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The war no ledger counts
On a March morning in Tehran, the rain that fell from a low, dirty sky was not really rain.
Residents described droplets that smeared like oil on car windscreens and left black stains on balconies and skin.3
The night before, a string of oil depots on the city’s edge had burned for hours after airstrikes, sending a column of soot and unburned hydrocarbons into the atmosphere.3
As emergency crews fought the flames, environmental officials warned that the downpour was laced with sulphur, nitrogen oxides and fine particulates, a kind of modern “black rain” that would seep into soil and waterways.3
The city could see the damage in the sky, smell it in the streets, taste it with every breath.
For three decades, climate diplomacy has tried to put numbers on our warming future, yet one of the world’s largest emitters sits off to the side of the ledger, blurry at best, often invisible.
How big is war’s climate footprint?
Militaries travel by jet and armoured convoy, heat vast bases, consume steel and cement, and fight in ways that ignite cities, forests and fuel depots, but they remain only partially counted in national inventories.1
Estimates compiled by Scientists for Global Responsibility and the Conflict and Environment Observatory suggest that everyday military activity accounts for about 5.5 per cent of global greenhouse gas emissions, comparable to the entire aviation sector and larger than many countries’ economies.1
If the world’s armed forces formed a state, they would rank among the top handful of emitters on Earth, somewhere alongside Russia in the global league table.7
And that figure does not yet include the surges triggered when war actually begins, from burning infrastructure to reconstruction.
The best current estimates place the combined climate impact of militaries and war at between roughly one per cent of global emissions for direct operational fuel use and about five to six per cent when supply chains, weapons production and infrastructure are included.1
That makes war and preparation for war a carbon source on par with international aviation and shipping together.
Quantifying this impact has proven difficult for reasons that are as political as they are technical.
Why the numbers are so hard to see
Military fuel use is often classified, exercises and deployments cross borders, and there is no agreed method to account for the emissions from a missile strike that detonates a fertiliser plant or an artillery barrage that ignites a peat bog.10
National inventories submitted to the UN can list defence fuel and electricity in broad categories that obscure specific operations.
Still, where researchers can see clearly, the picture is stark.
Analysts estimate that if militaries were ranked like countries, they would come in around fourth in the world, behind only China, the United States and perhaps India, which is more than most energy‑intensive industries can claim.7
Mechanised warfare, with tanks, heavy armour and air campaigns, is particularly demanding, because jet fuel and diesel are energy dense and burned in extraordinary quantities across long supply lines.1
High‑tech militaries, such as those of the United States and other NATO members, tend to have more efficient engines and better logistics, yet their global reach, large fleets and sprawling bases mean efficiency gains are more than offset by scale.
Current wars, present‑tense emissions
The abstract numbers become less abstract in places like Ukraine.
Since Russia’s full‑scale invasion in 2022, a coalition of Ukrainian and European organisations has tried to count the war’s climate damage, from tanks to refineries.5
Their most recent assessment estimated that in the first two years alone, the conflict generated around 175 million tonnes of carbon dioxide equivalent, roughly the annual emissions of a mid‑sized industrial nation.5
The sources are varied.
Direct combat operations burn vast amounts of fuel, while artillery and missile strikes have destroyed energy infrastructure, triggering long‑lasting gas leaks and fires on offshore platforms.5
Landscape fires, many started by shelling and left to rage unchecked, have burned more than 90,000 hectares in a year, more than double the pre‑war average, sending plumes of carbon and soot into the atmosphere.2
From Gaza to the Sahel: conflicts off the spreadsheet
In the Middle East, attacks on oil depots and power stations have produced similar patterns.
Fires at depots near Tehran released toxic smoke that turned rainfall black, while damage to water and electricity systems left neighbourhoods without safe supplies, forcing emergency reliance on diesel generators and tanker fleets.3
In Gaza and parts of Syria and Iraq, strikes on power plants and pipelines have cut electricity from grids, pushing hospitals and households towards improvised, high‑emitting backup solutions.10
In Myanmar and across the Sahel, where satellite coverage and monitoring are patchier, reports describe scorched villages, burned cropland and degraded rangelands, yet the emissions rarely appear in national accounts.
Smaller, persistent conflicts in parts of Africa and Southeast Asia receive far less attention than headline wars, despite their cumulative footprint on land, air and water.
Black rain and broken ecosystems
When a refinery, fertiliser plant or petrochemical complex explodes, the damage unfolds in layers that run far beyond the initial blast radius.
Combustion sends carbon dioxide and short‑lived climate pollutants like black carbon into the air, while incomplete burning releases volatile organic compounds, sulphur dioxide and nitrogen oxides that help form smog and acid rain.3
Heavier hydrocarbons condense onto soot particles, hitching a ride back to the ground in oily, discoloured precipitation.
The “black acid rain” reported after depot fires near Tehran is a vivid example.
Residents faced a mix of carcinogenic compounds in the air, contaminated drinking water and crop damage as acidic droplets fell on fields and urban gardens.8
Similar phenomena were observed around burning oil wells in Kuwait during the 1991 Gulf War, when smoke darkened the sky and residues accumulated in soil and surface waters.
