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2. The reduced net carbon uptake over Northern Hemisphere land causes the close-to-normal CO 2 growth rate in 2021 La Niña

Author

Liu, Junjie, primary, Baker, David, additional, Basu, Sourish, additional, Bowman, Kevin, additional, Byrne, Brendan, additional, Chevallier, Frederic, additional, He, Wei, additional, Jiang, Fei, additional, Johnson, Matthew S., additional, Kubar, Terence L., additional, Li, Xing, additional, Liu, Zhiqiang, additional, Miller, Scot M., additional, Philip, Sajeev, additional, Xiao, Jingfeng, additional, Yun, Jeongmin, additional, and Zeng, Ning, additional

Published
2024
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5. Global CO2 gridded flux fields from 14 atmospheric inversions in GCB2023

Author

Luijkx, Ingrid, Chevallier, Frederic, Roedenbeck, Christian, Niwa, Yosuke, Liu, Junjie, Feng, Liang, Palmer, Paul I., Bowman, Kevin, Peters, Wouter, Tian, Xiangjun, Piao, Shilong, Zheng, Bo, Lloret, Zoé, Cozic, Anne, Jacobson, Andrew R., Yun, Jeongmin, Byrne, Brendan, Bloom, Anthony, Jin, Zhe, Wang, Yilong, Zhang, Hongqin, Zhao, Min, Wang, Tao, Ding, Jinzhi, Liu, Zhiqiang, Jiang, Fei, Ju, Weimin, Yang, Dongxu, Chandra, Naveen, Patra, Prabir, Luijkx, Ingrid, Chevallier, Frederic, Roedenbeck, Christian, Niwa, Yosuke, Liu, Junjie, Feng, Liang, Palmer, Paul I., Bowman, Kevin, Peters, Wouter, Tian, Xiangjun, Piao, Shilong, Zheng, Bo, Lloret, Zoé, Cozic, Anne, Jacobson, Andrew R., Yun, Jeongmin, Byrne, Brendan, Bloom, Anthony, Jin, Zhe, Wang, Yilong, Zhang, Hongqin, Zhao, Min, Wang, Tao, Ding, Jinzhi, Liu, Zhiqiang, Jiang, Fei, Ju, Weimin, Yang, Dongxu, Chandra, Naveen, and Patra, Prabir

Abstract

In this file, we include the data from the GCB2023 inversions on 1x1 degrees latitude-longitude. The variables include the prior and posterior land biosphere and ocean carbon fluxes. The land biosphere fluxes have been adjusted to a common fossil fuel emissions dataset (land_flux_only_fossil_cement_adjusted). This allows the inverse estimates to be compared to each other within this ensemble. In this case, we apply a fossil fuel and cement adjustment to account for minor remaining differences to GridFED v2023_1 (this GridFED version includes emissions from cement production and a sink from cement carbonation). For a comparison with bottom-up estimates, further adjustments need to be made, for the lateral fluxes, specifically rivers. In contrast to the version of this file in GCB2022, we do not provide the lateral adjusted inverse estimates, since different lateral flux data sets are available and it depends on the use which lateral adjustment would be applied. We do provide data to make this adjustment for 2 specific datasets for land and ocean: - Lateral river flux adjustment on land as provided by Ronny Lauerwald (The file is based on GlobalNEWS2 for organic C and the weathering CO2 sink after Hartmann et al. 2009 as used in Zscheischler et al 2017. But in this version, the organic C loads after GlobalNEWS are twice rescaled: 1) to the latitudinal pattern from Resplandy et al. (2018 NatGeo) and 2) to a synthesis of global estimates of organic C exports of about 500 Tg C/yr (for this you could for the time being cite Regnier et al. 2013, Nat Geo).). - River adjustment for the oceans from Lacroix et al, as used in RECCAP2.

