Net exchanges of CO₂, CH₄, and N₂O between China's terrestrial ecosystems and the atmosphere and their contributions to global climate warming

China's terrestrial ecosystems have been recognized as an atmospheric CO₂ sink_; however, it is uncertain whether this sink can alleviate global warming given the fluxes of CH₄ and N₂O. In this study, we used a process-based ecosystem model driven by multiple environmental factors to examine the net warming potential resulting from net exchanges of CO₂, CH₄, and N₂O between China's terrestrial ecosystems and the atmosphere during 1961-2005. In the past 45 years, China's terrestrial ecosystems were found to sequestrate CO₂ at a rate of 179.3 Tg C yr^-1 with a 95% confidence range of (62.0 Tg C yr^-1, 264.9 Tg C yr^-1) while emitting CH₄ and N₂O at rates of 8.3 Tg C yr^-1 with a 95% confidence range of (3.3 Tg C yr^-1, 12.4 Tg C yr^-1) and 0.6 Tg N yr ^-1 with a 95% confidence range of (0.2 Tg N yr^-1, 1.1 Tg N yr^-1), respectively. When translated into global warming potential, it is highly possible that China's terrestrial ecosystems mitigated global climate warming at a rate of 96.9 Tg CO₂eq yr^-1 (1 Tg = 10¹² g), substantially varying from a source of 766.8 Tg CO ₂eq yr^-1 in 1997 to a sink of 705.2 Tg CO₂eq yr^-1 in 2002. The southeast and northeast of China slightly contributed to global climate warming; while the northwest, north, and southwest of China imposed cooling effects on the climate system. Paddy land, followed by natural wetland and dry cropland, was the largest contributor to national warming potential; forest, followed by woodland and grassland, played the most significant role in alleviating climate warming. Our simulated results indicate that CH₄ and N₂O emissions offset approximately 84.8% of terrestrial CO₂ sink in China during 1961-2005. This study suggests that the relieving effects of China's terrestrial ecosystems on climate warming through sequestering CO₂ might be gradually offset by increasing N₂O emission, in combination with CH₄ emission.