Climate change is increasingly discussed in the context of security, especially national security. What so-called “climate security” means is often muddled, however. This is partly because the term “security” is loosely defined, often used a catch-all term for bad things. Meanwhile, national security experts are unlikely to have the background or inclination to dig into primary scientific literature to consider the full weight of adverse climate change effects on people and nations. In this article, I endeavor to explain why ongoing and future climate change should be considered a security issue. I hope to show that stresses to people and societies from climate change are multidimensional and concurrent, leading to risks that span human, national, and global security.
A Clash Over Science
First, a bit of history.
While serving as Director of Environment and Natural Resources at the National Intelligence Council (NIC), I was often asked to explain how climate change could be considered a national security issue. Indeed, a classified climate security paper that I produced for the White House was eventually sanitized and issued as the NIC White Paper Implications for US National Security of Anticipated Climate Change. I was, and remain, proud of the document, especially since it had been many years since the intelligence community commented publicly about climate change. Still, because there were so many approvers along the way, the final report felt a little undercooked and less sharp than I had hoped. Interestingly, another NIC product that I helped develop on another ecological security topic, Global Implications for Illegal, Unregulated, and Unreported (IUU) Fishing, was published on the public-facing NIC website the same day.
About a year after I returned to my post at the State Department as Senior Analyst and Senior Scientist in the Bureau of Intelligence and Research (INR), I was asked to testify to the House Permanent Select Committee on Intelligence (HPSCI) for a June 2019 unclassified hearing on the national security implications of climate change. Since INR’s Statement for the Record would be unclassified, entered into the Congressional record, and available to the American public, I believed this was a good opportunity to build on the NIC White Paper on climate change. In particular, I thought it was important to illustrate for the American people how scientific findings from the academic literature propagate into statements of risk, rather than pulling national security language seemingly out of thin air.
Unfortunately, the National Security Council and the White House Office of Legislative Affairs balked at the inclusion of climate science in the document. This was not the first time that the Trump White House had shown hostility towards science, nor would it be the last. After some ugliness, the White House made the decision to suppress the written testimony from being transmitted to Congress. This was a rather unusual step to take towards an element of the intelligence community attempting to respond to its House oversight committee. Furthermore, the State Department’s Bureau of Legislative Affairs refused to honor Chairman Adam Schiff’s follow-on request to transmit the suppressed document, and other supporting information, to Congress. (You can read my New York Times op-ed from July 2019 on the matter, and why I resigned in protest from a decade of government service). Many of that document’s arguments, however, are explored below.
What are National Security and Human Security?
Although notoriously difficult to define precisely, national security is nevertheless the government’s most important role. What constitutes national security has enormous consequences for how a government’s financial resources, personnel, and attention are allocated. And notably, national security involves elements of the U.S. government including but beyond the Department of Defense.
The National Security Act of 1947 established national security as an organizing principle for important functions of the United States government. In addition to consolidating the Army, Navy, and the newly-established Air Force under the Secretary of Defense, the legislation formally established the Central Intelligence Agency. It also called for the formation of the National Security Council (NSC) to coordinate policies on behalf of the President concerning domestic, foreign, and military issues. Over time, the role of the NSC expanded to match most of the major concerns of the Executive Branch.
As mandated by Congress, since 1986 the NSC has formulated a National Security Strategy (NSS) that outlines an administration’s major national security concerns and how it plans to deal with them. Observers within and outside government pay close attention to which issues are included — or not — in a new administration’s NSS to get a spin-free signal of its priorities. For example, after appearing in national security strategies dating back almost twenty years, climate change was completely absent in the Trump administration’s NSS, which clearly signaled its allergy to the issue. Several national security governmental agencies—notably the Departments of Defense, State, Treasury, Homeland Security, and Energy, as well as the intelligence community—use the NSS to guide their own implementation strategies.
The U.S. intelligence community often considers an event a national security concern when it: (a) produces a noticeable, even if temporary, degradation of one of the elements of U.S. national power: geopolitical, military, economic, informational, (b) indirectly influences the United States through a strategically important ally or partner, or (c) causes adverse effects that indirectly consume U.S. resources. Not all geographies are equal and, from the perspective of the United States, issues that involve our allies, adversaries, strategic partners, nuclear states, and countries in our backyard more readily cross the national security threshold.
