Estimation and spatiotemporal analysis of the carbon-emission efficiency of crop production in China

Low-carbon crop production can mitigate global warming. Carbon-emission efficiency of crop production, which reflects the gap between actual and ideal emissions under local conditions, has garnered considerable attention. Nevertheless, the designs, indicator systems, and approach selection of past studies have limitations. To overcome these limitations, we developed a theoretical model for the carbon-emission efficiency of crop production, estimated the efficiencies in 30 Chinese provinces between 2001 and 2019 using an extended slack-based measurement, investigated the spatiotemporal evolution of the efficiencies, and explained the regional disparities among the efficiencies using σ and spatial β-convergence tests. The main conclusions are as follows: (1) Carbon emissions from crop production in China increased from 198.8 to 246.0 Mt between 2001 and 2019. The emissions peaked at 262.8 Mt in 2015. The share of emissions from agricultural materials (33.9%), straw burning (26.6%), rice fields (26.5%), and soil management (13.0%) decreased in that order. (2) The national carbon-emission efficiency of crop production decreased from 0.802 to 0.729 between 2001 and 2015, reaching 0.868 in 2019, indicating that the gap between actual and ideal emissions expanded first and shrank later. The high-efficiency provinces were first clustered in southern China and gradually agglomerated in northeastern, eastern, and northwestern China. (3) The efficiency showed σ-convergence in the eastern and western regions. Conditional β-convergence appeared in all regions, and spatial interaction positively affected the convergence. The findings indicate that local solutions are necessary to enhance the efficiencies of the provinces based on their characteristics, while spatial spillover and convergence can be harnessed to narrow the gaps among the efficiencies of different provinces. • A framework for analyzing the carbon-emission efficiency of crop production is developed. • A global slack-based measurement with undesirable output is applied for efficiency estimation. • Crop carbon sequestration is introduced into the indicator system as a desirable output. • Carbon emissions from crop production in China peaked at 262.8 Mt in 2015. • Spatial interaction positively affected the convergence of the carbon-emission efficiency.