Published
2024

8. RECCAP2 Future Component: Consistency and Potential for Regional Assessment to Constrain Global Projections

Author

Jones, Chris D., primary, Ziehn, Tilo, additional, Anand, Jatin, additional, Bastos, Ana, additional, Burke, Eleanor, additional, Canadell, Josep G., additional, Cardoso, Manoel, additional, Ernst, Yolandi, additional, Jain, Atul K., additional, Jeong, Sujong, additional, Keller, Elizabeth D., additional, Kondo, Masayuki, additional, Lauerwald, Ronny, additional, Lin, Tzu‐Shun, additional, Murray‐Tortarolo, Guillermo, additional, Nabuurs, Gert‐Jan, additional, O’Sullivan, Mike, additional, Poulter, Ben, additional, Qin, Xiaoyu, additional, von Randow, Celso, additional, Sanches, Marcos, additional, Schepaschenko, Dmitry, additional, Shvidenko, Anatoly, additional, Smallman, T. Luke, additional, Tian, Hanqin, additional, Villalobos, Yohanna, additional, Wang, Xuhui, additional, and Yun, Jeongmin, additional

Published
2023
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11. Regional inversion shows promise in capturing extreme-event-driven CO2 flux anomalies but is limited by atmospheric CO2 observational coverage

Author

Byrne, Brendan, primary, Liu, Junjie, additional, Bowman, Kevin W., additional, Yin, Yi, additional, Yun, Jeongmin, additional, Ferreira, Gabriel, additional, Ogle, Stephen, additional, Baskaran, Latha, additional, He, Liyin, additional, Li, Xing, additional, Xiao, Jingfeng, additional, and Davis, Kenneth J., additional

Published
2023
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12. The greenhouse gas budget of terrestrial ecosystems in East Asia since 2000

Author

Wang, Xuhui, primary, Gao, Yuanyi, additional, Jeong, Sujong, additional, Ito, Akihiko, additional, Bastos, Ana, additional, Poulter, Benjamin, additional, Wang, Yilong, additional, Ciais, Philippe, additional, Tian, Hanqin, additional, Yuan, Wenping, additional, Chandra, Naveen, additional, Chevallier, Frederic, additional, Fan, Lei, additional, Hong, Songbai, additional, Lauerwald, Ronny, additional, Li, Wei, additional, Lin, Zhengyang, additional, Pan, Naiqing, additional, Patra, Prabir K., additional, Peng, Shushi, additional, Ran, Lishan, additional, Sang, Yuxing, additional, Sitch, Stephen, additional, Maki, Takashi, additional, Thompson, Rona L., additional, Wang, Chenzhi, additional, Wang, Kai, additional, Wang, Tao, additional, Xi, Yi, additional, Xu, Liang, additional, Yan, Yanzi, additional, Yun, Jeongmin, additional, Zhang, Yao, additional, Zhang, Yuzhong, additional, Zhang, Zhen, additional, Zheng, Bo, additional, Zhou, Feng, additional, Tao, Shu, additional, Canadell, Josep G., additional, and Piao, Shilong, additional

Published
2023
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13. National CO2 budgets (2015–2020) inferred from atmospheric CO2 observations in support of the global stocktake

Author

Byrne, Brendan, primary, Baker, David F., additional, Basu, Sourish, additional, Bertolacci, Michael, additional, Bowman, Kevin W., additional, Carroll, Dustin, additional, Chatterjee, Abhishek, additional, Chevallier, Frédéric, additional, Ciais, Philippe, additional, Cressie, Noel, additional, Crisp, David, additional, Crowell, Sean, additional, Deng, Feng, additional, Deng, Zhu, additional, Deutscher, Nicholas M., additional, Dubey, Manvendra K., additional, Feng, Sha, additional, García, Omaira E., additional, Griffith, David W. T., additional, Herkommer, Benedikt, additional, Hu, Lei, additional, Jacobson, Andrew R., additional, Janardanan, Rajesh, additional, Jeong, Sujong, additional, Johnson, Matthew S., additional, Jones, Dylan B. A., additional, Kivi, Rigel, additional, Liu, Junjie, additional, Liu, Zhiqiang, additional, Maksyutov, Shamil, additional, Miller, John B., additional, Miller, Scot M., additional, Morino, Isamu, additional, Notholt, Justus, additional, Oda, Tomohiro, additional, O'Dell, Christopher W., additional, Oh, Young-Suk, additional, Ohyama, Hirofumi, additional, Patra, Prabir K., additional, Peiro, Hélène, additional, Petri, Christof, additional, Philip, Sajeev, additional, Pollard, David F., additional, Poulter, Benjamin, additional, Remaud, Marine, additional, Schuh, Andrew, additional, Sha, Mahesh K., additional, Shiomi, Kei, additional, Strong, Kimberly, additional, Sweeney, Colm, additional, Té, Yao, additional, Tian, Hanqin, additional, Velazco, Voltaire A., additional, Vrekoussis, Mihalis, additional, Warneke, Thorsten, additional, Worden, John R., additional, Wunch, Debra, additional, Yao, Yuanzhi, additional, Yun, Jeongmin, additional, Zammit-Mangion, Andrew, additional, and Zeng, Ning, additional