Fire on the land, heat in the air
War‑related fires also contribute to regional warming, especially when they consume carbon‑rich ecosystems.
In Ukraine, shelling has ignited steppe grasslands and forested areas, releasing stores of carbon and damaging habitats that would otherwise act as weak but important sinks.4
Soot from these fires can travel hundreds of kilometres, darkening snow and ice and accelerating melt.
On the ground, explosions and intense heat alter soil chemistry.
Cratered landscapes can see compaction, loss of organic matter and contamination with metals and explosive residues, all of which reduce long‑term productivity.10
Agricultural recovery may take years, especially where unexploded ordnance and mines make remediation difficult.
In rivers, lakes and coastal waters, the sudden influx of chemicals, fuel and debris can nudge ecosystems towards acidification or eutrophication, stressing fish populations and drinking water supplies.
When infrastructure becomes fuel
Modern warfare increasingly targets the same networks that underpin low‑carbon transitions, such as power stations, transmission lines and pipelines.
Each destroyed facility is both a source of immediate emissions and a loss of future decarbonisation capacity.
Analyses of the war in Ukraine attribute tens of millions of tonnes of emissions to the destruction of civilian infrastructure in the conflict’s early months, when whole neighbourhoods burned and industrial sites were hit.5
Fires at oil storage facilities and gas pipelines added additional pulses as hydrocarbons burned in the open air or leaked for days.5
Fires are the most visible component of wartime emissions.
Urban bombardment produces dense plumes of soot, while burning oil depots and refineries can create mega‑fires that rival some of the largest industrial accidents on record.3
These events inject both carbon dioxide and aerosols into the atmosphere, with complex regional climate effects.
Reconstruction’s long carbon tail
Even when the guns fall silent, the climate cost of war continues to grow.
The emissions from rebuilding can exceed those from the fighting, especially where entire neighbourhoods or industrial belts must be reconstructed with concrete, steel and asphalt.4
Cement alone accounts for around eight per cent of global carbon dioxide emissions, largely because producing the main binder in concrete requires heating limestone to high temperatures, which releases process emissions and burns fuel.9
In Iraq, years of occupation and conflict saw the rapid construction of blast walls and fortifications, each with an embodied carbon footprint from cement and steel, while post‑war rebuilding added another surge as damaged infrastructure was replaced.10
In parts of Syria and the Balkans, reconstruction efforts have begun to experiment with lower‑carbon cement blends and more efficient building designs, yet progress is uneven.9
The central question is whether post‑war rebuilding can become an opportunity to leapfrog fossil‑fuel dependence rather than simply recreate the systems that existed before.
Analysts argue that if international reconstruction funds tied finance to low‑carbon power, efficient housing and resilient infrastructure, the long carbon tail of war could be shortened significantly.11
Climate‑aligned rebuilding is not yet the default, but there are signs that financiers and development banks are starting to integrate emissions criteria into some post‑conflict plans.
The reporting gap that history built
The invisibility of military emissions is not an accident of methodology, it is the product of negotiation.
During talks on the Kyoto Protocol in the 1990s, the United States successfully pushed to exclude many categories of military emissions from binding targets and reporting, citing national security concerns.12
Emissions from war itself, as well as from international bunker fuels used by militaries, did not have to be fully disclosed.
The Paris Agreement, adopted in 2015, removed the explicit exemption but replaced it with something more subtle.
Countries are now free to report military emissions, but they are not required to separate them clearly, and methods remain voluntary and inconsistent.13
An analysis by civil society groups found that some major military powers failed to submit any up‑to‑date emissions inventory for the relevant cycle, while others reported implausible drops in military emissions during ongoing conflicts.14
Researchers estimate that a significant share, perhaps most, of global military emissions remain effectively invisible to policymakers because they are buried in aggregate energy use or not reported at all.1
Proposals now circulating in climate and security circles call for mandatory, standardised reporting of military fuel use, supply chains and war‑related damage as part of future transparency rules.10
Wars, energy markets and strained resources
If military emissions sit in the shadows, the broader energy effects of war are more immediately visible on trading screens and household bills.
Conflicts that threaten oil and gas supply routes can send prices soaring, prompting governments to scramble for alternative sources.
The invasion of Ukraine in 2022 triggered a rapid reshaping of Europe’s energy system.
Russian pipeline gas fell sharply, replaced in part by liquefied natural gas imports, coal reactivation and, crucially, an accelerated build‑out of renewables and efficiency measures in several countries.2
Analysts argue that the war both slowed and sped the energy transition, as emergency coal use rose in the short term while structural dependence on Russian gas eroded.2
Geopolitical instability often nudges governments towards short‑term energy security at the expense of long‑term climate commitments.
New fossil fuel investments justified as “temporary” can lock in infrastructure for decades, while defence supply chains, including steel, explosives and fuel refining, remain highly carbon intensive.10
The more resources flow to armament, the less fiscal space may exist for clean energy, adaptation or loss and damage finance.