By the 1990s, the prevailing paradigm that security necessarily focused solely on the nation-state was increasingly challenged, and arguments to consider a “human security” based on the needs of individuals began to take root. Access to food and water, protection from disease and violence, and preservation of economic livelihoods and human rights are often mentioned as components of human security. Looking at risks to individuals and communities is important to adequately convey how changing ecological conditions are disruptive. Not only will people in vulnerable nations be at risk but so too will be vulnerable populations in wealthier nations.
During my government service, when answering climate security questions from senior officials about which populations will be affected by whichever climate hazard was salient, I would often respond with the phrase “the vulnerable and the unlucky.” After witnessing the large numbers of people in the last few years adversely affected by storms, floods, wildfires, heatwaves, and disease, the notion of those assumed vulnerable versus unlucky may be deserving of revision.
Changes in Temperature and pH Alter Many Earth System Processes
The Earth’s atmosphere is undergoing an unequivocal long-term warming trend, as clearly shown in the temperature plot above (which shows NASA data, but the same trend is seen in other independent data sets). Notably, if a senior national security official were to dispute the scientific consensus that atmospheric warming is due almost entirely to the enhanced greenhouse effect, they would still nonetheless need to consider the national security consequences of this thermal pulse. (This is why, in an attempt to maintain a self-consistency, diehard climate denialists find themselves needing to dismiss a whole host of other climate-linked phenomena, such as coral bleaching and changing disease patterns, while adopting rather outlandish conspiracy theories, such as NASA-is-tampering-with-the-data and scientists-are-duping-us-to-get-rich.)
Unfortunately, this temperature increase is not experienced in a vacuum but rather in the context of other Earth system stresses, most notably overfishing, habitat conversion, nutrient imbalances, pollution, plastics, and the direct exploitation of organisms. Meanwhile, ocean waters are becoming less alkaline through the direct absorption of carbon dioxide in the atmosphere. The logarithmic nature of the pH scale can mask the seriousness of ongoing ocean acidification, which can have devastating effects on many marine organisms and ecosystems.
The Intergovernmental Panel on Climate Change, and other scientific bodies, have observed changes in other Earth system processes, all of which are important to consider in terms of potential stresses to people and nations. Although the list is long, it is almost certainly far from complete as changing meteorological variables trigger other unforeseen biophysical, ecological, and sociological outcomes.
Extreme weather events, such as heatwaves, floods, droughts, storms, and heavy precipitation, pose major risks to people in all regions. These events may happen more or less often, with different intensities, or in novel regions compared to historical patterns, and any of these changes may be significantly disruptive. For types of extreme events that increase in frequency, the geographic and temporal distribution will be increasingly important. For example, modest extreme events that are clustered, compounded, or sequential may be more disruptive than more powerful isolated events. There are almost certainly analogous abrupt events waiting in the biosphere, such as the sudden emergence of a destructive pest or mass die-off of organisms in a particular species. Although not characterized in this article, the potential for high-impact, low-probability events, such as rapid melting of ice sheets or abrupt changes in atmospheric and ocean circulation, are important when fully assessing risks from climate change to people and nations.
Climate-Linked Stresses to Humans and Societies
Humans and societies may experience the disruptive effects of climate change directly, such as through death, injury, or loss of shelter, or indirectly, such as through the impairment or collapse of systems and institutions that support people. In some cases, climate-linked stresses will exacerbate existing social and political problems — the so-called threat multiplier effect — while, in other cases, creating new problems. Some stresses will be acute and target particular sectors or regions, while others will be diffuse and multi-sectoral. Some climate-linked stresses, such as disruptions to the global food supply, will have worldwide ramifications. As we march further into the 21st century, we should expect that these stresses will be felt increasingly concurrently.
Although ghoulish to discuss, it would be nonetheless dishonest to argue that climate change effects are solely negative. Indeed, some populations or sectors will almost certainly experience some degree of benefits. Cold-weather deaths, for example, are expected to decrease as winters warm, and some freshwater supplies will be temporarily boosted by increased glacier melt. Rainforests are expected to become greener and some croplands are expected to become more productive. Most plants grow better under increased levels of carbon dioxide under laboratory conditions. (The latter is the main argument of the wacky “CO2 is Good!” crowd, who must disregard essentially all other negative effects of carbon dioxide to arrive at this predetermined conclusion.) It is clear, however, that negative effects will overwhelm any positive benefits from climate change for most of the world.