Published
2023
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14. RECCAP2 Future Component : Consistency and Potential for Regional Assessment to Constrain Global Projections

Author

Jones, Chris D., Ziehn, Tilo, Anand, Jatin, Bastos, Ana, Burke, Eleanor, Canadell, Josep G., Cardoso, Manoel, Ernst, Yolandi, Jain, Atul K., Jeong, Sujong, Keller, Elizabeth D., Kondo, Masayuki, Lauerwald, Ronny, Lin, Tzu Shun, Murray-Tortarolo, Guillermo, Nabuurs, Gert Jan, O’Sullivan, Mike, Poulter, Ben, Qin, Xiaoyu, von Randow, Celso, Sanches, Marcos, Schepaschenko, Dmitry, Shvidenko, Anatoly, Smallman, Luke, Tian, Hanqin, Villalobos, Yohanna, Wang, Xuhui, Yun, Jeongmin, Jones, Chris D., Ziehn, Tilo, Anand, Jatin, Bastos, Ana, Burke, Eleanor, Canadell, Josep G., Cardoso, Manoel, Ernst, Yolandi, Jain, Atul K., Jeong, Sujong, Keller, Elizabeth D., Kondo, Masayuki, Lauerwald, Ronny, Lin, Tzu Shun, Murray-Tortarolo, Guillermo, Nabuurs, Gert Jan, O’Sullivan, Mike, Poulter, Ben, Qin, Xiaoyu, von Randow, Celso, Sanches, Marcos, Schepaschenko, Dmitry, Shvidenko, Anatoly, Smallman, Luke, Tian, Hanqin, Villalobos, Yohanna, Wang, Xuhui, and Yun, Jeongmin

Abstract

Projections of future carbon sinks and stocks are important because they show how the world's ecosystems will respond to elevated CO2 and changes in climate. Moreover, they are crucial to inform policy decisions around emissions reductions to stay within the global warming levels identified by the Paris Agreement. However, Earth System Models from the 6th Coupled Model Intercomparison Project (CMIP6) show substantial spread in future projections—especially of the terrestrial carbon cycle, leading to a large uncertainty in our knowledge of any remaining carbon budget (RCB). Here we evaluate the global terrestrial carbon cycle projections on a region-by-region basis and compare the global models with regional assessments made by the REgional Carbon Cycle Assessment and Processes, Phase 2 activity. Results show that for each region, the CMIP6 multi-model mean is generally consistent with the regional assessment, but substantial cross-model spread exists. Nonetheless, all models perform well in some regions and no region is without some well performing models. This gives confidence that the CMIP6 models can be used to look at future changes in carbon stocks on a regional basis with appropriate model assessment and benchmarking. We find that most regions of the world remain cumulative net sources of CO2 between now and 2100 when considering the balance of fossil-fuels and natural sinks, even under aggressive mitigation scenarios. This paper identifies strengths and weaknesses for each model in terms of its performance over a particular region including how process representation might impact those results and sets the agenda for applying stricter constraints at regional scales to reduce the uncertainty in global projections.

