Limiting the rise in global mean temperatures relies on reducing carbon dioxide (CO2) emissions and on the removal of CO2 by land carbon sinks. China is currently the single largest emitter of CO2, responsible for approximately 27 per cent (2.67 petagrams of carbon per year) of global fossil fuel emissions in 20171. Understanding of Chinese land biosphere fluxes has been hampered by sparse data coverage2,3,4, which has resulted in a wide range of a posteriori estimates of flux. Here we present recently available data on the atmospheric mole fraction of CO2, measured from six sites across China during 2009 to 2016. Using these data, we estimate a mean Chinese land biosphere sink of −1.11 ± 0.38 petagrams of carbon per year during 2010 to 2016, equivalent to about 45 per cent of our estimate of annual Chinese anthropogenic emissions over that period. Our estimate reflects a previously underestimated land carbon sink over southwest China (Yunnan, Guizhou and Guangxi provinces) throughout the year, and over northeast China (especially Heilongjiang and Jilin provinces) during summer months. These provinces have established a pattern of rapid afforestation of progressively larger regions5,6, with provincial forest areas increasing by between 0.04 million and 0.44 million hectares per year over the past 10 to 15 years. These large-scale changes reflect the expansion of fast-growing plantation forests that contribute to timber exports and the domestic production of paper7. Space-borne observations of vegetation greenness show a large increase with time over this study period, supporting the timing and increase in the land carbon sink over these afforestation regions.
Subscribe to Journal
Get full journal access for 1 year
only $3.83 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
GRACE data are available from http://grace.jpl.nasa.gov. ABC data are available from https://www.wenfo.org/wald/global-biomass. The NDVI, EVI and LAI data were retrieved from the online Data Pool, courtesy of the NASA Land Processes Distributed Active Archive Center, USGS/Earth Resources Observation and Science Center (https://lpdaac.usgs.gov/data_access/data_pool). CO2 mole fraction data from the Chinese sites used in this study are available at https://doi.org/10.17632/w3bwmr6rfg.1 on http://data.mendeley.com. Requests for further information about these data should be directed to S.F. Source data are provided with this paper.
We acknowledge the Python Software Foundation: Python Language Reference, version 3.7.7; available at http://www.python.org. We also acknowledge Matplotlib (v3.1.3, 10.5281/zenodo.3984190)52. The community-led GEOS-Chem model of atmospheric chemistry and transport is maintained centrally by Harvard University (http://acmg.seas.harvard.edu/geos/) and is available on request. The ensemble Kalman filter code is publicly available as PyOSSE (https://www.nceo.ac.uk/data-tools/atmospheric-tools/).
Le Quéré, C. et al. Global carbon budget 2018. Earth Syst. Sci. Data 10, 2141–2194 (2018).
Peylin, P. et al. Global atmospheric carbon budget: results from an ensemble of atmospheric CO2 inversions. Biogeosciences 10, 6699–6720 (2013).
Thompson, R. L. et al. Top-down assessment of the Asian carbon budget since the mid 1990s. Nat. Commun. 7, 10724 (2016).
Jiang, F. et al. A comprehensive estimate of recent carbon sinks in China using both top-down and bottom-up approaches. Sci. Rep. 6, 22130 (2016).
Pan, Y. et al. A large and persistent carbon sink in the world’s forests. Science 333, 988–993 (2011).
Zhang, Y., Yao, Y., Wang, X., Liu, Y. & Piao, S. Mapping spatial distribution of forest age in China. Earth Space Sci. 4, 108–116 (2017).
Williams, R. A. Mitigating biodiversity concerns in eucalyptus plantations located in South China. J. Biosci. Med. 3, 57099 (2015).
Barlow, J. M., Palmer, P. I., Bruhwiler, L. M. & Tans, P. Analysis of CO2 mole fraction data: first evidence of large-scale changes in CO2 uptake at high northern latitudes. Atmos. Chem. Phys. 15, 13739–13758 (2015).
Schimel, D. S. et al. Recent patterns and mechanisms of carbon exchange by terrestrial ecosystems. Nature 414, 169–172 (2001).
Takahashi, T. et al. Climatological mean and decadal change in surface ocean pCO2, and net sea–air CO2 flux over the global oceans. Deep Sea Res. II 56, 554–577 (2009).
Rödenbeck, C. et al. Data-based estimates of the ocean carbon sink variability — first results of the Surface Ocean pCO2 Mapping intercomparison (SOCOM). Biogeosciences 12, 7251–7278 (2015).
Gregg, J. S., Andres, R. J. & Marland, G. China: emissions pattern of the world leader in CO2 emissions from fossil fuel consumption and cement production. Geophys. Res. Lett. 35, L08806 (2008).
