Calculating the costs of war

To fuel such change, Crawford works to make clear the full cost of military activity, providing data on dollars spent, lives lost, and the broader costs to society. The cofounder of the Costs of War project at Brown University, which focused on the consequences of 9/11, Crawford recently reported on the environmental impacts of the military in her book The Pentagon, Climate Change, and War: Charting the Rise and Fall of US Military Emissions (MIT Press).

Begun as an effort to understand the military’s carbon footprint for a class she taught on climate change, her book traces military-related emissions from the advent of fossil-fueled vehicles in the 19th century to today, when the US Department of Defense (DOD) is the largest institutional greenhouse-gas emitter on the planet. Crawford reveals that the military has known about the potential impact of emissions since oceanographer Roger Revelle testified to Congress in the 1950s about the risk that they would warm the sea and melt Arctic ice, potentially creating new Soviet ports.

The Office of Naval Research went on to fund significant research into emissions, and the military has worked for decades to minimize its impact on the environment because global warming has operational consequences, Crawford explains. The changing salinity of the ocean can affect sonar, for example.

The DOD does not, as a rule, explicitly report its military emissions. So Crawford used raw data on fuel use provided by the Department of Energy (DOE) to calculate them from 1975 to today—and says she thinks her number for 1975 to 2008 is an underestimate. Meanwhile, the DOE reported that the US military emitted the equivalent of 48 million metric tons of carbon dioxide in 2022 (more than many small countries).

Still, the US military has cut emissions from a high of 110 million metric tons in 1991. “We’ve already reduced, and we could reduce some more,” she says. Humans have proved they can make great changes over time, she adds, so she’s hopeful humans can both address climate change and end war.

To fuel such change, Crawford works to make clear the full cost of military activity, providing data on dollars spent, lives lost, and the broader costs to society. The cofounder of the Costs of War project at Brown University, which focused on the consequences of 9/11, Crawford recently reported on the environmental impacts of the military in her book The Pentagon, Climate Change, and War: Charting the Rise and Fall of US Military Emissions (MIT Press).

Begun as an effort to understand the military’s carbon footprint for a class she taught on climate change, her book traces military-related emissions from the advent of fossil-fueled vehicles in the 19th century to today, when the US Department of Defense (DOD) is the largest institutional greenhouse-gas emitter on the planet. Crawford reveals that the military has known about the potential impact of emissions since oceanographer Roger Revelle testified to Congress in the 1950s about the risk that they would warm the sea and melt Arctic ice, potentially creating new Soviet ports.

The Office of Naval Research went on to fund significant research into emissions, and the military has worked for decades to minimize its impact on the environment because global warming has operational consequences, Crawford explains. The changing salinity of the ocean can affect sonar, for example.

The DOD does not, as a rule, explicitly report its military emissions. So Crawford used raw data on fuel use provided by the Department of Energy (DOE) to calculate them from 1975 to today—and says she thinks her number for 1975 to 2008 is an underestimate. Meanwhile, the DOE reported that the US military emitted the equivalent of 48 million metric tons of carbon dioxide in 2022 (more than many small countries).

Still, the US military has cut emissions from a high of 110 million metric tons in 1991. “We’ve already reduced, and we could reduce some more,” she says. Humans have proved they can make great changes over time, she adds, so she’s hopeful humans can both address climate change and end war.