China's carbon emissions may have been a lot less than we thought

Smog arrives at the banks of Songhua River, Jilin province of China. ChinaFotoPress/ChinaFotoPress via Getty Images

China’s carbon emissions have been overestimated for more than a decade and may be 14% less than previous estimates, according to the latest research.

Scientists re-evaluated emissions from burning fossil fuels and cement production from 1950 to 2013 and found that emissions for coal-fired power production were largely overestimated.

The revised estimates of China’s carbon emissions, published in the journal Nature, were produced by an international team of researchers, led by Harvard University, the University of East Anglia and the Chinese Academy of Sciences and Tsinghua University in collaboration with 15 other international research institutions.

Zhu Liu from Harvard University and colleagues reassessed China’s carbon emissions from the burning of fossil fuels and the production of cement, using new measurements of emission factors, the amount of carbon oxidised per unit of fuel consumed.

This chart shows the difference between this study and previous official estimates:

They estimate that China’s emissions were 14% lower than estimates by the Emission Database for Global Atmospheric Research in 2013 and 12% lower than the inventory China reported to the United Nations Framework Convention on Climate Change in 2005.

The authors say the emission factors for coal are on average 40% lower than the default values recommended by the Intergovernmental Panel on Climate Change.

Emissions from cement production were 32% to 45% lower.

Dabo Guan of the University of East Anglia says the key contributor to the new estimates is fuel quality which for the first time was taken into consideration.

This is something the Intergovernmental Panel on Climate Change (IPCC) and most international data sources don’t do.

“China is the largest coal consumer in the world, but it burns much lower quality coal, such as brown coal, which has a lower heat value and carbon content compared to the coal burned in the US and Europe,” says professor Guan.

“China is one of the first countries to conduct a comprehensive survey for its coal qualities and a global effort is required to help other major coal users, such as India and Indonesia, understand their physical coal consumptions as well as the quality of their coal types.”

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