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Climate and Social Stress: Implications for Security Analysis (2013)

Chapter: 5 Climate Events and National Security Outcomes

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Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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5

Climate Events and National Security Outcomes

Traditionally, the primary security concerns of the United States and other nations have included the prevention of external assault, the prevention of insurrections and other large-scale domestic violence, and the maintenance of the political and economic stability of the state. U.S. national security concerns also extend to similar threats faced by our allies and by other states considered to be of critical importance for our national security. Other situations, such as major humanitarian crises, pandemics, or disruptive migration, which may threaten the stability of U.S. allies or other states and perhaps lead to a direct U.S. response, are also increasingly considered part of the landscape of potential security risks. All of these risks, which we refer to in the conceptual framework in Chapter 2 as security outcomes, have the potential to be affected by climate change and climate events.

Chapter 1 provided a brief review of the major scenarios linking climate change to U.S. security interests that have emerged in studies from the policy community and the intelligence and security agencies of the U.S. government. As noted there and discussed further in Chapter 2, the main focus of this report is scenarios in which climate events cause harm to systems that support human well-being by exceeding the ability of these systems to cope, respond, and recover. Depending on other factors, such harm may result in large-scale political and social outcomes that have the potential to affect U.S. national security. With the exception of events such as direct damage to military facilities caused by extreme weather, we believe the causal relationship between climate change and specific climate events and security outcomes is likely to be indirect, with complex and

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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contingent causal pathways in between. This chapter is intended to explore the evidence that the social sciences can add to our understanding of the connections between climate events and major security-relevant outcomes. It is not possible in this study to examine all possible links, so this chapter examines a selection of some of the most commonly mentioned relationships. It begins with an examination of the connections between climate events and some of the major outcomes—such as threats to water, food, and health security; humanitarian crises; and disruptive migration—that are frequently cited in the policy literature, and it then discusses traditional security outcomes, such as political instability and interstate and internal conflict.

WATER, FOOD, AND HEALTH SECURITY

Water Security

Basics of Supply and Demand

The fundamental role that water plays in sustaining and supporting life, a healthy environment, and human well-being is drawing high-level international attention to the availability and quality of water as an essential component of development. Increasing access to safe drinking water and basic sanitation is a key component of the Millennium Development Goals (United Nations, 2012), and the period 2005–2015 was named as the United Nations International Action Decade “Water for Life.”1 More fundamentally, water is essentially irreplaceable. With other resources, such as energy and food resources, there are a number of substitutes that can be used to meet the societal needs for these resources. Currently, however, water can only be replenished at costs that are beyond the reach of many of the most water-stressed countries. Conflict over water availability or caused by issues related to delivery of water resources to meet competing needs of energy, food, and health thus have the potential to define critical climate-related conflicts and relief challenges across the globe.

Projections of future availability of freshwater suggest increasing imbalances between supply and demand. Between 1970 and the mid-1990s the amount of economically available water per person dropped by more than 35 percent (United Nations, 1997, quoted in Wolf, 2007:242), and one frequently quoted estimate (2030 Water Resources Group, 2009) projects a gap of 40 percent between global water requirements and accessible, reliable water supply by 2030. “This global figure is really the aggregation of a very large number of local gaps, some of which show an even worse situa-

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1 See http://www.un.org/waterforlifedecade/ (accessed July 5, 2012).

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
×

tion: one-third of the population, concentrated in developing countries, will live in basins where this deficit is larger than 50 percent” (p. 5). However, it is important to keep in mind that the models contain many uncertainties and assumptions about factors such as patterns of economic growth or the potential of technology to improve resource management, and these uncertainties and assumptions can have a significant effect on the models’ results.

The agricultural sector is currently responsible for around 70 percent of freshwater consumption. Patterns of land use, population growth, and rapid urbanization, along with economic development that may require more water (for power generation or production processes, for example) and changing dietary patterns with impacts on agricultural production that also increase need for water, can be expected to have significant effects on demand, in some cases creating or exacerbating competition for supplies.2 Contributing to the pressure is the fact that many countries depend on water sources that must be shared. As Wolf (2007) noted, “There are 263 rivers around the world that cross the boundaries of two or more nations” (p. 245). In total, these river basins account for just under half of Earth’s land area, are home to 40 percent of the world’s population, and make up some part of 145 countries (Wolf et al., 1999). A number of these basins—the Indus, Nile, Tigris–Euphrates, Jordan, Brahmaputra, and Amu Darya river systems, for example—are in areas of strategic importance for the United States (Office of the Director of National Intelligence, 2012). “In addition, about 2 billion people worldwide depend on groundwater, which includes approximately 300 transboundary aquifer systems” (United Nations–Water, 2008:1). Even in the absence of climate change there are multiple reasons for the intelligence community to pay attention to water issues.

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2 “The drivers of this resource challenge are fundamentally tied to economic growth and development. Agriculture accounts for approximately 3,100 billion m3, or 71 percent of global water withdrawals today, and without efficiency gains will increase to 4,500 billion m3 by 2030 (a slight decline to 65 percent of global water withdrawals). The water challenge is therefore closely tied to food provision and trade. Centers of agricultural demand, also where some of the poorest subsistence farmers live, are primarily in India (projected withdrawals of 1,195 billion m3 in 2030), sub-Saharan Africa (820 billion m3), and China (420 billion m3). Industrial withdrawals account for 16 percent of today’s global demand, growing to a projected 22 percent in 2030. The growth will come primarily from China (where industrial water demand in 2030 is projected at 265 billion m3, driven mainly by power generation), which alone accounts for 40 percent of the additional industrial demand worldwide. Demand for water for domestic use will decrease as a percentage of total, from 14 percent today to 12 percent in 2030, although it will grow in specific basins, especially in emerging markets” (2030 Water Resources Group, 2009:6).

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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Potential Effects of Climate Change3

Climate change is likely to have a number of effects on water supplies, which will vary considerably across and within regions. For example, during the past several decades there have been noticeable shifts in the frequency and distribution of precipitation. Dry areas are expected to get drier and wet areas wetter. Scientists project that the subtropics, where one finds most of the world’s deserts, will experience a 5 to 10 percent reduction in precipitation for each degree of global warming. Subpolar and polar regions, on the other hand, are likely to experience more precipitation, especially in the winter.

In addition, warmer temperatures mean more evaporation; warmer air can also hold more water vapor, leading to a measurable increase in the intensity of precipitation in some areas. Observations from many parts of the world indicate that a statistically significant increase in the intensity of heavy rainstorms has occurred. One of the effects of this escalation is an increased risk of flooding. And the intensity is projected to increase even in areas when overall precipitation declines.

These changes in precipitation will have a direct effect on annual streamflow, which is essentially equivalent to runoff, the amount of snow or rain that flows into rivers and streams. This is a key measure of the availability of freshwater. Climate models project that streamflow will decrease in many temperate river basins, especially in arid and semiarid regions. As discussed in the next section, a key question is whether the effects of climate change on water supply, combined with significant human impacts on supply and demand, could lead to tensions and conflict that become concerns for U.S. security.

Water and Conflict

Disputes over water date back millennia; the Water Conflict Chronology List, for example, begins with an account of a Sumerian legend from 3,000 BCE that resembles the Biblical story of Noah. Five hundred years later two Sumerian city-states, Lagash and Umma, provided the first written record of going to war over water; the rulers of Lagash diverted water from boundary canals to deny supplies to neighboring Umma, setting the conflict in motion.4

The idea that water scarcity could be a direct source of violent internal or international conflict has produced a literature on “water wars” from both academic and policy sources (see, for example, Cooley, 1984; Starr,

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3 The material in this section is taken from National Research Council (2012b:23–25).

4 Water Conflict Chronology List: see http://www.worldwater.org/conflict/list/ (accessed June 20, 2012).

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
×

1991; Bulloch and Darwish, 1993; Homer-Dixon, 1994, 1996; Remans, 1995; Amery, 2002). Another literature counters that the dynamics are more complex and offer the prospect for cooperation in the management of shared resources (Elhance, 1999; Marty, 2001; Chatterji et al., 2002; Wolf et al., 2003). Concerns about water insecurity as a source of tension and conflict feature prominently in many of the government and policy community studies of the ways in which climate change could affect U.S. and international security in the coming decades (see, for example, Fingar, 2008; Defense Science Board, 2011; Office of the Director of National Intelligence, 2012). It is important to note that none of the major reports forecasts that the conflicts arising between countries over water will lead to war, although most see the potential for various forms of internal violence.

Fortunately, water is one resource for which there is a substantial research base as well as significant data sources with which to assess associations and causal linkages. One of the best known is the Water Conflict Chronology of the Pacific Institute, with data on cases from 3000 BCE to 2010.5 Another is the International Water Events Database maintained by the Institute for Water and Watersheds at Oregon State University, which coded events from media sources between 1950 and 2008 on a 14-point scale to capture a range of conflict and cooperation behaviors.6 Studies that examine data from both sources suggest:

  • Cooperation rather than conflict is the norm with regard to water relations. In the vast majority of cases water resources are shared in a cooperative fashion and conflicts are worked out via treaties. Co-

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5 Current, sometimes overlapping categories of types of conflicts now include

  • Control of water resources (state and non-state actors): where water supplies or access to water is at the root of tensions.
  • Military tool (state actors): where water resources, or water systems themselves, are used by a nation or state as a weapon during a military action.
  • Political tool (state and non-state actors): where water resources, or water systems themselves, are used by a nation, state, or non-state actor for a political goal.
  • Terrorism (non-state actors): where water resources, or water systems, are either targets or tools of violence or coercion by non-state actors.
  • Military target (state actors): where water resource systems are targets of military actions by nations or states.
  • Development disputes (state and non-state actors): where water resources or water systems are a major source of contention and dispute in the context of economic and social development. (Water Conflict Chronology List: see http://www.worldwater.org/conflict.html (accessed June 23, 2012)

6 The scale ranges from –7 for a formal declaration of war to +7 for a decision on unification into one nation; an international water treaty is considered a +6. For more information, see http://www.transboundarywaters.orst.edu/database/interwatereventdata.html (accessed November 15, 2012).

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
×

operative items in the Water Events Database represent two-thirds of the total over a period of more than 50 years; there are no cases in which conflicts over water lead to formal declarations of war (the most extreme form of conflict behavior on the scale) (Michel, 2009). The cases in the Water Conflict Chronology yield only one genuine interstate water war in history; in many cases water is a tool or a target rather than a cause of conflict (Wolf, 2007).

