Jiang Fei, He Wei, Ju Weimin, Wang Hengmao, Wu Mousong, Wang Jun, Feng Shuzhuang, Zhang Lingyu, Chen Jing M
Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, International Institute for Earth System Science, Nanjing University, Nanjing 210023, China.
Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing 210023, China.
Fundam Res. 2022 Feb 15;2(3):357-366. doi: 10.1016/j.fmre.2022.02.001. eCollection 2022 May.
China, the Unite States (US), the European Union (EU), India, and Russia are the world's top 5 fossil fuel and cement CO (FFC) emitting countries or regions (CRs). It is very important to understand their status of carbon neutrality, and to monitor their future changes of net carbon fluxes (NCFs). In this study, we implemented a well-established global carbon assimilation system (GCAS, Version 2) to infer global surface carbon fluxes from May 2009 to December 2019 using both GOSAT and OCO-2 XCO retrievals. The reductions of flux uncertainty and XCO bias, and the evaluation of posterior flux show that GCAS has comparable and good performance in the 5 CRs. The results suggest that Russia has achieved carbon neutrality, but the other 4 are still far from being carbon neutral, especially China. The mean annual NCFs in China, the US, the EU, India, and Russia are 2.33 ± 0.29, 0.82 ± 0.20, 0.42 ± 0.16, 0.50 ± 0.12, and -0.33 ± 0.23 PgC yr, respectively. From 2010 to 2019, the NCFs showed an increasing trend in the US and India, a slight downward trend after 2013 in China, and were stable in the EU. The changes of land sinks in China and the US might be the main reason for their trends. India's trend was mainly due to the increase of FFC emission. The relative contributions of NCFs to the global land net carbon emission of China and the EU have decreased, while those of the US and India have increased, implying the US and India must take more active measures to control carbon emissions or increase their sinks. This study indicates that satellite XCO could be successfully used to monitor the changes of regional NCFs, which is of great significance for major countries to achieve greenhouse gas control goals.
中国、美国、欧盟、印度和俄罗斯是全球五大化石燃料和水泥二氧化碳（FFC）排放国或地区。了解它们的碳中和状况，并监测其未来净碳通量（NCF）的变化非常重要。在本研究中，我们实施了一个成熟的全球碳同化系统（GCAS，版本2），利用GOSAT和OCO - 2的XCO反演数据，推断2009年5月至2019年12月的全球地表碳通量。通量不确定性和XCO偏差的降低以及后验通量的评估表明，GCAS在这五个国家或地区具有相当且良好的性能。结果表明，俄罗斯已实现碳中和，但其他四个国家或地区距离碳中和仍有很大差距，尤其是中国。中国、美国、欧盟、印度和俄罗斯的年均NCF分别为2.33±0.29、0.82±0.20、0.42±0.16、0.50±0.12和 - 0.33±0.23PgC/yr。2010年至2019年期间，美国和印度的NCF呈上升趋势，中国在2013年后略有下降趋势，欧盟则保持稳定。中国和美国陆地碳汇的变化可能是其趋势的主要原因。印度的趋势主要是由于FFC排放量的增加。中国和欧盟的NCF对全球陆地净碳排放的相对贡献有所下降，而美国和印度的贡献有所增加，这意味着美国和印度必须采取更积极的措施来控制碳排放或增加碳汇。本研究表明，卫星XCO可成功用于监测区域NCF的变化，这对主要国家实现温室气体控制目标具有重要意义。
