focus on the adverse social effects of scarcity of water, cropland, and pasture. Scarcity, he argues, results from a decrease in the supply of a resource, an increase in the demand for a resource, or a socially engineered change in access to a resource. Under conditions of resource scarcity, Homer-Dixon contends that developing countries may experience resource capture (one group seizes control of the resource) or ecological marginalization (people are forced to move into resource-poor lands), either of which may contribute to violent conflict. Continuing this trajectory of thought, Colin Kahl argues that resource scarcity may generate state failure ( a collapse of functional capacity and social cohesion) or state exploitation (in which a collapsing state acts to preserve itself by giving greater access to natural resources to groups it believes can prop it up). Although some researchers are not persuaded by arguments linking environmental stress to state failure and violent conflict, many others regard them as compelling, and many policymakers and practitioners have absorbed these arguments into their world views.

The third strand of analysis involved in integrating climate change and national security builds on the environment and security literature by focusing on the real and potential societal effects of climate change. Climate change scientists are observing changes in the distribution of water, increases in the intensity of severe weather events, longer heat waves, longer droughts, and sea-level rise and flooding. Some worry that continued global warming will move the planet across critical thresholds, causing “black swan” events such as massive gas releases, rapid glaciation, or microbial explosions. There are several ways in which such changes could generate threats to national security.

Summarizing the discussion above, challenges to national security can be organized into three groupings: anything that weakens the elements of national power; contributes to state failure; or leads to, supports, or amplifies the causes of violent conflict. Climate change has the potential to have a negative impact in each of these domains (see Table 1).

National power. National power depends on many variables, including environmental factors such as geography and resource endowment, military capacity, intelligence capacity, and a range of social factors, including population size and cohesiveness, regime type, and the size and performance of the national economy. Climate change has the potential to affect all of these elements of national power. For example, militaries may be less effective at projecting and exercising power if they have to operate in flooded terrain or during a heat wave. Warming that affects land cover could reduce a country’s renewable resource base. Intelligence is difficult to gather and analyze in a domain marked by uncertainty about social effects.

Perhaps the area of greatest concern, however, is that climate change might undermine economic development, especially in poor and fragile states. The economist Paul Collier has argued that the bottom billion people on the planet currently live in states that are failing to develop or are falling apart. He contends that these states are often enmeshed in interactive conditions and processes that inhibit development: chronic violent conflict, valuable natural resources such as oil or diamonds that groups vie to control, unstable neighboring countries creating chronic transboundary stress, and government corruption and inefficiency. An increase in costly and hard-to-manage events such as floods, droughts, heat waves, fires, pandemics, and crop failures would probably be an enormous additional burden on these countries, introducing a daunting new layer of development challenges and hence weakening a central element of national power.

State failure. The authors of the 2009 report of the International Federation of the Red Cross and Red Crescent Societies wrote that, “The threat of disaster resulting from climate change is twofold. First, individual extreme events will devastate vulnerable communities in their path. If population growth is factored in, many more people may be at significant risk. Together, these events add up to potentially the most significant threat to human progress that the world has seen. Second, climate change will compound the already complex problems of poor countries, and could contribute to a downward development spiral for millions of people, even greater than has already been experienced.” The 2010 report notes that the cost of climate-related disasters tripled from 2009 to 2010 to nearly $110 billion. Disasters are costly, and the costs appear to be mounting dramatically. From the perspective of state failure, disasters are deeply alarming because they shift scarce funds away from critical activities such as building infrastructure, investing in skills development, and implementing employment and poverty-reduction programs, and into emergency relief. Such a shift can have a direct and very negative impact on a government’s functional capacity.

The same argument can be advanced for the diffuse longer-term effects of climate change that might affect food security, public health, urban development, rural livelihoods, and so on. Under conditions of either abrupt or incremental change, people may be displaced into marginal lands or unwelcoming communities, enticed by extremist ideology, compelled to resort to crime in order to survive, or take up arms, all of which risk overtaxing the government, deepening social divisions, and breeding distrust and anger in the civilian population.