  • For most of the water resources shared across national boundaries, the patterns reflect a mix of conflict and cooperation (Wolf, 2007; Zeitoun and Mirumachi, 2008).
  • Most shared water resources are governed by some sort of international agreement; more than 150 international treaties to govern fresh water were put in place between 1946 and 1999 (Yoffe et al., 2003).
  • Negotiations over water management and formal water agreements tend to continue even during periods of intense, sometimes violent, political conflict, including for rivers such as the Indus between India and Pakistan, the Mekong, and the Jordan between Israel and Jordan (Wolf, 2007).
  • These encouraging trends aside, the cases in the Water Conflict Chronology, as well as a number of country or regional studies, show substantial conflict, some of it violent, at the national and sub-national level (Postel, 1999; Wolf, 2007; National Research Council, 2012c). For example, some research suggests that as one moves from the international to the local level, the likelihood and intensity of violence increases (Giordano et al., 2002). This speaks to the importance of national political capacity, including water management systems and institutions, as well as to particular sources of local stress.

If the implications of the research on historical patterns in water resources and conflict suggest that cooperation or a mix of cooperation and conflict is the more likely outcome and that traditional interstate war is highly unlikely, how much does this tell us about the future? Should we assume that past positive trends will continue? A report from the National Research Council (National Research Council, 2012c) and four articles in the 2012 special issue of the Journal of Peace Research all examine water and issues of international cooperation and conflict in areas of interest to the United States. The National Research Council report examines the potential impacts of climate change on water security in the Hindu–Kush Himalayan region, which includes parts of Afghanistan, Bangladesh, Bhutan, China, India, Nepal, and Pakistan, and is the source of many of Asia’s major rivers, including the Indus, Ganges, and Brahmaputra. It concludes that

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
×

Changes in the availability of water resources may play an increasing role in political tensions, especially if existing water management institutions do not evolve to take better account of the social, economic, and ecological complexities in the region. Agreements will likely reflect existing political relations more than optimal management strategies. The most dangerous situation to monitor for is a combination of state fragility (encompassing, e.g., recent violent conflict, obstacles to economic development, and weak management institutions) and high water stress. (National Research Council, 2012c, pp. 4–5)

Focusing on the inherently fragile Middle East and the Israeli–Palestinian case in particular, Feitelson et al. (2012) argue that because of increasing desalinization and water recycling efforts, climate change will have limited direct effects in that region—with the exception of Gaza, which already suffers a water deficit compounded by the ongoing Israeli–Palestinian tensions. From the authors’ perspective the greater danger is if climate change generally, and water scarcity issues specifically, are taken and “used” by the contending parties to harden their negotiating positions. In an especially volatile region, that is a troubling possibility.

Bernauer and Siegfried (2012) focus on possible water conflict in the Syr Darya river basin in Central Asia, which they described as a zone that is “highly conflict-prone and [where] attempts to solve the problem have thus far failed [and where] climate change will exacerbate the problem” (p. 228). While emphasizing the possibility of increasing stress between Kyrgyzstan and Uzbekistan over runoff control and the lack of an international water management institution capable of resolving conflicts in the catchment basin, they conclude that it is more of a medium- to long-term problem. In the larger context of transboundary rivers where climate change will logically lead to “international tensions and increase the possibility of military conflict” (p. 223), Tir and Stinnett (2012) find that between 1950 and 2000 institutionalized agreements were able to offset the risks of conflict for parties to river treaties.

Taking this approach to another level and examining the recent history in 276 international river basins, De Stefano et al. (2012) are cautiously optimistic about the role of river basin organizations in “assuaging potential interstate conflict or country grievances, which may be caused by an increase in interannual water variability due to climate change” (p. 203). Looking ahead, however, they identify 14 high-risk transboundary basins with significant risks from climate change impacts. They conclude

The picture portrayed by these data is two-fold. First, there are those well-known basins that are currently at high risk, such as the Congo/Zaire, the Niger, and Lake Chad. Secondly, there are basins with a medium present variability that are projected to experience substantial increases in vari-

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
×

ability, such as the Catatumbo basin shared by Venezuela and Colombia. Some of the BCUs [basin country units] in this latter group have very high population densities, such as the Turkish portion of the Asi/Orontes (101 people/square km), which could exacerbate the human impacts of climate change. It is interesting to note that, with two exceptions, all the basins identified as meriting further study due to present variability (eight in total) are in Africa. Conversely, by 2050, only half of the basins identified are in Africa, the rest being distributed between Latin America and Eastern Europe/Western Asia. (p. 202)

De Stefano et al. conclude that most of the current high-risk catchment basins are currently in North Africa or sub-Saharan Africa but that this will change in coming decades, with high-risk transboundary river basins developing in many other world regions.

Famine and Severe Food Insecurity

The international humanitarian community has a strict definition of “famine” along with set criteria for its declaration: At least 20 percent of households in an area face extreme food shortages with a limited ability to cope; acute malnutrition rates exceed 30 percent; and [attributable] death rates exceed two persons per day per 10,000 population. With global food production outpacing even global population growth in the past half-century, famine thus defined is no longer the specter it once was (Ó Gráda, 2009, 2011).

Occurrences of famine in the past 30 years can be attributed to access or “entitlement” issues usually associated with nondemocratic systems and price-versus-family-resource problems (Sen, 1981, 1999). Only five such events in the past three decades have been internationally declared: Ethiopia in 1984–1985, Somalia in 1991–1992, North Korea in 1996, the Gode–Somali region of Ethiopia in 2000, and Sudan in 2008. In all of these cases famine was caused either by supply-disrupting violence or interdiction and resulting isolation or else a regime’s commitment to autarky (Ó Gráda, 2011).

The case of Ethiopia in 1984–1985, in which the famine had multiple causes, is particularly instructive. The sequence of events leading to the famine began with a drought, which was followed by the ruling regime’s attempt to impose a socialist model of development against an ethnically and regionally based internal opposition and then the regime’s diverting of international food assistance intended for that region in order to weaken the opposition. Along with the collapse of the Soviet Union, which at the time was providing the Ethiopian government with major assistance and

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
×

political support, all of these factors contributed to the eventual 1991 collapse of the Mengistu regime (Keller, 1992).

Unless climate change leads to the collapse of a major global or regional environmental system and negatively affects global food stocks in a major way, in our judgment it is unlikely that famine by the above strict definition will occur in the next 10 years. There are several reasons: (1) more numerous and more consolidated democratic systems; (2) vastly improved information flows and a well-developed international monitoring and alert system (most notably the Famine Early Warning Systems Network [FEWS NET]; see Appendix E); (3) a globalized relief system with relatively fast and flexible transportation options; (4) an attentive and globalized media; and (5) a large number of proactive nongovernmental organizations with standing links to the media.

On the other hand, Ó Gráda’s (2011) recent arguments on “those factors that would affect the likelihood of famine over the next decade or two” paint a much less optimistic picture, with the observation that “while democracy may prevent famine, democracy is less likely, and less likely to last…where famine is a risk” (p. 58). That is, special attention must be paid to countries that are either still authoritarian or where democratic systems are relatively weak and unconsolidated. Moreover, the picture— and the number of countries meriting special monitoring—becomes more complicated if we relax the strict definition of famine.

Each year the United Nations Food and Agricultural Organization places a set of countries into three at-risk tiers on the basis of their food security: those facing “exceptional shortfalls” (six in 2011), those suffering “widespread lack of access” (also six in 2011), and those facing “severe localized food insecurity” (18 in 2010). Market forces and the globalized international relief system can be expected to help these situations somewhat, but those nations in these three tiers that are also characterized by internal violence or supply interdictions warrant particular attention, especially if they are authoritarian or only weakly democratic.

Finally, because access to food is the crucial concept underlying entitlement and in most places price determines access or lack thereof, and because any real or perceived food supply problem will affect price, climate change impacts are likely to be a factor in—or blamed for—food price spikes and food security crises.

Pandemics and Health Security

An epidemic occurs when the number of cases of a particular disease substantially exceeds what is expected in a specified population over a given time period, and a pandemic is defined as an epidemic of infectious disease that has spread through human populations across large regions.

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
×

The infectious diseases with the greatest potential to cause epidemics are generally transmitted from human to human directly (e.g., influenza) or indirectly through disease vectors (e.g., yellow fever). As recent experiences with SARS and H5N1 have shown, even just the threat of a pandemic can severely disrupt business activity, trade, and travel as well as creating diplomatic challenges between countries.

Only certain diseases have the potential to cause a pandemic. The International Health Regulations, which went into force in June 2007, are intended to help the international community prevent and respond to acute public health risks that have the potential to cross borders and threaten people worldwide. The regulations provide a foundation for assessment and notification used in determining whether a public health emergency of international significance is likely. At the level of individual countries, many national governments identify diseases that must be reported by health care providers. These “notifiable diseases” are ones for which regular, frequent, and timely information regarding individual cases is considered necessary for disease prevention and control.

Any health outcome that is seasonal or sensitive to weather could be affected by climate change. This includes, but is not limited to, health outcomes associated with extreme weather and climate events, changes in air quality, infectious diseases, and malnutrition (Confalonieri et al., 2007). The health outcomes with the greatest potential to affect political stability are those in which extreme weather and climate events cause significant morbidity and mortality, leading to calls for international assistance, as well as those associated with pandemics.

The causal chain between an exposure to a pathogen and the development of a disease is complex; exposure is necessary but not sufficient to cause disease (see Figure 5-1). Infectious doses vary across diseases: Only a few pathogens are needed to cause viral diseases, while hundreds to thousands are required to cause some diarrheal diseases, such as cholera. The immune status of the exposed individual is critically important, with individuals who are undernourished, immune compromised, or suffering from other diseases generally more susceptible and more seriously affected. Furthermore, how individuals respond to an infection varies. Acute infections range from a self-limiting disease to fatal; chronic infections may leave some individuals as carriers who continue to be infectious. Other important factors influencing the burden of infectious diseases include sanitation, the quality and accessibility of public health and health care services, land use changes, population density, and travel patterns.

Emerging and re-emerging diseases are of growing concern to the public health community. These include newly recognized microbes or disease syndromes; diseases that are becoming more severe or harder to treat successfully (e.g., malaria due to drug resistance); diseases whose incidence

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
×

image

FIGURE 5-1 Causal relationships linking climate change to disease outcomes.
SOURCE: National Research Council (2001).

is increasing in areas where the pathogen is already present; and diseases expanding into areas where they were not previously present (e.g., Lyme disease in Canada). The numbers of emerging and re-emerging diseases are increasing, with 175 human infectious diseases considered to be emerging as of a decade ago (Taylor et al., 2001). The number of emerging diseases is expected to continue to increase in the future, with pathogens that infect more than one host species more likely to emerge than single-host species (Taylor et al., 2001).