Liu, Z. et al. Reduced carbon emission estimates from fossil fuel combustion and cement production in China. Nature 524, 335–338 (2015).
Piao, S. L. et al. The carbon budget of terrestrial ecosystems in East Asia over the last two decades. Biogeosciences 9, 3571–3586 (2012).
Piao, S. et al. The carbon balance of terrestrial ecosystems in China. Nature 458, 1009–1013 (2009).
Tian, H. et al. Net exchanges of CO2, CH4, and N2O between China’s terrestrial ecosystems and the atmosphere and their contributions to global climate warming. J. Geophys. Res. Atmos. 116, G02011 (2011).
Zhang, H. et al. Net terrestrial CO2 exchange over China during 2001–2010 estimated with an ensemble data assimilation system for atmospheric CO2. J. Geophys. Res. Atmos. 119, 3500–3515 (2014).
Wang, Q. et al. Primary estimation of Chinese terrestrial carbon sequestration during 2001–2010. Sci. Bull. 60, 577–590 (2015).
Fang, J. Y., Chen, A. P., Peng, C. H., Zhao, S. Q. & Ci, L. Changes in forest biomass carbon storage in China between 1949 and 1998. Science 292, 2320–2322 (2001).
Pan, Y., Luo, T., Birdsey, R., Hom, J. & Melillo, J. New estimates of carbon storage and sequestration in China’s forests: effects of age-class and method on inventory-based carbon estimation. Clim. Change 67, 211–236 (2004).
Yokota, T. et al. Global concentrations of CO2 and CH4 retrieved from GOSAT: first preliminary results. Sci. Online Lett. Atmos. 5, 160–163 (2009).
Zeng, W., Tomppo, E., Healey, S. P. & Gadow, K. V. The national forest inventory in China: history — results — international context. For. Ecosyst. 2, 23 (2015).
Liu, J., Li, S., Ouyang, Z., Tam, C. & Chen, X. Ecological and socioeconomic effects of China’s policies for ecosystem services. Proc. Natl Acad. Sci. USA 105, 9477–9482 (2008).
Wang, S. et al. Relationships between net primary productivity and stand age for several forest types and their influence on China’s carbon balance. J. Environ. Manage. 92, 1651–1662 (2011).
Yu, Y. et al. Influence of site index on the relationship between forest net primary productivity and stand age. PLoS One 12, e0177084 (2017).
Du, H. et al. Carbon storage in a eucalyptus plantation chronosequence in Southern China. Forests 6, 1763–1778 (2015).
Xu, K., Yang, D., Xu, X. & Lei, H. Copula based drought frequency analysis considering the spatio-temporal variability in Southwest China. J. Hydrol. 527, 630–640 (2015).
Cooperative Global Atmospheric Data Integration Project. Multi-laboratory compilation of atmospheric carbon dioxide data for the period 1957–2017; obspack_co2_1_GLOBALVIEWplus_v4.1_2018_10_29 (NOAA Earth System Research Laboratory, Global Monitoring Division, 2018); https://doi.org/10.25925/20181026
Sasakawa, M. et al. Continuous measurements of methane from a tower network over Siberia. Tellus B 62, 403–416 (2010).
Saeki, T. et al. Carbon flux estimation for Siberia by inverse modeling constrained by aircraft and tower CO2 measurements. J. Geophys. Res. Atmos. 118, 1100–1122 (2013).
Fang, S. X. et al. In situ measurement of atmospheric CO2 at the four WMO/GAW stations in China. Atmos. Chem. Phys. 14, 2541–2554 (2014).
Fang, S. X., Tans, P. P., Steinbacher, M., Zhou, L. X. & Luan, T. Comparison of the regional CO2 mole fraction filtering approaches at a WMO/GAW regional station in China. Atmos. Meas. Tech. 8, 5301–5313 (2015).
Kuze, A., Suto, H., Nakajima, M. & Hamazaki, T. Thermal and near infrared sensor for carbon observation Fourier-transform spectrometer on the Greenhouse Gases Observing Satellite for greenhouse gases monitoring. Appl. Opt. 48, 6716–6733 (2009).
OCO-2 Science Team. ACOS GOSAT/TANSO-FTS ACOS Level 2 Bias-Corrected XCO2 and Other Select Fields from the Full-Physics Retrieval Aggregated as Daily Files V7.3 (GES DISC, 2016); https://disc.gsfc.nasa.gov/datacollection/ACOS_L2_Lite_FP_7.3.html (accessed October 2017).
