From the dumping of defoliants like Agent Orange on forests in Vietnam to oil wells set ablaze during the Gulf War and the contamination of the aquifers bombed in Gaza, environmental destruction has long been a by-product of conflict.
Less talked about is the impact of war and the military on the climate crisis. This is partly because military emissions have been largely exempted from international climate treaties, starting with the 1997 Kyoto Protocol.
"The US military did not want to limit its supremacy by being constrained," explained Neta C. Crawford, professor of political science at Boston University and co-director of the Costs of War project. In the wake of the collapse of the Soviet Union in 1990, the military feared that emission constraints might sacrifice its newfound "global hegemony."
Yet if the US military was a nation, it would be one of the top 50 largest greenhouse gas emitters in the world, putting it above Sweden or Denmark, says Crawford in her paper on "Pentagon Fuel Use, Climate Change, and the Costs of War."
Her research is one of a growing body of work that has recently revealed the outsized carbon emissions of the global military system.
One breakout 2019 study by Lancaster and Durham University researchers shows that the US military, the world's largest war machine, is itself the single biggest institutional consumer of hydrocarbons on the planet.
Conflict and climate: A double-edged sword
Though the militaries around the world have for decades been concerned that a growing climate crisis will be the key trigger of future conflict, they have done little to address their role in exacerbating this climate change.
Military willingness to prepare for conflict caused by displacement and resources scarcity linked to increased drought and flooding, for example, has ironically failed to incorporate strategies to mitigate the root cause of this crisis, says Crawford.
"They are ahead of the curve on adapting but are not ahead on their impact," Crawford said of the US military, noting that the navy is already insulating itself from sea level rise by raising up its bases in ports and harbors from Virginia to Florida.
Armies have been pioneers in utilizing solar energy, hybrid-powered vehicles and biofuels, especially in combat zones like Afghanistan, to reduce reliance on diesel fuel power that can be attacked during transportation. Too often, however, climate adaptation initiatives have a purely military end, says Patrick Bigger, a lecturer at the Lancaster University Environment Centre and an expert on US military emissions.
"Any green impacts are an added bonus to the main goal of increasing force readiness," he said of US military climate adaption strategies that do not address the carbon "bootprint" of a war machine that uses some 270,000 barrels of oil a day.
Climate impacts beyond emissions
Doug Weir, research and policy director at The Conflict and Environment Observatory (CEOBS), says the military needs to move beyond "energy security" motivations and instead look to the "broader benefits" for the climate.
But even if the military shifted to renewables to reduce its massive carbon emissions, war exacerbates climate impacts in manifold ways.
After the decades-long Colombia conflict, deforestation occurred on a much wider scale due to the governance vacuum left in territory held by the FARC rebels, notes Weir. "You've seen huge increases in deforestation," he said of these "ungoverned spaces" where former carbon sinks are now "contributing to emissions as well as impacting biodiversity."
"Awareness and coverage of this topic is more or less absent from the climate debate," said Deborah Burton, co-founder of Tipping Point North South (TPNS), a UK climate justice cooperative that is advocating for a "transform defense" concept that will align military strategies to climate mitigation.
One solution will be "to shut down the military machine in a way, to slow it down and shrink it," said Benjamin Neimark, senior lecturer at the Lancaster University Environment Centre — including shutting some of the 800 US military bases maintained in over 70 countries.
But it's a message that may not play very well politically in the US, said Patrick Bigger, noting that President Joe Biden's recent raising of climate targets made little mention of military emissions.
Though Biden invoked a "whole-of-government" approach to his new climate action plan, he did not include a Department of Defense that consumes "a majority of [the government's] discretionary spending" via a near $800 billion (€658 billion) annual budget, Bigger added.
Lack of transparent reporting
The EU military, the world's second-largest armed forces, are often unwilling to report many of their emissions due to "national security" concerns, explains Linsey Cottrell, CEOBS' environmental policy officer and co-author of a report on the EU military carbon footprint.
Cottrell estimates that UK military emissions are "at least three times higher" than reported, since indirect emissions generated by the production of military equipment and weapons, for example, are not included.
"If you don't measure it you can't manage it," Cottrell said. "You need robust, comparable and transparent reporting."
This feeds into what Weir calls "a general culture of environmental exceptionalism when it comes to militaries." Not only have war emissions been excused from national carbon calculations: Militaries also enjoy exemptions from some chemical and waste management standards, including on mercury, he explains.
Fossil fuel lock-in
Crawford notes that the burning of oil wells and the destruction of fossil fuel infrastructure during war is another impact that is not reported. By one estimate, the blazing oil wells during the 1991 Gulf War accounted for 2-3% of global emissions that year.
The lack of climate accountability allows militaries to perpetuate a "fossil-fuel lock-in," Bigger said.
He notes that the upcoming 2022 US military budget will include commissions for new petrol-fueled jets and warships that will "invariably" run on carbon-heavy bunker fuel.
"How can top militaries decarbonize when fossil-fuel guzzlers will be in service for the next decades?" Burton said of long-term contracts for weapons such as a new fleet of F35 fighter jets said to consume near 6,000 liters of fuel (1,585 gallons) per flight hour.
NATO talks up net-zero emissions
But carbon neutrality has started to creep into the military lexicon. The North Atlantic Treaty Organisation (NATO) recently urged member states of its massive army to reach net-zero emissions by 2050.
Cottrell says that NATO's net-zero rhetoric, while welcomed, will be meaningless unless "state members follow through and provide meaningful pledges." This so far hasn't happened. She says that targets for energy conservation and a transition to renewables backed by regular and transparent reporting must underline commitments in the lead-up to the pivotal COP26 climate summit in Glasgow in November.
Climate activist Burton says that the global annual military budget is now around $2 trillion (€1.6 trillion) a year — around 12 times the annual climate budget — and wants governments to adopt a Green New Deal "Plus" policy that marks a retreat from "big-ticket weaponry."
Meanwhile, the Conflict and Environment Observatory has recently called for governments to make a military greenhouse gas emission reduction pledge at COP26 that is consistent with the 1.5-degree Celsius target specified by the Paris climate accord.