Weather and climate changes have the potential of interacting with other factors to alter both the geographic range and the intensity of transmission of a number of infectious diseases, thereby creating the potential for pandemics. Evidence indicates that weather and seasonal to interannual climate variability influence the geographic distributions and seasonal variation patterns of many infectious diseases (National Research Council, 2001). Temperature, precipitation, and humidity affect the life cycles of many pathogens and vectors, thus affecting the timing and intensity of outbreaks. These variables can affect vector survival, reproduction, development, and biting rates as well as pathogen reproduction and development. Climate changes can also alter ecosystems and create other stresses in ways that influence pathogen genetics or establish new interactions between hosts

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
×

and microbes that create opportunities for the emergence of new infectious disease threats (Keesing et al., 2010).

Influenza

Unlike the familiar seasonal influenza epidemics, influenza pandemics occur irregularly and spread worldwide, infecting a large proportion of the human population and causing significant morbidity and mortality. Annual influenza epidemics result from a gradual shifting of surface antigens on the influenza virus that allows it to evade host immune responses (Smith et al., 2004). Influenza pandemics can occur when a novel virus to which humans have little or no immunity, such as influenza A/H1N1, jumps to humans from avian or mammalian hosts; pigs, chickens, and ducks are the species most often implicated in this process (Centers for Disease Control and Prevention, 2009). East Asia and Southeast Asia are often the source of new influenza strains.

The best known influenza pandemic, the Spanish flu, occurred in 1918– 1919 (Barry, 2005). Most of those who died were young, healthy adults between the ages of 15 and 44 (Patterson and Pyle, 1991). Because this pandemic occurred during and immediately after World War I, it is difficult to accurately estimate the total number of deaths. Mortality rates varied between and within countries and continents, with mortality in Europe estimated at approximately 1.1 percent (Ansart et al., 2009). Estimates for the total number of deaths range from more than 20 million (Barry, 2005) to 39.3 million (Patterson and Pyle, 1991) and higher.

Because influenza is strongly seasonal and the well-understood person-to-person transmission of influenza cannot explain the appearance of an epidemic, there is growing research interest in environmental triggers. In temperate regions, weather and climate variability can affect influenza incidence in two potentially complementary ways. Influenza consistently peaks during winter, when conditions for aerosol-borne transmission are favored and indoor crowding facilitates transmission (du Prel et al., 2009), and absolute humidity strongly influences the airborne survival and transmission of influenza (Shaman and Kohn, 2009). These factors provide evidence suggesting why epidemics occur during cold and dry weather. This is supported by analyses in the United States showing that the onset of wintertime influenza-related mortality is associated with anomalously low absolute humidity in the prior weeks; indeed, seasonality could be modeled with absolute humidity alone (Shaman et al., 2010). Modeling influenza-like illnesses in Europe has demonstrated a significant correlation between absolute humidity and temperature at the time of infection (van Noort et al., 2011). When a weather-dependent influenza-like illness factor was included in the model, the size of an epidemic was found to depend not

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
×

only on the susceptibility of the population at the beginning of the influenza season but also on the weather conditions as the epidemic unfolded. This is consistent with modeling of the timing of pandemic influenza outbreaks, which appear to be driven by a combination of absolute humidity conditions, levels of susceptibility, and changes in population-mixing and contact rates (Shaman et al., 2011).

The El Niño–Southern Oscillation (ENSO) cycle has been implicated in influenza transmission (Viboud et al., 2004; Shaman and Lipsitch, 2012). The four most recent human influenza pandemics (1918, 1957, 1968, and 2009) were first identified in boreal spring or summer and were preceded by La Niña conditions in the equatorial Pacific (Shaman and Lipsitch, 2012). Changes in the phase of the ENSO alter the migration, stopover time, fitness, and interspecies mixing of migratory birds, which may affect their mixing with domestic animals. La Niña conditions appear to bring divergent influenza subtypes together in some parts of the world, favoring the reassortment of influenza (i.e., the mixing of the virus’s genetic material into new combinations) through simultaneous multiple infections of individual hosts that can lead to the generation of novel pandemic strains.

Recent evidence indicates that dust can transport influenza viruses for long distances (Chen et al., 2010), suggesting that increased desertification from climate change and other factors could facilitate the spread of pathogenic viruses. Influenza in the tropics exhibits highly variable transmission patterns across countries, with recent studies identifying a range of environmental variables, specific to particular locations, which are associated with outbreaks (Soebiyanto et al., 2010).

Yellow Fever

Yellow fever, a viral hemorrhagic fever, has been one of the great scourges of mankind, periodically causing high mortality over at least the past 400 years (Weaver and Reisen, 2010). Approximately 200,000 cases, including 30,000 deaths, occur each year in Africa (90 percent of all cases) and in Central and South America (Barnett, 2007). Between the 18th and 20th centuries, epidemics occurred in many countries in the Americas, Africa, and Europe. Until the early 20th century many epidemics occurred in port cities of North and South America, associated with the importation of both the vector and the virus on sailing ships, where onboard transmission cycles occurred (Weaver and Reisen, 2010). In 1793 approximately 1 in 10 residents of Philadelphia died during an epidemic of yellow fever (Rogers et al., 2006). Mortality from yellow fever and malaria caused the failure of the French Panama Canal project in the 1880s and 1890s. The Yellow Fever Commission, founded as a consequence of excessive disease

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
×

mortality during the Spanish–American War in 1898, concluded that the best way to control the disease was to control the mosquito that carried the virus. William Gorgas successfully eradicated yellow fever from Havana by destroying larval breeding sites. This strategy of source reduction was then used to reduce disease problems, finally permitting construction of the Panama Canal.

In contrast to the significant global campaigns to address malaria, another vector-borne disease that could be affected by climate change, a lack of continuing financial support for the vector-control strategies that successfully eliminated yellow fever from many regions led to reemergence of the disease (Gardner and Ryman, 2010). A dramatic resurgence of yellow fever has occurred since the 1980s in sub-Saharan Africa and South America, including the first epidemic in Kenya in 12 decades (Barnett, 2007). The largest outbreak of yellow fever in South America since the 1950s occurred in Peru in 1995, with cases also reported in Bolivia, Brazil, Colombia, Ecuador, and Peru. Approximately 2.5 billion people live within the current range of Aedes aegypti, the mosquito historically most responsible for spreading the virus, and must be considered at risk. The recent rapid spread in the United States and elsewhere of Aedes albopictus, a mosquito species that carries a number of arboviruses, including some that cause disease in humans, as well as dengue viruses in its native Asia, has also increased the risk of epidemics (Rogers et al., 2006).

The majority of persons infected with yellow fever virus experience no or only a mild illness (Gardner and Ryman, 2010). The incubation period in people who develop the disease is typically three to six days, with initial symptoms that include the sudden onset of fever, chills, severe headache, back pain, general body aches, nausea, and vomiting, fatigue, and weakness. Individuals who become symptomatic but recover can have weakness and fatigue for up to several months. In about 15 percent of cases, after a remission of hours to a day, a more severe form of the disease develops, characterized by high fever, jaundice, bleeding, and eventually shock and failure of multiple organs. Case-fatality rates vary widely, from around 20 percent to more than 50 percent (Barnett, 2007).

Yellow fever is now primarily a rural disease. In the neotropics, established permanent transmission cycles between nonhuman primates and canopy-dwelling mosquitoes present a constant threat of spillover to humans (Weaver and Reisen, 2010). The possible return of outbreaks of urban yellow fever is a serious potential public health risk in Africa and South America (Barrett and Higgs, 2007). Urban yellow fever results in large, explosive epidemics when travelers from rural areas introduce the virus into areas with high human population density. These outbreaks tend to spread outwards to cover a wide area, affecting up to 20 percent of the population with high case-fatality rates. No treatment outside of supportive care exists.

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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Mosquitoes capable of transmitting yellow fever exist in regions where the disease does not presently occur and in regions, such as Asia, where yellow fever has never occurred (Weaver and Reisen, 2010). It is not understood why the African strains of yellow fever have not invaded Asia, as have other distantly related viruses, or why urban epidemics of yellow fever disappeared from the Americas since the major campaign to eliminate Aedes aegypti began in the mid-20th century (Weaver and Reisen, 2010). Although Aedes aegypti has returned to more than its original range, yellow fever remains largely a zoonotic and rural disease in South America.

Weather and climate are major factors in determining (1) the geographic and temporal distribution of the mosquitoes that carry yellow fever, (2) the characteristics of their life cycles, (3) the dispersal patterns of the yellow fever virus, (4) their evolution, and (5) the efficiency with which they are transmitted to vertebrate hosts (Gould and Higgs, 2009). For example, Schaeffer et al. (2008) developed a tool to predict the abundance of two species of Aedes using climate data; water availability in breeding sites was considered the main environmental variable affecting the mosquito life cycle. The recent cases of chikungunya fever (carried by a mosquito species that is also capable of carrying yellow fever) in northern Italy support the concern that, in the presence of susceptible hosts, an environment that favors rapid mosquito replication with a suitable climate for yellow fever transmission may cause epidemic outbreaks of immense proportions.

HUMANITARIAN CRISES

Although they are terms widely used in the media and at times by relief agencies in funding appeals, there is no standard or internationally agreed upon definition of either “humanitarian crisis” or “humanitarian disaster.” Both terms would seem to refer to situations in which a large number of people are found to be in immediate danger from marginal and deteriorating conditions such as those discussed earlier in this chapter (e.g., problems with food, water, or health security). The causes of situations referred to by these terms have ranged from genocide (e.g., Rwanda in 1994), war (e.g., northern Iraq in 1991), and civil conflict (e.g., Darfur after 2003) to such disasters as the Haitian earthquake of 2010 or Cyclone Nargis, which hit Myanmar in 2008. Although the terms have been stretched, if not abused, to cover many other hazards or events (e.g., the SARS epidemic of 2002– 2003), the fundamental image appears to be that standard disaster-response efforts, particularly by national governments, have partially or completely failed or are about to fail and that the international community may need to be involved, often massively.

