The study adopts what it calls the “apparent consumption” approach, which is calculated by balancing domestic fuel production, international trade and other elements less subject to accounting errors. It also allows imported and domestically produced fuels to be tracked separately so that different emissions factors can be applied.
Researchers found that the total energy consumption in China was 10 percent higher between 2000 and 2012 than reported in the country’s national statistics. But when coal quality was taken into account, there was an average 40 percent drop in overall emissions from power generation and a 45 percent fall in emissions from cement-making.
Glen Peters, a senior researcher at the Center for International Climate and Environmental Research in Oslo and one of the nearly two dozen authors who worked on the study, called the 2.9 gigatons of overestimated carbon “not insignificant.” But he also cautioned that China’s emissions data will certainly be in for more changes.
He noted that China’s census, which was published after the Nature study was completed, revises energy consumption upward again by about 10 percent and coal consumption by 14 percent—potentially wiping out emissions reductions.