Published
2023

15. Quantification of regional terrestrial biosphere CO2 flux errors in v10 OCO-2 MIP models using airborne measurements.

Author

Yun, Jeongmin, Liu, Junjie, Byrne, Brendan, Weir, Brad, Ott, Lesley E., McKain, Kathryn, Baier, Bianca, and Gatti, Luciana V.

Subjects
MEASUREMENT errors, BIOSPHERE, AREA measurement, SENSITIVITY analysis, ORBITS (Astronomy)
Abstract

Multi-inverse modeling inter-comparison projects (MIPs) provide a chance to assess the uncertainties in inversion estimates arising from various sources such as atmospheric CO2 observations, transport models, and prior fluxes. However, accurately quantifying ensemble CO2 flux errors remains challenging, often relying on the ensemble spread as a surrogate. This study proposes a method to quantify the errors of regional terrestrial biosphere CO2 flux estimates from 10 inverse models within the Orbiting Carbon Observatory-2 (OCO-2) MIP by using independent airborne CO2 measurements for the period 2015–2017. We first calculate the root-mean-square error (RMSE) between the ensemble mean of posterior CO2 concentration estimates and airborne observations and then isolate the CO2 concentration error caused solely by the ensemble mean of posterior terrestrial biosphere CO2 flux estimates by subtracting the errors of observation and transport in seven regions. Our analysis reveals significant regional variations in the average monthly RMSE over three years, ranging from 0.90 to 2.04 ppm. The ensemble flux error projected into CO2 space is a major component that accounts for 58–84 % of the mean RMSE. We further show that in five regions, the observation-based error estimates exceed the atmospheric CO2 errors computed from the ensemble spread of posterior CO2 flux estimates by 1.37–1.89 times, implying an underestimation of the actual ensemble flux error, while their magnitudes are comparable in two regions. By identifying the most sensitive areas to airborne measurements through adjoint sensitivity analysis, we find that the underestimation of flux errors is prominent in eastern parts of Australia and East Asia, western parts of Europe and Southeast Asia, and midlatitude North America, suggesting the presence of systematic biases related to anthropogenic CO2 emissions in inversion estimates. The regions with no underestimation were southeastern Alaska and northeastern South America. Our study emphasizes the value of independent airborne measurements not only for the overall evaluation of inversion performance but also for quantifying regional errors in ensemble terrestrial biosphere flux estimates. [ABSTRACT FROM AUTHOR]

Published
2023
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16. National CO2 budgets (2015–2020) inferred from atmospheric CO2 observations in support of the global stocktake

Author

Byrne, Brendan, Baker, David F., Basu, Sourish, Bertolacci, Michael, Bowman, Kevin W., Carroll, Dustin, Chatterjee, Abhishek, Chevallier, Frédéric, Ciais, Philippe, Cressie, Noel, Crisp, David, Crowell, Sean, Deng, Feng, Deng, Zhu, Deutscher, Nicholas Michael, Dubey, Manvendra K., Feng, Sha, García Rodríguez, Omaira Elena, Griffith, David W. T., Herkommer, Benedikt, Hu, Lei, Jacobson, Andrew R., Janardanan, Rajesh, Jeong, Sujong, Johnson, Matthew S., Jones, Dylan B. A., Kivi, Rigel, Liu, Junjie, Liu, Zhiqiang, Maksyutov, Shamil, Miller, John B., Morino, Isamu, Notholt, Justus, Oda, Tomohiro, O'Dell, Christopher, Oh, Young-Suk, Ohyama, Hirofumi, Patra, Prabir K., Peiro, Hélène, Petri, Christof, Philip, Sajeev, Pollard, David F., Poulter, Benjamin, Remaud, Marine, Schuh, Andrew, Sha, Mahesh Kumar, Shiomi, Kei, Strong, Kimberly, Sweeney, Colm, Te, Yao, Tian, Hanqin, Velazco, Voltaire A., Vrekoussis, Mihalis, Warneke, Thorsten, Worden, John, Wunch, Debra, Yao, Yuamzhi, Yun, Jeongmin, Zammit Mangion, Andrew, and Zeng, Ning

