As an institution, the U.S. military is the world's single largest consumer of energy and emitter of climate-altering carbon pollution, on par with the entire nation of Venezuela.
Now for the first time, research by a University of Utah sociologist documented how military spending tracks in near lockstep with emissions. Brett Clark and his coauthors conclude that reducing those expenditures can lead to significant reductions of energy use and, thereby, carbon emissions.
Can the military play a role in climate mitigation?
"Of course, the military affects the environment in a certain capacity, but we usually think of it in regard to war, such as the consequences of bombing or destruction on that front, or maybe the waste left," said Clark, a professor in the U College of Social & Behavioral Science. But most of the military's emissions occur in non-combat situations, such as moving fleets and equipment around, training pilots, testing aircraft, or just keeping the AC running at hundreds of bases.
Military expenditures and energy use, 1975 to 2022.
Were it a nation, the U.S. military's carbon emissions would rank 47th, with 900 bases and installations on U.S. soil and another 800 overseas. Between 2010 and 2019, the military released a total of 636 million metric tons of carbon dioxide equivalent.
"If the U.S. military is the largest single institution as far as burning of fossil fuels and carbon emissions, what happens on that side of the equation has huge implications," Clark said. "In this current climate as far as attacks on climate science, expansion of military operations, pushing other countries to greatly expand their militaries, military spending, given its direct connection to energy consumption and fossil fuel emissions, has huge implications for the world as far as thinking about climate mitigation. To ignore it comes at our own peril."
Along with colleagues from Penn State University and University of British Columbia, Clark recently published an analysis of military spending's relationship with emissions in PLOS Climate. The team tracked specific kinds of military energy use between 1975 and 2022, and then compared various strategies for reducing emissions over the next 10 years.
Aviation consumes the lion's share of fuel
They examined only energy directly used in military and training operations, such as fuel burned by planes, ships and terrestrial vehicles, and electrical use at bases. Jet fuel accounted for 55% of this energy use.
"Reducing aviation activities must be a key focus given its share of energy consumption," lead author Ryan Thombs of Penn State told the BBC . "Aviation is very energy-intensive, and any serious effort to reduce the military's footprint will require focusing on this category."
The world's militaries vast energy consumption and its impact on climate crisis is understudied by the scientific community, which is a surprising and significant oversight, the paper argues. "Military leaders and their institutions consider anthropogenic climate change to be a threat multiplier to geopolitical stability and national security, and some scholars have suggested that the world's militaries are potentially helpful actors in global climate governance and other sustainability efforts," the authors wrote.
To inform the study, the team used data compiled by the U.S. Department of Energy and the Stockholm International Peace Research Institute 's military expenditure database. The researchers tracked energy use in British thermal units, or BTU, and expenditures in inflation-adjusted 2021 dollars.
'Asymmetrical' responses to changes in spending
Military energy use and spending fluctuated widely since the end of the Vietnam War in 1975, when it dropped, then soared during the "peacetime" buildup under President Ronald Reagan, dropped with the end of the Cold War, and exploded again with the wars in Iraq and Afghanistan. While military spending is far greater now than 50 years ago, fuel consumption fell by more than half–to 622 trillion BTU–due to more efficient equipment and a wave of base closures in the 1990s. Military spending, meanwhile, climbed from $464 billion to $812 billion in 2022.
The authors processed the data to see how military energy use would be affected by changes in spending. "We found that a 1% increase in military expenditures had a 0.648% increase in energy," Clark said. "But on the flip side, a 1% decrease in military expenditures resulted in 1.09% decrease."
The team's findings show that sustained cuts could result in annual energy savings on par with what the nation of Slovenia or the state of Delaware consumes annually by 2032.
But just as important to Clark is what doesn't get funded when defense budgets expand. "Military spending, that's public spending," Clark said. "The more you spend on that front generally results in a massive decrease in general public spending for social programs, health care, education, and programs to address climate change. If you expand military consumption, you're taking away public money to address all those other realms."
