中国食物系统温室气体排放与吸收研究进展

Research progress of greenhouse gas emissions and sequestration of the Chinese food system

我国食物系统温室气体核算研究相对缺乏,相关研究多散见于农业和畜牧业部门,难以满足碳达峰、碳中和背景下减排和固碳的需求。本文提出了一个涵盖土地利用、土地利用变化和林业(LULUCF)、农业生产、产后食物供应部门的食物系统温室气体排放与吸收的核算框架;通过文献综述、温室气体排放量收集和排放参数推算,剖析了各环节排放核算方法的差异和排放参数的不确定性。结果表明,粪尿和秸秆还田、农药和农膜生产、食物加工、批发和零售以及草地的碳排放(或吸收)参数的变异系数(CVs)在35%以上。未来食物系统温室气体核算研究需:1)在农业生产部门,细化农业活动排放参数,整合基于终端能源消费和农业生产过程的温室气体核算方法,并加强农业投入品能耗研究;2)在LULUCF部门,建立适用于全球变化研究的土地利用分类体系,识别食物系统相关的土地利用过程,将实地调查核算法和基于过程模型的核算方法相互校验;3)在产后食物供应部门,明确各环节排放的核算范围,有针对性地选择投入产出-生命周期评价法(EIO-LCA)、基于过程的生命周期评价法(PLCA)与终端能源消费核算法等。本文可进一步为食物系统温室气体减排提供科学依据。

Studies on the country’s food system and greenhouse gas(GHG)accounting are still lacking in China.Most of previous studies have focused on crop and livestock production,which are hard to meet the demands of both GHG reduction and sequestration,against the backdrop of the“carbon peak and neutrality”policy.In this study,we proposed a food system GHG accounting framework that covers land use,land use change,and forests(LULUCF);agricultural production;and post-production food supply sectors.Through literatures review,collecting emission data,and reverse-calculating emission factors,we analyzed the differences in accounting methods and the uncertainties of emission parameters for various GHG emission(or sequestration)segments in the Chinese food system.Results showed that the coefficients of variables(CVs)of the emission or storage parameters of manure and crop straw application,pesticides and film production,food processing,food retail and wholesale,and grassland sinks were above 35%.Our suggestions for future studies are as follows:1)in the agricultural production sector:refine emission factors of agricultural activities,harmonize different energy use accounting methods(e.g.,final energy consumption accounting and process-based accounting methods),and reinforce research on energy consumption of agricultural input manufacturing enterprises;2)in the LULUCF sector:establish the land use classification dedicated to global change research,identify the land use processes associated with the food system,and crosscheck the field measure-based accounting method and the process-based accounting method;3)in the post-production food supply sector:clarify the accounting scopes of each stage and select the environmental input-output life cycle assessment method,the processbased life cycle assessment method,or the final energy consumption accounting method.This study could further provide scientific basis for GHG reduction in food systems.