Methane Emissions from Landfills Differentially Underestimated Worldwide

Associate Professor 

School of Civil and Environmental Engineering

Nanyang Technological University, Singapore 

Landfill methane (CH4) emissions account for ~10% of all anthropogenic CH4 emissions globally, amounting to ~50 Tg per year. The current emission inventories utilize a first-order decay model as recommended by the Intergovernmental Panel on Climate Change. In contrast to recent top-down atmospheric inversion results, the mainstream bottom-up inventories exhibit significant biases, largely stemming from the inaccuracy in the a priori decay constant (k), an essential rate-controlling parameter in the model. We improve the k estimation method by incorporating compositional- and environmental-specific corrections, which are readily integrated into the Intergovernmental Panel on Climate Change’s model. The accuracy of CH4 emission predictions is significantly improved by using the corrected k values, which are benchmarked against the atmospheric inversion results. We extend the emission estimations to landfills worldwide and reveal up to 200% underestimations for individual landfills. Our findings highlight the importance of prioritizing landfill CH4 emission monitoring and reduction as one of the most cost-effective mitigation options to achieve current climate goals.

Xunchang Fei is an Associate Professor in the School of Civil and Environmental Engineering at Nanyang Technological University in Singapore. He earned his PhD from the University of Michigan, Ann Arbor, and his bachelor’s degree from Tongji University. Fei is the recipient of numerous prestigious awards, including the 2023 Environmental Geotechnics Prize from the UK’s Institution of Civil Engineers and the 2021 Arthur Casagrande Professional Development Award from the American Society of Civil Engineers.