Six months into the Iran war, the standoff in the Strait of Hormuz continues to rattle the global economy. Traders and governments are watching for signs of escalation, while households and companies are paying more for fuel and fearing energy shortages.
But the war is also taking a deeper, albeit less visible, environmental toll, driving up carbon dioxide emissions and undermining international cooperation on climate change. And unlike high oil prices, those costs will not disappear when the war ends.
Iran, of course, is just one geopolitical flashpoint. There are currently 65 active state-based armed conflicts worldwide, the highest number since records began in 1946.
While the Middle East and Ukraine dominate news headlines, the civil wars in Sudan and Myanmar are still raging. Global military spending rose for the eleventh consecutive year in 2025, reaching nearly US$2.9 trillion. By contrast, official development assistance fell by more than 23 per cent in real terms—the largest annual decline on record.
Meanwhile, the climate crisis continues to escalate. The past three years have been the warmest on record, and every year between 2015 and 2025 ranks among the 11 warmest ever measured.
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Energy security and climate security are not the same thing, but they now reinforce each other. Restarting coal plants or finding safer oil suppliers would do little to protect the world from future energy or environmental shocks.
A 2025 report by the Planetary Boundaries Science Lab found that seven of Earth’s nine planetary boundaries have been breached, with ocean acidification being the latest to fall outside the safe range. An intensifying El Niño could make matters worse, heating an already exceptionally warm planet and increasing the likelihood of disruptive droughts, floods, and other weather extremes.
Conflict-related emissions remain poorly captured by climate accounting, making it hard to estimate the Iran war’s full environmental impact. Military emissions are often reported incompletely, if they are reported at all, and are rarely subject to scrutiny. A 2026 review of 263 separate studies found that more than 90 per cent of emissions linked to military operations and conflicts go unaccounted for. Methods are improving, but estimates still vary depending on what counts as military activity and how damaged infrastructure is assessed.
Earlier this year, an analysis by the Climate and Community Institute estimated that the first 14 days of fighting between the United States, Israel, and Iran generated more than five million metric tons of carbon dioxide equivalent (CO2e) emissions, more than Iceland emits in a year. Emissions have continued to rise since then, though there is no comparable estimate for the war as a whole.
The war’s carbon bill will keep growing after the fighting stops. Rebuilding damaged roads, homes, and industrial facilities requires producing vast quantities of highly carbon-intensive cement and steel. A 2024 study found that postwar reconstruction can generate an enormous carbon footprint, in some cases rivaling a country’s prewar emissions.
Then there is the war’s toxic legacy. Strikes on refineries and petrochemical facilities can release sulfur compounds, heavy metals, and other pollutants into the air and water, contaminating soils, aquifers, and coastal ecosystems in a region already suffering from extreme heat and water scarcity. Smoke plumes may disappear from satellite images within days, but the contamination can last for generations.
The war’s indirect effects may be even more damaging. Wars destroy physical assets, but they also change the calculations behind energy policy. When established routes become unreliable, governments and companies turn to supplies they consider secure and politically manageable, even if that means dirtier fuels.
In this respect, the closure of the Strait of Hormuz marks a turning point. Shipping through the waterway has been severely curtailed since the war began on February 28 and was effectively halted again in early July, creating what the International Energy Agency described as the “largest supply disruption in the history of the global oil market.”
Oil prices climbed above US$110 a barrel. The short-lived ceasefire between the US and Iran briefly reopened the Strait and brought prices down, but since it broke down and the negotiation window expired, shipping has been disrupted again and global energy markets have come under renewed pressure.
The resistible pull of king coal
Even though a single naval incident can now trigger a global energy crisis almost overnight, governments and markets are still banking on reliable fossil-fuel supplies. In July, for example, the US Energy Information Administration projected that Brent prices would fall to US$74 in the third quarter; days later, renewed US strikes rendered that forecast obsolete.
