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Should the Defense Dept. be exempt from cutting greenhouse gas emissions?

The department is not actually off the hook, nor should it be.

A US Air Force Boeing C-17A Globemaster III transport aircraft.Omar Marques/Getty

President Biden recently directed all federal agencies to cut greenhouse gas emissions. There’s just one problem, according to a new letter from 28 members of Congress: The single largest source of greenhouse gases in the federal government, the Department of Defense, is off the hook. The signatories to the letter, led by Senator Ed Markey, want the president to live up to his pledges on climate change by denying the Pentagon an exemption for military emissions.

The senator has a point. With the exception of nuclear-powered aircraft carriers and submarines, US armed forces depend on petroleum, chewing through around 90 million barrels a year.


At the same time, it’s not a realistic request. Imagine this scenario: President Vladimir Putin of Russia invades Ukraine, then begins amassing troops on Estonia’s border. NATO members agree to send troops to protect their ally, but Biden has to decline because flying C-130s full of soldiers to Eastern Europe would violate greenhouse gas targets. Or imagine that a powerful typhoon directly hits the Asian megacity of Manila, killing thousands of people and displacing millions. The Philippines asks the US military to support emergency relief efforts, citing the longstanding mutual defense treaty, but the helicopters, aircraft, and ships consume too much fossil fuel to be deployed. Fortunately, China is able and all too eager to help the island nation. If that’s all too far from home, then imagine any US governor asking for the National Guard to respond to a fire, flood, storm, terrorist attack, or other catastrophic incident, and the answer has to be no.

No US president is going to agree to constrain military options in this way in order to cut greenhouse gases. Fortunately, there are better ways to advance climate policy, including at the Department of Defense.


No one actually knows the size of the defense sector’s carbon footprint (the Biden administration is taking bold steps to fix that, with accounting for the entire defense supply chain), but the Department of Defense itself emitted around 55 million metric tons of greenhouse gases in 2019. That’s significant for a single institution, but it adds up to less than 1 percent of America’s overall greenhouse gas footprint, which totaled about 6.6 billion metric tons in 2019.

In other words, if Biden were to completely eliminate the entire military tomorrow, it would barely make a dent in US greenhouse gas emissions. The largest American contributors to global climate change are all in the civilian economy — industry, agriculture and land use, electricity, transportation, and buildings. Even with better accounting of the defense sector, the main contributors will probably still be things like petrochemicals, power plants, and personal vehicles (an Abrams tank may get lousy gas mileage, but there are less than 5,000 of them, and they don’t travel very many miles in a normal workweek). A focus on the military would be a distraction from more important climate action priorities.

Still, the Defense Department is not actually off the hook, nor should it be. Most large corporations in the United States are taking environmental, social, and governance considerations seriously as both good business and responsible stewardship, and the Defense Department must also do so. Biden’s new executive order will accelerate the department’s ESG investments, including the electrification of almost 180,000 passenger vehicles and light-duty trucks, following in the footsteps of companies such as Amazon. It will also provide an additional push for clean electricity.


But the department should also take aggressive steps because it will make for a better national defense. It has spent billions in recent years on repairs to bases damaged by storms, ice, fires, and floods, and it makes sense to invest more in resilience than recovery. To that end, the Biden administration is improving the Trump-era Defense Climate Assessment Tool, which analyzes the vulnerabilities of military bases to climate change. And while it’s tough to get around the military’s overwhelming reliance on petroleum fuels in the near term, that reliance is a vulnerability, in addition to a contribution to a globally destabilizing phenomenon.

The Defense Department should invest more in energy innovation because that legacy fossil-fuel force is vulnerable to modern weapons and out of step with trends in warfare, such as unmanned systems, robotics, artificial intelligence, and cyber. Finally, the department has an important role to play in understanding how climate change may shape future military missions, from disaster relief to combat, even if civilian government agencies such as FEMA and USAID have a more central role to play in actually building disaster resilience and stability in a degraded environment.

In fact, it’s worth remembering that the reason US armed forces consume so much fuel is less because they are profligate and more because they are so heavily used. The United States has been in a nearly continuous state of conflict since its founding, and that demand for troops is what’s generating at least half of the greenhouse gas emissions. Arguably, the best thing the president could do to limit the Defense Department’s greenhouse gas emissions is to be more discerning about the use of force, which seems to be the underlying point of Markey’s letter.


Unfortunately, Putin may have something to say about that.

Sharon E. Burke is president of Ecospherics. She served in the administrations of Barack Obama, George W. Bush, and Bill Clinton, most recently as an assistant secretary of defense.