Co-benefits of Water-Saving Irrigation for Mitigating CH 4 Emissions from Rice Cultivation in China: Insights from the Past Seven Decades

Methane (CH₄) emissions from rice cultivation in China have long been a significant contributor to global greenhouse gas budgets, yet their long-term trends have remained uncertain due to a lack of comprehensive evaluation. Here, we develop a detailed CH₄ emission inventory for rice cultivation in China from 1949 to 2021 based on process-based modeling and machine learning techniques with multiple integrated databases and field measurements. Emissions peaked at 12.3 ± 5.5 Tg year^-1 in 1976, declined by 42% over the following two decades, and stabilized at 5.8 ± 2.6 Tg after 2003. Pre-1980s, emission change (1.5% year^-1) was closely tied to changes in rice yield per capita (1.8% year^-1), cultivated area (1.0% year^-1), and populations (2.0% year^-1). Afterward, the widespread adoption of water-saving irrigation and improved production practices decoupled CH₄ emissions from socioeconomic development, leading to a substantial reduction in emissions by approximately half, particularly in East, South, and Central China. Since the 2000s, the influences of most factors have plateaued, highlighting the need for innovative strategies to meet increasingly stringent climate targets. Water-saving irrigation has already delivered notable benefits and, combined with innovative cultivation practices, holds potential for further emission reductions in the future.