Fearing energy shortages, many governments are responding to the crisis by leaning more heavily on fossil fuels. Coal plants scheduled to close may now stay open, mothballed capacity could be restored, and emergency gas contracts may end up becoming permanent.
Signs of this fossil-fuel resurgence are already visible. Several countries have increased coal generation or delayed plant closures in recent months, echoing the scramble for fossil fuels that followed Russia’s 2022 invasion of Ukraine.
By May, 109 countries had announced energy-related measures in response to the war. Nearly 20 governments introduced structural measures to improve efficiency or accelerate electrification, but most of these interventions were aimed at conserving fuel and shielding consumers. While some measures may help cushion the shock, they also risk locking in the very dependencies that caused the crisis in the first place.
Notably, this is the first major oil crisis in which there are mass-market clean alternatives. The crisis may make coal and natural gas more attractive in the short term, but over time it could also erode confidence in imported fossil fuels and strengthen the political and economic case for electrification.
This is not to suggest that the transition to clean energy will be smooth sailing. Batteries, solar panels, and wind turbines all depend on critical minerals produced and processed through highly concentrated global supply chains. According to one recent estimate, the full implementation of China’s rare-earth export controls could put US$6.5 trillion in annual downstream production outside China at risk.
Some of these vulnerabilities are often overlooked in energy-policy debates, as they involve little-known inputs like sulfur and sulfuric acid, which are essential to the production of phosphate fertiliser and to processing copper, cobalt, and nickel. The Middle East produces around one-quarter of the world’s sulfur, and nearly half of all seaborne supply passes through the Strait of Hormuz. Recent disruptions have already led China to curb sulfuric acid exports, raising costs across both mineral and fertiliser supply chains.
With electrification and food production also exposed to concentrated supply chains and maritime chokepoints, speed has become crucial. While an LNG terminal or a thermal power plant can take years to complete, rooftop solar, batteries, and efficiency upgrades can be deployed much faster.
Clean energy, however, is still constrained by high financing costs, permitting delays, inadequate grids, and concentrated supply chains. Even so, solar panels and batteries can be installed piece by piece without waiting for a single large project to come online.
Strengthening domestic manufacturing could help address some of these problems, but producing every mineral and component at home would be prohibitively expensive and unrealistic. Rather than seeking self-sufficiency, countries should build diversified supply chains that can survive the loss of one supplier without seizing up.
Alternatives to oil also come with their own environmental costs. Consider biofuels. When oil and gas prices rise, corn, palm oil, soy, and sugar become more attractive, since they can be easily integrated into existing fuel systems. But clearing carbon-rich forests to make room for fuel crops can create an emission debt that would take decades to pay off.
Moreover, increased biofuel demand does not necessarily translate into higher crop prices. How much farmers actually stand to gain depends on government mandates, refining capacity, and commodity markets. And when crop prices do rise, so does the value of farmland, making forest clearing even more lucrative.
The Iran war is already forcing that trade-off. Governments grappling with a fuel-price crisis tend to cut budgets, and environmental agencies rarely have the necessary political muscle to protect theirs. That creates room for land grabbing and illegal logging, which criminal organisations are quick to exploit.
Another vulnerability is food production. Though the effects of displacing farmers and disrupting cultivation can take months, even years, to manifest, the Iran war has sped up the process by throwing commodity markets into chaos. Disruptions to sulfuric acid and natural-gas shipments from the Gulf, for example, are already raising costs for import-dependent farmers.
The World Bank expects its fertiliser price index to rise by more than 30 per cent in 2026, reflecting higher input costs, biofuel demand, and the Hormuz crisis. Poorer countries, where farmers have less access to credit and governments have fewer resources to cushion price shocks, will be hit the hardest.
Russia’s invasion of Ukraine showed how quickly a war in one part of the world can jeopardise food security in another. The war in Iran is now hitting the same, already strained supply chains. A fertiliser shortage that delays planting may not get as much media attention as a missile strike, but its consequences can be even more devastating and longer-lasting.
