【Report】Climate Change as an International Security Issue

Ole Wæver

On June 18, 2026, Ole Wæver, Professor of International Relations at the University of Copenhagen, gave a presentation on climate change as a security issue at Ritsumeikan University.

The presentation began with opening remarks by Prof. Kenki Adachi and Prof. Keiichi Shirato, Director of the Institute of International Relations and Area Studies.

Prof. Wæver began his presentation by explaining that climate change began to be treated as a security issue in 2007, when the Doomsday Clock incorporated it as an equally destructive threat alongside nuclear weapons.

Prof. Wæver explained that his presentation would focus on unpacking two arguments for why climate change poses security threats. The first is a causal argument that asserts climate change causes war. The second sees climate change itself as a threat. He emphasized that this distinction matters because the policy prescriptions that flow from them radically differ. Whereas the solution that flows from the first argument is the adaptation to a more conflict-prone world, the prescription that emanates from the second is the prevention or mitigation of climate change.

Regarding the first argument that climate change causes war, Prof. Wæver examined its accuracy. He showed that the causal linkage between climate change and war is more complex than what some pundits make it out to be. He underscored that rather than being an independent variable that directly causes war, climate change amplifies the existing causes of war, such as ethnic and religious tensions, economic issues, and territorial disputes.

On the second argument that asserts climate change itself as a threat, Prof. Wæver examined whether it is wise to treat it as a security issue. Drawing on the securitization theory or the Copenhagen School of international relations theory—the theoretical framework that he helped develop—Prof. Wæver explained that in most major states, climate change is “securitized” in that it is accepted as a security issue. He explained possible extraordinary measures that states can pursue to tackle the threat posed by climate change.

Prof. Wæver concluded his presentation by noting that the securitization of climate change can have both negative and positive consequences. He also introduced avenues for future research on securitization and climate change.

During the Q&A, the audience asked many questions—such as those regarding securitization theory, the utility of securitizing climate change, the hierarchy of security issues, and China’s role as a rule-setter in climate politics.