China's CO2 emissions overestimated

New research shows burning of low-grade coal produced lower amounts of carbon

New research published in the journal Nature shows that coal burned in China actually produced 40 percent less carbon than had previously been assumed.

The study, based on an examination of more than 600 types of coal from 4,200 coal mines in 2012 in China, drew the conclusion that the average Chinese coal burned has produced 40 percent less carbon than figures used by the United Nations' Intergovernmental Panel on Climate Change.

The research concluded that from 2000-2013 China produced 2.9 gigatons less carbon than previous estimates of its cumulative emissions.

The revised estimates of China's carbon emissions were produced by an international team of researchers, led by Harvard University, the University of East Anglia, the Chinese Academy of Sciences and Tsinghua University, in collaboration with 15 other international research institutions.

Guan Dabo, a professor of climate change economics at the University of East Anglia, who is one of the authors of the paper, says this research allows China to realize a more accurate estimate of its actual carbon emissions so future actions and policies could more appropriately solve climate change issues.

Guan says although carbon emissions from coal and other sources have been a topic of fierce academic debate and interest over the years, the large amount of capital and human resources required to conduct thorough research has been a burden, China is encouragingly moving to invest in accurate emissions research.

The paper, which Guan co-authored with other researchers both inside China and internationally, is a part of the work of China's strategic priority research program Climate Change: Carbon Budget and Relevant Issues at the Chinese Academy of Sciences.

This research program hopes to have a more accurate understanding of China's true emissions quantity so the country will have its own reliable estimates at international climate change negotiation tables.

The research by Guan and his colleagues discovered that because China's coal quality is worse than the international norm, its emissions and energy produced is less than international standards.

Put into context, and taking into account other fuels used, China's real CO2 emissions level overall is 14 percent less than the emissions calculated by IPCC in 2013. However, the revised number still puts China as the world's largest emitter of carbon emissions, about 1.5 times that of US emissions in 2013.

IPCC figures are based on international assessments provided by independent bodies, including those by the Carbon Dioxide Information Analysis Centre in the US and the Emissions Database for Global Atmospheric Research in the European Union, which are the official data sources for the IPCC Fifth Assessment Report in 2013.

Guan says the new research is not an attempt to allow China to shed its responsibility to reduce carbon emissions, but purely an academic study to put the truth of China's emissions into the public domain, and make it more accessible to other researchers.

In addition, he says China's low quality coal also produces less energy than international standards, so in the long term China still needs to work hard to move away from coal as a form of energy and increase renewable energy consumption.

Guan says it is encouraging to see China becoming so active in carbon emissions assessment rather than relying on international estimates, so that China can have more focused strategy to reduce carbon emissions and also better present its case at international negotiations.

He says one key example of China's investment in such assessments is the Multi-resolution Emission Inventory for China project, which is a database of carbon dioxide emissions statistics, led by Tsinghua University.

The model can be used to support climate models at different spatial resolution and time scale. It also used satellite data to evaluate and validate the emission inventories. Recently it demonstrated that Ozone Monitoring Instrument satellite observations have the capability to monitor emissions from large point sources in China.

"This project plays a great role in helping the academic world do more encompassing research about China's carbon emissions," Guan says.

Dave Reay, a professor of carbon management at the University of Edinburgh, says this new research is credible from an academic perspective.

"It's an impressive piece of research. This study shows just how important assumptions about how much carbon is emitted for any given activity are," Reay says.

"Most nations still rely heavily on 'default' emission factors from the IPCC for their annual emissions accounts. Inevitably these broad averages can mean national estimates end up being under or overestimates of the real emissions. By developing updated, location-specific emission factors, the uncertainties can be reduced and governments can better plan their climate change mitigation efforts," Reay says.

He says the research highlights the importance of investing in improved emissions measurement and monitoring, especially in developing nations. "If we can improve emissions accounting for all nations then we can better tackle these emissions."

Reay has also reiterated Guan's point that the new study should not be an opportunity for China to weaken its emissions reduction strategy.

"China remains the largest CO2 emitter in the world, so there is still a lot of work to do. Certainly, this reduced estimate of emissions from China does not mean that current and planned climate change mitigation efforts should be weakened.

" If we are to avoid the most dangerous impacts of anthropogenic climate change, then global emissions need to halve by 2050, and that will require deep and sustained emissions cuts for all the big emitters, including China," Reay says.

Michael Rea, chief operating officer at the Carbon Trust, a London-based nonprofit organization, says the new research does not change the core issues that need to be addressed in Paris.

"Based on current global trajectories, we are well off track for meeting the international ambition of limiting global warming to within 2 C," Rea says.

"China has already demonstrated clear leadership in making progress to decarbonize its economy through its 12th Five-Year Plan (2011-15), and the 13th currently under preparation. From a Carbon Trust perspective we believe it is critical that China continue to show ambition and demonstrate action as China's decisions really matter at a global level," Rea says.

Rea adds that from a strategic perspective, China would benefit greatly from moving away from coal as a source of fuel.

"Coal has been instrumental in driving economic growth at a scale that has rapidly lifted much of China's population out of poverty; however, this has come at a cost that can be seen in the deteriorating air quality in many Chinese cities," Rea says.

"There is an incredibly strong business case for China to continue to invest in energy efficiency and low carbon technologies at scale to create a clean, low carbon energy system, that not only addresses climate change, but will continue to drive material growth and prosperity in China," he says.

Meanwhile, Guan says although his group's research is the most comprehensive study of China's coal emission to date, there is still room for improvement in the future, and he acknowledges there are limitations to the research.

"In order to have more comprehensive and accurate understanding of China's emissions, follow-up research projects can be done, because China's coal consumption composition is constantly changing and it is important to have continuous research to reflect more up-to-date information."

cecily.liu@chinadaily.com.cn