Exploring the spatiotemporal evolution and coordination of agricultural green efficiency and food security in China using ESTDA and CCD models

Improving agricultural green efficiency (AGE) is related not only to food security but also to health and the environment. It is the key to achieving sustainable development goals (SDGs). Achieving the coordinated development of AGE and food security is an important starting point to achieving the sustainable development of agriculture and promote national food security. However, at present, little analysis and research have been conducted on the coordination of AGE and food security. In this study, using the SBM model based on undesirable output and the food gap rate (FGR) to measure AGE and food security, respectively, an exploratory spatio-temporal data analysis (ESTDA) model, panel grey correlation model and coupling coordination degree (CCD) model were used to measure the spatiotemporal evolution characteristics, as well as their degree of correlation and coordination. The results show that (1) China's AGE showed downward and upward trends in 2000–2002 and 2003–2019, respectively. The high and low values of food security risks were relatively scattered, and no obvious spatial agglomeration was found. The risk level of food security decreased significantly at the end of the study period. (2) The spatial structure of AGE in central, western and northeast China is more stable than that in eastern and northwest China; Shandong and Hubei have strong temporal and spatial dependence on food security risks, which are vulnerable to external influences and fluctuate drastically. The food security risks of Heilongjiang, Inner Mongolia, Eastern Shanghai, Zhejiang, Fujian, Guangdong and Tibet in the northeast are relatively stable in the direction of spatial dependence. (3) The local spatial structure of China's AGE is unstable, while the local spatial structure of FGR is relatively stable, and change in the relative position is difficult. From the perspective of transfer subjectivity or independence, the local spatial structure of China's AGE and FGR is affected by neighboring regions, but local factors still have a great impact. (4) Overall, the contribution of AGE to food security in the northeast and eastern regions is significant, and the overall degree of coupling and coordination of AGE and the food security coefficient have gradually improved. However, the degree of coupling and coordination in southwest China and most of central China has remained in a state of serious imbalance.