International agencies could be overestimating greenhouse gas emissions from China by more than 14%, according to a team of international scientists. Researchers said global organizations were basing their calculations on “inaccurate assumptions” about China’s coal burning. Findings of the study were published Wednesday in the journal Nature.

China's Carbon Count Is Grossly Overestimated

China’s locally produced coal emits less carbon

It doesn’t mean that the total level of carbon dioxide in the country’s atmosphere is any lower than previously estimated. The accumulation of greenhouse gases is measured independently. What’s more, scientists found that the official Chinese figures underestimated the country’s total energy consumption by close to 10% between 2002 and 2012.

International organizations were using a globally averaged formula to calculate CO2 emissions. But when scientists looked in detail at the quality of coal used in China, they found that it contained much less carbon and burned less efficiently than previously assumed. It means each ton of coal used in China produced less CO2 and less energy upon burning than thought.

It may have a significant impact on Beijing’s proposed commitments to cut the emission of greenhouse gases. Chinese President Xi Jinping promised last year that the country’s carbon emissions would stop growing after 2030. China accounts for more than 33% of the world’s total greenhouse gas emissions. So, if China’s emissions fall by 15%, the global CO2 emission will be 5% less.

The default international conversions don’t apply to China

Steven J. Davis of the University of California and co-author of the study, said his team measured thousands of samples of coal from mines across the country. They found that the Chinese coal produced 40% less carbon than international agencies assumed. The study concludes that agencies like the European Union’s Emissions Database for Global Atmospheric Research (EDGAR) overestimated China’s carbon emissions by 14% by using default conversion rates.

Since China mostly uses cheaper, low-quality coal produced from local mines, which is burned in less efficient furnaces than are typical in Western countries, the international default conversions don’t apply to China. It’s the first time fuel quality has been taken into consideration, which the previous estimates have clearly missed.