Subjects
Temperature increase, Carbon dioxide emission, Climate change
Abstract

Accurate accounting of emissions and removals of CO2 is critical for the planning and verification of emission reduction targets in support of the Paris Agreement. Here, we present a pilot dataset of country-specific net carbon exchange (NCE; fossil plus terrestrial ecosystem fluxes) and terrestrial carbon stock changes aimed at informing countries’ carbon budgets. These estimates are based on “top-down” NCE outputs from the v10 Orbiting Carbon Observatory (OCO-2) modeling intercomparison project (MIP), wherein an ensemble of inverse modeling groups conducted standardized experiments assimilating OCO-2 column-averaged dry-air mole fraction (XCO2 ) retrievals (ACOS v10), in situ CO2 measurements or combinations of these data. The v10 OCO-2 MIP NCE estimates are combined with “bottom-up” estimates of fossil fuel emissions and lateral carbon fluxes to estimate changes in terrestrial carbon stocks, which are impacted by anthropogenic and natural drivers. These flux and stock change estimates are reported annually (2015–2020) as both a global 1◦ × 1 ◦ gridded dataset and a country-level dataset and are available for download from the Committee on Earth Observation Satellites’ (CEOS) website: https://doi.org/10.48588/npf6-sw92 (Byrne et al., 2022). Across the v10 OCO-2 MIP experiments, we obtain increases in the ensemble median terrestrial carbon stocks of 3.29–4.58 PgCO2 yr−1 (0.90–1.25 PgC yr−1 ). This is a result of broad increases in terrestrial carbon stocks across the northern extratropics, while the tropics generally have stock losses but with considerable regional variability and differences between v10 OCO-2 MIP experiments. We discuss the state of the science for tracking emissions and removals using top-down methods, including current limitations and future developments towards top-down monitoring and verification systems. This research has been supported by the European Commission, Horizon 2020 Framework Programme (CoCO2 (grant no. 958927 856612/EMME-CARE)) and Copernicus Atmosphere Monitoring Service (grant no. CAMS73), the Australian Research Council (grant nos. DP190100180, DE180100203, DP160100598, LE0668470, DP140101552, DP110103118, DP0879468 and FT180100327), the Environmental Restoration and Conservation Agency (grant no. JPMEERF21S20800), the Korea Meteorological Administration (grant no. KMA2018-00320), the National Aeronautics and Space Administration (grant nos. 20-OCOST20-0004, 80NSSC18K0908, 80NSSC18K0976, 80NSSC20K0006, 80NSSC21K1068, 80NSSC21K1073, 80NSSC21K1077, 80NSSC21K1080, 80HQTR21T0069, NAG512247, NNG05GD07G, NNH17ZDA001N-OCO2 and NNX15AG93G), and the National Oceanic and Atmospheric Administration (grant no. NA18OAR4310266).

Published
2023

18. Supplementary material to "National CO2 budgets (2015–2020) inferred from atmospheric CO2 observations in support of the Global Stocktake"