The gravest climate change threat, however, is that states will fail because they can no longer function as their territories disappear under rising seas, an imminent threat to the Maldives and some 40 other island states. Glacial-outburst floods might cause similar devastation in countries such as Nepal, and a change in the ocean conveyer that warms the northeast Atlantic Ocean could cause countries such as the United Kingdom to disappear under several feet of ice within a few years. These starkly existential threats have become the single most important national security issue for many vulnerable countries. Last year, the president of the Maldives held a cabinet meeting underwater to bring attention to this type of threat.

Violent conflict. Building on the insights of Homer-Dixon, Kahl, and many others, it is reasonable to suggest that climate-induced resource scarcities could become key drivers of violent conflict in the not too distant future. On this front, another area of particular concern has to do with so-called climate refugees. In 2006, Sir Nicholas Stern predicted that 200 million people could be permanently displaced by mid-century because of rising sea levels, massive flooding, and long, devastating droughts. Large flows of poor people from rural to urban environments and across ethnic, economic, and political boundaries would cause epic humanitarian crises and be extremely difficult to manage. One can easily imagine such stress becoming implicated in violent conflict and other forms of social disruption.

Stern’s prediction is of the back-of-the-envelope variety and has faced criticism from researchers such as Henrik Urdal, who argues that the “potential for and challenges related to migration spurred by climate change should be acknowledged, but not overemphasized. Some forms of environmental change associated with climate change like extreme weather and flooding may cause substantial and acute, but mostly temporal, displacement of people. However, the most dramatic form of change expected to affect human settlements, sea-level rise, is likely to happen gradually, as are processes of soil and freshwater degradation.” The bottom line, however, is that nobody knows for sure what the scale and social effects of climate-increased population flows will be.

The basic concerns suggested above are well captured in the many publications that followed the publication of the 2007 Intergovernmental Panel on Climate Change (IPCC) reports. For example, the CNA Corporation report National Security and the Threat of Climate Change concluded that “climate change acts as a threat multiplier for instability in some of the most volatile regions of the world.” Further, it predicted that “projected climate change will add to tensions even in stable regions of the world.” Similarly, the German Advisory Council on Global Change’s report World in Transition: Climate Change as a Security Risk said that “Climate change will overstretch many societies’ adaptive capacities within the coming decades.” The tenor of much recent writing is that climate change will weaken states that are already fragile, and it will contribute to violent conflict, intensify population displacement, increase vulnerability to disasters, and disrupt poverty alleviation programs, especially in South Asia, the Middle East, and sub-Saharan Africa, where large numbers of people, widespread poverty, fragile governments, and agricultural economies conspire to create heightened vulnerability.

The counterargument

The case against linking climate change to national security raises concerns about each of the strands of argument outlined above and is rather intuitive. Insofar as the language of national security itself is concerned, three important criticisms have been advanced. In a series of editorials in Foreign Policy magazine, Stephen Walt contends that a careful reading of the arguments about climate change made in the CNA report and in similar documents makes it clear that this is simply not a national security issue, at least not for the United States. In the foreseeable future, climate change may cause serious problems in places such as Bangladesh that spill over into places such as India, but these problems and the responses they will trigger are better described as humanitarian issues. For Walt and other realist thinkers, national security is about the survival of the state, and apart from black swan events we can imagine but not predict or prepare for, threats of this magnitude have been and continue to be threats of military aggression by other states. Walt asks us to consider what we gain in terms of analysis, strategy, and policy formulation by expanding the domain of national security into areas where immediate or near-term threats to the survival or even well-being of the United States are vague or unknown, even though the rhetoric used to describe them is often urgent and dramatic.

The tenor of much recent writing is that climate change will contribute to violent conflict, intensify population displacement, increase vulnerability to disasters, and disrupt poverty alleviation programs.