Climate diplomacy in the crosshairs
Instead of strengthening emission-reduction plans or protecting forests, governments are focused on containing energy prices and securing fuel supplies. It’s not difficult to see why: climate policies are a hard-enough sell without households and companies complaining about surging fuel costs. Climate diplomacy is among the easiest things to put off.
As worsening droughts dry out rivers and fuel wildfires across Europe and North America, the timing could hardly be worse. Last year’s United Nations Climate Change Conference (COP30) in Belém ended without adopting roadmaps to shift away from fossil fuels or halt and reverse deforestation. The Brazilian presidency subsequently launched both initiatives outside the formal COP30 agreement, but those efforts must now compete with a war that is consuming diplomatic attention and public money.
Yet the consequences of delaying decarbonisation are no longer hypothetical. Every year that fossil-fuel use rises and forests continue to disappear puts more pressure on the climate system, increasing the risk of further ice-sheet loss, weaker ocean circulation, more erratic rainfall, and severe damage to vital ecosystems.
Like all wars, the Iran war will eventually end. Shipping will resume, reconstruction contracts will be signed, and the world’s attention will move on. But carbon-intensive infrastructure built in response to an energy shock can remain in place for decades, while damaged ecosystems may never fully recover.
Although the war has made climate negotiations more difficult, geopolitical turmoil need not derail the energy transition. Embracing biofuels and returning to coal are policy choices, and governments can choose not to sacrifice the Amazon to keep fuel prices down.
Avoiding that outcome requires clear guardrails. Any decision to keep coal plants running should have an expiry date, and emergency gas purchases shouldn’t lock countries into decades of supply they may not want. Environmental enforcement should be protected from emergency budget cuts. And when reconstruction gets underway, it should favour lower-carbon materials.
These measures must be paired with public investment, as energy shocks tend to turn climate policies into political liabilities. Governments will need to cushion the blow, but relief should go to lower-income households instead of subsidising electricity across the board. They must also invest in measures that permanently reduce demand, including decentralised clean power and better public transit.
Renewables are already starting to reduce dependence on contested borders and dangerous sea lanes. Global renewable power capacity reached a record 5,149 gigawatts last year, with 692 gigawatts added in 2025 alone. Renewables accounted for 85.6 per cent of all new power capacity and now comprise almost half of installed global generating capacity, though the world is far off track from the goal of tripling renewable capacity by 2030.
These figures measure capacity rather than generation, but they show how quickly power systems are changing. Renewables do not make countries immune to crisis. Grids can be attacked or fail, and much of the equipment they rely on moves through global supply chains. What they do reduce is exposure to imported fuels.
The Iran war has made the security benefits of clean energy hard to ignore. After all, domestically generated solar and wind power cannot be blockaded at a strait halfway around the world. Yet efforts to reduce oil dependence can create new vulnerabilities. Renewed pressure on tropical forests from increased biofuel demand shows what happens when ecosystems are treated as expendable.
Energy security and climate security are not the same thing, but they now reinforce each other. Restarting coal plants or finding safer oil suppliers would do little to protect the world from future energy or environmental shocks. The only durable course is to accelerate the transition away from fossil fuels while building clean-energy systems that are more diverse, decentralised, and resilient.
Lourenço Bustani contributed to this commentary.
Robert Muggah, Co-Founder of the Igarapé Institute and the SecDev Group, is a fellow at the Robert Bosch Academy. Carlos Nobre, a senior scientist at the University of São Paulo’s Institute for Advanced Study, is Co-Chair of the Science Panel for the Amazon. Johan Rockström, Director of the Potsdam Institute for Climate Impact Research and Professor of Earth System Science at the University of Potsdam, is Co-Chair of the Global Commission on the Economics of Water.
Copyright: Project Syndicate, 2026.
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