Elevated atmospheric carbon dioxide(CO_(2)) concentrations have caused global climate change such as global warming and more frequent climate extremes. Countries worldwide have proposed carbon neutrality strategies to...Elevated atmospheric carbon dioxide(CO_(2)) concentrations have caused global climate change such as global warming and more frequent climate extremes. Countries worldwide have proposed carbon neutrality strategies to curb the rising CO_(2) concentrations. To investigate the impact of China's carbon neutrality goal on atmospheric CO_(2) concentrations, we conducted a series of ideal simulations from 2015 to 2019 using a global 3D chemistry transport model, Goddard Earth Observing System Chemistry(GEOS-Chem). Compared with the column-averaged dry-air mole fraction of atmospheric CO_(2) (XCO_(2) ) from Orbiting Carbon Observatory-2(OCO-2) and surface CO_(2) measurements in Obs Pack, we find that GEOS-Chem effectively reproduces the spatiotemporal variability of CO_(2) . The model exhibits a root mean square error(RMSE) of 1.51 ppm(R^(2)=0.89) for OCO-2 XCO_(2) in China and 2.65 ppm(R^(2)=0.75) for surface CO_(2) concentrations at the WLG station. Further, compared to 2.83 ppm yr^(-1)in the control experiment, we suggest that net-zero CO_(2) emissions in China decelerate the increasing trends of XCO_(2) to 1.81 ppm yr^(-1),making a decrease of approximately 35.89%. Meanwhile, the seasonal cycle amplitude(SCA) of XCO_(2) is moderately reduced from 7.39±0.81 to 6.75±0.70 ppm, representing a relative reduction of 9.91%. Spatially, net-zero CO_(2) emissions induce a more significant decrease in XCO_(2) trends over northern and southern China, while their impact on SCA is more evident in northern and northeastern China. Moreover, ideal experiments demonstrate that zero fossil CO_(2) emissions lead to a greater attenuation of the linear trends of XCO_(2) by 40.81%, while the absence of terrestrial CO_(2) sinks largely diminishes the SCA by 16.61%. Additionally,trends and SCA in surface CO_(2) concentrations exhibit almost identical decreasing responses to net-zero CO_(2) emissions but display greater sensitivities compared to XCO_(2) . Overall, our study underscores the potential of China's carbon neutrality goal in mitigating global warming, underscoring the need for concerted and collaborative efforts from nations worldwide.展开更多
China,the Unite States(US),the European Union(EU),India,and Russia are the world’s top 5 fossil fuel and cement CO_(2)(FFC)emitting countries or regions(CRs).It is very important to understand their status of carbon ...China,the Unite States(US),the European Union(EU),India,and Russia are the world’s top 5 fossil fuel and cement CO_(2)(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_(2)retrievals.The reductions of flux uncertainty and XCO_(2)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^(−1),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_(2)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.展开更多
TanSat is China’s first greenhouse gases observing satellite.In recent years,substantial progresses have been achieved on retrieving column-averaged CO_(2)dry air mole fraction(XCO_(2)).However,relatively few attempt...TanSat is China’s first greenhouse gases observing satellite.In recent years,substantial progresses have been achieved on retrieving column-averaged CO_(2)dry air mole fraction(XCO_(2)).However,relatively few attempts have been made to estimate terrestrial net ecosystem exchange(NEE)using TanSat XCO_(2)retrievals.In this study,based on the GEOS-Chem 4D-Var data assimilation system,we infer the global NEE from April 2017 to March 2018 using TanSat XCO_(2).The inversion estimates global NEE at−3.46 PgC yr^(-1),evidently higher than prior estimate and giving rise to an improved estimate of global atmospheric CO_(2)growth rate.Regionally,our inversion greatly increases the carbon uptakes in northern mid-to-high latitudes and significantly enhances the carbon releases in tropical and southern lands,especially in Africa and India peninsula.The increase of posterior sinks in northern lands is mainly attributed to the