China is the world’s leading emitter of heat-trapping gases other than carbon dioxide. In 2018, such emissions were roughly 2.5Gt CO2e—about one-fifth of total Chinese emissions. (Data with respect to these other heat-trapping gases are not as good or current as data with respect to CO2, making precise estimates difficult.)
After CO2, the most significant heat-trapping gas is methane. Recent estimates of Chinese methane emissions range from just over 1 Gt to 1.75 Gt CO2e per year (roughly 10%–15% of China’s annual emissions of heat-trapping gases). A study released in early 2019 found significant increases in Chinese methane emissions in the past decade. Methane emissions in China come from coal mining, rice farming, waste disposal, livestock production and leakage during production and distribution of natural gas, among other sources.
China is a major producer and consumer of HFCs, a pollutant used in refrigeration and air-conditioning with a global warming potential more than 10,000 times greater per molecule than CO2. One recent study estimated HFC emissions of 113 Mt CO2e (1.0% of total emissions) in China in 2013. The Chinese government’s Second Biennial Update Report to the UNFCCC estimated HFC emissions of 214 Mt CO2e (1.9% of total emissions) in China in 2014.
In May 2019, Nature published a study that found evidence of illegal production of CFCs in Shandong and Hebei. (CFCs are a banned ozone-depleting chemical with a global warming potential more than 4,600 times greater per molecule than CO2.) In a statement, the Chinese Ministry of Ecology and Environment raised questions about the study findings but stressed its determination and commitment to stopping any illegal CFC production.
 J. Olivier and J. Peters, Trends in Global CO2 and Total Greenhouse Gas Emissions: 2018 Report (PBL Netherlands Environmental Assessment Agency, December 12, 2018) at pp.38, 42 (2.6 out of 13.5 Gt CO2e total in 2017); People’s Republic of China, Second Biennial Update Report on Climate Change (December 2018) at p.16 (2.0 out of 12.3 Gt CO2e total in 2014); Jiang Lin et al., “Non-CO2 Mitigation Pathways for China: Preliminary Results,” China Energy Group, Lawrence Berkeley National Laboratory (June 2018).
 J. Olivier and J. Peters, Trends in Global CO2 and Total Greenhouse Gas Emissions: 2018 Report (PBL Netherlands Environmental Assessment Agency, December 12, 2018) at p.43 (1,740 Gt CO2e in 2017); People’s Republic of China, Second Biennial Update Report on Climate Change (December 2018) at p.16 (1.16 Gt CO2e in 2014, using a 100-year GWP of 21. If the same data were reported using the 100-year GWP of 28 adopted in the IPCC’s Fifth Assessment Report, the value would 1.55 Gt CO2e in 2014); World Bank Data, “Table 3.9: Trends in Greenhouse Gas Emissions” (1.75 Gt CO2e in 2012); Scot Miller et al., “China’s coal mine methane regulations have not curbed growing emissions,” Nature Communications (January 29, 2019).
 Second Biennial Update Report on Climate Change (December 2018) at p.16.
 Xuekun Fang et al., “Hydrofluorocarbon (HFC) Emissions in China: An Inventory for 2005−2013 and Projections to 2050,” Environmental Science & Technology (2016) at 2030 at p. 2030; People’s Republic of China, Second Biennial Update Report on Climate Change (December 2018) at p.16.
 M. Rigby et al., “Increase in CFC-11 emissions from eastern China based on atmospheric observations,” Nature (May 22, 2019); James Griffiths, “Spike in banned ozone-eating CFC gases linked to China in new research,” CNN.com (May 25, 2019).