A more limited term, with its roots in the 1970s and 1980s conflicts in southern Sudan, Mozambique, and Angola is “complex humanitarian

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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emergency” (CHE), which refers to a situation in which violence creates large population displacements either within countries (creating “internally displaced persons”) or across national borders (refugees). As Natsios explained in 1995:

[C]omplex humanitarian emergencies are defined by five common characteristics: the deterioration or complete collapse of central government authority; ethnic or religious conflict and widespread human rights abuses; episodic food insecurity, frequently deteriorating into mass starvation; macroeconomic collapse involving hyperinflation, massive unemployment and net decreases in GNP; and mass population movements of displaced people and refugees escaping conflict or searching for food. (p. 405)

Given the general global decline in violent conflict since the early to mid-1990s discussed later in the chapter, there seems to be little likelihood, especially in the next 10 years, that climate change per se will generate the kinds of conflicts that lead to CHEs that require massive international community responses. More likely will be “humanitarian crises” (our preferred term) where (1) large numbers of people are in immediate peril from either a climate-related, relatively fast-onset event (e.g., a heat wave, flood, cyclone, or pandemic) or a relatively slow-onset event (e.g., a drought, crop failure, food shortage, or forced migration); (2) local coping and national responses are seen as inadequate to address these needs, thus requiring major assistance from the international community and, in particular, the U.S. government; and (3) the dynamics of the longer-term recovery may lead to security conditions of major concern to the United States.

DISRUPTIVE MIGRATION

Climate change–induced migration is often implicated in scenarios in which climate change leads to violence (Reuveny, 2007). This section considers the current state of knowledge on the connections between climate change, migration, and national security. In defining migration, a distinction is typically made between internal migration, which entails population movement within a country, and international migration, where population movement extends across international borders. It is also important to keep in mind other features of population movement, such as whether it is temporary or permanent and whether it is voluntary or forced. Even within these different categories, migration can take a variety of forms, including: temporary or permanent displacement of a population following some type of climate event or other disruptive event, such as a tsunami or nuclear accident; forced or voluntary migration out of an area of political or military conflict; temporary or permanent relocation of a population from an area threatened by flooding or inundation; and temporary or permanent move-

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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ment from one region or country to another for economic opportunity. Climate change may be directly or indirectly associated with many of these different forms of migration.

It important to recognize that most types of migration are not regarded as a direct security threat and that the decision to migrate is in fact often an appropriate and effective response under a wide variety of circumstances. Given the emphasis in this report on climate change and U.S. national security, we are particularly interested in a specific type of migration, which we term “disruptive migration.” Disruptive migration, which may be internal or international, generally involves large-scale movements of populations that are socially, economically, or politically disruptive, either in the area of origin, the area of destination, or in sensitive border regions that may be affected by population movements.

Some writers on the connections between migration and environmental change have characterized climate change as a major driver of migration (e.g., Warner et al., 2010). Yet the empirical evidence base on this issue is extremely limited (Black et al., 2011b; Lilleør and Van den Broeck, 2011). In a recent comprehensive review of estimates and predictions of human displacement as the result of environmental change, Gemenne (2011) finds a notable lack of consensus on either the number of individuals displaced by environmental change or a methodology to derive such a number. Some key reasons for this lack include disagreement about the definition of an “environmental migrant” or “environmental refugee,” limited data on the magnitude of internal displacements, and failure in many studies to distinguish between ongoing demographic shifts and population changes that are the result of migration (Biermann and Boas, 2010; Gemenne, 2011). Gemenne (2011) further notes that most studies of this type emphasize predictions about potential future displacement or population movement based on estimates of populations that will be exposed to environmental stress such as storm surges and sea level rise (e.g., Biermann and Boas, 2010) rather than on documentation of the actual numbers of people displaced by past or ongoing environmental change.

Despite limited evidence on this issue, most studies recognize that the linkages between migration and environment are multifaceted and complex (Perch-Nielson et al., 2008; Warner, 2010; Afifi, 2011; Black et al., 2011b; Hugo, 2011; Renaud et al., 2011; Seto, 2011). In examining recent evidence on the connections between environmental change and migration, Black et al. (2011b) drew upon the broader literature on the drivers of migration and concluded that changes in environment are among a “family” of migration drivers (see Figure 5-2). These drivers, which include economic, political, social, and demographic factors, generally act in combination, so that environmental drivers cannot be entirely separated from other types of drivers (Black et al., 2011a). Seto (2011) comes to a similar conclusion

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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image

FIGURE 5-2 Environmental drivers interact both directly and indirectly with other drivers of migration.
SOURCE: Black et al. (2011b). Copyright 2011. Reprinted with permission from Elsevier.

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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in a meta-analysis of recent scientific literature on the drivers of migration into 11 coastal megacities located in delta regions in Asia and Africa. The study finds that migration to these cities, which include Bangkok, Dhaka, Guangzhou, and Karachi, has primarily resulted from a combination of economic, demographic, political, and social factors rather than environmental conditions. Yet the study also notes the difficulty of separating out these other factors from environmental conditions such as land degradation, land scarcity, or extreme events (Seto, 2011).

In exploring the environmental drivers of migration in more detail, Black et al. (2011b) suggest that environmental change may directly contribute to migration through mechanisms that contribute to changes in the reliability or availability of ecosystem services such as productivity of land; food, energy, and water security; and exposure to hazards. Environmental change may indirectly contribute to migration through its effects on economic drivers, such as livelihood opportunities, or on political drivers, such as conflicts associated with availability and access to resources. Connections between environmental change and migration can be seen in the case of Niger, where Afifi (2011) found that environmental degradation, including the interrelated problems of drought, deforestation, and soil degradation, led to reduced incomes among farmers, herders, and fisherman, thereby contributing to economic migration. Afifi’s study (2011), which was based on fieldwork conducted during 2008 in two regions of the country (Niamey and Tillabéri), found that migrants were typically young men who left their families behind in search of work either in another region or in another country. Most of the approximately 60 migrants interviewed in the study identified economic factors such as poverty and unemployment as key reasons for migrating, but almost all (90 percent of those interviewed) indicated that environmental problems also played a role in their decision to migrate (Afifi, 2011).

Recent literature further emphasizes that individual or household migration decisions are generally dependent not only upon social, economic, political, and demographic drivers, but also on the particular characteristics of individuals and households, including level of wealth, education, worldviews, ethnicity, and so forth. Individual migration decisions are also influenced by what Black et al. (2011b) term “intervening obstacles or facilitators,” such as an individual’s social network, legal and political mechanisms, the presence of recruitment agencies, and so forth (see Figure 5-2). As such, the same set of “structural” drivers may contribute to different outcomes for different households depending both on a household’s characteristics and on intervening barriers and facilitators to migration.

While caution is needed when generalizing from past findings to a future climate where extreme climate events will be more likely and more severe, we can postulate that disruptive migration may potentially result

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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from direct environmental stresses associated with climate change as well as from the indirect effects of climate change–induced environmental change on economic and political conditions. Climate change may constitute a direct environmental driver of either temporary or permanent migration via its effects on the availability of ecosystem services including, for example, the supply of freshwater, which may change under altered rainfall regimes; coastal flood protection, which may be lost as the result of sea level rise; and changes in the productivity of agricultural lands as a result of changes in temperature and precipitation regimes (Black et al., 2011b). Climate change may also affect the likelihood of droughts, coastal storms, and other types of hazardous climate events, which may temporarily or permanently displace susceptible households. Climate change may indirectly contribute to migration, whether temporary or permanent, via effects on economic, political, and social drivers. For example, climate change may influence agricultural and natural resource–related livelihood opportunities in a particular region, or it may contribute to political conflicts within a region over water or other resources. In all of these cases climatic shocks and stresses interact in complex ways with the other known drivers of migration so that the effects of climate events are not monotonic (i.e., more intense climate events do not necessarily lead to more migration) and they also depend on other causal variables (Warner, 2010; Black et al., 2011b).

When considering the migration decisions of individuals and households, it is important to keep in mind that climate changes may lead to alterations in a household’s characteristics, which, in turn, can influence the actions of individuals. For example, climate change may create conditions that result in a long-term decline in a household’s wealth and assets, which in turn can both increase the motivation to migrate and decrease the ability of members of the household to migrate in search of new economic opportunities. Policies intended to facilitate adaptation to climate change may provide incentives for a household either to relocate or to remain in a region. Another critical factor for migration decisions is the effectiveness of responses to climate events. As noted in the discussion of humanitarian crises, effective response is a key determinant of whether an extreme climate event becomes a humanitarian crisis. Extreme events have often resulted in temporary, internal population displacement but have rarely led to permanent migration (Perch-Nielsen et al., 2008; Lilleør and Van den Broeck, 2011). Effective immediate responses to extreme events and effective recovery efforts might therefore be expected to reduce population displacement or to shorten the duration of displacement.

Several types of security threats can be identified as possible results of climate change–related migration. Broad migration trends indicate that over the past 30 years large cities have been growing faster in low-elevation coastal zones than elsewhere and that these trends are likely to continue

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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(Seto et al., 2011). New migrants to these cities tend to be highly exposed to climate stresses, including storm surge and sea level rise, because they often tend to move to locations, such as floodplains and hill slopes, that are highly exposed to environmental hazards. They also tend to be more susceptible to being harmed because, within receiving cities, migrants are typically poorer than resident populations and in many cases have little knowledge of local environmental risks in a new city and may therefore be unaware of the risks of moving to areas that lie within flood plains or are otherwise hazard-prone. These interrelated trends suggest that climate change–related threats to human security may be just as prominent in areas of migration destination, particularly urban ones that receive large numbers of immigrants, as in areas of emigration. Migrants into new areas may also place strains on governmental or other resources and may potentially contribute to new types of conflicts, particularly within receiving areas that are already under social stress (Reuveny, 2007). Large flows of immigrants can also create or contribute to security threats in sensitive border or transition regions.

Although much of the discussion on climate change and migration emphasizes displacement or unplanned migration, it is also important to recognize that migration is an adaptation strategy to environmental change that may be necessary and even beneficial under some circumstances (McLeman and Smit, 2006; Tacoli, 2009; Black et al., 2011c; Foresight, 2011). In some cases migration may reduce security threats by taking pressure off local resources or by bringing new revenue into a local area as the result of international remittances. Paradoxically, climate change may also undermine options for adaptation via its effects on the assets and other characteristics of households. Migration typically requires a significant outlay of financial resources, yet actions needed to cope with environmental changes (e.g., selling land or livestock) can reduce a household’s assets to the point that family members who could adapt by migrating may not have the resources to do so. Those households or individuals who cannot migrate out of a region that is undergoing environmental change are among the most vulnerable (Black et al., 2011c). Regions with large concentrations of “trapped” populations that are unable to migrate may pose a new type of human security threat. When an extreme climate event occurs, these “poorest of the poor” may end up trapped in environmentally degraded areas, creating situations that are ripe for humanitarian catastrophe (Foresight, 2011).

