Global fossil CO2 emissions set to fall 0.4% in 2026 as Iran war hits oil

The world's carbon dioxide emissions from burning fossil fuels are on course to fall slightly this year, but scientists say it is for the wrong reasons. The Global Carbon Budget 2026, published on Tuesday 10 November by the Global Carbon Project, projects that CO2 from fossil fuels and cement will drop by about 0.4% to 38.2 billion tonnes (GtCO2). The main driver is a 1.9% fall in emissions from oil after the Iran conflict and the closure of the Strait of Hormuz pushed up prices and cut supply.

The projection is preliminary. The report's range runs from a 1.5% fall to a 0.6% rise, so a small increase cannot be ruled out. And because emissions from deforestation and fires are rising, total CO2 emissions are still expected to reach a record 43.3 GtCO2, slightly above 42.8 GtCO2 in 2025.

What does the Global Carbon Budget measure?

The Global Carbon Budget is an annual assessment by more than 140 researchers, led by the University of Exeter's Pierre Friedlingstein. This is its 21st edition, published in the journal Earth System Science Data alongside a related study in Nature Climate Change. It tracks where CO2 comes from (fossil fuels, cement and land-use change such as deforestation) and where it goes (the oceans, land ecosystems and the atmosphere).

"Fossil emissions" in the report combine fossil fuels and cement production. "Land-use emissions" cover deforestation, forest degradation, wood harvest, peatland drainage and fires, minus regrowth. The "remaining carbon budget" is the estimated amount of CO2 the world can still emit while keeping a given chance of limiting warming to a target such as 1.5C above pre-industrial levels.

Why are fossil emissions falling this year?

Oil is the story. The report projects oil emissions will fall by 1.9%, or about 243 million tonnes of CO2, one of the largest annual drops on record outside the Covid-19 year of 2020, according to a Carbon Brief analysis co-written by Friedlingstein. Petrol and diesel prices in the US, China and the EU were 10% to 50% higher than in 2025, depending on fuel and period. Oil emissions are projected to fall in every major region, with the biggest drop in China at 4.6%.

Clean technology played a role too. A parallel study by the same team estimates that growth in electric vehicles accounted for around a fifth of the fall in oil emissions in 2026.

Other fuels moved differently. Coal emissions are projected to rise by 0.6%, as strong growth in India outweighs sharp falls in the EU and US. Gas emissions are expected to dip 0.3%, which is effectively flat. Coal remains the largest source, at about 41% of fossil CO2, ahead of oil at 33% and gas at 21%.

"It's downwards which sounds good, but this is largely driven by the war in Iran, what's happened in the Strait of Hormuz," study co-author Glen Peters of Norway's CICERO Center for International Climate Research told the Associated Press. "So in a way, a little bit of good news, but for the wrong reasons."

Which countries are cutting emissions and which are rising?

The report's 2026 projections for the largest emitters are:

• China, about 32% of global fossil emissions: down 0.9%, with oil falling 4.6%, gas down 0.9% and coal up 0.3%. The report links this to renewables growth and a milder summer than 2025's record heat.
• United States, about 13%: down 1.3%, mainly because coal emissions fall 6.7% after an unusual rise in 2025.
• India, about 8%: up 4.4%, faster than its 3.5% annual average over the past decade, with coal up 5.9%.
• European Union, about 6%: down 1.5%, with coal down 2.9% and oil down 1.8%.
• Japan, about 2.5%: down 1.0%, continuing a longer decline.
• International aviation and shipping: each down about 1%, partly because of reduced traffic in the Middle East.
• Rest of the world, about 38%: down 0.7%, mostly from oil.

Every country figure carries its own uncertainty range. The report also found that 40 countries, together responsible for 26% of global fossil emissions, significantly cut emissions while growing their economies over 2016 to 2025, up from 22 countries in the previous decade.

If fossil emissions are down, why are total emissions at a record?

Land-use emissions are projected to rise to 5.1 GtCO2 in 2026 from 4.4 GtCO2 in 2025. The report attributes the increase to peat fires, almost all started by people, and forest degradation in south-east Asia during drier conditions linked to this year's strong El Niño. Carbon Brief notes that if land-use emissions had stayed at 2025 levels, total emissions would have fallen slightly to around 42.6 GtCO2.

Over the longer term the picture is mixed. Land-use emissions averaged 4.9 GtCO2 a year over 2016 to 2025, about 21% lower than the decade before. Total emissions grew by an average of 0.3% a year over the past decade, compared with 1.7% a year in the decade before that. Brazil, the Democratic Republic of the Congo and Indonesia together account for around 54% of land-use emissions.