China's greenhouse gas budget during 2000-2023.

Abstract

National greenhouse gas (GHG) budget, including CO₂, CH₄ and N₂O has increasingly become a topic of concern in international climate governance. China is paying increasing attention to reducing GHG emissions and increasing land sinks to effectively mitigate climate change. Accurate estimates of GHG fluxes are crucial for monitoring progress toward mitigating GHG emissions in China. This study used comprehensive methods, including emission factor methods, process-based models, atmospheric inversions, and data-driven models, to estimate the long-term trends of GHG sources and sinks from all anthropogenic and natural sectors in China's mainland during 2000-2023, and produced an up-to-date China GHG Budget dataset (CNGHG). The total gross emissions of the three GHGs show a 3-fold increase from 5.0 (95% CI: 4.9-5.1) Gt CO₂-eq yr^-1 (in 2000) to 14.3 (95% CI: 13.8-14.8) Gt CO₂-eq yr^-1 (in 2023). CO₂ emissions represented 81.8% of the GHG emissions in 2023, while 12.7% and 5.5% were for CH₄ and N₂O, respectively. As the largest CO₂ source, the energy sector contributed 87.4% CO₂ emissions. In contrast, the agriculture, forestry and other land use sector was the largest sector of CH₄ and N₂O, representing 50.1% and 66.3% emissions, respectively. Moreover, China's terrestrial ecosystems serve as a net CO₂ sink (1.0 Gt CO₂ yr^-1, 95% CI: 0.2-1.9 Gt CO₂ yr^-1) during 2012 to 2021, equivalent to an average of 14.3% of fossil CO₂ emissions. Our GHG emission estimates showed a general consistency with national GHG inventories, with gridded and sector-specific estimates of GHG fluxes over China, providing the basis for curtailing GHG emissions for each region and sector.