Growing contribution to radiative forcing from China's on-farm nitrous oxide emissions requires more attention

Agricultural systems are important emission sources of non-CO₂ greenhouse gases (GHGs), including the relatively short-lived GHG methane (CH₄). As a pivotal emitter, China's CH₄ emissions have received wide attention. For the first time, this study applied an indicator of radiative forcing-based climate footprint (RFCF) to compare the climate impacts of China's on-farm non-CO₂ GHG emissions including CH₄ and nitrous oxide (N₂O). We found that, with short atmospheric lifetime, CH₄'s contribution to RFCF has plateaued in 2011 at 3.37 mW m^-2 and achieved the goal of net zero increase to radiative forcing (RF) in 2017. However, the long-lived N₂O emissions form an increasingly important proportion of the total RFCF at China's farm gate over time. The contribution from CH₄ emissions to the total global on-farm RFCF experienced a downward trend, while that from N₂O emissions has been trending upward during 1961-2021. It indicates the need of more attention on the long-lived climate forcer N₂O in China. The RFCF indicator informs about whether progress is being made toward RF stabilization. It is recommended to widely apply the RFCF approach to re-examine and inform climate actions in China's agricultural systems as well as sectors with substantial biogenic CH₄ emissions.