The Invisible Front: How War Is Burning the Climate - Lethal Heating Editor BDA

Armed conflict releases hundreds of millions of tonnes of greenhouse gases, yet militaries operate almost entirely 
outside global climate accounting

Key Points

Global military activity accounts for an estimated 5.5% of total greenhouse gas emissions, placing it fourth among the world's largest national emitters. 1 Russia's three-year war in Ukraine has generated roughly 230 million tonnes of CO₂ equivalent, more than the combined annual output of Austria, Hungary, the Czech Republic, and Slovakia. 6 The first 120 days of Israel's campaign in Gaza produced emissions exceeding the annual output of 26 nations, with reconstruction projected to add tens of millions of tonnes more. 9 Military emissions reporting was exempted under the 1997 Kyoto Protocol after US pressure; the 2015 Paris Agreement made reporting voluntary, and most countries still disclose nothing. 12 Post-war reconstruction is one of the largest hidden carbon costs of conflict: rebuilding Syria's damaged housing alone is projected to release around 22 million tonnes of CO₂. 15 Rising defence budgets compete directly with climate finance; global military spending hit a record $2.7 trillion in 2024, while the $100 billion annual climate finance pledge to developing nations remains unmet. 3

The burning began in the dark. 

In February 2022, as Russian armoured columns crossed the Ukrainian border and artillery shells tore open industrial facilities along the Donbas, a different kind of damage was accumulating, invisible but measurable: the carbon footprint of a major land war in the 21st century. 

Within weeks, researchers at a small Dutch-based non-profit, the Initiative on GHG Accounting of War, began logging what no international climate body was required to track. 

Within seven months, they had documented at least 100 million tonnes of carbon dioxide equivalent released into the atmosphere. The equivalent, they noted, of the Netherlands' entire annual output.

That calculation was only the beginning. By the third anniversary of Russia's full-scale invasion in February 2025, total war-related emissions had reached 230 million tonnes of CO₂ equivalent, comparable to the combined yearly output of four Central European nations. ⁶ 

The figure encompasses battlefield fuel use, the burning of forests and agricultural land along the front lines, the destruction of energy infrastructure, and the airspace rerouting that has forced civilian aircraft onto longer, more fuel-intensive paths across a continent. It does not yet include the enormous carbon cost of rebuilding what was destroyed.

Ukraine has become the most closely studied climate casualty of modern warfare. But the dynamics playing out across its scorched plains and shattered cities are not unique. From Gaza to the Sahel, from Myanmar's contested borderlands to the oil fields of Libya, armed conflict is quietly generating greenhouse gas emissions on a scale that existing international frameworks are simply not designed to count. War, it turns out, has a carbon footprint, and it is enormous.

The Scale of the Problem

Researchers at the Conflict and Environment Observatory and Scientists for Global Responsibility published a landmark estimate in 2022: the world's militaries, taken together, account for roughly 5.5% of total global greenhouse gas emissions. ¹ 

If armies and defence industries were a single country, they would rank as the world's fourth-largest emitter, behind only China, the United States, and India, but ahead of Russia. That figure, the researchers noted, covers only peacetime operations and the supply chains that sustain them. The additional emissions generated by active conflict were not included.

Quantifying those conflict emissions is far harder than it sounds. Satellite imagery can detect fires; chemical sensors can identify pollutants; proxy indicators, including fuel consumption records, weapons delivery logs, and damage assessments, can fill some gaps. But the data is fragmentary, access to conflict zones is restricted, and the methodologies for estimating wartime emissions are still being developed. A further complication is that destruction of industrial infrastructure often temporarily reduces civilian emissions, making it easy to misread a country at war as cleaner than it was before. ¹⁶ 

The actual picture, once fires, reconstruction, and military fuel use are included, points firmly in the other direction.

Wartime emissions compare unfavourably with sectors the public knows well. The global aviation industry produces approximately 2.5% of annual CO₂ emissions. The entire military sector, at 5.5%, is roughly double that. Cement production, one of industry's most notorious emitters, accounts for around 8%. Shipping contributes about 2.9%. War, in other words, belongs in the same league as heavy industry, yet it appears in almost no national climate account. ²

Not all forms of warfare generate equal emissions. Mechanised land war, with its fuel-hungry tanks, armoured personnel carriers, and artillery supply chains, is among the most carbon-intensive. Aerial bombing campaigns add enormously to that total: a single modern fighter jet burns through tonnes of fuel per sortie, and the industrial production of precision-guided munitions is itself highly energy-intensive. 

