Climate Change is a National Security Issue — But Not for the Reasons You Think


The connection between climate change, conflict, and U.S. national security is receiving increasing attention from political analystsgovernment agencies, and even the White House. At COP21, President Obama called climate change an economic and security challenge. Recent research has emphasized the link between climate and violence. Although some commentators argue that climate change will have—or is already having—major direct effects on U.S. security interests, much of the debate has argued in favor of a more nuanced interpretation given the complex set of drivers that relate climate change to military assets and social conflict.

Climate change can affect conflict around the world in uncertain and complex ways, although we can’t establish the magnitude of a causal relationship with confidence. In addition, there are unresolved hypotheses about indirect climate-security linkages, such as destabilization. Consequently, it is difficult to effectively and appropriately factor climate change into U.S. policy decisions about how to manage conflict. We can nonetheless make confident statements about the ways in which climate change might and might not suggest changes in current US security policy, since there are a number of more direct ways in which climate change is likely to affect national security in the near-term.

We need to identify the areas—both internationally and domestically—where we understand the likely climate impacts on national security and where those impacts might require us to make a significant change in current practices. This will help us prioritize resources to combat climate change and decide how much to plan and budget for climate change induced impacts.

Cause and effect is hard: the case of the Syrian Refugee Crisis

The challenge in establishing and acting on a relationship between climate change and geopolitical destabilization and social conflict is that the empirical evidence is thin.

The ongoing Syrian conflict, which produced one of the largest migrations of displaced people in the last 100 years, is an example, of a situation that lacks straightforward evidence of the role of climate change. Many have argued that while the conflict was the result of multiple complex factors, key among them were drought-induced water shortages and agricultural collapse. One argument is that severe drought led to substantial population movement that fomented or exacerbated the ongoing civil conflict.

We do not have clear evidence, however, of the specific role climate change played in Syria. For example, we don’t know how much more severe the pre-conflict drought would have been absent climate change. We don’t know how important, interdependent, or independent the other migration-inducing factors may have been. Climate change projections suggest that we will have more frequent and intense droughts, which may in turn contribute to destabilizing vulnerable regions, particularly in the Middle East. But right now, we don’t know how large these effects are. As climate changes become larger over time, however, these links may be easier to measure and understand.

Stronger evidence exists for other climate impacts to national security, such as the impact of rising oceans and increased storm surge on coastal defense posts or changes to Arctic territorial expansion from declining sea ice. These are areas where security policy can find surer footing.

What We Still Don’t Know But Need To

As a starting point, we need more evidence on the causal role of climate conditions on past conflicts, even in the Syrian case. If robust links between climate and conflict can be demonstrated, then incorporating future projected climate impacts on regional water supplies, agricultural productivity, and other key social institutions could help guide global policy decisions and defense strategies for these vulnerable regions.

The first step is to get better information on how humans respond to climate-induced severe weather events, whether by fighting or fleeing, and in cases like Syria, how migration decisions are related to extreme weather events. For example, in 2009, prior to the Arab Spring, RAND worked with the World Bank to survey 4,000 households in five Middle East and North African countries about migration behavior and perceptions of extreme weather. Although that work found that migration was one of the actions households took when facing floods and droughts, it was not the only or necessarily the first response.

In addition to measuring and understanding the cause and effect relationships between climate change and conflict, we need to be able to characterize the relative magnitude of these effects. Determining that climate change will affect agricultural productivity is important, but equally important is our ability to say how that effect compares to changes in agricultural technology improvements. Similarly, to be able to calibrate a security policy response to climate change, policy makers need to know how important droughts and floods are relative to other factors that cause people to migrate—like war or non-climate induced urbanization. They need to know how these factors stack up, or they risk overreacting.

Prioritizing Based On What We Do Know

There are other, more certain climate change implications for national security in both the near-term and long-term. These issues are different from the more generalized effects of climate change on weather patterns because they are based on issues and problems we are relatively certain will happen—and soon. There are a few areas we recommend focusing on: estimating budgetary impacts of and policy responses to rising sea level and changes in hurricane patterns; balancing national security concerns and energy sector innovation in the Arctic region; and revising expectations and policies for military humanitarian assistance/disaster relief efforts as weather patterns become more volatile.

Sea Levels and Hurricanes: Although there is still uncertainty in, for example, when and how much sea level will rise along the U.S. coast or how hurricane patterns and intensity may change, we are fairly confident within about what the likely impacts will be. In part this is because these effects are relatively easier to project and measure than the complex systems that drive conflict abroad.

Rising seas are expected to increase the magnitude and frequency of flooding within vulnerable, coastal communities and defense infrastructure positioned on U.S. coasts.  A recent GAO study estimated these effects, showing that coastal military installations may be vulnerable to sea level rise. The same can be done for civilian infrastructure. RAND has conducted research on future trends and mitigation approaches to storm damage in coastal Louisiana. Recently, we calculated the economic costs of a “future without action” to infrastructure and economic activity for civilian populations in parts of Louisiana vulnerable to climate-induced land loss.

The Arctic Region: While high northern sea ice melt contributes to overall sea level rise, the reduced ice also permits exploration of a wealth of new territory that may contain oil, gas, and mineral resources. The United States has a keen interest in monitoring this neighboring Arctic territorial opening, not only for energy assets, but also for national security concerns. Russia has already announced its intention to augment its military presence in this region. China is also likely to capitalize on new Arctic resource availability, despite its relatively far geographic distance. Accurate satellite observations of Arctic sea ice extent and associated geopolitical activity in the region provide clearer connections between climate and policy options in this setting. Monitoring physical and political changes will be crucial to guiding U.S. military posture and securing resources in the Arctic.

Disaster Management Policies: The U.S. military also plays a critical role in coping with large-scale natural disasters, whether military assets are at risk or not. Where climate change increases the potential damage or frequency from hurricanes, forest fires, or other acute natural disasters, increased stress and strain could be placed on U.S. military resources, assuming the role the military plays in disaster response and recovery remain unchanged. That assumption is critical, however, and should be subject to analysis and debate. An alternative response to climate change may be to adjust expectations of how and when defense resources are used to respond to international (or domestic) natural disasters.

Tackling the Big, Unanswered Questions

A central goal of the Paris Agreement is to keep global average temperature increases below 1.5°C —although climate models suggest even 2°C is unlikely without dramatic changes to emissions trajectories. To aid decision making, ideally we would try to ‘price’ the value of limiting climate change in terms of national security: how much violence might be prevented by keeping temperatures within 2˚C, and what would that additional security be worth?

These questions are challenging to answer in any rigorous way, precisely because the linkages between climate, conflict, and security are not yet well established. We need better data and better methods to inform policy makers about the relative contribution of climate change to various national security threats. A first step could be to rank or prioritize the likely national security implications of climate change.

All U.S. policy decisions can and should be guided by clear evidence—and climate change policy is no exception. The United States should focus on addressing the clearest vulnerabilities, such as securing coastal defense infrastructure, which are best supported by evidence of current and future climate changes and where incorporating climate change may substantially change the policy decisions. While addressing these issues, further work is needed to demonstrate causal links between climate change and conflict. Ultimately, climate change may be only a secondary (or tertiary) influence on social conflict, but there are nearer threats and strong reasons to act on other, more knowable national security issues, even without a full understanding of the climate-conflict dynamic.


Neil Berg is an associate physical scientist and Nick Burger is a senior economist at the nonprofit, nonpartisan RAND Corporation.