China has been underreporting its coal consumption for years, experts said Wednesday after reports that official statistics have been revised upwards by hundreds of millions of tonnes a year.
The National Bureau of Statistics raised the figures for coal consumption in previous years by as much as 17 percent in its most recent yearbook, the New York Times reported.
For 2012 alone the increase was 600 million tonnes, it said - over 70 percent of the United States' annual coal consumption, and implying that China's annual emissions of greenhouse gas carbon dioxide had been underestimated by more than Germany's total yearly output.
The development comes ahead of a UN climate summit in Paris, which will seek to unite all the world's nations in a single agreement on tackling climate change, but is expected to see difficult negotiations on how the burden should be divided between countries.
The new figures suggest that Chinese emissions have been a significantly larger driver of global warming than previously thought.
The National Bureau of Statistics did not immediately confirm the revisions to AFP, and the figures from its energy statistical yearbook are not available on its website.
But at a coal conference in Beijing, Zhou Fengqi, an advisor to the National Development and Reform Commission, China's top planning body, told AFP: "The new figures are more accurate than before." The data has depended on incomplete provincial statistics, he said.
"We always felt there was a gap between the National Coal Association's statistics and the National Bureau of Statistics figures. Now the national figures have progressed, and more accurately reflect the situation." Song Guojun, professor of environmental economics at Renmin University, said the adjusted figures were "certainly more reliable".
"Coal is a very common thing in China. At the county level and below, and even at the city level, there were many sources of coal use which did not make it into the official statistics gathering mechanism," he said.
A shift towards more environmentally friendly development is China's "duty and contribution to humanity" as one of the world's largest countries, Premier Li Keqiang said this week during a visit by French President Francois Hollande.
China has pledged that its carbon dioxide emissions will peak by "around 2030".
Yang Fuqiang, senior climate change advisor at the Natural Resources Defense Council, a US environmental campaign group, said the new coal statistics would not necessarily affect the Paris negotiations, as Beijing's commitment was "only about a peak rather than the total volume of CO2 emissions".
But "there will be more concern about the volume of emissions", he added.