Research presented at a 2025 American Academy of Arts and Sciences roundtable explored whether lighter technologies, such as drones and cyberattacks, might reduce a conflict's carbon footprint over time. The tentative conclusion was that, while individual strikes may emit less, the combination of more frequent use and the eventual need to rebuild what such weapons destroy will likely offset any efficiency gains. ¹⁷

Two Conflicts, One Planet

In Ukraine, war has become the largest single source of the country's carbon emissions. A 2025 assessment by the Initiative on GHG Accounting of War found that 36% of all war-related greenhouse gases came directly from military activity, including fuel burned by tanks, jets, and supply vehicles, plus the steel, concrete, and explosives used to construct and maintain hundreds of kilometres of frontline fortifications. ⁷ 

Another 27% is attributable to reconstruction activity already underway. The rest is distributed across energy infrastructure destruction, civilian aviation rerouting, and the displacement of refugees across Europe.

The fires are among the most alarming findings. In 2024 alone, roughly 965,000 hectares of Ukrainian land burned, more than twice the total area burnt across the entire European Union that same year. Landscape fires along the front lines accounted for 48.7 million tonnes of CO₂, a 113% increase on the preceding two years. ⁸ 

The fires result from a lethal combination: artillery-sparked blazes during dry summer conditions, climate-driven heat extremes, and the practical impossibility of firefighting in active combat zones. Climate change and the war are amplifying each other.

In Gaza, the carbon arithmetic is compressed into a far smaller geography. Researchers from Queen Mary University of London and Lancaster University published a study in early 2024 finding that the first 120 days of fighting generated between 420,000 and 652,000 tonnes of CO₂ equivalent from direct military activity alone, more than the annual emissions of 26 individual countries. ⁹ 

When pre-war construction, such as tunnel infrastructure, and projected post-war reconstruction are factored in, the total rises to more than 61 million tonnes. That number exceeds the combined annual emissions of Sweden and Portugal.

The reconstruction estimate is significant. By January 2024, between 36% and 45% of buildings in Gaza had been destroyed or damaged. Rebuilding 100,000 damaged structures using conventional techniques would generate at least 30 million tonnes of greenhouse gases, equivalent to New Zealand's annual output. ¹⁰ 

Cement and steel, the fundamental materials of urban reconstruction, are two of the most carbon-intensive industries on earth. Every bombed city carries within it a future emission debt.

Beyond Ukraine and Gaza, emissions from conflicts in Myanmar, the Sahel, Yemen, and the Democratic Republic of Congo receive far less scientific attention, not because they are small but because monitoring them is even harder. The DRC, for instance, has lost vast tracts of tropical forest to the pressures of prolonged conflict and displacement, releasing stored carbon on a scale that is only partially captured by satellite systems. 

Researchers who gathered at the American Academy of Arts and Sciences in 2025 warned explicitly that smaller but persistent conflicts were being systematically overlooked in global emissions accounting. ¹⁷

Black Rain and Poisoned Ground

When a fuel depot is struck by a missile, the immediate result is a fireball visible from kilometres away. The longer-term result is more insidious. Large-scale hydrocarbon fires, and the war in Ukraine has produced hundreds of them, generate enormous plumes of black carbon, a mix of soot and chemical particulates that absorbs solar radiation and accelerates atmospheric warming. 

These plumes can travel thousands of kilometres. Research on the 1991 Gulf War oil fires, which consumed roughly 700 Kuwaiti wells over nine months, found that the resulting soot contributed to the accelerated melting of Tibetan glaciers, thousands of kilometres from Kuwait. ¹⁶ 

The fires contributed more than 2% of global fossil fuel CO₂ emissions in that single year.

Urban bombardment creates analogous contamination on a smaller but more geographically concentrated scale. When buildings collapse, they release decades of stored materials: asbestos, heavy metals, PCBs, and fuel residues. In Gaza, a preliminary assessment by the United Nations Environment Programme in June 2024 found that approximately 37 million tonnes of debris had accumulated, contaminating soil and groundwater with toxic substances. ¹¹ 

These contaminants disrupt soil chemistry in ways that reduce long-term land productivity, effectively converting farmland into dead zones for years or decades.