decreased carbon release during the nongrowing season,and the decrease of carbon uptakes in tropical and southern lands basically occurs throughout the year.Evaluations against independent CO_(2)observations and comparison with previous estimates indicate that although the land sinks in the northern middle latitudes and southern temperate regions are improved to a certain extent,they are obviously overestimated in northern high latitudes and underestimated in tropical lands(mainly northern Africa),respectively.These results suggest that TanSat XCO_(2)retrievals may have systematic negative biases in northern high latitudes and large positive biases over northern Africa,and further efforts are required to remove bias in these regions for better estimates of global and regional NEE.展开更多
Sudden mega natural gas leaks of two Nord Stream pipelines in the Baltic Sea(Denmark)occurred from late September to early October 2022,releasing large amounts of methane into the atmosphere.We inferred the methane em...Sudden mega natural gas leaks of two Nord Stream pipelines in the Baltic Sea(Denmark)occurred from late September to early October 2022,releasing large amounts of methane into the atmosphere.We inferred the methane emissions of this event based on surface in situ observations using two inversion methods and two meteorological reanalysis datasets,supplemented with satellite-based observations.We conclude that approximately 220±30 Gg of methane was released from September 26 to October 1,2022.展开更多
基金supported by the National Key Research and Development Program of China (Grant No. 2022YFB3904801)the National Natural Science Foundation of China (Grant No. 42475129)+2 种基金the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20221449)the Xizang Science and Technology Innovation Base Construction Project (Grant No. XZ202401YD0008)the National Key Scientific and Technological Infrastructure project “Earth System Numerical Simulation Facility” (Grant No. 2023-EL-ZD-00022)。
文摘Elevated atmospheric carbon dioxide(CO_(2)) concentrations have caused global climate change such as global warming and more frequent climate extremes. Countries worldwide have proposed carbon neutrality strategies to curb the rising CO_(2) concentrations. To investigate the impact of China's carbon neutrality goal on atmospheric CO_(2) concentrations, we conducted a series of ideal simulations from 2015 to 2019 using a global 3D chemistry transport model, Goddard Earth Observing System Chemistry(GEOS-Chem). Compared with the column-averaged dry-air mole fraction of atmospheric CO_(2) (XCO_(2) ) from Orbiting Carbon Observatory-2(OCO-2) and surface CO_(2) measurements in Obs Pack, we find that GEOS-Chem effectively reproduces the spatiotemporal variability of CO_(2) . The model exhibits a root mean square error(RMSE) of 1.51 ppm(R^(2)=0.89) for OCO-2 XCO_(2) in China and 2.65 ppm(R^(2)=0.75) for surface CO_(2) concentrations at the WLG station. Further, compared to 2.83 ppm yr^(-1)in the control experiment, we suggest that net-zero CO_(2) emissions in China decelerate the increasing trends of XCO_(2) to 1.81 ppm yr^(-1),making a decrease of approximately 35.89%. Meanwhile, the seasonal cycle amplitude(SCA) of XCO_(2) is moderately reduced from 7.39±0.81 to 6.75±0.70 ppm, representing a relative reduction of 9.91%. Spatially, net-zero CO_(2) emissions induce a more significant decrease in XCO_(2) trends over northern and southern China, while their impact on SCA is more evident in northern and northeastern China. Moreover, ideal experiments demonstrate that zero fossil CO_(2) emissions lead to a greater attenuation of the linear trends of XCO_(2) by 40.81%, while the absence of terrestrial CO_(2) sinks largely diminishes the SCA by 16.61%. Additionally,trends and SCA in surface CO_(2) concentrations exhibit almost identical decreasing responses to net-zero CO_(2) emissions but display greater sensitivities compared to XCO_(2) . Overall, our study underscores the potential of China's carbon neutrality goal in mitigating global warming, underscoring the need for concerted and collaborative efforts from nations worldwide.
