Methane and nitrous oxide budget for Chinese natural terrestrial ecosystems

Abstract China's natural terrestrial ecosystems (NTEs) are significant sources and sinks of methane (CH₄) and nitrous oxide (N₂O), two potent non-CO₂ greenhouse gases. This article reviews CH₄ and N₂O inventories for China's NTEs, derived from site-specific extrapolation and models, to elucidate their spatiotemporal emission patterns. Despite progress, significant gaps remain, including large uncertainties due to model limitations and inconsistent driving data, insufficient assessments of integrated global warming potential (GWP) under long-term land-use and climate changes, the lack of freshwater emission inventories, and the need for more observations, refined prior sectoral contributions, and novel methods like isotopic signature applications in machine learning and inversion techniques. This review offers a new perspective by compiling a new CH₄ and N₂O inventory and evaluating their integrated GWP for 1980–2020, developed using multi-model approaches to assess climate and land-use impacts. The review underscores the importance of CH₄ and N₂O sources and sinks, offering recommendations to enhance carbon sequestration and reduce emissions.