Analysis: World’s biggest historic polluter – the US – is pulling out of UN climate treaty
Simon Evans
01.08.26Simon Evans
08.01.2026 | 1:12pmThe US, which has announced plans to withdraw from the global climate treaty – the UN Framework Convention on Climate Change (UNFCCC) – is more historically responsible for climate change than any other country or group.
Carbon Brief analysis shows that the US has emitted a total of 542bn tonnes of carbon dioxide (GtCO2) since 1850, by burning fossil fuels, cutting down trees and other activities.
This is the largest contribution to the Earth’s warming climate by far, as shown in the figure below, with China’s 336GtCO2 significantly behind in second and Russia in third at 185GtCO2.
The US is responsible for more than a fifth of the 2,651GtCO2 that humans have pumped into the atmosphere between 1850 and 2025 as a result of fossil fuels, cement and land-use change.
China is responsible for another 13%, with the 27 nations of the EU making up another 12%.
In total, these cumulative emissions have used up more than 95% of the carbon budget for limiting global warming to 1.5C and are the predominant reason the Earth is already nearly 1.5C hotter than in pre-industrial times.
The US share of global warming is even more disproportionate when considering that its population of around 350 million people makes up just 4% of the global total.
On the basis of current populations, the US’s per-capita cumulative historical emissions are around 7 times higher than those for China, more than double the EU’s and 25 times those for India.
The US’s historical emissions of 542GtCO2 are larger than the combined total of the 133 countries with the lowest cumulative contributions, a list that includes Saudi Arabia, Spain and Nigeria. Collectively, these 133 countries have a population of more than 3 billion people.
See Carbon Brief’s previous detailed analysis of historical responsibility for climate change for more details on the data sources and methodology, as well as consumption-based emissions.
Additionally, in 2023, Carbon Brief published an article that looked at the “radical” impact of reassigning responsibility for historical emissions to colonial rulers in the past.
This approach has a very limited impact on the US, which became independent before the vast majority of its historical emissions had taken place.
