Growing Contribution to Radiative Forcing from China's On-Farm Nitrous Oxide Emissions Requires More Attention

Abstract

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 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 have 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.

Keywords: agriculture, biogenic methane, climate change, net zero