The role of rice cultivation in changes in atmospheric methane concentration and the Global Methane Pledge

• Published in: Global change biology 2023-05, Vol.29 (10), p.2776-2789
• Main Authors: Wang, Jinyang, Ciais, Philippe, Smith, Pete, Yan, Xiaoyuan, Kuzyakov, Yakov, Liu, Shuwei, Li, Tingting, Zou, Jianwen
• Format: Article
• Language: English
• Subjects: Agriculture - methods; Anthropogenic factors; Carbon footprint; Charcoal; climate‐smart practice; Cultivation; Emission inventories; Emissions; GHG inventory; global warming; Grain cultivation; Greenhouse Gases; Intergovernmental Panel on Climate Change; Methane; Methane - analysis; Mitigation; mitigation potential; Ocean, Atmosphere; Oryza; Rice; Rice fields; rice production; Sciences of the Universe; Soil; Straw; straw management
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/gcb.16631

Resumption of the increase in atmospheric methane (CH4) concentrations since 2007 is of global concern and may partly have resulted from emissions from rice cultivation. Estimates of CH4 emissions from rice fields and abatement potential are essential to assess the contribution of improved rice management in achieving the targets of the Global Methane Pledge agreed upon by over 100 countries at COP26. However, the contribution of CH4 emissions from rice fields to the resumed CH4 growth and the global abatement potential remains unclear. In this study, we estimated the global CH4 emissions from rice fields to be 27 ± 6 Tg CH4 year−1 in the recent decade (2008–2017) based on the 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. The trend of CH4 emissions from rice cultivation showed an increase followed by no significant change and then, a stabilization over 1990–2020. Consequently, the contribution of CH4 emissions from rice fields to the renewed increase in atmospheric CH4 concentrations since 2007 was minor. We summarized the existing low‐cost measures and showed that improved water and straw management could reduce one‐third of global CH4 emissions from rice fields. Straw returned as biochar could reduce CH4 emissions by 12 Tg CH4 year−1, equivalent to 10% of the total reduction of all anthropogenic emissions. We conclude that other sectors than rice cultivation must have contributed to the renewed increase in atmospheric CH4 concentrations, and that optimizing multiple mitigation measures in rice fields could contribute significantly to the abatement goal outlined in the Global Methane Pledge. Rice cultivation constitutes one of the important anthropogenic sources of methane emissions, yet its effect on the change of atmospheric methane concentration remains uncertain. Here we estimated global methane emissions from rice paddies using emission factors from the latest IPCC National Greenhouse Gas Guidelines, revealing a minor contribution of rice cultivation to the renewed increase in atmospheric methane concentrations since 2007. We further assessed and underscored the contribution of optimized measures to reduce methane emissions from rice fields to the Global Methane Pledge.