Explosions themselves alter soil structure. The detonation of high explosives compacts soil, fragments its chemistry, and introduces heavy metals, including lead, copper, and zinc from shell casings, into the ground at concentrations that inhibit plant growth and leach into groundwater. 

In Ukraine, ammunition containing heavy metals has contaminated agricultural land across some of the country's most productive farming regions. Ukraine's agriculture sector accounts for around 60% of the country's exports; the long-term damage to that soil represents an economic and ecological loss that extends far beyond the current war. ⁸

Water systems are particularly vulnerable. In Gaza, the destruction of eight wastewater treatment plants, of which six had been damaged or destroyed by May 2024, resulted in an estimated 130,000 cubic metres of raw sewage being discharged daily into the Mediterranean Sea. ¹⁰ 

The groundwater beneath Gaza, already stressed by decades of over-extraction, has been further contaminated by munitions residues and the collapse of sanitation infrastructure. The Mediterranean plume from such discharge carries biological and chemical pollutants into shared regional waters, crossing borders regardless of political agreements.

The Carbon Cost of Destruction

The destruction of cities is a form of carbon release that operates on a vast but largely uncounted scale. Buildings, bridges, pipelines, and power stations represent embodied carbon, the cumulative emissions produced when they were first manufactured and constructed. When they are bombed, that embodied carbon does not disappear; it joins the ongoing atmospheric ledger as debris management and reconstruction demand yet more energy. 

Clearing the rubble from Aleppo and Homs alone, according to estimates by the Conflict and Environment Observatory, would require more than a million truck journeys. ¹⁶ 

Each of those journeys burns diesel. Each load likely contains hazardous materials.

Modern cities, precisely because they concentrate so much energy infrastructure, are acutely vulnerable to this form of cascading damage. The bombing of electricity grids, transformer stations, gas pipelines, and district heating systems does not merely deprive civilians of warmth and light. It forces the substitution of dirtier, less efficient energy sources, including diesel generators, wood burning, and coal-fired backup systems, often for years after the fighting has stopped. 

In eastern Ukraine, chemical factories, oil refineries, and coal processing facilities have been among the most heavily targeted sites. The resulting toxic releases have contaminated the Dnipro river basin and the Black Sea. ²⁰

Damage to dam and water management infrastructure creates the longest-lasting environmental cascades. The destruction of the Kakhovka dam in Ukraine in June 2023 released a torrent of contaminated water across a vast agricultural floodplain, destroyed riparian ecosystems, and deposited an unknown volume of munitions residues and industrial pollutants into the lower Dnipro and the Black Sea. The ecological recovery from an event of that magnitude is measured in decades, not years.

The Long Carbon Tail of Reconstruction

Post-war reconstruction is, in many respects, the most underappreciated chapter of war's climate impact. The Iraq War between 2003 and 2008 was responsible for an estimated 141 million tonnes of CO₂ equivalent, according to a study by Oil Change International. In that same period, only 21 EU member states individually produced more emissions than the war itself generated. ¹⁸ 

Much of that total came not from the fighting but from the logistics, fuel supply chains, and the early phases of reconstruction.

Syria's civil war, which has left roughly 60% of urban infrastructure damaged or destroyed, carries an estimated reconstruction emission debt of 22 million tonnes of CO₂ for housing alone, not counting roads, power stations, schools, or hospitals. ¹⁵ 

In practice, reconstruction in conflict-affected countries has rarely incorporated climate considerations. Iraq and Syria both relied heavily on oil revenues and conventional construction, locking in carbon-intensive infrastructure for another generation. Gas flaring, in which excess petroleum gas is simply burned off rather than captured, intensified in Libya, Syria, and Yemen during and after their respective conflicts, a trend that has continued long after the fighting receded.

Ukraine presents what may be the most consequential reconstruction opportunity yet seen. President Zelensky has spoken of needing at least $5 billion per month for rebuilding. The international community has been debating whether that rebuilding could be structured around clean energy, energy efficiency, and decentralised renewable systems rather than the gas-dependent grid Ukraine relied on before the war. 