Budgets, bombs and missed opportunities
The relationship between conflict spending and climate investment is not purely arithmetic, but the tension is clear.
Global military expenditure has reached record levels in recent years, even as climate finance has struggled to meet pledged targets for mitigation and adaptation support in vulnerable countries.10
Rising defence budgets can crowd out public funds for decarbonising transport, retrofitting homes or protecting coastlines.
Wars also reverberate through commodity markets.
Disruptions to oil, gas, fertiliser and grain exports from conflict zones can push up prices worldwide, with knock‑on effects for food security and political stability.15
Governments facing angry voters over energy bills or food costs may hesitate to impose carbon prices or phase out fossil fuel subsidies.
At the same time, climate stress is emerging as a risk factor for future conflicts.
Assessments summarised in the latest IPCC reports find that higher temperatures, drought and extreme weather can exacerbate grievances, undermine livelihoods and contribute to violent conflict risk, particularly in parts of Africa and Asia where institutions are already fragile.15
War feeds warming, which in turn can feed more insecurity.
Recovery, justice and watching the smoke
Ecosystems damaged by war can take years, sometimes decades, to recover.
Forests regrow slowly on shell‑scarred hillsides, wetlands clogged with debris struggle to filter water, and soils contaminated with metals or hydrocarbons may require costly remediation before they can support crops again.10
In some post‑war landscapes, conservation groups have used demilitarised zones as unexpected refuges for wildlife, but these are exceptions rather than the rule.
There are also examples of deliberate environmental restoration built into recovery.
In the Balkans, international and local efforts have focused on cleaning industrial hot spots, improving wastewater treatment and upgrading power systems after the conflicts of the 1990s.11
In Iraq and parts of Syria, projects to rehabilitate marshlands and contaminated sites have begun to reconnect communities with their ecosystems.10
The legal tools for holding combatants accountable for environmental harm remain weak.
International humanitarian law recognises some limits on “widespread, long‑term and severe” environmental damage, yet prosecutions are rare and thresholds high.10
Campaigners argue for stronger norms that would treat large‑scale ecological destruction during war as a serious crime.
One promising frontier is real‑time environmental monitoring during conflicts.
Advances in satellite observation, open‑source intelligence and sensor networks could allow international bodies, journalists and civil society to track fires, pollution events and infrastructure damage as they occur.5
If the world can see the smoke more clearly, it may become harder to ignore the warming it represents.
Conclusion: counting what we choose to see
In Tehran, the black rain eventually stopped, though the residues it carried into rivers, fields and lungs will linger far longer than the news cycle that briefly noticed them.
In Ukraine, the fires that trace the jagged front continue to burn, contributing to a tally of emissions that will shape the country’s climate future long after the last trench is abandoned.5
In quieter conflicts that never make global headlines, forests are cleared, rivers polluted and communities displaced, leaving smaller but no less real scars.
War has always rearranged landscapes, destroyed cities and disrupted economies.
In a rapidly warming world, it also rearranges the atmosphere, pushing more carbon into a space already dangerously crowded with human exhaust.1
The fact that so much of this remains off the books is a choice, not an inevitability, rooted in fears about transparency that now collide with the need for planetary accounting.
As climate negotiations edge toward tighter carbon budgets, the question is not only how many tanks or fighter jets a nation can afford, but how many tonnes of carbon its security doctrine quietly assumes.
If we began to count the full climate cost of war, from fuel depots to black rain, would we still make the same choices about what keeps us safe, or would our idea of security shift toward something less combustible and more compatible with a liveable climate?
References
- CEDARE, “Contribution of Military and War to Global Emissions” (summarising Scientists for Global Responsibility and CEOBS estimates)
- ClimaTalk, “How Are Wars Affecting Climate Change?”
- Thairath, report on oil depot fires, toxic smoke and black acid rain in Iran
- Ukrainian War Environmental Consequences Work Group, “Environmental Consequences of the War in Ukraine”
- Ecoaction et al., “Climate Damage Caused by Russia’s War in Ukraine”
- Earth.org, “Warfare Now Largest Source of Ukraine’s Annual Carbon Emissions”
- American Academy of Arts & Sciences, “The Environmental Impacts of Modern Wars”
- The Nation Thailand, “Black Acid Rain Hits Iran After Oil Depot Blasts”
- SAEA, “Syria Reconstruction as Cement Industry Lowers Carbon Footprint”
- Climate Diplomacy, “Regional Breakdown of the IPCC’s Warnings and What They Mean for Peace and Security”
- Climate Analytics, “Decarbonising Electricity, Cement, Iron and Steel, and Chemicals in the Western Balkans”
- Impakter, “Military Exemptions: How One of the World’s Largest Polluters Gets a Free Pass”
- Stop the War, “Silence on Military Emissions Reveals a Dangerous Blind Spot”
- Bombay Breed, “The One Emitter the Paris Agreement Forgot to Name”
- Climate Diplomacy, “What Does the Sixth IPCC Synthesis Report Say About Climate Security and Peace?”
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