By John Conger and Marc Kodack

The U.S. Department of Defense (DoD) has been widely recognized for its consistent recognition of the threat of climate change, as well as its continued efforts to maintain climate resilience efforts even as much of the rest of the Administration reflects a more climate skeptic position.  At the same time, some have pointed out that DoD is a major source of the emissions that drive the very change they’re concerned about.  So what’s the deal? Let’s dive into it a bit.

1. Is DoD the largest emitter of greenhouse gases?

It depends. While DoD is the single largest emitter in the U.S. federal government, it represents just over 1 percent of all U.S. emissions. In turn, all U.S. emissions represent 15 percent of global emissions.  Therefore, DoD represents a pretty small percentage of global emissions. As the Climate Security Plan for America states, we need a much broader emissions reduction strategy that addresses the entire U.S. economy, and the entire globe, in order to avoid catastrophic security futures.  Even reducing DoD emissions to zero would not come close to meeting the necessary reductions to avoid serious risks. That said, DoD can certainly do its part to reduce emissions in a way that’s consistent with its mission, and help lead the national and global clean energy transition.

2. Does the DoD emit more than some entire nations, such as Portugal and Sweden?

Some have drawn comparisons between DoD emissions and the emissions from some entire nation states, concluding that DoD is a disproportionate part of the problem. Comparing the DoD to the emissions of Portugal or Sweden may be jarring, but it isn’t necessarily the best comparison. After all, lining up nations and federal agencies creates an apples-to-oranges comparison. Both Portugal and Sweden have roughly 10 million people whereas the DoD is comprised of 2.87 million people. The DoD’s most recent annual budget is $675 billon, while the GDP’s of Portugal and Sweden are $217 billion and $538 billion respectively – and comparing GDP to an annual budget isn’t a perfect comparison either. Another factor to consider is that neither Portugal or Sweden have the same global presence (and subsequent energy demands) to maintain as the U.S. DoD.

Within the United States, the DoD is the largest emitter in the U.S. Government because DoD is the largest organization in the U.S. Government with global responsibilities and operations.  Specifically, DoD is comprised of 2.87 million people, activities in 160 countries spread across 4,775 individual locations, with 585,000 facilities (buildings, structure, and linear structures).  There isn’t a straightforward translation of this energy to emissions, however, as the energy DoD buys in one region may be powered by zero-emissions hydro or nuclear power plants, while others could be powered by a local plant that uses coal.  Gradually, as the nation’s energy usage transforms, so will this contribution by DoD.

3. What are the Main Sources of DoD emissions?

As highlighted by a paper published in June 2019 by Brown University’s Watson Institute for International and Public Affairs which examined the Department of Defense’s (DoD) fuel use and associated greenhouse gas emissions from military operations and installations, fuel use is the dominant source of energy use by DoD, and consequently its emissions profile. DoD data points to the fact that aircraft dominate that fuel use, and widebody aircraft (cargo and refueling) dominate aircraft fuel usage.  It comes as no surprise that most of these aircraft are procured and operated by the Air Force, and that they continue to do research on more efficient aircraft engine technologies.  In addition, Transportation Command continues to work on increasing the efficiency of cargo aircraft schedules, which results in lower costs and lower fuel use.

4. How do DoD aircraft emissions compare to commercial airliners?

So how does DoD aircraft fuel use compare to a civilian analog such as the airlines?  Globally, airlines see a much higher fuel use – and consequently a much higher emissions level – than DoD.  Looking at 2017, the airline industry (U.S. carriers only) used 17.3 billion gallons of fuel.  The Brown paper cites DoD figures that it used 85 million barrels of fuel – or 3.6 billion gallons – in the same year, which is only 20% of the amount used by U.S. airlines.

The message here isn’t that we need to look at airlines instead of DoD, but rather that it’s important to look at all sources of aircraft emissions and emissions in general.  Broad improvements in aircraft technology would address them all at the same time, just like transition to renewable power plants can reduce the emissions associated with DoD buildings.  More broadly, it’s important to better understand what drives emissions numbers and energy use in order to properly address the problem.

5. What about DoD installations?

The Brown paper does note that a significant proportion of emissions come from DoD’s installation footprint.  DoD faces a difficult challenge due to a combination of the sheer number of buildings it owns and the inefficiency of those buildings – driven both by budget limitations that undervalue preventative maintenance (DoD has a maintenance backlog that exceeds $100 billion) and by the large number of old and historic buildings it maintains (which are, by their nature, relatively inefficient).

Nonetheless, DoD continues to reduce its emissions footprint by pursuing energy efficiency and renewable energy initiatives, particularly where they can reduce costs and increase resilience.  Some emissions benefits are masked, as DoD will enable the development of utility scale solar farms and sign long-term agreements with the developers, but allow the developers to keep the renewable energy certificates.  DoD doesn’t get credit for emissions reductions for these projects, but the projects wouldn’t have happened without them.

6. What should be done?

The bottom line is that it’s in the DoD’s own interest to reduce its emissions, both in terms of doing its part to reduce climate change risks, and in order to reduce its dependence on fossil fuels – including in theater, where protecting fuel convoys can cost many American lives. But as the world transitions to cleaner energy sources, the DoD must work during the transition to continue to meet its primary mission. Individual action on emissions by DoD is important, could send a strong signal to energy markets, and could position the DoD on the leading edge of new technologies. However, much broader economy-wide action, and international action, is needed to meaningfully reduce emissions to avoid climate change trajectories that can have severely disruptive, and catastrophic, security consequences.