Research progress of rural regional system carbon effect from the perspective of Dual Carbon

As an important constituent of national land space, rural carbon emission reduction and sink increase are crucial for achieving the Dual Carbon goal. The rural carbon effect involves carbon emissions and sinks, and the estimation results vary widely between studies, with no consistent conclusions owing to different accounting scopes, methods, indicators, and other factors. First, this study constructed a rural carbon cycle system based on the human-earth system theory. Second, a meta-analysis was used to integrate previous quantitative studies on rural carbon effects and estimate the overall effect size. Finally, factors influencing the rural carbon effect were summarized and suggestions for rural governance were proposed. This study aims to provide a reference for a quantitative understanding of the carbon effect of the rural regional system. The results show that 1) carbon emissions from agricultural production account for approximately 20% of the total rural carbon emissions, while carbon emissions from agriculture account for 10.37% of the total average annual carbon emissions in China, with approximately 30% originating from crop cultivation and approximately 70% from livestock farming. Fertilizer application accounts for 58.23% of crop cultivation carbon emissions, whereas 67.40% of livestock farming carbon emissions originats from animal enteric fermentation. Applying 1 t less nitrogen fertilizer can reduce carbon emissions by 9.526 t CO₂, which is equivalent to an electricity saving of 9555 kWh and can be used to produce 27 t of rice. Improving nitrogen use efficiency by 1% conserves 375 000 t of raw coal, and reducing the number of cattle and sheep by 1% can reduce carbon emissions from livestock farming by 4.48%. 2) Approximately 80% of rural carbon emissions originates from residential living, which has a higher carbon reduction potential than agricultural production. Nearly 65% of residential living carbon emissions are indirectly generated, with housing construction accounting for 45.32%. Coal burning contributes to approximately 80% of direct carbon emissions, and replacing coal consumption by 1% with biomass energy can reduce residential living carbon emissions by 36 248 000 t CO₂, corresponding to an electricity saving of 3636 kWh. Additionally, in the process of urbanization, the cost of eliminating 91.54 million tons of increased carbon emissions from a 1% rural-to-urban population shift would account for at least 6.1 billion Yuan. 3) Between 1990 and 2022, the net carbon sink of rural China assumed a growth trend, and the average annual rural net carbon sink was 500 258 200 t·a⁻¹, equivalent to saving 736 million tons of standard coal and 12.3 billion Yuan in carbon sequestration costs. Net rural carbon emissions in China increased from 1990 to 2022; however, the carbon sequestration potential of farmland protection cultivation has not yet been fully exploited. Increasing the rural environmental governance level by 2% using emerging technologies can reduce the carbon emissions from rural agricultural production by 2%. Therefore, it is proposed to increase investment in the research and development of new long-acting fertilizers, promote an ecological agriculture model that integrates planting and breeding, enhance efforts to publicize the low-carbon living concept, and advance the construction of rural digital energy systems to fully utilize the potential for rural emission reduction and sink increase.