A series of reports produced by the Costs of War Project says the American military is contributing significantly to climate change, emitting more greenhouse gases than some developed countries and compromising national security in the process. The United States Department of Defense is “the world’s largest institutional user of petroleum and correspondingly, the single largest producer of greenhouse gases in the world,” according to Pentagon Fuel Use, Climate Change and the Costs of War, a report by Neta C. Crawford, a co-director of the project, based at Brown University’s Watson Institute. The report estimates U.S. military greenhouse gas emissions exceeded 1.2 billion tonnes between 2001, when the war on terror began, and 2017. In 2017 alone, the Pentagon’s greenhouse gas emissio...