Assessing uncertainties and discrepancies in agricultural greenhouse gas emissions estimation in China: A comprehensive review

Due to diverse methodologies and data sources, China's agricultural greenhouse gas (AGHG) emissions estimates demonstrate significant variability. A quantitative review was conducted on the prevalence and application of various accounting methods to clarify and reduce discrepancies in AGHG emissions estimation techniques and data application. Using a systematic PRISMA framework, 4257 global studies were analyzed, yielding 681 AGHG emission records from 57 papers and four databases explicitly focusing on China. The analysis reveals similarities between Chinese and global research trends, concentrating on environmental science, soil science, and ecology. Furthermore, the spatial scale and methodologies for China's AGHG emissions estimation are relatively centralized, with 53.21% of the research targeting site-specific scales and 74.12% employing inventory methods and statistical analysis. Regarding the variability in China's AGHG emission estimates between 1996 and 2020, estimates ranged from 100 to 800 Mt. C-eq, with the highest estimate being approximately 25 times the minimum within the same period. Notably, compared to the average AGHG emissions calculated for 1996-2020 (284.7 to 548.7 Mt. C-eq), estimates from the FAO and Our World in Data were higher by an average of 114.7% and 81.9%, respectively. These findings underscore the need to enhance remote sensing and survey data application and standardize AGHG emissions estimation methodologies and boundaries to ensure comparability across various accounting methods and datasets. This study conducts a quantitative analysis to identify and bridge the gaps in AGHG emission evaluation techniques, laying the groundwork for establishing a more comprehensive and resilient framework for AGHG emissions assessments.