Ahead of the UN Climate Change Conference (COP31) meeting in Antalya, Turkiye next month, an expert writing in The BMJ's climate issue argues that accurate data on greenhouse gas emissions during armed conflict is urgently needed to hold militaries, governments, and individuals accountable for the environmental impact of war.
Benjamin Neimark at Queen Mary University of London says understanding the scale of conflict emissions "is an essential first step in addressing the military's oversized contribution to the climate crisis."
Greenhouse gases resulting from armed conflicts are a serious problem, he writes. The first 14 days of the Iran war alone produced more than the total climate pollution of Iceland in 2024 - roughly five million tonnes of carbon dioxide, while five years of war in Ukraine has released almost 311 million tonnes of carbon dioxide - the equivalent of annual emissions in France.
And in Gaza, carbon emissions during the first 15 months of the conflict were more than 30 million tonnes - equivalent to the amount of carbon absorbed by 33 million acres of forests in a year.
Emissions can range from fossil fuels burned by fighter jets, cargo planes, tanks, and naval ships to more indirect emissions from powering bases, making weapons, deploying troops, and reconstruction after conflicts, he explains.
Yet since the 2015 Paris agreement, all military reporting of conflict related emissions has been voluntary, leaving researchers to conduct their own assessments of how much carbon has been emitted during a conflict.
However, he points out that in 2025 the International Court of Justice issued a landmark advisory opinion confirming that governments have a legal responsibility to protect the climate system, prevent harm to the best of their ability, and cooperate internationally.
Although military emissions were not directly addressed in the advisory, a supplementary declaration noted that state obligations "include responsibility to address the impacts resulting from armed conflict and other military activities."
Since then, several legal cases have been brought against major climate change polluters in domestic and international courts. Yet, up to this point no legal action has been taken against militaries for climate related emissions.
In all of this, data are essential to provide a clearer picture of the environmental costs of war - not just economic costs, but the costs to humans and the climate system they depend on, he writes. Such data can be used as evidence in a courtroom to hold militaries, governments, and individuals accountable and to help set targets to cut emissions.
"Governments should establish mandates requiring militaries to report their emissions during both peacetime and active conflict," he concludes.
