Carbon Emissions Fall 0.4% in 2026, and Most of the Dip Is the War

Global fossil-fuel carbon dioxide emissions are on course to fall 0.4% this year, to 38.2 billion metric tons, but the main cause is the oil shock from the Iran war, not a breakthrough in climate policy. ^[2][3]

The estimate comes from the Global Carbon Budget 2026, the annual accounting of where carbon dioxide comes from and where it goes. An international team of more than 140 scientists published it as a preprint on November 10, and it is under review at the journal Earth System Science Data. ^[1][2]

A companion analysis in Nature Climate Change, written by researchers from the same project, sets out what moved the number. ^[3]

What the war did

The drop sits almost entirely in oil. The budget projects oil emissions down 1.9%, natural-gas emissions down 0.3% and coal emissions up 0.6%. ^[1][3]

The researchers tie the oil decline to the energy shock from the Iran conflict: higher prices and constrained supply, with the disruption around the Strait of Hormuz at the centre. Glen Peters, a co-author, said the drop was largely driven by the war and by events in the strait. ^[3][6]

The Strait of Hormuz is the narrow passage at the mouth of the Persian Gulf through which a large share of the world's seaborne oil travels. When it is disrupted, fuel gets scarce and dear, and people and businesses burn less of it. Nobody chose that. Emissions fell because supply failed.

Peters described the pattern as emissions rising and then suddenly dropping by about 2%, which is not what a gradual structural decline looks like. ^[1][6]

What clean energy did

The study does not say the war did everything. Electric vehicles, solar and wind are cutting emissions too, and the analysis counts them.

Solar and wind avoided an estimated 4.1 billion metric tons of CO2 in 2025 and are projected to avoid 4.6 billion this year. Electric vehicles avoided 0.19 billion tons in 2025 and are projected to avoid 0.24 billion in 2026. ^[3]

But the extra work those technologies do in 2026 accounts for only about 20% of the projected fall in oil emissions. ^[3] The Global Carbon Project's own summary credits both clean-power growth and the Iran conflict. ^[5] The war is the larger part of the story, and it is not the whole of it.

The analysis also asks whether clean energy is growing fast enough to outrun demand. Between 2025 and 2028, it projects, economic growth and related trends would add 2.59 billion tons of CO2. At current deployment rates, electric vehicles, solar and wind would offset 63% of that. Under the study's accelerated scenario they would offset 79%. ^[3]

Even the faster path leaves more than a fifth of the added demand uncovered. At today's pace, more than a third goes uncovered.

Why it will not last

The history of these dips is not encouraging. Peters noted that the previous global declines, in 2009 and 2020, were each followed by a return to growth. ^[1][6] Those were the financial crisis and the pandemic. This time the cause is a war in the oil patch.

Fossil-fuel emissions rose by an average of 0.8% a year from 2019 to 2025, according to the analysis, so a 0.4% fall is a small step against a rising slope. ^[3]

The researchers say their 2025-2028 projections leave out short-term swings, including an expected recovery from the 2026 energy shock. They do not claim emissions will bounce back by a set amount or on a set date. ^[3] If oil supply and prices normalise, the cause of this year's dip goes away with them.

Pierre Friedlingstein, the budget's lead author, said a decline driven partly by geopolitical shocks is not a sustainable climate solution. Clean-energy deployment, he said, has to accelerate for emissions to peak and then fall for good. ^[4]

The wider carbon picture

Fossil fuels are not the whole ledger. Counting land-use change, the budget puts total CO2 emissions at 43.3 billion metric tons in 2026, up from 42.8 billion in 2025, a rise of about 1%. Deforestation, peat fires and forest degradation contribute to that increase. ^[4][6]

The sum of all human CO2 is therefore still climbing, because land-use emissions outweigh the small fall from fossil fuels. ^[4]

The national picture is uneven. The analysis estimates 2026 emissions falling 0.9% in China, 1.3% in the United States, 1.5% in the European Union and 1% in Japan, while rising 4.4% in India. ^[3][4]

The atmosphere does not respond to a one-year dip. The budget projects CO2 concentration at 427.7 parts per million this year, 54% above the pre-industrial level of about 278. ^[2]

How firm the number is

The 0.4% figure is a preliminary estimate. The budget's own range runs from a 1.5% decrease to a 0.6% increase, so a small rise cannot be ruled out. ^[2][3]

The estimate is built from energy and cement production data for fossil emissions, plus land-use data, atmospheric CO2 measurements, ocean models and vegetation models. The authors check it against other evidence, including atmospheric inversions, which work backward from measured air to find sources, and oxygen measurements. ^[2]

Final data may move the figure. The paper has not yet passed peer review, and the next evidence to watch is whether oil supply and prices recover, and what emissions do when they do.