The War On Climate – Closing the Military’s Emissions Gap

By Soroush Abolfathi, Ellie Kinney 24 November, 2025

Global military activity is the 4th biggest polluter after India but no reporting or reduction targets are required of the industry. Researchers Dr. Abolfathi & Kinney reveal how to hold this hidden carbon source accountable

From running military bases to rebuilding a city post-conflict, the climate cost of military activity is substantial; just 15 months of Israel's war in Gaza topped 31 MtCO₂e
Military emissions are a "black hole" as the Paris Agreement doesn't require disclosure, even though the US Dept of Defense is the world's largest single consumer of petroleum
Rising military spending reached a record US$2.7trn in 2024, so it's urgent that the growing military sector is included in global climate accounting & in curbing emissions

The world has seen a decade of rising military spending, reaching a record high of US$2.7 trillion in 2024. Every dollar spent on the military has a carbon cost – and a big one. Each dollar spent on the military generates more than twice the greenhouse gas (GHG) emissions of a dollar spent elsewhere.

Yet the climate impact of militaries is largely missing from climate policy.  Most countries – including top military spenders – report little to nothing of their military’s emissions in their national inventory reports to the UNFCCC. This reporting gap distorts our understanding of climate progress, and the true scale of emissions from military activity and warfighting remains hidden. As a result, the goals set under the Paris Agreement and the annual COP meetings ignore a large, unmeasured carbon source, undermining global climate action. Without mandatory reporting, the military carbon footprint will stay a “black hole” – hiding tens or hundreds of millions of tonnes of CO₂ each year.

Hidden emissions

Militaries are big polluters, with one estimate suggesting that everyday military activity is responsible for 5.5% of global emissions. This means that if the world’s militaries were a country, it would have the fourth largest carbon footprint – larger than Russia’s. From the running of military bases to increasingly large-scale training exercises, military activity comes with a considerable carbon cost; in the UK, the Ministry of Defence is responsible for more than half of the central government’s emissions, and meanwhile, the US Department of Defense is the world’s largest institutional consumer of fossil fuels.

Everyday military activity = 5.5% of global emissions…

…yet it is exempt from mandatory reporting

Estimates suggest that global militaries are responsible for around the same GHG emissions as civil aviation and the shipping industry combined, and yet this sector faces far less pressure to respond to the climate emergency. In 1997, the Kyoto Protocol exempted military emissions from UNFCCC reporting, and under the 2015 Paris Agreement, reporting military emissions is entirely voluntary. These exemptions have had a lasting impact; a recent analysis of EU militaries found an 82% gap in what militaries report to the UNFCCC.

The war on climate

More shocking still is the fact that 5.5% does not include the climate impacts of conflicts. The world is seeing the highest number of countries in conflict since World War II, and beyond the immediate and horrifying humanitarian impacts of warfighting, armed conflict can produce large, concentrated emissions from multiple sources. Some sources are visible, like fuel-hungry tanks and fires across landscapes, and others are less obvious, like the carbon cost of rerouting passenger flights to avoid dangerous airspace. This all points to a longer-term humanitarian impact of warfighting: the impacts of the climate crisis.

3 years of Russia’s war in Ukraine…

= annual emissions of Austria + Hungary + Czech Republic + Slovakia

Since there is no internationally agreed framework for measuring emissions from conflicts, we are largely reliant on estimations from researchers to plug the information gap. Russia’s full-scale invasion of Ukraine in 2022 marked the first time that researchers set about estimating the emissions of an ongoing conflict, in which the Initiative on the GHG Accounting of War estimates that three years of Russia’s war in Ukraine has resulted in 230 million tonnes of CO₂ equivalent (MtCO₂e), comparable to the combined annual emissions of Austria, Hungary, the Czech Republic, and Slovakia.

This research has highlighted the need to understand the climate impact of conflicts. Researchers have since estimated that the first 15 months of Israel’s war on Gaza topped 31 MtCO₂e. Of the immediate emissions, more than 99% came from Israel’s assault on Gaza. Both cases highlight a crucial point: wars are worsening the climate crisis. Yet many of their emissions are missing from global climate accounting.