SEVERE POLITICAL INSTABILITY AND STATE FAILURE

Extreme political instability, particularly when it substantially weakens or causes the overthrow or collapse of a strategically important regime or when it results in the onset of civil war, may have significant security

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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BOX 5-1
The Political Instability Task Force

The Political Instability Task Force (PITF) is an ongoing and unclassified research program funded by the Central Intelligence Agency that began work in 1994 as the Task Force on State Failure, a panel of academic scholars and meth-odologists. Its original task was to assess and explain the vulnerability of states around the world to political instability and state failure, focusing on events like the collapse of state authority in Somalia and the former Zaire and other onsets of disruptive regime change, civil war, genocide and mass killing, and onsets and terminations of democratic government. The task force uses open-source data and research to develop statistical models that can accurately assess countries’ prospects for major political change and can identify key risk factors of interest to U.S. policy makers.

SOURCE: Personal communication with Lawrence Woocher, PITF research director.

consequences for the United States. At least since the fall of the Shah of Iran in 1979, the U.S. government, including the intelligence community, has invested heavily in research to provide the basis for understanding and predicting the sources and onset of political instability in countries and regions of concern. Following the collapse of Somalia and the war in the Balkans, another related literature on “state failure” developed, again with substantial support from the U.S. government, including the intelligence community. In addition, other governments supported comparable research, and there was active research in the academic and think tank community as well.7 Two reviews of the literature on state failure (Bates, 2008; Marten, 2010) make clear the close relationships with efforts to understand the origins of extreme political instability, in particular, armed internal war.

One example of these connections, described in more detail in Box 5-1, is the work of the Political Instability Task Force (PITF), a research effort funded by the Central Intelligence Agency that began in the mid-1990s as the Task Force on State Failure. Over time and with continuing adjustments, the PITF has developed a model that is able to correctly identify the onset of “adverse regime change” or “ethnic or revolutionary war” two years in advance in 80 percent of the recorded instances. The methodology and results for a set of cases between 1955 and 2003 are described in the most recent published account of the PITF’s research available (Goldstone

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7 Marten (2010) includes discussions of a number of the other major research projects on state failure.

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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et al., 2010), although the committee also received a briefing on its more recent work (Goldstone, 2012).

As discussed further in Chapter 6, the PITF has examined hundreds of potential explanatory variables, finally concluding that the countries most susceptible to internal violence have been partial democracies pursuing policies that favor one segment of their population over others. The other two variables in the researchers’ statistical model, in addition to their characterization of political institutions and allocational policies, are infant mortality and the incidence of conflict in bordering states. The results, published in 2010, include some climate-related variables (e.g., the impact of drought) in the list of those that did not prove to be statistically significant.

Extending that assessment, Hewitt et al. (2012) developed the Peace and Conflict Instability Ledger, which assigns risk factors to all countries in the world (again without consideration of climate variables). This effort finds regional concentrations of risk in South Asia and in sub-Saharan Africa, suggesting that unusual climate events in those regions are of particular concern in terms of exacerbating the potential for political instability. As discussed further below, the Indus River valley is an area of particular concern because of a combination of political and environmental factors, including unusually severe drought and flooding, and a political process that has favored using available water for irrigation rather than for power generation but that has not allocated water equitably between the favored Punjab and the arid Sind regions. On the Peace and Conflict Instability Ledger, Pakistan has the seventh-highest risk factor in the world, with neighboring Afghanistan having the highest. In addition, while water-related issues in the Middle East, particularly among Israel, Syria, and Turkey, have been managed relatively well to date, the underlying tensions in the region could begin to affect that cooperation.

The recent literature exploring potential links between climate events and violent conflict is discussed in the next section. As described above, the literature on other forms of extreme political instability has generally not explored potential climate–security connections. As the Bates (2008) and Marten (2010) reviews make clear, most of the efforts to understand the origins of state failure focus primarily on economic factors, various forms of ethnic divisions, and the state of democratization in a particular country. Within and across each of these major categories, there is substantial disagreement on causal pathways and on which factors are likely to exert the most influence on the survival of a regime.

Bates (2008) also echoes suggestions from other literatures on the need for more data from below the national level to gain better insights into the dynamics of state failure:

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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Although recent research has tended to emphasize the political wellsprings of state failure, future research needs to employ new kinds of data. In addition to incorporating information concerning deeper political forces, it needs to make systematic use of subnational data. The origins of political disorder lie in conflicts whose own origins are, to a great degree, internal to the nation-state: regional inequality, conflicting partisan preferences, religious differences, and so on. Aggregate, national-level data offer the wrong optic by which to view within-country conflict. (p. 10)

His review cites several examples of what he considers an encouraging trend of introducing this type of data in an increasing number of studies.

One literature that does provide a more detailed exploration of potential climate–security links is the literature on the potential political impacts of disasters. Its findings generally support the conclusion that climate events that trigger disasters of various types are associated with political instability, although not in a straightforward way. The relationships, including causes and effects, are highly complex and contingent. The overall analytic challenge was well captured in a recent review of detailed analyses of several major disasters of the past, including some that led to state failures (Butzer, 2012). The review found that in many, but not all, instances, states survived the calamities, and it cautioned against drawing too straight a line between disasters and state failures, noting that state breakdowns differ because of the “great tapestry of variables” involved.

Studies of the political consequences of natural disasters in the modern era provide another source of useful insight. A series of case studies of different types of disasters by Olson and various collaborators (Drury and Olson, 1998; Gawronski and Olson, 2000, 2013; Olson, 2000; Olson and Gawronski, 2003, 2010; Poggione et al., 2012) indicates that while disasters often become quite “political,” disasters that result in major violence, falls of government, regime changes, and even state breakdowns are relatively rare in comparison with the total numbers of annual disasters. Indeed, the researchers’ line of argument suggests that a certain amount of political unrest and even violence should be expected in post-impact disaster situations, particularly when the response appears inadequate. Extrapolating from their work, it would seem that large-scale violence, regime change, or state breakdown requires a particular combination of factors that often take months to several years to manifest visibly: (1) incumbent political authorities with little public support at the time of the disaster; (2) a disaster response that is perceived to be under-resourced and poorly managed, especially if it is seen as characterized by favoritism, corruption, and lack of compassion; (3) a regime lacking broad, value-based “diffuse” legitimacy and dependent upon “specific” legitimacy (material rewards to key groups); and (4) well-organized pre-existing opposition groups within the system (e.g., political

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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parties) or outside it (insurgent, separatist, or revolutionary movements) that are capable of leading, organizing, and engaging in or increasing already existing anti-government or anti-regime violence.

The scenarios in which climate events are most likely to lead to risks to U.S. national security are in countries of security concern that have a significant likelihood of exposure to particular climate events combined with susceptible populations and life-supporting systems, weak response capacity, and underlying sources of potential political instability. Pakistan offers a case that illustrates these points particularly well, as described below. Another potential case, Egypt, is presented in Box 5-2.

BOX 5-2
Egypt

Of the many places in the world where climate dynamics might induce globally consequential disruption within a decade, Egypt is a principal possibility. Egypt’s population of some 80 million people consumes 18 million tons of wheat annually as a dietary staple, half of which is imported, with virtually all the rest dependent on water from the Nile River. The Nile flows through Sudan and Ethiopia before entering Egypt and accumulates nearly all of its volume upstream. The production of wheat and other food crops supported by the river is being burdened by population increases in all three countries. The countries’ current combined total of 208 million people is projected to reach 272 million by 2025, presumably generating an increase in agricultural production demand on the order of 30 percent or more within the watershed. In addition South Korea and Saudi Arabia have purchased large tracts of land in the watershed to assure imports for their own populations, and that will also add to the demand for water (Brown, 2011).

At the moment there is no broadly agreed projection of water flow in the Nile over the next decade and hence no widely accepted basis for estimating the risk of climate-induced disruption. There are historical reasons for acknowledging the possibility, however. In particular, between 1961 and 1964 there was a sharp increase in annual rainfall over Lake Victoria, adding a substantial amount of water to the White Nile branch of the watershed. Annual rainfall over the lake has receded in the intervening years, but it has not yet returned to the levels that generally prevailed from the time that annual records were initiated in 1869 up until 1961 (Sutcliffe, 2009). If that were to occur on a sustained basis, the three countries primarily affected would encounter very serious water management problems with no agreement in place to organize their respective responses. Their populations would encounter a threat to their food supply that no allocational arrangement would likely remove. In the past the existence of the Aswan Dam has buffered Egypt against fluctuations in river flow, but the continued increases in water demand, plus the potential loss of flow noted in the second paragraph, increase the potential that such buffering will be insufficient in the future.

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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Pakistan as an Example

Pakistan presents a clear example of a country where social dynamics and susceptibility to harm from climate events combine to create a potentially unstable situation. Pakistan’s economy depends heavily on water from the Indus River, and competition for this water is increasing. Therefore, Pakistan’s political and economic systems may be vulnerable to hydrologi-cal changes in the Indus system such as have been observed recently and which may be affected by climate change and variability at a subcontinental scale.

Agriculture is a central component of the Pakistani economy. The sector accounts for 21 percent of annual gross domestic product (the second-largest fraction by sector) and is by far the largest source of employment, employing 45 percent of Pakistani workers (Government of Pakistan, 2012). Furthermore, these percentages do not capture the dependence of other sectors on agriculture. Much of the agricultural production feeds domestic industry, particularly the cotton grown for the country’s large textile industry. Textiles and clothing make up a very large portion of Pakistan’s exports—approximately 50 percent in recent years—thus representing the country’s most important source of foreign currency (Government of Pakistan, 2012).

Given the low levels of rainfall in the agricultural areas of the country, Pakistan’s agricultural sector relies heavily on irrigation. The ratio of area of irrigated to rain-fed agricultural land is 4-to-1, the highest ratio worldwide (Nizamani et al., 1998). Water for irrigation is drawn primarily from three storage reservoirs on the Indus, making this crucial economic sector highly dependent on adequate flows in the Indus system.

Further stressing the Pakistani water system, demands for water for agricultural, domestic, and industrial uses are increasing. Agricultural production is intensifying, shifting from subsistence crops to commodity crops (mostly cotton, sugarcane, and rice) that produce more output but require more water; manufacturing activity is increasing as a share of the economy; and population growth, especially in urban areas, is requiring more withdrawals of Indus water for domestic consumption (World Bank, 2005). Additionally, hydroelectric power provides 37 percent of Pakistan’s electricity (Government of Pakistan, 2012), mostly from the reservoirs also used for irrigation-water storage, creating competition for water resources between agriculture and energy, at least at some times of the year.

