Rising disparities in grain self-sufficiency across China: Provincial divergence amidst overall national improvement

Food security is essential to the sustainability of any society. China's food security not only matters to itself, but also to the rest of the world. However, it remains unclear whether China, especially its internal provinces, has achieved or will achieve grain self-sufficiency – a central component of its national food security. This study assessed China's grain self-sufficiency ratio (GSSR) from 2000 to 2030 by quantifying grain production and demand at national, regional, and provincial levels. Combining machine learning and modeling methods, the impacts of climate change and geospatial heterogeneity in biophysical and demographic conditions on China's grain self-sufficiency were assessed. The results show that from 2000 to 2020, China's grain production increased faster than its demand, with GSSR exceeding 95 % after 2012. This trend is projected to continue, reaching 118 % by 2030. However, regional disparities in grain production will widen, with China's grain self-sufficiency becoming highly dependent on the northeast and a few key provinces. This divergence is driven by rising yields in major grain-producing provinces, where population decline and aging reduce consumption. In contrast, eastern provinces face growing demand due to population increases, while local production continues to fall. Farmland loss and climate change further increase future food security uncertainty. While farmland protection is necessary but not sufficient. Strengthening agricultural technology and implementing climate adaptation strategies are also necessary. This study offered a comprehensive, multi-scale evaluation and prediction of China's GSSR, incorporating future climate, land-use changes, and population dynamics. The findings highlighted growing regional disparities as a key uncertainty in China's future food security.