Decoupling of Carbon Footprint from Rice Yield Intensification in China: Spatiotemporal Evidence from an Extended National Life Cycle Assessment (2005-2022)

Contemporary rice-based food systems face the dual challenge of ensuring food security while mitigating climate change impacts. Understanding the long-term dynamics between rice productivity and its carbon footprint (CF) is crucial for devising sustainable intensification pathways. This study examines the relationship between CF and yield intensification in China’s rice production, the world's largest, from 2005 to 2022, employing an expanded, nationwide "cradle-to-sale" life cycle assessment. The results reveal a distinct decoupling between yield growth and CF after 2015, characterized by a total CF decreasing by 4.9 % (from 217 to 206 Tg CO 2 e) while rice output increased by 13.1 %. This observed decoupling was accompanied by macro-level indicators of improved resource efficiency across the rice system, including a 21.0% reduction in synthetic fertilizer use, a 5.0% improvement in nitrogen-use efficiency, and a 38.5% decline in water use per unit agricultural GDP. Methane from paddy fields remained the largest emission source (48.2–81.4% of total CF), with late-season Indica rice exhibiting the highest carbon intensity (2,911.8 g CO 2 e kg -1 ). By extending the system boundary to retail, this study captured post-harvest emissions (1.2–3.3 % of CF)—a previously underestimated segment. Our findings provide robust evidence that yield-CF decoupling, achieved in China through integrated efficiency gains, demonstrates that decoupling yield growth from CF via systematic resource efficiency improvement is technically achievable. This pathway hinges on the targeted integration of key technologies—including low-methane varieties, biochar, and precision irrigation—to sustain low-carbon intensification. This analysis, while subject to the limitations of model-based accounting using standardized emission factors and excluding soil organic carbon dynamics, demonstrates that carbon-efficient intensification in rice systems is an achievable reality, offering critical insights for sustainable agri-food transitions.