World’s Biggest Polluter Is in the US, Study Finds

The U.S. military has been identified as the largest single institutional emitter of greenhouse gases worldwide, according to a new study.

Newsweek reached out to the Department of Defense (DOD) via email for comment.

Why It Matters

The study cited the scale of energy consumption required for maintaining military bases, global transport of personnel, equipment, weapons and frequent training drills as central contributors to the broader carbon footprint. The findings underscore the global climate implications of the U.S. military’s operational scale.

What To Know

The study, led by Ryan Thombs of Penn State University and published in PLOS Climate on July 2, drew on publicly available data from the DOD spanning 1975 to 2022, linking reductions in military spending to significant decreases in energy consumption and greenhouse gas emissions.

Researchers found that a decrease in expenditures has a larger effect on slashing energy consumption than a rise in expenditures does on heightening energy usage. Additional analyses show that this is due to cuts in DOD energy consumption from facilities, vehicles and equipment, and jet fuel in particular.

“We started this study not entirely sure what we were going to find,” Thombs told Newsweek on Thursday. “There are published studies on the impacts of increasing militarization on environmental outcomes, but studying the effects of cutting military spending was an open question.

“I think the finding that cutting expenditures had a larger impact than increasing expenditures was a little bit surprising but made sense, and it is also the thing that really stood out in our analyses.”

The study also shows that spending cuts to the U.S. military could have significant ramifications for energy consumption.

“We show that large, sustained cuts to expenditures could produce annual energy savings similar to what the nation of Slovenia or the U.S. state of Delaware consumes annually by 2032,” Thombs said.

Andrew Jorgenson, sociology professor at the University of British Columbia and the study’s co-author, told Newsweek on Thursday that the study advances the interdisciplinary science on the societal causes of climate change.

While much prior research focuses on such factors as economic growth, corporations, population dynamics and technology, he said these new findings highlight the U.S. military’s role “in causing anthropogenic climate change, given the enormous volume of fossil fuels it consumes.”

“Our findings … underscores the necessity for considering the role of the U.S. military,” Jorgenson said. “It also suggests a pathway for meaningful decarbonization and climate mitigation, albeit a very difficult one given the Trump administration’s emphasis on increasing U.S. military spending and its attacks on climate science and climate policy, and the growing pressure for other nations throughout the world to increase their military spending as well.”

Pentagon’s Carbon Footprint Surpasses Most Countries

The U.S. military’s carbon output as of 2022 exceeded that of nearly 140 national governments, according to The Conversation. An Army Climate Strategy report from 2019 identified the DOD as the top institutional petroleum consumer globally.

In 2020, the U.S. Army’s electricity usage alone generated 4.1 million tons of greenhouse gases—1 million tons greater than Switzerland’s entire heat and electricity emissions in 2017.

In February 2022, the Army released a strategy pledging net-zero emissions by 2050 and a goal to electrify its military vehicle fleet and shift bases to carbon-free electricity. Climate change has become much less of a priority during the current Trump administration.

Defense Secretary Pete Hegseth, in a statement on March 10, downplayed the role of climate change within the DOD, The Independent reported. “We do training and warfighting,” Hegseth said, rejecting climate initiatives as outside the military’s responsibility. His stance diverged from both Pentagon climate policy in previous administrations and the department’s own research. Hegseth’s comments drew criticism, especially as the military’s annual emissions were reported to total approximately 51 million metric tons, largely from buildings and vehicles.

What People Are Saying

Chief Pentagon spokesperson Sean Parnell, on March 14: “The Pentagon … announced that we are eliminating woke climate change programs and initiatives inconsistent with our core warfighting mission.”

What Happens Next

Authors of the PLOS Climate study project that continued reductions in military spending through 2032 could result in dramatic annual energy savings.