Proponents argue the war presents a rare chance to leapfrog fossil fuel infrastructure entirely. ⁷ Sceptics note that the immediate pressure to restore heat, light, and industrial capacity tends to overwhelm long-term planning, and that international reconstruction funds have historically moved far more slowly than the carbon-intensive imperative to rebuild fast.

The Reporting Gap

In 1997, as diplomats in Kyoto negotiated what would become the world's first binding climate treaty, the Pentagon lobbied hard for an exemption. Military emissions, US officials argued, could not be disclosed without jeopardising national security, revealing the locations and readiness of forces to potential adversaries. 

The lobbying worked. The Kyoto Protocol excluded international military operations from national emissions totals and allowed countries to group domestic military emissions with civilian categories, obscuring the true military share. ¹²

The 2015 Paris Agreement technically ended the formal exemption. In practice, it replaced mandatory exclusion with voluntary disclosure, which amounts to much the same thing. Under the Paris framework, countries may report their military emissions but are not required to do so. According to the Military Emissions Gap organisation, which tracks reported data submitted to the UNFCCC, only four countries provide detailed disaggregated military fuel data. ¹³ 

A 2025 report by Scientists for Global Responsibility found that almost all official military emissions figures, even for countries with comparatively strong reporting practices, cover less than 10% of their actual military carbon footprint.

The practical result is that a sector producing an estimated 5.5% of global emissions operates in almost complete statistical darkness. Researchers working on the IPCC's Sixth Assessment Report have noted that the scenarios used to model future climate trajectories do not include a quantitative assessment of military spending's impact on CO₂ emissions. 

A 2025 peer-reviewed study in a leading environmental journal found that events such as the US-led War on Terror and Russia's invasion of Ukraine led to measurable increases in global CO₂ emission intensity, estimating that military spending growth accounted for 27% of the total change in emission intensity between 1995 and 2023. ⁴ 

That finding has not yet been incorporated into mainstream climate modelling.

Several credible proposals exist to address the gap. The Conflict and Environment Observatory has published a framework for mandatory military emissions reporting. Academics from Oxford, Lancaster, Columbia, and Harvard have co-signed calls for the UNFCCC to require explicit military reporting in national inventories. The European Parliament has called for transparent reporting by member states. ¹⁴ 

None of these proposals has so far produced binding change.

Energy Markets and the War Premium

Russia's invasion of Ukraine reshaped European energy policy faster than any Green New Deal had managed. As Russian gas supplies were severed or sanctioned, European governments scrambled for alternatives, reopening coal plants, racing to build liquefied natural gas import terminals, and accelerating renewable deployments at a pace that would have seemed impossible in 2021. 

The short-term reaction was unambiguously dirty: coal consumption rose sharply in Germany and across Eastern Europe in 2022 and 2023. The medium-term trajectory, however, pointed toward a faster clean energy transition, driven by the hard lesson that energy dependence on an aggressor is a strategic liability.

Whether that acceleration will persist is an open question. Geopolitical instability has a well-documented tendency to push governments toward energy security at the expense of climate commitments. Oil Change International estimated that Russian fossil fuel exports earned approximately €58 billion in just the first two months after the invasion, with the EU accounting for €39 billion of that total. ¹⁹ 

The revenue funded the continuation of the war. European dependence on Russian gas was not merely an environmental failure; it was a strategic one, and the two failures turned out to be inseparable.

Military supply chains are themselves highly carbon-intensive. Producing a modern tank requires enormous quantities of steel. Artillery shells consume both steel and explosives. Explosives production is energy-intensive and relies on chemical processes that generate significant nitrous oxide emissions. 

The US military is the world's largest institutional consumer of fossil fuels, and its supply chain emissions, covering the weapons and equipment it procures, roughly double its direct operational footprint. ⁵ 

As NATO members race to rearm, those supply chain emissions are multiplying across the alliance.

The Economic Displacement

Every dollar spent on a missile is a dollar not spent on a solar panel. The relationship is not quite that simple, but it is not entirely metaphorical either. Global military spending hit a record $2.7 trillion in 2024. In the same year, the long-standing pledge by wealthy nations to provide $100 billion annually in climate finance to developing countries remained unfulfilled, despite having been due since 2020. ³ 

The contrast is stark: the same governments that have consistently failed to meet their climate finance commitments spend 50 times as much on their militaries every year.

