Global heat-trapping carbon dioxide emissions from fossil fuels saw a slight decrease of 0.4% in 2026, but scientists attribute this reduction primarily to oil market disruptions caused by the war in Iran rather than deliberate climate action. The world emitted 42.2 billion tons (38.2 billion metric tons) of carbon dioxide this year, according to estimates from the Global Carbon Project published in the journal Earth System Science Data Discussions.
"It's downwards which sounds good, but this is largely driven by the war in Iran, what’s happened in the Strait of Hormuz," said study co-author Glen Peters, a scientist at the CICERO Center for International Climate Research in Norway. "So in a way, a little bit of good news, but for the wrong reasons."
The conflict has effectively closed the Strait of Hormuz, a critical route for petroleum products, leading to increased global oil prices. In line with this, oil emissions dropped by nearly 2%, while natural gas emissions fell 0.3%, and coal emissions rose 0.6%.
This marks the third time in the 21st century that global carbon pollution has dropped, with previous decreases occurring during the 2009 global recession and the 2020 COVID-19 pandemic. In those past instances, hopes for a shift towards clean energy following the crises did not ultimately materialize, according to Peters.
While the overall fossil fuel emissions saw a slight decrease, total global carbon dioxide emissions, including those from land-use changes like deforestation, increased by 1%. Deforestation and human-caused peat fires contributed more to the overall CO2 increase than the reduction in fossil fuel burning.
Major polluting nations like China, the United States, Europe, and Japan showed approximately a 1% drop in emissions, which Peters again linked to the oil shock. India's fossil fuel pollution, however, increased by 4.4%.
Some experts noted positive signs, such as China's emission reduction and significant investments in renewable energy and electric vehicles, suggesting a potential fundamental transformation of its economy. However, concerns remain that the gains from the war-induced crisis might be temporary, with unaffected oil-producing nations potentially increasing exploration outside the Middle East.
The study highlights the immense scale of ongoing emissions, with approximately 1,335 tons of carbon dioxide entering the atmosphere every second. "We shouldn't lose sight of the bigger picture. The world is still pumping more than a thousand (metric tons) of carbon dioxide into the atmosphere every second," said Mohamed Adow, director of the environmental group Power Shift Africa. Peters added, "It’s very abstract to think about the magnitude of stuff we throw in the atmosphere every year, but it’s a ginormous number. If it was black and not transparent, the sky would be dark."