中国农业系统近40年温室气体排放核算

基于排放因子法构建了包含种植业和牲畜养殖业的农业系统温室气体排放核算体系，系统核算了1980-2020年我国全国尺度上的农业系统温室气体排放总量和变化趋势，并在区县级尺度下对1980、2000、2011年的中国农业系统的温室气体排放量进行核算，对比不同阶段农业系统温室气体排放变化的时空异质性规律。研究发现：1980-2020年我国农业系统温室气体排放量呈波动增长趋势，增长了近46%。CH₄是农业系统排放贡献最大的温室气体，占总排放量的47.33%。我国农业系统温室气体排放与不同地区农业生产方式有关，CH₄排放量高的地区主要位于我国主要水稻产区以及旱地作物产区。CO₂排放量高的地区主要位于东北、西北等地区以及华东地区。N₂O排放量较高地区主要位于西北的主要畜牧养殖地区，以及我国农业经济发展水平高的中南部地区。研究有助于揭示我国农业温室气体排放的动态特征，现状规律，以及空间差异性特征，从农业减排角度为实现双碳目标提供科学参考。

Accounting of greenhouse gas emissions in the Chinese agricultural system from 1980 to 2020

Human activities are one of the main reasons for increasing the concentration of greenhouse gases in the atmosphere and causing the natural greenhouse effect. Among them, agricultural production activity is one of the important sources of greenhouse gas emissions. Based on the emission factor method, this paper constructs a greenhouse gas emission accounting system of the agriculture including planting industry and livestock breeding industry. The study systematically calculated the total greenhouse gas emission trend of Chinese agricultural system from 1980 to 2020. More specifically, it calculated the greenhouse gas emission of Chinese agricultural system in 1980, 2000 and 2011 at the district and county level. Moreover, the temporal and spatial heterogeneity of greenhouse gas emissions in the agricultural systems at different stages was compared. It is found that the greenhouse gas emissions of the Chinese agricultural system showed a fluctuating growth trend from 1980 to 2020, with an increase of nearly 46%. CH₄, CO₂ and N₂O are the three major greenhouse gases emitted by the agricultural system. CH₄ is the greenhouse gas with the largest contribution to the emission of the agricultural system, which accounts for 47.33% of the total emission. The proportion of CO₂ in the greenhouse gas emissions from the agricultural system tends to increase. Changes in the share of N₂O in greenhouse gas emissions from agricultural systems are slight. From the perspective of the source of greenhouse gases in the agricultural systems, CH₄ emission mainly comes from rice field planting and crop straw combustion (56.20%). CO₂ emission mainly comes from the crop straw combustion (67.91%), and N₂O emission mainly comes from livestock breeding (50.89%) and nitrogen fertilizer application (31.05%). From the perspective of spatial distribution structure, greenhouse gas emissions from the Chinese agricultural system are related to agricultural production modes in different regions. The areas with high CH₄ emissions are mainly located in China''s main rice-producing areas and dryland crop-producing areas. The areas with high CO₂ emissions are mainly located in the northeast, northwest and other regions and east China. The areas with high N₂O emissions are mainly located in the major livestock breeding areas in the northwest, and in the central and southern areas where the agricultural economy has a high level of development. This study helps to reveal the dynamic characteristics, current status, and spatial differences of China''s agricultural greenhouse gas emissions, and provides a scientific reference for the realization of the dual-carbon goal from the perspective of agricultural emission reduction.