Reduced carbon emission estimates from fossil fuel combustion and cement production in China

A revised estimate of Chinese carbon emissions from fossil fuel burning and cement production is presented, based on updated energy consumption and clinker production data and two new sets of measured emission factors for Chinese coal. China emits large amounts of anthropogenic carbon, but its carbon emission estimates are highly uncertain. This paper presents a revised estimate of Chinese carbon emissions from fossil fuel burning and cement production based on updated energy consumption and clinker production data, and two new sets of measured emission factors for Chinese coal. The authors estimate of China's cumulative carbon emissions for the period 2000 to 2013 is 13% lower than previous estimates. Nearly three-quarters of the growth in global carbon emissions from the burning of fossil fuels and cement production between 2010 and 2012 occurred in China1,2. Yet estimates of Chinese emissions remain subject to large uncertainty; inventories of China’s total fossil fuel carbon emissions in 2008 differ by 0.3 gigatonnes of carbon, or 15 per cent1,3,4,5. The primary sources of this uncertainty are conflicting estimates of energy consumption and emission factors, the latter being uncertain because of very few actual measurements representative of the mix of Chinese fuels. Here we re-evaluate China’s carbon emissions using updated and harmonized energy consumption and clinker production data and two new and comprehensive sets of measured emission factors for Chinese coal. We find that total energy consumption in China was 10 per cent higher in 2000–2012 than the value reported by China’s national statistics6, that emission factors for Chinese coal are on average 40 per cent lower than the default values recommended by the Intergovernmental Panel on Climate Change7, and that emissions from China’s cement production are 45 per cent less than recent estimates1,4. Altogether, our revised estimate of China’s CO2 emissions from fossil fuel combustion and cement production is 2.49 gigatonnes of carbon (2 standard deviations = ±7.3 per cent) in 2013, which is 14 per cent lower than the emissions reported by other prominent inventories1,4,8. Over the full period 2000 to 2013, our revised estimates are 2.9 gigatonnes of carbon less than previous estimates of China’s cumulative carbon emissions1,4. Our findings suggest that overestimation of China’s emissions in 2000–2013 may be larger than China’s estimated total forest sink in 1990–2007 (2.66 gigatonnes of carbon)9 or China’s land carbon sink in 2000–2009 (2.6 gigatonnes of carbon)10.