Implications for Human Security
Before turning to national security outcomes, I usually first discuss the human security aspects of climate security. This is because many national security outcomes, such as political instability and social discohesion, are rooted in grievances and anger arising from human insecurity. Risks to human security usually emerge from the interactions of multiple factors rather than from a single cause. For example, the impact of a severe drought on a livestock farmer’s livelihood is dependent on the prior health of the livestock, dependence on livestock income, and economic resilience of the household, among other factors. Past episodes of insecurity often worsens the vulnerability to future risks. The following sections illustrate some of the risks to human security from climate change, but are not exhaustive.
Death or Injury From Direct Harm. Extreme weather events, such as tropical storms, droughts, wildfires, and flooding, are major contributors to human fatalities and injuries. Periods of extreme heat can be especially deadly. For example, the death toll from the 2003 European heatwave has been estimated at more than 70,000 people. Meanwhile, the number of extremely destructive hurricanes, such as Katrina and Harvey, have become more common than their less powerful counterparts.
Water stress. Water use has been growing at more than twice the rate of the human population for decades. Nearly 1.8 billion people, a quarter of the world’s population, now reside in countries that face extremely high water stress. Water scarcity is especially acute in Middle East countries and India. Even in countries with low water stress, some populations are nevertheless hard pressed to acquire water. For example, glacier recession in Peru has greatly impeded water availability for people downstream. Water shortages in some highly urbanized centers are increasing; Sao Paolo, Cape Town, and Chennai have faced extreme shortages in the past few years.
Food insecurity. More than 500 million people now live in areas affected by soil erosion or desertification that supports plant growth, while more than 820 million people are undernourished. A cycle of conflict and drought has exacerbated child hunger in Africa, with 3 out of 4 children now experiencing stunting on the continent. For populations in Asia and Africa that are highly-dependent on fish as a source of protein, even small climate-linked perturbations in fish supplies can lead to malnutrition or hunger.
Erosion of economic livelihoods. Degradation of fisheries from warming waters and overfishing undermines the livelihoods of many fishers worldwide. Capital investments in fishing infrastructure can then become difficult to repay, and the economic livelihoods of entire communities can be affected. Agricultural crops that fail, underperform, or swing dramatically in reliability bring negative effects for farmers and their families. In severely afflicted countries like India and Pakistan, large numbers of farmers have died by suicide after weak or failed growing seasons. Livelihoods dependent on the health of vulnerable animals, such as livestock or bees, are at risk.
Loss of residence and property. Housing and property are affected by many climate stressors, such as sea-level rise, storm surges, flooding, and wildfires. Higher sea levels make destructive storm surges push farther inland than before, which is accompanied by more nuisance flooding. Deforestation and clearing of mangroves make many homes especially vulnerable to extreme events. Extreme weather events, particularly floods and fires, are likely to push home and flood insurance out of reach for homeowners, even in developed countries while insurers may become stricter about who can obtain coverage.
Risks to human health and well-being. Changes in climate conditions alters the geographic range, intensity, and duration of many infectious diseases. Young children and older people, populations experiencing social marginalization through poverty or migration status, and individuals already suffering adverse health conditions are especially prone to periods of extreme heat. Respiratory health suffers from wildfires and dust storms. Warming temperatures are projected to expose half the world’s population to mosquitos by 2050 as they expand their geographic range. Higher temperatures also increase mosquito biting frequency and the reproductive cycle of microbes within the mosquito. Rising temperatures also lead to longer allergy seasons and can worsen air pollution. This can increase the risk and severity of asthma attacks and cause more allergies.
Negative impacts on education. Tropical storms and wildfires can destroy or damage buildings, or schools may be repurposed to shelter displaced people. Many of the children are temporarily unable to attend classes, and some do not return. Households dependent on agriculture can suffer losses to income and food security from heatwaves and drought, preventing them from paying school fees. Girls are especially affected in many countries. The prenatal period and first few years of life are critically important for brain health. Undernutrition, air and water pollution, and heat stress are all associated with physiological conditions leading to poor cognitive development and lower educational attainment later in life.
