The U.S. military emits more greenhouse gases than most countries

From troops deployed in Afghanistan to fleets of Naval ships stationed outside of Japan and Army installations throughout Germany, the U.S. military has a footprint all over the world. As it turns out, it has a pretty big carbon footprint, too. Two new studies published this month found that the U.S. military's greenhouse gas emissions make it one of the biggest emitters in the world, polluting at a higher rate than more than two-thirds of all countries.

One study, published earlier this month by Brown University, examined the U.S. military's greenhouse gas emissions from 1975 to 2017. Researchers found that the Department of Defense's operations have been one of the largest contributors to energy consumption, accounting for as much as 80 percent of all U.S. government energy use. Emissions peaked for the Defense Department in 2004, in the midst of ongoing wars in Iraq and Afghanistan. At the time, military operations produced 85 million metric tons of carbon dioxide and other greenhouse gases.

The Pentagon has managed to shrink its carbon footprint in recent years, but it is still massive. Researchers at Brown University estimate it is responsible for producing more than 59 million metric tons of greenhouse gases in 2017. That is more emissions than Portugal, Sweden, or Denmark produce in a year. In fact, it's more than about 140 other countries. Recent studies suggest that if the U.S. military was a country, it would rank somewhere between the 47th and 55th biggest polluter in the world.

Much of that comes from operations, which eat up a ton of fossil fuels. The Defense Department consumed nearly 86 million barrels of oil in 2017 alone. Another study, published by the Transactions of the Institute of British Geographers, found that the U.S. military bought about 269,230 barrels of oil every day, emitting more than 25,000 kilotonnes of carbon dioxide in burning that fuel. Most of that was purchased by the U.S. Air Force, which purchased just short of $5 billion worth of fuel in 2017, followed by the Navy buying $2.8 billion, and the Army buying up just under $1 billion. That perhaps isn't surprising when you find out just how big of gas guzzlers military equipment can be. Researchers reported that a B-2 stealth bomber burns up 4.28 gallons per mile.

To put into perspective just how quickly emissions can add up, Professor Neta C. Crawford, co-director of the Costs of War Project at Brown University, highlighted the cost of a single mission:

In January 2017, two B-2B bombers and 15 aerial refueling tankers traveled more than 12,000 miles from Whiteman Air Force Base to bomb ISIS targets in Libya, killing about 80 suspected ISIS militants. Not counting the tankers’ emissions, the B-2s emitted about 1,000 metric tons of greenhouse gases.

While costs certainly peak when equipment and vehicles are put into action in the field, the Department of Defense racks up a significant carbon profile just through day-to-day operations. As much as 40 percent of the military's greenhouse gas emissions come from the Defense Department's extensive military installations both at home and overseas.

The good news is that the Pentagon has acknowledged global warming as a legitimate issue. In 2014, it published a report that found climate change to be a threat that poses "immediate risks" to military operations and could present new national security challenges. In recent years, the Department of Defense has worked to reduce its reliance on fossil fuel. General James Mattis, the former Secretary of Defense for the first two years of the Trump administration, encouraged moving toward renewable energy sources in an effort to be "unleashed from the tether of fuel." The goal, of course, wasn't to save the environment but rather to ensure the military could continue its operations unencumbered by oil, which is costly to move and a vulnerable target during war time. Still, it represents a move in the right direction even if the motivation is more utilitarian than idealistic.

Unfortunately, the push may be too little, too late. As the paper published by Brown University warns, climate change will likely have significant consequences around the world, causing new crises that the U.S. military may become involved in. Those operations will undoubtedly require a significant amount of fuel, resulting in even more greenhouse emissions. Without some drastic changes, there's a vicious cycle on the horizon.