China’s carbon emission may be significantly lower that it had been assumed. According to a research published in Nature this week, China has produced around 40% less carbon emissions than estimated.
An ecologist at Harvard University and also lead author of the study Zhu Liu says, that at the beginning of the project they thought that the emissions might actually be higher than estimated. However, the surprising finding doesn’t mean China is not the world’s largest emitter of carbon dioxide – China’s carbon output for 2013 is still more than two-thirds higher than that of the United States, the second-largest emitter.
The study also underlines many uncertainties in the methods that the scientists normally use while calculating the emissions of countries.
How are emissions measured?
International organisations try to measure accurate CO2 emissions using the energy data and established “emissions factors,” which detail the amount of carbon produced by the fuel being burned. These factors are usually averages based on assumption about the type of coal being used.
China regularly reveals only energy statistics but no statistics of carbon emissions. However, this new study is based on data found in over 4,000 coal mines in China and in lab tests of 602 coal samples. When the researchers compared emission factors based on their own tests, they found out they were about 40%lower than emission factors assumed by other organizations, including Intergovernmental Panel on Climate Change (IPCC).
The Harvard study
According to the new study, China emitted over the period 2000-2013 almost three gigatonnes of carbon less than estimated, which is around 10% of the global total on emissions in any one year.
Data on energy consumption and production at the provincial and national levels released by the Chinese government often conflict with each other and are revised frequently. The team of ecologist at the Harvard University analysed the data on energy production and on exports and imports of coal, oil and gas. They found out that China’s fossil fuel use was 1o% above than the government estimated, but that country’s overall emissions were lower. That is because China uses poor quality brown coal that contains less carbon than higher grade coal , which means that burning it produces less energy and less CO2.
“This is probably the best available estimate of emissions from coal burning in China, and that is an important contribution,” says for Nature Gregg Marland, a geologist at Appalachian State University in Boone, North Carolina, and a co-author of the study. But he adds that the revised figure is within the range of uncertainty reported in existing inventories.
Zhu Liu suggests that if China’s emissions would be reduced by 15%, the global total would be 5% less than it is now. But many specialists disagree.
“China’s emissions may be a bit less than we thought, but we know how much total CO2 there is in the atmosphere and it is monitored globally,” said Prof Dave Reay from the University of Edinburgh.
The team of researchers is still waiting for the Chinese government to release revised estimates of energy production over the past decade. Unlike some other specialists, Liu thinks that the estimates of his team are unlikely to change. The uncertainty in defining and measuring energy consumption still remains a big problem, as the researchers work with data gained from Chinese government and don’t know, what kind of assumption the government is actually making with them.