Competition for water between the agricultural and power sectors is already intense and is likely to increase. Policy decisions by the government, dominated by influential landowners of Punjab and Sind, have allocated water to irrigation purposes instead of to power generation (Ghumman, 2012a), triggering protests from industrialists and the general urban popu-

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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lation. Protests over power outages, although not new in Pakistan, have led to increasing civil unrest over the past five years (News International, 2012). With the onset of a sweltering summer, power shortfall hit a record high of 8,000 megawatts in 2012, or nearly 45 percent of national demand (Ghumman, 2012b), leading to 18 to 20 hours per day of power outages and stoking riots and mass-scale protests (Ghumman, 2011a). Reports from the ground recorded violent protests throughout the country. In a recent episode of escalating violence, rioters burned trains, damaged banks and gas stations, looted shops, blocked roads, and, in some instances, targeted homes of members of the National Assembly and provincial assemblies (Express Tribune, 2012). According to a senior local police officer in the largest city, Karachi, on average there were at least six protests against power outages in the city per day in 2011 (Dawn, 2011). Competition between water uses is likely to increase if government plans are implemented to increase hydroelectric capacity as a cheaper alternative to imported fossil fuels (Pakistan Water and Power Development Authority, 2011).

As a result of these demographic and economic changes, an already tight water supply is becoming increasingly stressed, to the point that Pakistan has been described as “one of the most water-stressed countries in the world” (World Bank, 2005:viii). In quantitative terms, in 1951 some 6,880 cubic yards of surface water were available per person in Pakistan. By 2010 that had dropped to 1,358 cubic yards per person, and it is projected to decrease to 1,046 cubic yards by 2025 (Pakistan Water and Power Development Authority, 2011).

Recent hydrological events in the Indus system suggest the kinds of stresses climate events can put on this society. In 2010 a shift in the distribution of monsoonal rainfall led Pakistan to experience massive flooding, inundating one-fifth of the land area of the country, in one of the worst natural disasters the country has faced (National Research Council, 2012c). In 2011 the Indus River System Authority (IRSA), Pakistan’s institution responsible for monitoring the flow of Indus basin rivers and apportioning its waters among the provinces, reported indications of drought and water shortage at storage reservoirs on the Indus, according to press reports (Dawn, 2011). Although individual extreme events cannot be attributed with confidence to climate change, increased frequency and intensity of drought and flooding are consistent with climate change projections.8

Beyond the short-term events, there is some evidence that the mass

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8 The Intergovernmental Panel on Climate Change fourth assessment report (Intergovernmental Panel on Climate Change, 2007) projects lower annual average precipitation in the subtropics but also a greater incidence of high precipitation events, so that a greater concentration of total precipitation is expected to occur in extreme events and an even greater increase in dry periods is expected than implied by the drop in average annual precipitation.

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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balance of the Karakoram glaciers in the headwaters of the Indus system— the source for the great majority of the river’s water (Archer and Fowler, 2004)—has been changing in ways that may reduce river flows. Glacial and snow melt are more important to water supplies in Pakistan than they are to countries farther east in the Himalayan region, where monsoons provide a much larger share of river flows (Bolch et al., 2012). Precipitation levels in winter, when most glacial accumulation occurs in the Karakoram area, have recently increased (Archer and Fowler, 2004; Bolch et al., 2012). Moreover, in contrast to most other regions in the world, mean air temperatures in the Karakoram have decreased in summer, when most of the loss of glacial mass occurs (Bolch et al., 2012). Hewitt (2005) found that Karakoram glaciers began increasing in area in the 1990s after several decades of observed retreat, but he could not reliably assess the mass balance (as opposed to areal extent) of the glaciers with the available data. It is clear from the data that the Karakoram glaciers are behaving quite differently than the rapidly retreating glaciers of the eastern Himalaya. The Karakoram glaciers show stable or increasing areas and possibly mass (National Research Council, 2012c).

Definitive statements on changes in the glacial mass and in the river flows in the Indus basin would require data from land-based observations of the glaciers, which do not exist for lack of observing stations, and hydrological records from the Indus, which are classified by the Pakistani government. However, the available observations do fit a coherent story of changing glacial mass, which Hewitt (2005) attributes to climatic changes. Because streamflow in the Indus system is so dependent on glacial and snow melt (Archer and Fowler, 2004), and because the Pakistani economic and social systems are so dependent upon the Indus, changes in the mass balance of Karakoram glaciers or hydrology of the Indus are of extreme importance to Pakistani society.

Despite the threats that climate change may pose to the Pakistani society through effects on water supply, there is no public mechanism in place to record the fluctuations either on the upstream or the downstream parts of the Indus basin and no solid basis for making projections. The only data available to gauge the fluctuations in river flows are maintained by IRSA and are classified for political reasons. Press accounts and some technical reports indicate the country’s increasingly stressed water resources (e.g., Pakistan Institute of Legislative Development and Transparency, 2011) and its leaders’ difficulties dealing with the problem. For example, Pakistan’s hydropower infrastructure has not been able to meet the ever-growing power demands, and the government has been unable to set a target date to solve the problem (Saifuddin, 2012).

The Pakistan case illustrates well how a highly stressed environmental system on which a tense society depends can be a source of political insta-

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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bility and how that source can intensify when climate events put increased stress on the system. It also illustrates the value to security analysis of monitoring the many social, economic, environmental, and political elements of such as system. We return to the monitoring issues in Chapter 6.

INTERSTATE AND INTRASTATE CONFLICT AND VIOLENCE

Patterns of Violent Conflict

As background for the discussion of research about climate–conflict connections, it is useful to note several general trends in global patterns of internal and interstate conflict since the end of World War II. Traditionally researchers have used the threshold of 1,000 battle-related deaths in a year when defining a “war.” There are several large databases that track the incidence of conflicts, including different types of wars and armed conflicts around the world. In addition, there are projects to track other forms of political violence (e.g., armed attacks and political murders) or political conflict that may fall short of violence (e.g., riots).9 And scholars frequently develop their own datasets to explore specialized topics, such as detailed explorations of patterns of conflict and political violence in a particular region. As discussed further in Appendix E, government agencies, private foundations, and others are making significant investments in efforts to take advantage of new technologies and enhanced computing power in order to gather more refined data about political and social violence of all types.

Much of the research on climate–security connections relies on the Uppsala Conflict Data Program (UCDP) at Uppsala University in Sweden, which has been collecting data from public sources since the 1970s.10 UCDP provides data on “armed conflicts,” in which at least one party is the government of a state and for which battle-related deaths range from 25 to 1,000 in a year, and “wars,” in which battle-related deaths surpass 1,000 a year. The dataset goes back to 1946 and at the time of this report extends through 2011. UCDP also maintains a number of other specialized databases on such things as intrastate conflict without the involvement of a government (data

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9 A listing of the major datasets on international conflict and cooperation, maintained as an online appendix to the ISA Compendium Project of the International Studies Association, may be found at http://www.paulhensel.org/compendium.html.

10 Information about UCDP, including descriptions of its databases, definitions of its vari ables, and a variety of graphics, is available at http://www.pcr.uu.se/research/UCDP/.

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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image

FIGURE 5-3 Trends in armed conflicts, 1946-2011.
SOURCE: Themnér and Wallensteen (2012). Copyright © 2012 by Sage Publications. Reprinted by permission of Sage. Graphic also available from the Uppsala Conflict Data Program (UCDP) website, see http://pcr.uu.se/digitalAssets/122/122554_conflict_type_2011jpg.jpg (accessed December 26, 2012).

available from 1989 to 2011). As shown in Figure 5-3,11 the UCDP data reflect two broad trends that also appear in the other major databases:

  • The decades since World War II have experienced a relatively small number of interstate armed conflicts, both in absolute numbers and, especially, relative to intrastate conflict. This is particularly note worthy because, with the end of colonial rule and then the dissolution of the Soviet Union and other states following the end of the Cold War, the number of nation-states has grown substantially. For

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11 The four types of conflicts shown in the figure are defined as:

  • “Interstate conflict,” a conflict between two or more governments;
  • “Extra-state conflicts,” the term used primarily for colonial conflicts, the last of which ended in 1974;
  • “Intra-state conflicts,” conflicts between a government and a nongovernment party, with no interference from other governments; and
  • “Internationalized intra-state conflicts,” conflicts in which the government side, the opposing side, or both sides, receive troop support from other governments that actively participate in the conflict. See Uppsala Conflict Data Program, http://www.pcr.uu.se/research/ucdp/definitions/ (accessed June 2, 2012).
Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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example, the United Nations has grown from 51 founding members in 1945 to today’s 193 member states.

  • After peaking in the period immediately following the end of the Cold War, the number of intrastate armed conflicts generally declined through 2010.

In 2011 the number of active conflicts increased to 37, from 31 in 2010, the largest increase between any two years since 1990 (Themnér and Wallensteen, 2012), although the total was still well below the peak of 53 active conflicts in the early post-Cold War years. Six of the conflicts were categorized as wars; the conflict between Cambodia and Thailand, although considered minor, represented a new interstate conflict. The growth “was primarily driven by an increase in conflicts on the African continent, and is only in part due to events tied to the Arab Spring, which mostly led to other forms of violence than conventional armed conflict” (Themnér and Wallensteen, 2012:1).

One implication that the small number of interstate conflicts over the past 60 years has for research on climate-security connections is that it is difficult to use the limited recent experience to forecast potential trends. Other issues related to interstate wars and crises are discussed below.

Interstate Wars and Crises

The limitations imposed on forecasting by the relatively small number of interstate wars in recent decades are compounded by the continuing changes in the fundamental characteristics of the international system since the end of the Cold War. These circumstances make it extremely difficult to test competing hypotheses about risk factors for interstate conflict that would be relevant to current circumstances. In addition to these difficulties there is a lack of consensus among scholars about the causes of such wars (Levy and Thompson, 2010) and about how they compare with the sources of internal conflict. These are problems that affect any effort to understand the risks of a return to more frequent interstate conflict.