Author

Byrne, Brendan, primary, Baker, David F., additional, Basu, Sourish, additional, Bertolacci, Michael, additional, Bowman, Kevin W., additional, Carroll, Dustin, additional, Chatterjee, Abhishek, additional, Chevallier, Frédéric, additional, Ciais, Philippe, additional, Cressie, Noel, additional, Crisp, David, additional, Crowell, Sean, additional, Deng, Feng, additional, Deng, Zhu, additional, Deutscher, Nicholas M., additional, Dubey, Manvendra, additional, Feng, Sha, additional, García, Omaira, additional, Griffith, David W. T., additional, Herkommer, Benedikt, additional, Hu, Lei, additional, Jacobson, Andrew R., additional, Janardanan, Rajesh, additional, Jeong, Sujong, additional, Johnson, Matthew S., additional, Jones, Dylan B. A., additional, Kivi, Rigel, additional, Liu, Junjie, additional, Liu, Zhiqiang, additional, Maksyutov, Shamil, additional, Miller, John B., additional, Miller, Scot M., additional, Morino, Isamu, additional, Notholt, Justus, additional, Oda, Tomohiro, additional, O’Dell, Christopher W., additional, Oh, Young-Suk, additional, Ohyama, Hirofumi, additional, Patra, Prabir K., additional, Peiro, Hélène, additional, Petri, Christof, additional, Philip, Sajeev, additional, Pollard, David F., additional, Poulter, Benjamin, additional, Remaud, Marine, additional, Schuh, Andrew, additional, Sha, Mahesh K., additional, Shiomi, Kei, additional, Strong, Kimberly, additional, Sweeney, Colm, additional, Té, Yao, additional, Tian, Hanqin, additional, Velazco, Voltaire A., additional, Vrekoussis, Mihalis, additional, Warneke, Thorsten, additional, Worden, John R., additional, Wunch, Debra, additional, Yao, Yuanzhi, additional, Yun, Jeongmin, additional, Zammit-Mangion, Andrew, additional, and Zeng, Ning, additional

Published
2022
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19. National CO2 budgets (2015–2020) inferred from atmospheric CO2 observations in support of the Global Stocktake

Author

Byrne, Brendan, primary, Baker, David F., additional, Basu, Sourish, additional, Bertolacci, Michael, additional, Bowman, Kevin W., additional, Carroll, Dustin, additional, Chatterjee, Abhishek, additional, Chevallier, Frédéric, additional, Ciais, Philippe, additional, Cressie, Noel, additional, Crisp, David, additional, Crowell, Sean, additional, Deng, Feng, additional, Deng, Zhu, additional, Deutscher, Nicholas M., additional, Dubey, Manvendra, additional, Feng, Sha, additional, García, Omaira, additional, Griffith, David W. T., additional, Herkommer, Benedikt, additional, Hu, Lei, additional, Jacobson, Andrew R., additional, Janardanan, Rajesh, additional, Jeong, Sujong, additional, Johnson, Matthew S., additional, Jones, Dylan B. A., additional, Kivi, Rigel, additional, Liu, Junjie, additional, Liu, Zhiqiang, additional, Maksyutov, Shamil, additional, Miller, John B., additional, Miller, Scot M., additional, Morino, Isamu, additional, Notholt, Justus, additional, Oda, Tomohiro, additional, O’Dell, Christopher W., additional, Oh, Young-Suk, additional, Ohyama, Hirofumi, additional, Patra, Prabir K., additional, Peiro, Hélène, additional, Petri, Christof, additional, Philip, Sajeev, additional, Pollard, David F., additional, Poulter, Benjamin, additional, Remaud, Marine, additional, Schuh, Andrew, additional, Sha, Mahesh K., additional, Shiomi, Kei, additional, Strong, Kimberly, additional, Sweeney, Colm, additional, Té, Yao, additional, Tian, Hanqin, additional, Velazco, Voltaire A., additional, Vrekoussis, Mihalis, additional, Warneke, Thorsten, additional, Worden, John R., additional, Wunch, Debra, additional, Yao, Yuanzhi, additional, Yun, Jeongmin, additional, Zammit-Mangion, Andrew, additional, and Zeng, Ning, additional

Published
2022
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20. Enhance seasonal amplitude of atmospheric CO2 by the changing Southern Ocean carbon sink

Author

Yun, Jeongmin, Jeong, Sujong, Gruber, Nicolas, Gregor, Luke, Ho, Chang-hoi, Piao, Shilong, Ciais, Philippe, Schimel, David, Kwon, Eun Young, Yun, Jeongmin, Jeong, Sujong, Gruber, Nicolas, Gregor, Luke, Ho, Chang-hoi, Piao, Shilong, Ciais, Philippe, Schimel, David, and Kwon, Eun Young