Lasting climate legacies

The climate impact of wars doesn’t end with a ceasefire. The Initiative on the GHG Accounting of War lists post-war reconstruction as a likely source of 27% of the emissions caused by Russia’s invasion of Ukraine, since rebuilding destroyed hospitals, schools and apartment blocks will require massive volumes of carbon-intensive construction material. In the devastated Gaza Strip, researchers estimate that the carbon cost of reconstruction could be greater than the annual GHG generated individually by 135 countries, equivalent to the annual emissions of Portugal or Sweden.

Post-war reconstruction of Gaza could produce more GHG than the annual emissions of 135 countries

Maintaining peace agreements can also come with a carbon cost; peacekeeping missions account for 41.6% of the UN system’s reported GHG emissions. This means that peacekeeping has a key role to play in the UN’s journey to net zero, but it is also uniquely positioned to push for progress on transparency and decarbonisation across the military sector. UN peace operations are already demonstrating how transparent reporting can support decarbonisation through the implementation of an environmental strategy, which has seen emissions reduced over recent years.

An escalating global arms race

The urgency of quantifying military emissions is underscored by today’s global arms frenzy, with military spending rising year on year for the past decade. Europe’s spending jumped more than 30% from 2021–24, while NATO members are reaching for military budgets at 5% of GDP. If current trends persist, global military spending could reach up to US$6.6 trillion by 2035.

Yet military spending continues to climb…

…NATO members’ military budgets are nearly 5% of GDP…

…global spending could be US$6.6trn by 2035

These trends carry clear climate implications. Recent calculations estimate that the collateral climate damage caused by NATO’s planned increases in military spending will amount to $134–298 billion annually. NATO’s 31 countries represent only 9% of total world emissions, yet in 2024, military spending rose in every region globally. Short-term thinking in military spending decisions has long-term impacts, with governments locked into fossil fuel-reliant equipment for decades to come.

The evidence is clear: military activities and conflicts are significant yet uncounted sources of emissions. To address climate change, this “military emissions gap” must be closed.

Our recommendations

No sector can be exempt from climate action. First and foremost, transparency is needed; states should be required to include emissions from the full scope of military activities, including warfighting, in their national inventory reports to the UNFCCC. We need a standardised approach to military emissions reporting across all governments.

Secondly, militaries must commit to emissions reduction plans in line with the Paris Agreement’s ambition to limit warming to 1.5°C. Decarbonisation efforts must be extended beyond tackling just military bases and buildings to encompass procurement and operations, including fuel-intensive exercises. Governments should include these commitments within their national climate plans (Nationally Determined Contributions).

1. More transparency

2. Militaries to have transition plans for 1.5°C

3. Public awareness on the hidden carbon costs of military activity

Finally, public awareness must grow. Governments should clearly communicate to the public how increased military expenditure decisions impact climate action. Reallocating even small fractions of defence budgets could dramatically advance climate goals. In the meantime, journalists, campaigners and academia must continue to expose the hidden carbon cost of military activity and push for policy change.

In this era of escalating crisis, we need a whole-of-society approach to climate action and a united global response. Integrating military emissions into the climate agenda is essential – only with transparency can we address the full scope of humanity’s impact on the climate. We can no longer bury our heads in the sand and ignore the climate impact of dramatically rising militarism.

Further readings

More on Latest

Author: Soroush Abolfathi
Dr Soroush Abolfathi is a Reader in Water and Environmental Modelling whose work focuses on how climate change and human activities shape environmental risks. His current project, The War On Climate, examines the often-overlooked contributions of conflict and military operations to global emissions and climate impacts.
Read more from Soroush Abolfathi →
Author: Ellie Kinney
Ellie Kinney is Climate Advocacy Coordinator at the Conflict and Environment Observatory. She coordinates the Military Emissions Gap, a project which monitors and analyses military emissions data and advocates for accountability for the military's contribution to the climate crisis.
Read more from Ellie Kinney →
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