On the specific question of climate change as a source of interstate conflict, there is very little systematic evidence, and the causal mechanisms are not well understood. One study (Tol and Wagner, 2010) did find that, for the period 1000 to 1900, low temperatures in Europe coincided with an elevated risk of interstate war. Beyond that finding, prolonged severe drought is the most common type of correlation studied, but this may be in part because it is the easiest anomaly to detect in the ancient record, and it may not be representative of the consequences of climate change in general. As discussed earlier in the chapter, the one area in which there is clear historical evidence of an effect—disputes over shared water resources—the evidence indicates

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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that the outcome is more likely to be cooperation than war (Wolf, 2007). As we already noted with regard to conflicts over water, the literature from the policy community and government agencies discussed in Chapter 1 generally does not foresee that the effects of climate change will lead to war in the traditional sense of violent interstate conflict. Other forms of conflict— including potential violence within states—are considered far more likely.

During the Cold War the possibility of a regional political crisis spiral-ing out of control and leading to direct U.S.–Soviet confrontation led to substantial research on the dynamics of interstate crises (George, 1991; McCalla, 1992). Much of the recent research, however, has focused on the risks of crises that lead to the start or recurrence of internal conflicts.12 There has also been almost no effort to explore empirically whether climate factors might lead to or exacerbate tensions between states to a point short of outright war. Again, disputes over water resources are the one exception. A better understanding of how climate change or events might affect crisis dynamics, particularly in regions where there are other reasons to be concerned about the risks of interstate conflict, could contribute to an understanding of the potential for violence.

Internal Conflict

This section reviews the new and rapidly growing academic literature that explores links between climate stress and internal armed conflict. In the 1990s the accumulating evidence and emerging scientific consensus that the planet was in the early stages of a fundamental and profound climate change was accompanied by suggestions in the peer-reviewed academic literature that this change could lead to increasing levels of violence. The link between climate stress and the outbreak of internal war has been the subject of a dramatic increase in original empirical research about climate–security connections (see Figure 5-4).

The core thesis for those arguing for a link between climate and violent conflict is that climate change–induced health problems and resource scarcity (in particular, the availabilities of water, food, and energy) will lead to interstate violence and intrastate unrest, instability, and armed conflict in the most directly affected nations or regions. Homer-Dixon (1991, 1994, 1999, 2007) and Swart (1996) were among the earlier articulators of this concern in the peer-reviewed literature, followed later by Sachs (2005, 2007), Kahl (2006), Stern (2007), and Lee (2009), among others.

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12 See, for example, Stein (2010) and the work of the International Crisis Group at http://www.crisisgroup.org/ (accessed November 15, 2012). There are obvious exceptions, such as concerns about the impact of nuclear proliferation in the Middle East or Northeast Asia, or Arab–Israeli tensions.

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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image

FIGURE 5-4 Growth in peer-reviewed literature on climate stress and armed political conflict, 1980–2012.*
NOTE: *2012 (through June) doubled to project annual rate. SOURCE: Committee analysis using the SCOPUS database of peer-reviewed literature, July 2, 2012.
SOURCE NOTE: The search looked for some combination of climate-related and conflict-related words in the article’s title, abstract, or list of key words. The climate-related terms were climate, rain, drought, flood, cyclone, hurricane, ENSO, El Niño, and water; the conflict- related terms were civil war, internal war, international war, transboundary conflict, transboundary violence, political conflict, political violence, armed conflict, armed clash, and genocide.

Some scholars have questioned the basis for linking climate change so directly to probabilities of increased conflict, internal as well as international, and, more broadly, to social and political instability. They question the conceptual and empirical bases of the arguments as well as the methodologies employed. The first major collection of peer-reviewed cautionary literature on the posited linkage between climate change and violence was a special 2007 issue of the cross-disciplinary journal Political Geography edited by Nordås and Gleditsch; it found no systematic empirical connections between climate change and conflict, although the editors noted the need for much further research (Nordås and Gleditsch, 2007). Salehyan (2008) followed that collection with a survey of the state of the literature whose title indicated its cautious conclusion: “From Climate Change to Conflict? No Consensus Yet.”

In a study commissioned by the World Bank, Buhaug et al. (2010) came to a similarly cautious conclusion, noting that “numerous questions are unanswered regarding the proposed causal association between climate change and conflict” (p. 75). However, these researchers also of-

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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fered a multi-step “synthesized causal model” to link climate change with conflict, which has the same sort of complex, contingent relationships as the framework we presented in Chapter 2. Their model proposes that “adverse climate change” could lead to increasing natural disasters, rising sea levels, and worsening resource scarcities, all three of which are posited to lead directly to increased or forced migration and then, both directly and indirectly, to “loss of economic activity, food insecurity, and reduction in livelihoods” (p. 82). The model also identifies such pre-existing conditions as poor governance, societal inequalities, and “bad neighbors” (countries characterized by ongoing violence) as well as population pressure exacerbated by migration, and it offers five “social effects of climate change [that] have been suggested as intermediating catalysts of organized violence”: political instability, social fragmentation, economic instability, inappropriate response (possibly meaning inappropriate adaptation), and additional migration, all of which act in a feedback loop (p. 81).

The authors conclude by arguing that these five putative social effects of adverse climate change could lead to either increased opportunities to organize violence or increased motivation to instigate violence, with the end result being an increased risk of armed conflict. The authors repeatedly caution, however, that their model was intended for further research and testing purposes, and they emphasize that “whether adverse climatic changes result in any of these social effects depends largely on the characteristics of the affected area” (p. 81, our emphasis).

In a special section on human conflict in Science in May 2012, Scheffran et al. came to conclusions similar to those of Buhaug and his colleagues, in particular that “current debates over the relation between climate change and conflict originate in a lack of data, as well as the complexity of pathways connecting the two phenomena” (p. 869). They offer a different—but similarly complex—model with multiple potential causal linkages, and they provide a list of core research questions that need to be explored.

Another major set of papers in the peer-reviewed literature appeared in the February 2012 special issue of the Journal of Peace Research titled “Climate Change and Conflict.” Guest editor N.P. Gleditsch introduced the issue by noting that while violence in general “is on the wane in human affairs, even if slowly and irregularly” (citing Goldstein, 2011, and Pinker, 2011), recently “pundits and politicians, along with a few scholars, have raised the specter that this…trend…might be reversed by environmental change generally and by climate change specifically” (Gleditsch, 2012:3). His overall assessment of the special issue’s papers was that:

[I]t seems fair to say that so far there is not yet much evidence for climate change as an important driver of conflict. In recent reviews of the literature, Bernauer, Böhmelt & Koubi (2012) and Gleditsch, Buhaug & Theisen

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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(2011) conclude that although environmental change may under certain circumstances increase the risk of violent conflict, the existing evidence indicates that this is not generally the case. (p. 7)

He adds, however,

that One of the lessons that the large-N community could learn from proponents of case studies is the emphasis on interaction effects. Homer-Dixon (1994) and Kahl (2006) do not argue that environmental change generally and climate change specifically have a major impact on conflict—the effect plays out in interaction with exogenous conflict-promoting factors (Buhaug, Gleditsch, and Theisen, 2008, 2010). Koubi et al. (2012) and Tir and Stinnett (2012) take a step in this direction in testing for interactions with institutions and regime type respectively. (p. 6)

Several of the articles in the special issue do offer more nuanced conclusions. In their modeling of range wars among pastoral groups in East Africa, for example, Butler and Gates (2012) are careful to note that they are really examining “weather change, particularly…drought.” They conclude that conflict is actually more likely in situations of water abundance than in situations of water scarcity (in East Africa at least) and that the role of the state in defining and equitably administering rights to water is crucial to either outcome. In another of the special issue’s articles, Hendrix and Salehyan (2012) report the results of an analysis that employed a new database of more than 6,000 instances of social conflict (including low-level conflict) in East Africa between 1997 and 2009 combined with rainfall variability measures for the same period. The authors find “a curvilinear relationship between rainfall and social conflict” and conclude that (consistent with Butler and Gates above) “armed conflict is more likely to break out in wetter years” (p. 46). They also argue that because so many African agricultural economies are “especially sensitive to rainfall shocks” and have “low adaptive capacity,” climate change will have marked, but highly varying, effects on that continent.

Using more disaggregated conflict data from East Africa for the same time period (1997–2009), Raleigh and Kniveton (2012) explore rebel (anti-government) versus communal violence and find that:

[A]nomalous rainfall conditions, irrespective of sign, are likely to enhance the probability of conflict. However,…the highest incidence of rebel conflict appears to occur in extreme dry rather than wet conditions…[but] incidences of communal violence appear to occur in extreme wet rather than dry conditions. (p. 62)

Then drawing from two case studies of pastoralist conflict (raiding, in particular) in northern Kenya, Adano et al. (2012) find that “more conflicts

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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and killings take place in wet seasons of relative abundance, and less in dry season times of relative scarcity, when people reconcile their differences and cooperate” (p. 77). More relevant for possible generalizing, however, is how Adano et al. capture the importance of local coping mechanisms:

During drought periods, pastoralists in northern Kenya deploy social institutions that mediate agency toward cooperation and guarantee access to resources (water) for all, thereby reducing violent conflict. Remoteness and inaccessibility…weaken government initiatives to provide adequate security, but local arrangements moderate conflicts when scarcity peaks. (p. 77)

The problem with this somewhat optimistic picture from Adano et al. (see also Solnit, 2010), is that it does not consider what would happen if climate change were to induce some combination of increased rainfall variability and immigration of affected peoples from other areas. This would result in a not inconsiderable challenge. How quickly and effectively, then, could the local social coping mechanisms adapt to the changing situation? Local coping mechanisms are usually borne of relatively static, or at least bounded, conditions and numbers of players with years of patterned interactions, but climate change may change both of those parameters.

