Reducing US Military Spending Could Lead to
Substantial Decreases in Energy Consumption
Ryan P. Thombs, Andrew K. Jorgenson, and Brett Clark / PLOS Climate
Abstract
(July 2, 2025) ‑ The US military is a significant contributor to the climate crisis and other sustainability concerns. However, there is very limited research on how changes in US military spending directly impact Department of Defense energy consumption and thereby greenhouse gas emissions.
Here, we conduct a time series analysis of the relationship between US Department of Defense (DOD) direct energy consumption and US military expenditures from 1975 to 2022, and we test for directional asymmetry in the effect of expenditures on energy consumption.
We estimate error correction models, which we ensure are free from residual autocorrelation and structural breaks. We find that a decrease in expenditures has a larger effect on decreasing energy consumption than an increase in expenditures does on increasing consumption.
Further analyses reveal that this is due to cuts in DOD energy consumption from facilities and vehicles and equipment, and jet fuel in particular. We also illustrate the potential impacts of different spending decisions on DOD energy consumption and present a forecast from 2023 to 2032 for seven different scenarios. We show that sustained cuts to US military expenditures could result in annual energy savings on par with what the nation of Slovenia or the US state of Delaware consumes annually by 2032.
INTRODUCTION
The impact of the world’s militaries on energy consumption and the climate crisis is greatly understudied by the scientific community [1–5]. This is surprising and a significant oversight. Military leaders and their institutions consider anthropogenic climate change to be a threat multiplier to geopolitical stability and national security [6–11], and some scholars have suggested that the world’s militaries are potentially helpful actors in global climate governance and other sustainability efforts [12].
However, nations with higher military spending are slower to ratify international environmental and climate mitigation agreements, such as the Kyoto Protocol [13,14]. A small body of cross-national research, using statistical analyses, also finds that nation-states with relatively greater military spending consume larger amounts of fossil fuels and emit higher levels of carbon pollution [15–22].
While suggestive of climate and energy impacts, these macro-comparative studies do not analyze the effect of military spending on direct measures of militaries’ energy consumption or greenhouse gas emissions.
Recent scholarly commentaries [10,23,24] and case studies [1,25] focus on the US military’s contribution to the climate crisis, describing its substantial energy use, high-level of anthropogenic emissions, and the fact that it is the largest institutional emitter in the world [25].
According to the US Department of Defense (DOD), their Scope 1 and Scope 2 emissions were over 636 million metric tons of CO2e (MMTCO2e) for the 2010–2019 decade, with a general decline in annual emissions from over 76 million metric tons CO2e in 2010 to almost 55 million metric tons CO2e in 2019 [26].
These estimates are incomplete and conservative, as they, at minimum, exclude the DOD’s Scope 3 emissions [1]. Nevertheless, they rival the overall emissions of many nations for the US military is the largest and most powerful military in the world, with its annual expenditures being much greater than for any other national military [28].
The environmental effects of the US military, including its energy consumption and climate impacts, are not limited to troop deployments and war [18,22,29–31]. Supported by a significant budget, the US military continually invests in and pursues new technologies in weapons, transportation, and communications systems.
While some have closed through the years, the US military has over 900 domestic bases and installations, as well as nearly 800 international bases and smaller military installations (i.e., “lily pads”), staffed by deployed military personnel, throughout the world [3,32–35].
It is estimated that over half of the fuel consumed by national militaries is associated with flying fighter jets [36], and for the United States, as we discuss below, jet fuel accounts for nearly 55% of the average annual total DOD energy consumption over the past half century. These and other forms of fossil-fuel powered military equipment are used for the constant training of personnel in preparation for conflict [18,37].
Overall, the scale of the US military’s global infrastructure, including bases, transportation systems to move people, supplies, and weaponry by land, air, and water throughout the world, constant research and development, and never-ending preparations, training, and exercises, all involve the consumption of substantial amounts of fossil fuels [3,23,38].
To advance scientific understanding of the energy and climate impacts of militaries, and the US military in particular, we conduct a time series analysis of the relationship between US DOD direct energy consumption and US military expenditures from 1975 to 2022. A focus on measures of DOD direct energy consumption and US military spending helps resolve limitations of prior cross-national analyses that utilize national-level measures of energy or carbon emissions, and how they are associated with national military spending.
Additionally, another contribution is that we estimate both short-term and long-term effects of military expenditures on energy consumption. The models are estimated for (1) overall DOD energy consumption as well as separately for (2) facilities, (3) vehicles and equipment, (4) jet fuel, (5) all other energy sources, and (6) fossil fuel energy consumption. We also test for directional asymmetry in the effect of expenditures on consumption [39–43].
Directional asymmetry in the effect of military expenditures on DOD energy consumption could have significant implications for climate mitigation and other sustainability concerns, especially if it is found that the effect of a unit decrease in military expenditures on reducing consumption is larger in magnitude than the effect of a unit increase in expenditures on expanding DOD energy consumption [42,44].
Using state-of-the-art time series techniques, we find that a decrease in military expenditures has a larger effect on decreasing DOD energy consumption than an increase in expenditures does on increasing consumption. Further analyses reveal that this is due to cuts in DOD energy consumption from facilities and vehicles and equipment, and jet fuel in particular. We also develop a suite of forecasts to examine how various military spending scenarios may impact DOD energy consumption in the future.
Our findings show that sustained cuts to US military expenditures could result in annual energy savings on par with what the nation of Slovenia or the US state of Delaware consumes annually by 2032. These results suggest that cutting US military spending could have significant impacts on DOD energy consumption, and thereby, lead to reductions in greenhouse gas emissions.
Materials and Methods: Data
We analyze US DOD energy consumption data by fiscal year from 1975 to 2022, which is obtained from the US Department of Energy’s (DOE) comprehensive annual energy data and sustainability performance portal (https://ctsedwweb.ee.doe.gov/Annual/Report/Report.aspx). We investigate total DOD energy consumption, as well as by the individual DOD end use sectors—energy consumption by facilities and vehicle and equipment. The facilities end use sector refers to the energy used in DOD buildings, and the vehicle and equipment end use sector refers to the energy used in vehicles and equipment.
The vehicle and equipment end use sector can also be disaggregated by fuel type. We estimate additional models with jet fuel (the largest single category of energy consumption) as an outcome, all other energy sources besides jet fuel as an outcome, and a model with renewable energy sources removed to compare the effect of military spending on total energy consumption.
Renewables make up only 0.95% of total DOD energy consumption as of 2022. All energy consumption data is measured in billion BTU, which we convert to trillions for interpretability purposes for our figures.
We examine the impacts of increases and decreases in military spending on DOD energy consumption, which is constructed from US military expenditure data (constant 2021 US$) obtained from the Stockholm International Peace Research Institute’s [28] military expenditure database. The summary statistics for these variables are reported in S1 Table.
Read the full report online at https://journals.plos.org/climate/article?id=10.1371/journal.pclm.0000569