Demystifying science

Armed conflicts such as those in Iran, Ukraine, or Gaza are causing global greenhouse gas emissions to rise. But is this pollution significant or marginal? In short, does war hinder our efforts to achieve carbon neutrality?

The Question

“I am surprised to see that the numerous armed conflicts are not more often mentioned as an exacerbating factor in global warming. When Putin attacked Ukraine, I was dismayed to see the amount of greenhouse gases produced by all those Russian tanks consuming large amounts of oil, not to mention the airplanes, rockets, artillery fire, etc. Meanwhile, I felt guilty using my car to go to the grocery store,” wrote Pierre Turenne.

At least 5.5% of global emissions

Do armed conflicts significantly increase greenhouse gas emissions (GHGs), as Mr. Turenne suggests? The short answer is yes. But before evaluating armed conflicts, we must first analyze the emissions associated with permanent military structures, which precede any conflict. These represent about 5.5% of global GHG emissions.

Two British researchers arrived at this conclusion in a 2022 report titled Estimating the Military’s Global Greenhouse Gas Emissions. “If the world’s armies formed a single country, this figure would mean they would have the fourth-largest national carbon footprint in the world, exceeding that of Russia,” they estimated at the time. This is also four times the annual emissions of Canada. The three largest emitters of GHGs are China, the United States, and India.

This assessment is likely higher a few years later. “When we estimated global emissions associated with the armed forces, using 2019 data, military spending amounted to $1.9 trillion. In 2024, it totaled $2.7 trillion and is expected to continue rising,” says Doug Weir, director of the Conflict and Environment Observatory, a UK-based NGO.

But is this conclusion from the 2022 report reliable? “Yes and no,” responds Doug Weir. “This 5.5% figure corresponds to our best estimate of military emissions in peacetime and is based on 2019 data. It is an estimate because the data published by the militaries on their emissions are incomplete and their publication is voluntary under the Paris Agreement.” A report unveiled in 2025 also concluded that less than 10% of national armies compile and publish their polluting emissions.

Ongoing assessment

The current picture does not yet include the main ongoing armed conflicts in different regions of the world.

According to Doug Weir, the war in Ukraine marks the first attempt to track emissions generated by an ongoing conflict. “The results suggest that these emissions may exceed the annual emissions of many developed countries,” he says.

Recent estimates indicate that between 2022 and 2026, the war in Ukraine generated 311 million tons of CO₂ equivalent, equivalent to the annual emissions of the UK.

In Gaza, researchers estimated last year that the first 15 months of the conflict generated about 31 million tons of CO₂ equivalent in polluting emissions.

As for Iran, researchers are already working on producing a first estimate of the GHG emissions associated with the conflict, says Doug Weir.

For each conflict, consideration must also be given to the emissions produced in the context of reconstruction operations, adds the expert. This is not to mention the impacts on societies and economies, known as the social cost of carbon, points out Mr. Weir. “Just due to the proposed increases in NATO military spending, we foresee that climate damages could reach $298 billion per year.”