Intensified violence and crime. Rapid onset of adverse living conditions can contribute to violence between people. For example, changes in rainfall patterns and frequent droughts have reportedly sparked violent conflicts for years over water and grazing land between farmers and herders in Africa. In 2019, massacres in Mali, fueled by conflict over land and water resources, caused over 50,000 people to flee their homes. Locals cite water and food shortages as a growing influence on the number of child kidnappings in South Sudan, as groups spend more time on the move and resell children for profit as a side business.
Effects on human migration and mobility. The factors driving migration are complex and multifaceted, and people can migrate voluntarily or be forced by circumstances or coercion. The move can be permanent or semi-permanent and between and within countries. Extreme weather events generally displace people in the short term from the loss of their residence or economic livelihood. The increasing incidence and intensity of extreme events virtually guarantees that increased levels of human displacement will follow. A large fraction of displaced people, however, will attempt to return to their original residence if possible. Studies have established that vulnerability is inversely correlated with mobility, leading to those being most vulnerable and exposed to climate-linked stresses have the least capability to migrate.
Implications for National Security
While no nation is immune to the effects of ongoing and future climate change, some will be able to cope, adapt, or respond more effectively than others. Countries that are already failed or fragile, or in many cases otherwise distracted, are especially vulnerable to climate-linked stress. While this section is largely written from a U.S. national security perspective, similar arguments apply to most other developed countries. However, stresses in some lesser developed countries are probably better framed as critical or even existential threats since their concept of national security differs fundamentally from countries with a global presence. The next sections illustrate some of the national security risks arising from climate-linked stresses and, like the preceding section, not intended to be exhaustive.
Harm to citizens. One of the core missions of any government is to protect its citizens and ensure their well-being. The Preamble of the U.S. Constitution even calls out this responsibility in its clause “promote the general welfare.” The Earth’s warming trend is unambiguous, as are the concomitant risks to U.S. citizens, and promoting the general welfare clearly includes protection and recovery from the adverse effects of climate change.
Political instability. When amplified by existing tensions or grievances, human insecurity can drive political unrest and insurgency. Syria’s collapse into civil war was preceded and probably driven by an intense drought and the accompanying rural-to-urban migration. Venezuela’s problems were largely triggered by food insecurity. Further, climate-linked stresses can prevent or impede an already fragile state from recovering, while extensive international peacekeeping and stabilization efforts by US military and UN peacekeeping missions remained focused on this objective.
Heightened tensions over resources. Disputes over shared or disputed resources, such as water, arable land, timber, and fisheries are increasingly common on national and subnational scales. Water disputes have pitted states within India against each other and have sometimes turned violent. Sharing of transboundary water is a major source of tension between nations on the Nile, Mekong, Niger, Zambezi, Amu Darya, Indus, Brahmaputra, and Jordan River basins. Excessive groundwater pumping worldwide further exacerbates water and food security.
Adverse effects on militaries. Military capabilities and facilities on domestic and foreign territory will be increasingly threatened, including bases and training ranges. Operations and equipment will also need to be reconfigured to withstand harsher or rapidly changing conditions. Personnel may be increasingly unprepared or untrained for especially severe or novel conditions, such as fighting pests or combatting wildfires. Addressing simultaneous complex security situations may undermine military readiness or willingness to take on new missions. Similar arguments can be made for law enforcement agencies and other security services.
Risks to global systems and resources. Overexploitation, warming waters, and illegal fishing contribute to a dangerous reduction in vital marine fisheries that support over 4 billion people worldwide. About a billion of these depend on fish as their primary source of protein. Ocean acidification is stressing phytoplankton and other organisms that form the base of the marine food network. Ongoing biodiversity loss and extinction of species are reducing the integrity of the ecosystems that support animal and plant life on Earth.
Risks to global supply chains. As the global food supply chain has evolved to move consumables around the planet to more people, systemic efficiencies such as just-in-time delivery and distribution hubs have introduced weaknesses with far-reaching implications. For example, the global food supply chain is likely quite vulnerable to multiple concurrent disruptions. Resultant price shocks, as seen in 2008, can likewise reverberate rapidly across the world, triggering almost immediate constraints on food availability far from the points of disruption. Other commodities reliant on tightly coupled links within a global supply chain are probably similarly susceptible to systemic failure. Hubs or chokepoints in especially vulnerable regions, such as tropical coasts or areas prone to heatwaves, are at higher risk.