Rising defence budgets are not merely displacing climate spending at the national level. They are generating additional emissions through the investments themselves. Research by macroeconomist Balázs Markó at Bocconi University found that for every percentage point increase in military spending, total emissions rise by between 0.9% and 2%. ² 

NATO's 2025 commitment to a target of 5% of GDP for each member nation, if met, would double the alliance's combined military expenditure between 2025 and 2030, generating an estimated additional 840 million tonnes of emissions compared with a scenario where spending remained at 2% of GDP.

Climate change itself is increasingly identified as a driver of future conflict, creating the feedback loop that many researchers now consider the most dangerous long-term dynamic in the field. Water scarcity, crop failure, extreme heat, and displacement are already documented contributors to instability in the Sahel, in the Horn of Africa, and across parts of the Middle East. 

If warming continues to generate the conditions that make conflict more likely, and conflict generates the emissions that accelerate warming, the system becomes self-reinforcing in the most dangerous possible way.

Recovery, Accountability, and What Comes Next

How long do ecosystems take to recover from the damage of war? The honest answer is: it depends on the damage, and sometimes the answer is never. Vietnam's forests took decades to partially recover from the aerial spraying of Agent Orange, a herbicide that destroyed an estimated 4.5 million acres of forest and farmland and left soil contamination that persists today. 

Ukraine's nature reserves, more than 12,000 square kilometres of which have become active combat zones, will require at least 15 years to recover from the direct physical damage alone, according to preliminary Ukrainian government estimates. ²⁰ 

The chemical contamination and unexploded ordnance that now covers roughly 30% of the country's territory complicate that timeline substantially.

There are examples where environmental restoration has been incorporated into post-conflict recovery. El Salvador, after its civil war, invested in watershed management and reforestation as part of a broader rural recovery programme. Rwanda made systematic forest restoration central to its post-genocide agricultural strategy. Bosnia invested in mine clearance partly because the contaminated land was economically unusable. These are partial models, not templates. ¹⁶ 

None of them operated at the scale and complexity that Ukraine, Syria, or Gaza now present.

International legal frameworks for environmental accountability in war remain weak. The Rome Statute of the International Criminal Court recognises widespread, long-term, and severe damage to the natural environment as a potential war crime, but prosecutions on those grounds are extremely rare. 

A group of researchers at Goldsmiths and the Palestinian Environmental NGOs Network has called for Israel to be investigated under Rome Statute provisions for systematic agricultural destruction in Gaza. Ukrainian officials are building a reparations case against Russia partly on climate damage grounds, estimating total climate liability at more than $42 billion using a social cost of carbon of $185 per tonne. ⁶ 

Both cases face the same obstacle: no binding international mechanism exists to adjudicate climate damages caused by war.

Environmental monitoring during conflict is emerging as a potential new area for cooperation. Satellite systems operated by the European Union, including the Sentinel-5P instrument used to track atmospheric pollutants, have already produced detailed data on air quality changes over Gaza and Ukraine. 

Researchers using those tools have tracked spikes in carbon monoxide, sulphur dioxide, and methane as infrastructure burns and waste management collapses. The science is ahead of the policy: the data exists, the methodologies are improving, but no international body is yet required to act on what the satellites see.

Conclusion: The Unanswered Question

There is a particular kind of cognitive dissonance at work in contemporary climate politics. Governments negotiate emissions cuts, publish net-zero targets, and announce clean energy subsidies while simultaneously increasing military budgets, fighting wars, and exempting their armed forces from the reporting requirements they impose on every other sector. The gap between what is measured and what matters has rarely been wider.

The research being produced now, from the meticulous carbon accounting of Ukraine's war to the satellite studies of Gaza's air quality, represents a genuine scientific advance. For the first time, it is becoming possible to measure, in near real time, what armed conflict costs the atmosphere. That knowledge is valuable. Whether it will translate into accountability, into changed behaviour at the negotiating table or on the battlefield, is a different question entirely.

The atmosphere does not distinguish between a tonne of CO₂ from a coal plant and a tonne from a burning oil depot struck by a cruise missile. Both warm the planet. Both narrow the window for the action the IPCC says is still possible. If the world is serious about climate, it will eventually have to reckon with the emissions it has been most reluctant to count. 

The question is whether that reckoning comes in time to matter, or only after the damage has been done.

References

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