A very different concern comes from scholars such as Daniel Deudney, Barry Buzan, and Ole Waever, who worry about militarizing or securitizing climate change and the environment. Like Walt, they are not suggesting that climate change is a trivial matter; rather, they worry about whether framing it as a national security issue and thus linking it to military and intelligence tools is wise. This linkage, they suggest, might inhibit certain forms of global cooperation by drawing climate change into the zero-sum mentality of national security. It might encourage Congress to authorize significant funds, a good thing in principle, but insofar as these funds are expended through the defense community, this may prove a costly and inefficient way of promoting adaptation, mitigation, and disaster response. It might encourage the government to conclude that extraordinary measures are acceptable to fight climate change—actions that could make many scientists, development specialists, social entrepreneurs, business leaders, and environmentalists uncomfortable.

Finally, a third concern has been expressed within the United Nations (UN), largely in response to efforts by the secretary general and by countries such as Germany to frame climate change as an issue that should be considered by the UN Security Council. On the one hand, this could give the five countries of the world that are permanent members of the Security Council—China, France, Russia, the United Kingdom, and the United States—enormous leverage over this issue, and not all of the other member countries are convinced that this would lead to good, fair, and effective outcomes. On the other hand, some countries in the UN, especially the G77 countries, think that it may prove to be in their long-term interest to have climate change framed as primarily a development issue rather than as a national or even global security issue. Such a frame could serve as the basis for lucrative compensation payments, development assistance, and special funds for adaptation and mitigation. In short, then, linking climate change and national security may compromise responses to the former, muddy the rationale of the latter, reinforce global inequities, and reduce development assistance as resources are transferred to humanitarian and military activities.

The second strand of argument has to do with the relationship between environmental stress and major outcomes such as violent conflict and state failure. Critics of this literature, such as Nils Petter Gleditsch and Marc Levy, point to its methodological and analytical weaknesses. To date, studies have been inconclusive. There appears to be a correlation between certain forms of environmental change, such as sudden changes in water availability, and violent conflict or state failure, but the findings are tentative and must compete with other variables that correlate nicely with disastrous social outcomes. Case studies are often quite persuasive, but they are in some sense easier to shape and their authors may be selecting for relationships that in fact are atypical.

Insofar as the case for integrating climate change and national security draws on arguments that environmental stress contributes to violent conflict and state failure, these skeptics emphasize that this literature is young and flawed by speculation. A frequent concern is that after the initial outburst of largely theoretical claims advanced in the 1990s, there has not been much progress in weeding through these claims and bolstering and clarifying those that are most promising from the perspective of empirical data. Moreover, very little has been done to estimate the extent to which environmental stress has generated effective positive responses such as innovation, adaptation, and cooperation. If for every Haiti there are a dozen Costa Ricas, then the alarm bells may be ringing too loudly.

Finally, the third strand of the case for integrating climate change and national security is rooted largely in the IPCC reports, and especially AR4, released in 2007. But although increases in the amount of carbon in the atmosphere, the severity of storms, the average global temperature, and so on are well documented, the social effects of these trends are far more speculative. Will climate change really tend to intensify the (possibly weak) relationships between environmental stress and national security? Even if it does, is securitizing these relationships wise, or should they be cast more explicitly in terms of humanitarian crises, global inequities, development challenges, population displacements, and poverty alleviation?

The Danish economist Bjorn Lomberg has been vocal in this arena, arguing that the environmental/climate security community underestimates the vast stocks of human ingenuity that are available to ease adaptation. Lomberg argues further that it is not at all clear that investments in climate change response are the best investments to make in terms of the safety and welfare of the human species. Here the idea of the fungibility of different forms of capital is relevant. If over the next 50 years we can make great gains per dollar invested in technologies that can be used for multiple purposes, and much smaller gains in terms of shifting the alarming global trend in carbon emissions, is the latter really a wise course of action? A large stock of technological capital, enabled by shrewd investments today, might be far more beneficial to the current poor and to all future generations than steps that marginally reduce greenhouse gas emissions or add small amounts of forest cover, or than steps that do much more along these lines but only by radically reducing investments elsewhere.