Adverse effects on key economic sectors. Actuaries that calculate insurance risks and premiums based on data have begun to rank some aspects of climate disruption, such as sea level rise and wildfire risk, higher than cyber damages, terrorism, and financial instability. Countries heavily dependent on tourism revenues may be especially vulnerable to extreme weather events or rapid ecological shifts.
Humanitarian crises. The World Bank estimates two billion people already live in fragile and conflict-affected areas of the world and, by 2030, at least half of the world’s poor will live in these settings. These populations are at a disproportionately higher risk to climate-linked hazards. Extreme events amplified by climate change may pose newfound challenges, particularly when compounded events occur with greater frequency or severity in the same area. The exposure and resilience of people and assets of those affected are critical factors in how crises unfold.
Decreased integrity or reliability of infrastructure. The rate of electricity blackouts in the United States has increased tenfold over the past 20 years, arising from new patterns of extreme heat and storms. For regions especially reliant on power for households and industries, there are associated implications for human health, livelihoods, and crime.Water is widely considered to be the greatest threat to roads, bridges, and other transport infrastructure — and floods, storms, and rising sea levels will bring greater damage to older or non-reinforced construction. Internet outages are likely to increase in frequency from extreme heat and intense storms.
Loss of Territory. Many armed conflicts have historically been fought over sovereignty. Sea level rise and subsidence complicate international and regional talks over shifting land and maritime boundaries. In particular, sea level rise and saltwater intrusion of coastal aquifers threaten to displace some island populations entirely.
Changing or emerging geostrategic domains. The Arctic includes the territory of numerous nations but lacks a regional treaty that establish governance of access to its waters and resources. Rapid changes in the Arctic are driving many countries to studying their own military capabilities and plans to effectively operate in the region. Some have started to rebuild their forces, while most others remain in the planning stages. Icebreakers are increasingly mentioned as a critical instrument of support to military needs. Competition over regional and international maritime domain is likely to intensify as fish stocks dwindle.
Changes in large-scale migration patterns. Climate-linked stresses will almost certainly drive an increasing number of people to migrate to other countries. Some projections estimate more than 140 million people could migrate by 2050, and many receiving nations will have neither the resources nor interest to host these migrants. Increasingly inhospitable conditions and losses of territory from sea level rise will likely spur some island nations, particularly in the tropical Pacific, to consider relocating large segments of its population elsewhere.
Altered patterns of infectious disease outbreaks. Climate change influences several aspects of the transmission of mosquito-borne disease, namely how long mosquitos survive, how well they reproduce, how frequently they bite, and the incubation rate of pathogens within the mosquito. The same argument applies to other vectors, such as rodents and snails. Human exposure to waterborne infections is exacerbated by both floods and droughts. The geographic range of most animals are changing, driving biotic mixing that in turn increases the risk of zoonotic disease transmission to humans. Climate change also degrades human health through other pathways, making them more susceptible to infection.
Heightened risk of climate-linked surprise. A large body of science indicates that Earth’s systems are being driven by natural and humanmade forces at extraordinarily high rates of change. For example, atmospheric carbon dioxide is currently increasing at the highest rate in perhaps 66 million years. Scientists are still working to quantify the magnitude of the temperature response to these increases, but the resultant thermal pulse is probably unprecedented in modern human history. The implications of abrupt changes across Earth’s systems for human, national, and global security could be severe.
Climate Security Outlook
Going forward, the disruption to people and nations imparted by climate change and its associated climate security effects depends critically on at least four factors:
- The degree to which known levels of greenhouse gases drive temperature increases; large, small, or in-between
- The degree to which the multiplicity of concurrent or sequential climate-linked stresses interact with each other
- The degree to which the drivers of climate change, particularly greenhouse gas emissions, will be mitigated
- The degree to which people’s exposure and vulnerability to climate-linked stresses are reduced
The first two factors are scientific concerns and active areas of research, and lie largely outside of human control. People’s choices, however, dictate the magnitude of the last two. The large range of uncertainties means that quantifying the appropriate timeframe for action is difficult, which is complicated by the fact that actions will often require many years to bear fruit. Absent extensive mitigating factors or events, there appear to be few plausible future scenarios where significant, perhaps catastrophic, harm does not arise from the compounded effects of climate change.