Abstract

The enhanced seasonal amplitude of atmospheric CO 2 has been viewed so far primarily as a Northern Hemisphere phenomenon. Yet, analyses of atmospheric CO 2 records from 49 stations between 1980 and 2018 reveal substantial trends and variations in this amplitude globally. While no significant trends can be discerned before 2000 in most places, strong positive trends emerge after 2000 in the southern high latitudes. Using factorial simulations with an atmospheric transport model and analyses of surface ocean P co 2 observations, we show that the increase is best explained by the onset of increasing seasonality of air-sea CO 2 exchange over the Southern Ocean around 2000. Underlying these changes is the long-term ocean acidification trend that tends to enhance the seasonality of the air-sea fluxes, but this trend is modified by the decadal variability of the Southern Ocean carbon sink. The seasonal variations of atmospheric CO 2 thus emerge as a sensitive recorder of the variations of the Southern Ocean carbon sink.

Published
2022
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21. Short-term reduction of regional enhancement of atmospheric CO2 in China during the first COVID-19 pandemic period

Author

Sim, Sojung, primary, Lee, Haeyoung, additional, Oh, Eunsil, additional, Kim, Sumin, additional, Ciais, Philippe, additional, Piao, Shilong, additional, Lin, John C, additional, Mallia, Derek V, additional, Lee, Sepyo, additional, Kim, Yeon-Hee, additional, Park, Hoonyoung, additional, Yun, Jeongmin, additional, and Jeong, Sujong, additional

Published
2022
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22. Spatiotemporal variations in urban CO2 flux with land-use types in Seoul.

Author

Park, Chaerin, Jeong, Sujong, Park, Moon-Soo, Park, Hoonyoung, Yun, Jeongmin, Lee, Sang-Sam, and Park, Sung-Hwa

Subjects
URBAN land use, ENERGY consumption of buildings, COLD (Temperature), TRAFFIC flow, METROPOLIS
Abstract

Background: Cities are a major source of atmospheric CO2; however, understanding the surface CO2 exchange processes that determine the net CO2 flux emitted from each city is challenging owing to the high heterogeneity of urban land use. Therefore, this study investigates the spatiotemporal variations of urban CO2 flux over the Seoul Capital Area, South Korea from 2017 to 2018, using CO2 flux measurements at nine sites with different urban land-use types (baseline, residential, old town residential, commercial, and vegetation areas). Results: Annual CO2 flux significantly varied from 1.09 kg C m− 2 year− 1 at the baseline site to 16.28 kg C m− 2 year− 1 at the old town residential site in the Seoul Capital Area. Monthly CO2 flux variations were closely correlated with the vegetation activity (r = − 0.61) at all sites; however, its correlation with building energy usage differed for each land-use type (r = 0.72 at residential sites and r = 0.34 at commercial sites). Diurnal CO2 flux variations were mostly correlated with traffic volume at all sites (r = 0.8); however, its correlation with the floating population was the opposite at residential (r = − 0.44) and commercial (r = 0.80) sites. Additionally, the hourly CO2 flux was highly related to temperature. At the vegetation site, as the temperature exceeded 24 ℃, the sensitivity of CO2 absorption to temperature increased 7.44-fold than that at the previous temperature. Conversely, the CO2 flux of non-vegetation sites increased when the temperature was less than or exceeded the 18 ℃ baseline, being three-times more sensitive to cold temperatures than hot ones. On average, non-vegetation urban sites emitted 0.45 g C m− 2 h− 1 of CO2 throughout the year, regardless of the temperature. Conclusions: Our results demonstrated that most urban areas acted as CO2 emission sources in all time zones; however, the CO2 flux characteristics varied extensively based on urban land-use types, even within cities. Therefore, multiple observations from various land-use types are essential for identifying the comprehensive CO2 cycle of each city to develop effective urban CO2 reduction policies. [ABSTRACT FROM AUTHOR]

Published
2022
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23. The Greenhouse Gas Budget of Terrestrial Ecosystems in East Asia Since 2000

