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Boisi Center for Religion and American Public Life

Just War Theory and the Environmental Consequences of War

Boisi Center for Religion and American Public Life

Laurie Johnston, assistant professor of theology and religious studies at Emmanuel College, began her March 17 talk at the Boisi Center by highlighting the connection between warfare and the environment. While modern war can have devastating effects on the natural environment, the environment itself can also influence relations between groups and states, causing violence and war. According to Johnston, just war theory can be used to explore the ethical implications of war on the environment. 

Just war theory delineates a set of criteria that must exist for a war to be just from a Catholic perspective. Johnston argued that proportionality is the most important criterion in relation to war and the environment. This principle requires policymakers to weigh the environmental cost of war against the other benefits of waging a war. Johnston said that this question is fundamentally about what we value. At times waging a war could prevent future environmental destruction. At other times, war can greatly damage the environment, such as when the United States used Agent Orange during the Vietnam War. 

Johnston highlighted the influence of Pope Francis’ recent encyclical Laudato Si’ and the 2015 Paris Climate Conference on public discourse generally, and specifically on policy about war and its impact on the environment. The Paris agreement forced militaries to track carbon emissions, ending an exemption they previously had. Some estimates report that military emissions make up about one-fifth of global carbon emissions, Johnston said. 

While warfare affects the environment, Johnston argued that the environment also affects human relationships. Johnston said droughts and other extreme weather events tend to aggravate social or economic tensions, which may lead to war. Johnston ended her remarks by noting the United States military has recognized that climate change will pose security risks around the world in the coming decades.