Intensifying climate change will increase the future risk of violent armed conflict within countries, according to a study published today in the journal Nature. Synthesizing views across experts, the study estimates climate has influenced between 3% and 20% of armed conflict risk over the last century and that the influence will likely increase dramatically.

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In a scenario with 4 degrees Celsius of warming (approximately the path we’re on if societies do not substantially reduce emissions of heat-trapping gases), the influence of climate on conflicts would increase more than five times, leaping to a 26% chance of a substantial increase in conflict risk, according to the study. Even in a scenario of 2 degrees Celsius of warming beyond preindustrial levels – the stated goal of the Paris Climate Agreement­ – the influence of climate on conflicts would more than double, rising to a 13% chance.

“Appreciating the role of climate change and its security impacts is important not only for understanding the social costs of our continuing heat-trapping emissions, but for prioritizing responses, which could include aid and cooperation,” said Katharine Mach, director of the Stanford Environment Assessment Facility and the study’s lead author.

Climate change-driven extreme weather and related disasters can damage economies, lower farming and livestock production and intensify inequality among social groups. These factors, when combined with other drivers of conflict, may increase risks of violence.

“Knowing whether environmental or climatic changes are important for explaining conflict has implications for what we can do to reduce the likelihood of future conflict, as well as for how to make well-informed decisions about how aggressively we should mitigate future climate change,” said Marshall Burke, assistant professor of Earth system science and a co-author on the study.

Finding consensus

Researchers disagree intensely as to whether climate plays a role in triggering civil wars and other armed conflicts. To better understand the impact of climate, the analysis involved interviews with and debates among experts in political science, environmental science, economics and other fields who have come to different conclusions on climate’s influence on conflict in the past.

Fari Awade draws water from a well in the community of Natriguel, Mauritania. Climate-related hazards, such as droughts, can cause economic shocks to agricultural communities, which may heighten the risk of armed conflict, according to a new Stanford-led study. (Image credit: Pablo Tosco/Oxfam)

The experts, who also served as co-authors on the study, agree that climate has affected organized armed conflict in recent decades. However, they make clear that other factors, such as low socioeconomic development, the strength of government, inequalities in societies, and a recent history of violent conflict have a much heavier impact on conflict within countries.

The researchers don’t fully understand how climate affects conflict and under what conditions. The consequences of future climate change will likely be different from historical climate disruptions because societies will be forced to grapple with unprecedented conditions that go beyond known experience and what they may be capable of adapting to.

“Historically, levels of armed conflict over time have been heavily influenced by shocks to, and changes in, international relations among states and in their domestic political systems,” said James Fearon, professor of political science and co-author on the study. “It is quite likely that over this century, unprecedented climate change is going to have significant impacts on both, but it is extremely hard to anticipate whether the political changes related to climate change will have big effects on armed conflict in turn. So I think putting nontrivial weight on significant climate effects on conflict is reasonable.”

Planning ahead

Reducing conflict risk and preparing for a changing climate can be a win–win approach. The study explains that adaptation strategies, such as crop insurance, post-harvest storage, training services and other measures, can increase food security and diversify economic opportunities, thereby reducing potential climate–conflict linkages. Peacekeeping, conflict mediation and post-conflict aid operations could incorporate climate into their risk reduction strategies by looking at ways climatic hazards may exacerbate violent conflict in the future.

However, the researchers make clear there is a need to increase understanding of these strategies’ effectiveness and potential for adverse side effects. For example, food export bans following crop failures can increase instability elsewhere.

“Understanding the multifaceted ways that climate may interact with known drivers of conflict is really critical for putting investments in the right place,“ Mach said.

Mach is also a senior research scientist in Earth system science. Burke is a center fellow at the Freeman Spogli Institute for International Studies and, by courtesy, at the Stanford Woods Institute for the Environment. Fearon is the Theodore and Frances Geballe Professor in the School of Humanities and Sciences and a senior fellow at the Freeman Spogli Institute for International Studies.

Other Stanford co-authors include: Chris Field, the Melvin and Joan Lane professor for Interdisciplinary Environmental Studies, a professor of biology and of Earth system science, Perry L. McCarty director of the Stanford Woods Institute for the Environment, and a senior fellow at the Precourt Institute for Energy; Kenneth Schultz, professor of political science; and Caroline Kraan, research professional at the Stanford Woods Institute for the Environment and the Stanford Environment Assessment Facility. Other co-authors include researchers from the University of Exeter, the Peace Research Institute Oslo, the Norwegian University of Science and Technology, the National Bureau of Economic Research, the University of Denver, the University of Antwerp, Lancaster University, the University of Colorado Boulder, the College of William & Mary, the University of Hamburg and Uppsala University.

The research was supported by the Alexander von Humboldt Foundation, the Stanford Woods Institute for the Environment, the European Research Council, the German Science Foundation and the Swedish Foundation for Strategic Environmental Research.