China’s coal use this century has been significantly underestimated, according to analysis of new Chinese data by the US Energy Information Administration, adding to climate change negotiators’ problems ahead of December’s UN conference in Paris.

based on revised data released by Beijing this summer, the EIA has concluded that the world’s largest polluter and consumer of coal burnt up to 14 per cent more of the fossil fuel between 2000 and 2013 than previously reported. It said this meant China’s energy consumption and production were also much higher.

The EIA’s analysis squares with the supercharged economic growth of the decade before 2013 and much slower growth now but throws into confusion the calculations on which climate change negotiators rely to determine the level of emissions produced by each nation. Talks this December in Paris will attempt to rein in those emissions, in the hopes of preventing dangerous global warming.

The fact that China has made GDP figures a political target has resulted in a remarkably smooth growth path, which critics say obscures the real cycles in the Chinese economy. Higher energy consumption from 2000-2013 would tally with other indicators of an economy that grew more quickly than official figures over that period suggest, including high commodity prices, a boom in coal mining and the proliferation of private mines and smelters.

Similarly, the motivation to hit targets may mask the extent of the current economic slowdown. A reported dro in China’s coal output in 2014 has cheered environmentalists, including Greenpeace, and raised hopes that the country’s emissions might peak and begin to decline before the official target of 2030.

The EIA’s analysis also concluded that growth in coal use was slowing dramatically. “In 2014, energy-content-based coal consumption was essentially flat”, while coal production fell by 2.6 per cent, it said.

Last month a study in the journal Nature argued that Chinese emissions were actually lower than estimated by international institutes, because of incorrect assumptions about the quality of Chinese coal. The authors said emissions were overestimated despite assuming the country’s actual coal consumption was 10 per cent higher than Chinese government data showed.

However, the revised Chinese statistics on which the EIA’s analysis is based indicate that energy released through coal consumption edged up slightly in 2014 compared with 2013, reflecting a greater proportion of higher-quality coal in the mix as dropping prices cut out the lowest-quality suppliers.