Action or lethargy?

The case for linking climate change and national security is robust but imperfect. This is partly because there remains considerable uncertainty about how climate change will play out in different social contexts and partly because the term national security is loaded with expectations and preferences that some analysts find worrisome.

If one finds the linkage persuasive, then there is much the United States can and should be doing on this front. For the past decade, innovation and response have taken place mainly at the state and city levels. Although this activity has in many ways been remarkable, it has not been uniform across the United States, and it connects poorly into larger global initiatives. In this latter regard, the United States has been particularly lethargic, a lethargy nourished by massive but not clearly successful investments in the war on terrorism and the financial bailout.

A few more years of lethargy could be detrimental to the United States in several ways. It could strengthen China, which has an enormous amount of capital to invest and is directing some of this into alternative energy and green technology—far more than the United States is. With or without climate change, the world’s need for new sources of cheap and reliable energy is growing, and China is positioning itself for an emerging market that could be huge. Delaying might force the United States to contend with a considerably more robust multilateral framework for addressing climate change, a framework that it has not helped to design or synchronize with other multilateral institutions that it does support. Delaying could impose huge long-term costs on the U.S. economy, as it finds itself compelled to deal with water shortages, dust bowls, and hurricanes in an emergency mode. Katrina disabused everyone, except perhaps politicians and other government officials, of the notion that the nation is adequately prepared for the severe events that climate science predicts. Even if the United States does not increase its own vulnerability to megadisasters, inaction may not be cheap, as the country finds itself embroiled in costly humanitarian efforts abroad. And finally, in the worst-case scenario, lethargy might enable the sort of global catastrophe that climate scientists have described as possible. It is hard to imagine what competing investments of the nation’s resources would warrant ignoring this issue.

So is climate change a national security issue? Climate change is the most protean of science-based discourses, with an admixture of confidence and uncertainty that allows it to be integrated into any political agenda—from calls for sweeping reforms of the international system to those for more research and debate. Climate change does not mobilize agreement or clarify choices so much as engender reflection on the values we hold, the levels of risk we are comfortable assuming, the strengths and weaknesses of the institutions and practices that exist to meet our personal needs and allocate our shared resources, and the sort of world we want to bequeath to our children and grandchildren.

Recommended Reading

  • Kurt M. Campbell, Climatic Cataclysm: The Foreign Policy and National Security Implications of Climate Change (Washington, DC: Brookings Institution Press, 2008).
  • CNA, National Security and the Threat of Climate Change, 2007; available at .
  • German Advisory Council on Global Change, World in Transition: Climate Change as a Security Risk (London: Earthscan, 2008).
  • Thomas Homer-Dixon, Environment, Scarcity and Violence (Princeton, NJ: Princeton University Press, 1999).
  • IFRC, World Disasters Report 2009; available at
  • Intergovernmental Panel on Climate Change, Working Group II Report: Climate Change Impacts, Adaptation, and Vulnerability, 2007a; available at:
  • Colin Kahl, States, Scarcity, and Civil Strife in the Developing World (Princeton, NJ: Princeton University Press, 2006).
  • Nicholas Stern, The Economics of Climate Change, 2006; available at
  • UN Environment Programme (UNEP), From Conflict to Peacebuilding: The Role of Natural Resources and the Environment (Geneva: UNEP, 2009).
  • Henrik Urdal, Demographic Aspects of Climate Change, Environmental Degradation and Armed Conflict. United Nations Expert Group Meeting on Population Distribution, Urbanization, Internal Migration and Development, January 2008.
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Cite this Article

Matthew, Richard A. “Is Climate Change a National Security Issue?” Issues in Science and Technology 27, no. 3 (Spring 2011).

Vol. XXVII, No. 3, Spring 2011