Two other studies that looked at broader sets of data come to contradictory conclusions. In a study of the relationship between conflict and the ENSO cycle Hsiang et al. (2011) examined civil conflict data for the 1950–2004 period and found that “the probability of new civil conflicts arising throughout the tropics doubles during El Niño years relative to La Niña years” and that “ENSO may have had a role in 21 percent of all civil conflicts since 1950” (p. 438). This article was picked up by the mass media and attracted significant attention. Theisen et al. (2011), in an article in the journal International Security, use a “high-resolution gridded dataset of Africa from 1960 to 2004 that combines georeferenced and annualized precipitation data with new data on the point location of civil war onset and the location and political status of ethnic groups to test the links between drought and the start of civil conflict” (p. 81). They conclude, “The results presented in this article demonstrate that there is no direct, short-term relationship between drought and civil war onset, even within contexts presumed most conducive to violence” (p. 105). They also suggest, however, that

future research needs to apply a broader understanding of political violence and armed conflict than is normally the case today. Given data limitations and a perception that major, state-based conflicts carry greater potential for political instability and state collapse than small-scale interethnic skirmishes, recent scholarship has focused almost exclusively on civil wars. This is reflected in the contemporary discourse on climate security, which is dominated by a state-centric approach. In contrast, nar-

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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ratives and news reports of conflict over diminishing resources frequently concern clashes between rivaling ethnic groups or between pastoralists and sedentary farmers. The conflicts in Assam in India, Darfur in Sudan, Kenya, Mali, and Mauritania, all central cases in the environmental security literature, were at least initially interethnic conflicts without explicit state involvement. Key questions in this regard are how environmental conditions and rapid environmental change affect intercommunal relations and local land use disputes, and what role the state plays in ending or fueling these conflicts. (p. 106)

Because climate change has the potential for an increase in the number or severity of various types of disasters caused by weather-related extreme events (cyclones, storm surges, floods, droughts, wildfires, etc.) or geographic shifts, or at least an expansion of their areas of incidence, there has been a renewed interest in the possible link between such events and interstate and intrastate violence.13 Using a time series for 1966–1980, Drury and Olson (1998) provided the first quantitative attempt to test for a relationship between disasters and political instability and found “a direct and positive linkage between disaster severity and ensuing levels of political unrest” (p. 153). Ten years later Nel and Righarts (2008) analyzed a much larger number of cases (183 from the period 1950–2000) and found a positive and robust relationship between natural disasters of all types and both major (more than 1,000 killed) and minor (less than 1,000 killed) internal armed conflict occurring in the same year as the disaster as well as in the following year. Interestingly, when the analysis was limited to climate-type disasters only, there was only a correlation with major armed conflict, not minor. In a separate study that focused only on earthquakes, Brancati (2007) found a positive relationship between earthquakes and ensuing instances of political violence. The evidence indicates that climate events can contribute to social and political disruption in various ways, sometimes causing as much as a doubling of risks of adverse outcomes.

Recently, however, all of these findings and conclusions have been challenged by Omelicheva (2011), Bergholt and Lujala (2012), and Slettebak (2012), who question in different ways the previous studies’ variable specifications and measurements, particularly their inadequate inclusion of control variables in their models. On the whole, their arguments contend that when closer attention is paid to variable specification and measurement and the models are made more complex with closer attention to such things

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13 A separate stream of literature not treated here on the role of disasters/catastrophes, including ENSO-related events, in what might be called civilizational collapses or macro-system changes would include Davis (2002), Diamond (2005), Nur and Burgess (2008), Fagan (2009), and Johnson (2011) among others.

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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as regime type, prior instability, and governance capabilities, the political instability effects of disasters tend to disappear.14

Given the relatively early stage of development of the research field and the strong policy interest in the topic, these sorts of debates can be expected to continue. A search for complex and contingent relationships should improve the conceptual basis for future research and intelligence analysis.

CONCLUSIONS AND RECOMMENDATIONS

Evidence from the social science literature supports the general argument that climate change can contribute to social and political stresses that create security risks, but that these risks are not caused by climate change alone. They result from the conjunction of climatic conditions that generate potentially disruptive events with a variety of socioeconomic and political conditions. The effects of climate on security in the coming decade are therefore likely to be indirect and contingent, operating through effects on systems that support human well-being (e.g., food, water, or health systems) or on specific events and circumstances (violent conflicts, disruptive migrations), and to depend on other social, economic, environmental, and political conditions in the affected places. This assessment is consistent with the conclusions about climate-security connections that appear in most of the major policy and government assessments.

The strength of the evidence about the linkages between climate events and outcomes of security interest varies substantially within and across issue areas. A number of the linkages are tenuous or not well understood; others seem relatively robust. Some examples of such linkages are:

  • There is a statistically significant correlation between some forms of climate stress and the onset of some forms of armed internal conflict, but in general the causal pathways are not well understood.
  • Climate change is altering the host range for several disease vectors with the potential to cause major epidemics and perhaps pandemics, given global patterns of trade and travel.
  • Climate change is expected to cause changes in some of the basic and proximate conditions that can lead to increases in water insecurity, with the potential to affect food and health security.

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14 A second stream of literature not treated here involves the broader question of how publics evaluate the performance of their leaders in disasters, whether they are simply unthinkingly “responsive” (or, perhaps better, “reactive”) or more thoughtfully “attentive” (evaluative). This stream, with an overwhelming U.S. focus, was stimulated by Achen and Bartels (2004) and includes Malhotra and Kuo (2008), Healy and Malhotra (2009), and Gasper and Reeves (2011).

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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The empirical knowledge base on the connections between extreme events of many types, including climate events, and political instability or violence also suggests some hypotheses that are worthy of examination in future research. For example, the available evidence is consistent with the idea that climate events affecting places of national security interest to the United States are likely to create the potential for significant violence, conflict, or breakdown dependent upon seven factors:

  1. the nature, breadth, or concentration and depth of pre-existing social and political grievances and stresses;
  2. the nature, breadth, or concentration and depth of the immediate impacts of the climate event;
  3. the socioeconomic, geographic, racial, ethnic, and religious profiles of the most exposed groups or subpopulations as well as their susceptibilities and coping capacities;
  4. the ability and willingness of the incumbent government and its internal and external supporters to devise, publicize, and implement effective, transparent, and equitable short-term emergency response and then longer-term recovery plans;
  5. the extent to which emergent or established anti-government or anti-regime movements or groups are able to take strategic or tactical advantage of grievances or problems related to responses to the event;
  6. the type, breadth, and depth of legitimacy and support for authorities, the government, the regime, and the nation-state; and
  7. the coercive and repressive capacities of the government and its willingness and ability to engage in and carry out repression.

We reiterate that the available evidence indicates that the relationships are complex and uncertain between the kinds of climate events that can be expected to occur with greater frequency in the coming decade and the kinds of social or political outcomes that can become U.S. national security concerns. The picture is blurry in part because both the climatic and the political events of concern have been infrequent until now, making analysis of their relationships difficult. Available evidence on several of these connections, however, points to the same general finding we reported in Chapter 4 regarding the causes of social and political stresses, namely, that the effects of climatic events on outcomes of security significance are contingent on a variety of specific social, political, economic, and environmental conditions in affected places. Thus, even with a more extensive body of climate experience to draw upon, it is unlikely that simple, straightforward conclusions will be found that reliably link a climate event of a particular type with a particular kind of effect on conflict or on key aspects of social well-being.

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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In our judgment, it would be inappropriate to conclude from the evidence reviewed here that climate change will have no effects. In fact, the evidence indicates that climate events can contribute to social and political disruption in various ways. The appropriate conclusion is as follows:

Conclusion 5.1: It is prudent to expect that over the course of a decade some climate events—including single events, conjunctions of events occurring simultaneously or in sequence in particular locations, and events affecting globally integrated systems that provide for human well-being—will produce consequences that exceed the capacity of the affected societies or global systems to manage and that have global security implications serious enough to compel international response. It is also prudent to expect that such consequences will become more common further in the future.

Conclusion 5.2: The links between climate events and security outcomes are complex, contingent, and not understood nearly well enough to allow for prediction. However, the key linkages, as with societal disruptions, seem prominently to involve (a) exposures to potentially disruptive events directly or through globally integrated systems affecting human well-being and (b) vulnerabilities (i.e., susceptibility to harm and the effectiveness of coping, response, and recovery efforts). In addition, security outcomes depend on the reactions of social and political systems to actual or perceived inadequacies of response.

Available knowledge of climate–security connections that feature societal vulnerabilities, as reviewed in this and the previous chapters, indicates that security analysis needs to develop more nuanced understanding of the conditions—largely, social, political, and economic conditions—under which particular climate events are and are not likely to lead to particular kinds of social and political stresses and under which such events and responses to them are and are not likely to lead to significant security threats.

Recommendation 5.1: The intelligence community should participate in a whole-of-government effort to inform choices about adapting to and reducing vulnerability to climate change. As part of this effort, the intelligence community and other interested agencies should support research to improve understanding of the conditions under which climate-related natural disasters and disruptions of critical systems of life support do or do not lead to important security-relevant outcomes such as political instability, violent conflict, humanitarian disasters, and disruptive migration.

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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A major focus of this research effort should be on understanding the connections between harm suffered from climate events and political and social outcomes of security concern. These connections, which are arguably the most important aspects of climate change from a national security perspective, have received relatively little scientific attention until now. The disaster research community, which has been the locus of research on the political effects of climate events, has not been well connected to the climate research community. Nevertheless, the available research strongly suggests some plausible hypotheses to examine, such as the one above concerning seven factors that may link climate events to political conflict and instability. Efforts should be made to test such hypotheses systematically against historical data and, as climate change proceeds, against experience. There is also a need for fundamental research on some of the concepts that link harm to political outcomes.

Although there is extensive research on some of the factors influencing the vulnerability of populations to singular climatic events of various kinds, further investigation is needed to identify factors that influence vulnerability to sequences of events, such as repeated extreme precipitation events or linked physical and biological events driven by climate processes, and to events that occur in distant regions and disrupt food, energy, or strategic-product supply chains. There is also a need to develop real-time, local-scale metrics of key economic, social, and political components of vulnerability, as discussed further in Chapter 6 and Appendix E.

This research will need to use various methods and approaches. For example, given the complex and contingent relationships between climate events and such consequences as socioeconomic stress and political instability, a systematic set of longitudinal case studies is needed of the effects of climate events, using an explicit and common conceptual framework. These case studies need to cover at least five years post-impact and to include cases where an extreme event or several events produce no evidence of major so-cioeconomic or political stresses (“null” cases). The cases should cover all hazard types, with a special subset on climate-related hazard types. There is also a need for relatively large-N quantitative studies that focus on types and levels of disruptive events; mediating variables related to vulnerability, coping, and response that track multiple time periods; and ensuing internal political unrest, instability, or violence. There is also a need for cross-national, cross-cultural, and longitudinal public opinion research related to pre-event risk reduction and post-event coping, emergency response, and recovery in order to gain understanding of the factors affecting perceptions of adequacy of response.

We note that the needed knowledge tends to come from different communities of experts, which will need to communicate with each other but do

Suggested Citation:"5 Climate Events and National Security Outcomes." National Research Council. 2013. Climate and Social Stress: Implications for Security Analysis. Washington, DC: The National Academies Press. doi: 10.17226/14682.
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not necessarily do so now. The recommended interagency process can help bring these communities of experts together, because they tend to associate with different groups of agencies.

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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. Although focused on events outside the United States, Climate and Social Stress: Implications for Security Analysis recommends a range of research and policy actions to create a whole-of-government approach to increasing understanding of complex and contingent connections between climate and security, and to inform choices about adapting to and reducing vulnerability to climate change.

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