双视角下中国畜牧业甲烷排放的温室效应

Dual-Perspective Analysis of the Warming Effect of the Methane Emissions from Animal Husbandry in China

准确评价甲烷(CH_(4))的温室效应是制定有效减排路径的基础.首次采用新提出的、针对短寿命气候污染物(SLCP)设计的气候指标GWP-star(GWP^(*))对中国畜牧业CH_(4)排放的温室效应进行定量评价,并与常用的GWP指标评价结果相比较.结果表明,GWP的视角下我国畜牧业CH_(4)排放的温室效应持续增加.因此,畜牧业实现碳中和需要完全消除排放,或以增加碳汇、增加资源化利用的形式抵消每年稳定的CH_(4)排放.在GWP^(*)的视角下,2015~2019年间畜牧业CH_(4)排放的温室效应较20年前有所减少,降低的热量相当于从20年前的大气中减少2.1×10^(4)万t CO_(2)的热量,畜牧业只需每年有效降低0.3%的CH4排放则可在短期内实现自身碳中和.在中国畜牧业持续采取有效减排措施的情况下,采用GWP^(*)的标准制定减排目标比用GWP制定的减排目标更早达到,但选择GWP还是GWP*需要综合考虑评价的目的、评价的时间尺度和实际可操作性.

Accurate quantitative evaluation of the greenhouse effects of methane(CH_(4))is the foundation for developing effective mitigation strategies.This study was the first to quantitatively evaluate the warming effects of the CH_(4) emissions from animal husbandry in China using the recently proposed climate metric GWP-star(GWP^(*)),which is designed for short-lived climate pollutants(SLCP),and to compare the results with the commonly used climate metric global warming potential(GWP).The results showed:CH_(4)emissions from animal husbandry in China decreased from 957.0×10^(5) t in 2000 to 764.0×10^(5) t.The GWP results showed that the greenhouse effect of CH_(4) emissions from animal husbandry in China was increasing between 2015 and 2019,and the GWP^(*)results showed that it decreased compared to that 20 years ago.The amount of reduction was equivalent to removing the warming of 2.1×10^(8) t of carbon dioxide.Under the GWP evaluation system,achieving carbon neutrality in the livestock industry in China requires eliminating or offsetting stable annual CH4 emissions from increased carbon sinks.Instead,under the GWP^(*)evaluation system,China's livestock industry could achieve its carbon neutrality in the short term by effectively reducing CH_(4) emissions by only 0.3% per year.In the case that the livestock industry in China continues to take effective emission reduction measures,the reduction target under the GWP^(*)metric will be reached earlier than that under GWP.Still,the choice of GWP or GWP^(*)requires careful consideration of the objectives of evaluation,the time scale of assessment,and practical operability.