Zhang Zhen, Poulter Benjamin, Knox Sara, Stavert Ann, McNicol Gavin, Fluet-Chouinard Etienne, Feinberg Aryeh, Zhao Yuanhong, Bousquet Philippe, Canadell Josep G, Ganesan Anita, Hugelius Gustaf, Hurtt George, Jackson Robert B, Patra Prabir K, Saunois Marielle, Höglund-Isaksson Lena, Huang Chunlin, Chatterjee Abhishek, Li Xin
Department of Geographical Sciences, University of Maryland, College Park, MD 20742, USA.
Biospheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
Natl Sci Rev. 2021 Nov 11;9(5):nwab200. doi: 10.1093/nsr/nwab200. eCollection 2022 May.
Atmospheric methane (CH) concentrations have shown a puzzling resumption in growth since 2007 following a period of stabilization from 2000 to 2006. Multiple hypotheses have been proposed to explain the temporal variations in CH growth, and attribute the rise of atmospheric CH either to increases in emissions from fossil fuel activities, agriculture and natural wetlands, or to a decrease in the atmospheric chemical sink. Here, we use a comprehensive ensemble of CH source estimates and isotopic δC-CH source signature data to show that the resumption of CH growth is most likely due to increased anthropogenic emissions. Our emission scenarios that have the fewest biases with respect to isotopic composition suggest that the agriculture, landfill and waste sectors were responsible for 53 ± 13% of the renewed growth over the period 2007-2017 compared to 2000-2006; industrial fossil fuel sources explained an additional 34 ± 24%, and wetland sources contributed the least at 13 ± 9%. The hypothesis that a large increase in emissions from natural wetlands drove the decrease in atmospheric δC-CH values cannot be reconciled with current process-based wetland CH models. This finding suggests the need for increased wetland measurements to better understand the contemporary and future role of wetlands in the rise of atmospheric methane and climate feedback. Our findings highlight the predominant role of anthropogenic activities in driving the growth of atmospheric CH concentrations.
自2000年至2006年大气甲烷（CH）浓度稳定之后，自2007年起其浓度又出现了令人费解的增长。人们提出了多种假设来解释CH增长的时间变化，并将大气CH的上升归因于化石燃料活动、农业和天然湿地排放的增加，或者大气化学汇的减少。在此，我们使用了一套综合的CH源估算数据和同位素δC-CH源特征数据，以表明CH增长的恢复最有可能是由于人为排放增加所致。我们那些在同位素组成方面偏差最小的排放情景表明，与2000年至2006年相比，2007年至2017年期间农业、垃圾填埋和废物处理部门对CH增长恢复的贡献率为53±13%；工业化石燃料源的贡献率为34±24%，湿地源的贡献率最低，为13±9%。天然湿地排放大幅增加导致大气δC-CH值下降这一假设与当前基于过程的湿地CH模型无法相符。这一发现表明需要增加湿地测量，以便更好地了解湿地在大气甲烷上升和气候反馈中的当代及未来作用。我们的研究结果突出了人为活动在推动大气CH浓度增长方面的主要作用。