Author

Wang, Xuhui, Gao, Yuanyi, Jeong, Sujong, Ito, Akihiko, Bastos, Ana, Poulter, Benjamin, Wang, Yilong, Ciais, Philippe, Tian, Hanqin, Yuan, Wenping, Chandra, Naveen, Chevallier, Frédéric, Fan, Lei, Hong, Songbai, Lauerwald, Ronny, Li, Wei, Lin, Zhengyang, Pan, Naiqing, Patra, Prabir K., Peng, Shushi, Ran, Lishan, Sang, Yuxing, Sitch, Stephen, Takashi, Maki, Thompson, Rona Louise, Wang, Chenzhi, Wang, Kai, Wang, Tao, Xi, Yi, Xu, Liang, Yan, Yanzi, Yun, Jeongmin, Zhang, Yao, Zhang, Yuzhong, Zhang, Zhen, Zheng, Bo, Zhou, Feng, Tao, Shu, Canadell, Josep G., and Piao, Shilong

Abstract

East Asia (China, Japan, Koreas, and Mongolia) has been the world's economic engine over at least the past two decades, exhibiting a rapid increase in fossil fuel emissions of greenhouse gases (GHGs) and has expressed the recent ambition to achieve climate neutrality by mid‐century. However, the GHG balance of its terrestrial ecosystems remains poorly constrained. Here, we present a synthesis of the three most important long‐lived greenhouse gases (CO2, CH4, and N2O) budgets over East Asia during the decades of 2000s and 2010s, following a dual constraint approach. We estimate that terrestrial ecosystems in East Asia is close to neutrality of GHGs, with a magnitude of between −46.3 ± 505.9 Tg CO2eq yr−1(the top‐down approach) and −36.1 ± 207.1 Tg CO2eq yr−1(the bottom‐up approach) during 2000–2019. This net GHG sink includes a large land CO2sink (−1229.3 ± 430.9 Tg CO2yr−1based on the top‐down approach and −1353.8 ± 158.5 Tg CO2yr−1based on the bottom‐up approach) being offset by biogenic CH4and N2O emissions, predominantly coming from the agricultural sectors. Emerging data sources and modeling capacities have helped achieve agreement between the top‐down and bottom‐up approaches, but sizable uncertainties remain in several flux terms. For example, the reported CO2flux from land use and land cover change varies from a net source of more than 300 Tg CO2yr−1to a net sink of ∼−700 Tg CO2yr−1. Although terrestrial ecosystems over East Asia is close to GHG neutral currently, curbing agricultural GHG emissions and additional afforestation and forest managements have the potential to transform the terrestrial ecosystems into a net GHG sink, which would help in realizing East Asian countries' ambitions to achieve climate neutrality. East Asia (China, Japan, Koreas and Mongolia) is not only the hotspot of anthropogenic greenhouse gas (GHG, including CO2, CH4and N2O) emissions, but also a region with large CO2sink. However, the greenhouse gas balance of greenhouse gases over the region is poorly understood. In this study, we performed a synthesis for over 40 flux terms to provide the first‐of‐its‐kind GHG budget assessment over the decades of 2000s and 2010s. We find terrestrial ecosystems in East Asia is close to neutrality of GHGs. The bottom‐up approach summing up component fluxes estimated a net balance of −36.1 ± 207.1 Tg CO2eq yr−1, while the top‐down approach based on atmospheric inversions estimated a net balance of −46.3 ± 505.9 Tg CO2eq yr−1. This results from compensation of the large CO2sink by CH4and N2O emissions, and from compensation of net GHG sink over natural ecosystems by net GHG source over agricultural ecosystems. Thus, curbing agricultural GHG emissions has the potential to realizing the ambitious goal of achieving climate neutrality over East Asia. A comprehensive greenhouse gas (CO2, CH4and N2O) accounting including about 40 flux terms over East Asia is reportedTerrestrial ecosystems in East Asia are close to greenhouse gas neutralNatural ecosystems is a net greenhouse gas sink, compensated by a net source from agricultural ecosystems A comprehensive greenhouse gas (CO2, CH4and N2O) accounting including about 40 flux terms over East Asia is reported Terrestrial ecosystems in East Asia are close to greenhouse gas neutral Natural ecosystems is a net greenhouse gas sink, compensated by a net source from agricultural ecosystems

Published
2024
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