Assessing water-energy-food nexus efficiency for food security planning in China

Incorporating food security into the water-energy-food nexus, thereby establishing a water-energy-food-food security (WEF-FS) system, fosters multifaceted challenges of achieving food security. An extended dynamic series-loop data envelopment analysis model assesses WEF-FS efficiency by analyzing element interactions to identify inefficiencies and improvements. Kernel density estimation and standard deviation ellipse analysis explore spatiotemporal trends and provincial discrepancies in WEF-FS efficiency, guiding targeted policies. A two-way fixed effects model is constructed to investigate the impact of climate change on the WEF-FS efficiency. Findings include: (1) The proposed model efficiently handles interlinked activities within a unified framework. The average overall efficiency of China's WEF-FS system during 2011-2021 across 30 provinces was 0.77. Eastern regions excelled in water/energy subsystems, while western regions performed better in food/food security subsystems. (2) Provincial disparities in WEF-FS efficiency narrowed from 2013 to 2021, but issues related to food affordability, quality and safety remained critical challenges, particularly in the central region. Spatial variations aligned with a northeast-southwest axis, with the efficiency centroid in Henan shifting southeastward. (3) Climate change reduced WEF-FS efficiency via temperature and precipitation; Major Grain-Producing Regions buffer while Non-Major Grain-Producing Regions face tech-driven losses, with post-2016 reforms reversing impact. Regional characteristics must inform food security planning.