Investigation of China’s Anthropogenic Methane Emissions with Approaches, Potentials, Economic Cost, and Social Benefits of Reductions

Anthropogenic methane (CH4) emissions lead to global warming and air pollution. China has recently crafted a bottom-up approach to regulate its anthropogenic CH4 emissions; however, emissions during and after the COVID-19 lockdown have not been fully investigated using this updated method. In this study, we calculate provincial-level anthropogenic CH4 emissions in 2022 using this official bottom-up approach, explore feasible mitigation pathways, estimate reduction potentials, evaluate the economic cost of abatement, and assess the social benefits of reductions. The results show that China’s total anthropogenic CH4 emissions in 2022 were estimated to be 52.6 (49.8–55.6) Tg, approximately 47.6%, 39.5%, and 12.9% of which were from agricultural activities, energy utilization, and waste management, respectively; forest burning contributed 0.35 Gg. Using currently available approaches, China’s total yearly anthropogenic CH4 emissions can be reduced by around 33%, with an average reduction cost of USD 130.9 million per Tg of CH4. The social cost of CH4 was estimated to be USD 231.8 per metric ton, indicating that the negative impact of annual anthropogenic CH4 emissions was equal to 0.07% of China’s GDP. Despite the consistency between top-down inversions and our bottom-up inventory, we argue that the official guideline may underestimate China’s soil CH4 emissions due to changes in soil substrate availability, relative humidity, and the active layer of methanogens from global warming. Methods to improve current estimation accuracy are discussed. Owing to the slow international diffusion rate of methane-targeted abatement technologies, China needs to develop relevant technologies with independent intellectual property rights.