A recent comprehensive analysis conducted by Ryan Thombs and colleagues at Penn State University has revealed a striking link between U.S. military spending and the Department of Defense’s energy consumption, highlighting a previously underexamined pathway to reducing the country’s carbon footprint. Published in the open-access journal PLOS Climate on July 2, 2025, the study presents robust statistical evidence suggesting that reductions in military expenditures could lead to substantial decreases in fossil fuel use and greenhouse gas emissions by the U.S. military, the largest institutional source of such emissions globally.
The U.S. military’s contribution to anthropogenic climate change is enormous, stemming from the vast scale of operations required to maintain global dominance and strategic readiness. The Department of Defense operates thousands of bases worldwide, supports continuous training exercises, sustains research and development efforts, and manages a complex logistical network responsible for moving people, supplies, and weaponry around the world. Together, these activities consume vast quantities of energy, predominantly derived from fossil fuels, making the military a major driver of U.S. greenhouse gas emissions.
Unlike prior studies that have largely focused on national or sector-level correlations between military spending and emissions, this research is one of the first to analyze direct measurements of energy consumption specifically attributed to the Department of Defense. By compiling publicly available data spanning nearly five decades—from 1975 through 2022—the researchers were able to conduct detailed econometric analyses to understand the relationship between financial outlays and how those funds translate into energy demands. Their methodology involved isolating energy data related to facilities, vehicles, equipment, and particularly jet fuel—which accounted for a significant portion of petroleum consumption within military operations.
One of the study’s most notable findings is the asymmetrical effect that changes in military spending have on energy consumption. While increases in funding do drive higher energy use, the effect is relatively modest compared to the extent to which spending cuts reduce energy consumption. This means that reducing expenditures, even by modest amounts, could yield disproportionately large savings in fossil fuel consumption. This asymmetry also suggests that the dynamics of military budgeting, procurement, and operational scaling are complex and nonlinear, warranting further research to decode the underlying mechanisms.
Jet fuel consumption emerged as a critical component of this relationship. The U.S. military’s air fleets, ranging from fighter jets to refueling tankers and transport aircraft, represent one of the largest single users of petroleum in the country. Reductions in spending likely curtail flight hours, maintenance schedules, and the acquisition of fuel-intensive hardware, thereby decreasing overall jet fuel consumption. These reductions ripple through various departments and activities, highlighting how budgetary decisions manifest in concrete environmental impacts.
Forecasts developed by the researchers extended the analysis into the future, modeling the effects of continued trends from 2023 to 2032 under scenarios of both sustained spending increases and cuts. The projections revealed that consistent spending reductions could produce annual energy savings comparable to the entire yearly consumption of smaller economies or U.S. states. For instance, the amount of energy saved by 2032 through sustained cuts could match what the state of Delaware or the nation of Slovenia currently uses, underscoring the large-scale potential impact of military budgeting decisions on climate mitigation efforts.
The implications of the study stretch beyond mere accounting of emissions and energy consumption. Military leaders themselves are increasingly acknowledging that climate change constitutes a direct threat to national and global security. Anthropogenic climate disruptions exacerbate geopolitical tensions by undermining resource availability, destabilizing vulnerable regions, and escalating humanitarian crises. Thus, reducing the military’s carbon footprint aligns not only with environmental goals but also with strategic imperatives to safeguard future peace and security.
However, the study emphasizes that merely cutting military spending is not a panacea for climate change. The complexity of military operations and the multifaceted nature of energy consumption mean that reductions must be thoughtfully managed to balance national security concerns with environmental stewardship. For example, some energy usage is necessary to maintain readiness and deterrence, while other expenditures may represent inefficiencies or redundant capabilities that could be optimized or eliminated without compromising defense.
Technological innovation presents another avenue to complement budgetary actions. Investments in renewable energy sources, enhanced fuel efficiency, and alternative propulsion systems for military vehicles and aircraft could further decouple operational capacity from fossil fuel dependency. Integrating cleaner technologies into existing infrastructures and future military procurements could magnify the positive effects of spending cuts by improving energy productivity.
Moreover, transparency and the availability of detailed energy data within military departments play a crucial role in enabling effective policy formulations. The study itself relied heavily on open and public datasets, and the authors highlight the importance of continued data disclosure for rigorous research and informed decision-making. Greater clarity around defense energy use can drive targeted interventions and foster accountability in reducing emissions.
The researchers also call attention to the political and institutional challenges inherent in reducing U.S. military spending. Defense budgets are often politically sensitive and tied to broader considerations beyond environmental impact, including employment, industrial base stability, and international alliances. Therefore, climate-driven budgetary adjustments would require a concerted effort involving policymakers, military leadership, and the public to reconcile competing priorities.
In conclusion, this groundbreaking research opens a new chapter in the discourse on climate change mitigation by identifying the defense sector, and specifically U.S. military spending, as a pivotal lever for reducing fossil fuel consumption on a national and global scale. As the military grapples with the realities of climate change as a strategic threat, integrating sustainability into budgeting and operational planning emerges as both a necessary and promising strategy. Future research exploring the causal pathways of the observed asymmetrical effects could enable even more precise guidance for policymakers aiming to optimize defense expenditures while contributing to global climate goals.
The full study, “Reducing U.S. military spending could lead to substantial decreases in energy consumption,” is available as an open-access article in PLOS Climate, offering detailed data and analytic frameworks to support further interdisciplinary explorations at the intersection of security, economics, and environmental science. This research marks a vital step toward reconciling the imperatives of national defense with the pressing need for climate change mitigation.
Subject of Research: People
Article Title: Reducing U.S. military spending could lead to substantial decreases in energy consumption
News Publication Date: 2-Jul-2025
Web References: https://doi.org/10.1371/journal.pclm.0000569
References: Thombs RP, Jorgenson AK, Clark B (2025) Reducing U.S. military spending could lead to substantial decreases in energy consumption. PLOS Clim 4(7): e0000569.
Image Credits: “F15 Fighter Jet Belly” by TheBusyBrain, licensed under CC BY 2.0
Keywords: U.S. military spending, energy consumption, greenhouse gas emissions, Department of Defense, fossil fuels, jet fuel, climate change mitigation, defense budget, sustainability, environmental impact
