Four decades of full-scale nitrous oxide emission inventory in China.

China is among the top nitrous oxide (N 2 O)-emitting countries, but existing national inventories do not provide full-scale emissions including both natural and anthropogenic sources. We conducted a four-decade (1980 - 2020) of comprehensive quantification of Chinese N 2 O inventory using empirical emission factor method for anthropogenic sources and two up-to-date process-based models for natural sources. Total N 2 O emissions peaked at 2287.4 (1774.8 - 2799.9) Gg N 2 O yr -1 in 2018, and agriculture-developed regions, like the East, Northeast, and Central, were the top N 2 O-emitting regions. Agricultural N 2 O emissions have started to decrease after 2016 due to the decline of nitrogen fertilization applications, while, industrial and energetic sources have been dramatically increasing after 2005. N 2 O emissions from agriculture, industry, energy, and waste represented 49.3%, 26.4%, 17.5%, and 6.7% of the anthropogenic emissions in 2020, respectively, which revealed that it is imperative to prioritize N 2 O emission mitigation in agriculture, industry, and energy. Natural N 2 O sources, dominated by forests, have been steadily growing from 317.3 (290.3 - 344.1) Gg N 2 O yr -1 in 1980 to 376.2 (335.5 - 407.2) Gg N 2 O yr -1 in 2020. Our study produces a Full-scale Annual N 2 O dataset in China (FAN2020), providing emergent counting to refine the current national N 2 O inventories.