基金the National Key Research and Development Program of China(2021YFB3901001)the Natural Science Foundation of Jiangsu Province,China(BK20221449)+2 种基金the Basic Science Center Project of China(42288101)the National Natural Science Foundation of China(42141005 and 41807434)the Research Funds for the Frontiers Science Center for Critical Earth Material Cycling,Nanjing University(090414380031)。
基金This work is supported by the National Key R&D Program of China(Grant No.2020YFA0607504)the National Natural Science Foundation of China(Grant No.41907378)+1 种基金the Fundamental Research Funds for the Central Universities(Grants No.090414380030 and 020714380179)We acknowledge all atmospheric data providers to obspack_co2_1_GLOBALVIEWplus_v6.0_2020-09-11。
文摘China,the Unite States(US),the European Union(EU),India,and Russia are the world’s top 5 fossil fuel and cement CO_(2)(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_(2)retrievals.The reductions of flux uncertainty and XCO_(2)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^(−1),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_(2)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.
基金This work is supported by the National Key R&D Program of China(Grant Nos.2016YFA0600204 and SQ2019YFE013078)the National Natural Science Foundation of China(Grant Nos.41807434 and 41907378)+3 种基金the Key Research Program of the Chinese Academy of Sciences(ZDRW-ZS-2019-1)We acknowledge all atmospheric data providers to obspack_co2_1_GLOBALVIEWplus_v6.0_2020-09-11.The TCCON data were obtained from the TCCON Data Archive hosted by CaltechDATA at https://tccondata.org.The CarbonTracker CT2019 results are provided by NOAA ESRL,Boulder,Colorado,USA,from the website at http://carbontracker.noaa.govWe are also grateful to the High-Performance Computing Center(HPCC)of Nanjing University for doing the numerical calculations in this paper on its blade cluster systemThe TanSat data product service is provided by IRCSD and CASA(131211KYSB20180002).
文摘TanSat is China’s first greenhouse gases observing satellite.In recent years,substantial progresses have been achieved on retrieving column-averaged CO_(2)dry air mole fraction(XCO_(2)).However,relatively few attempts have been made to estimate terrestrial net ecosystem exchange(NEE)using TanSat XCO_(2)retrievals.In this study,based on the GEOS-Chem 4D-Var data assimilation system,we infer the global NEE from April 2017 to March 2018 using TanSat XCO_(2).The inversion estimates global NEE at−3.46 PgC yr^(-1),evidently higher than prior estimate and giving rise to an improved estimate of global atmospheric CO_(2)growth rate.Regionally,our inversion greatly increases the carbon uptakes in northern mid-to-high latitudes and significantly enhances the carbon releases in tropical and southern lands,especially in Africa and India peninsula.The increase of posterior sinks in northern lands is mainly attributed to the decreased carbon release during the nongrowing season,and the decrease of carbon uptakes in tropical and southern lands basically occurs throughout the year.Evaluations against independent CO_(2)observations and comparison with previous estimates indicate that although the land sinks in the northern middle latitudes and southern temperate regions are improved to a certain extent,they are obviously overestimated in northern high latitudes and underestimated in tropical lands(mainly northern Africa),respectively.These results suggest that TanSat XCO_(2)retrievals may have systematic negative biases in northern high latitudes and large positive biases over northern Africa,and further efforts are required to remove bias in these regions for better estimates of global and regional NEE.
基金supported by the National Key R&D Program of China(Grant No:2021YFB3901001)Research Funds for the Frontiers Science Center for Critical Earth Material Cycling,Nanjing University(Grant No:090414380031)National Natural Science Foundation of China(Grant No:42007198)。
文摘Sudden mega natural gas leaks of two Nord Stream pipelines in the Baltic Sea(Denmark)occurred from late September to early October 2022,releasing large amounts of methane into the atmosphere.We inferred the methane emissions of this event based on surface in situ observations using two inversion methods and two meteorological reanalysis datasets,supplemented with satellite-based observations.We conclude that approximately 220±30 Gg of methane was released from September 26 to October 1,2022.