Eldering, A. et al. The Orbiting Carbon Observatory-2 early science investigations of regional carbon dioxide fluxes. Science 358, eaam5745 (2017).
OCO-2 Science Team. OCO-2 Level 2 Bias-Corrected XCO2 and Other Select Fields from the Full-Physics Retrieval Aggregated as daily files. Retrospective Processing V8r (GES DISC, 2017); https://doi.org/10.5067/W8QGIYNKS3JC
Didan, K. MOD13C2 MODIS/Terra Vegetation Indices Monthly L3 Global 0.05 Deg CMG V006 (NASA EOSDIS Land Processes DAAC, 2015); https://doi.org/10.5067/modis/mod13c2.006
Swenson, S. & Wahr, J. Post-processing removal of correlated errors in GRACE data. Geophys. Res. Lett. 33, L08402 (2006).
Swenson, S. C. GRACE Monthly Land Water Mass Grids NETCDF Release 5.0 V5.0 (PODAAC, 2012); https://doi.org/10.5067/TELND-NC005 (accessed 27 September 2017).
Landerer, F. W. & Swenson, S. C. Accuracy of scaled GRACE terrestrial water storage estimates. Water Resour. Res. 48, W04531 (2012).
Liu, Y. Y. et al. Recent reversal in loss of global terrestrial biomass. Nat. Clim. Change 5, 470–474 (2015).
van der Werf, G. R. et al. Global fire emissions and the contribution of deforestation, savanna, forest, agricultural, and peat fires (1997–2009). Atmos. Chem. Phys. 10, 11707–11735 (2010).
Oda, T. & Maksyutov, S. A very-high-resolution (1 km × 1 km) global fossil fuel CO2 emission inventory derived using a point source database and satellite observations of nighttime lights. Atmos. Chem. Phys. 11, 543–556 (2011).
Oda, T. & Maksyutov, S. ODIAC Fossil Fuel CO 2 Emissions Dataset (ODIAC2016) (Center for Global Environmental Research, National Institute for Environmental Studies, 2015); https://doi.org/10.17595/20170411.001 (accessed 1 June 2017).
Shan, Y. et al. China CO2 emission accounts 1997–2015. Sci. Data 5, 170201 (2018).
Olsen, S. C. & Randerson, J. T. Differences between surface and column atmospheric CO2 and implications for carbon cycle research. J. Geophys. Res. Atmos. 109, D02301 (2004).
Feng, L., Palmer, P. I., Bösch, H. & Dance, S. Estimating surface CO2 fluxes from space-borne CO2 dry air mole fraction observations using an ensemble Kalman filter. Atmos. Chem. Phys. 9, 2619–2633 (2009).
Feng, L. et al. Evaluating a 3-D transport model of atmospheric CO2 using ground-based, aircraft, and space-borne data. Atmos. Chem. Phys. 11, 2789–2803 (2011).
Feng, L. et al. Estimates of European uptake of CO2 inferred from GOSAT XCO2 retrievals: sensitivity to measurement bias inside and outside Europe. Atmos. Chem. Phys. 16, 1289–1302 (2016).
Gurney, K. R. et al. Towards robust regional estimates of CO2 sources and sinks using atmospheric transport models. Nature 415, 626–630 (2002).
Saeki, T. & Patra, P. K. Implications of overestimated anthropogenic CO2 emissions on East Asian and global land CO2 flux inversion. Geosci. Lett. 4, 9 (2017).
Hunter, J. D. Matplotlib: a 2D graphics environment. Comput. Sci. Eng. 9, 90–95 (2007).
J.W. acknowledges support by the Strategic Priority Research Program of Chinese Academy of Sciences (grant no. XDA17010100) and funding from the UK Natural Environmental Research Council (NERC) National Centre for Earth Observation (NCEO). L.F., P.I.P. and H.B. are supported by the NERC NCEO (grant no. NE/R016518/1). H.B. acknowledges funding from the ESA CCI and C3S projects. P.I.P. also acknowledges funding from a Royal Society Wolfson Research Merit Award. Y.L. is supported by the international partnership programme of the Chinese Academy of Sciences (grant no. 134111KYSB20170010). S.F. is supported by the National Key Research and Development Program of China (grant no. 2017YFC0209700). D.Y. is supported by the National Key Research and Development Program of China (grant no. 2016YFA0600203). C.W.O. was supported by subcontracts from the OCO-2 project at the NASA Jet Propulsion Laboratory. J.W., L.F., P.I.P., Y.L., H.B. and D.Y. acknowledge funding from the ESA-MOST Dragon 3 Cooperation Programme. We gratefully acknowledge all CO2 ground observations contributors to the obspack_co2_1_GLOBALVIEWplus_v4.1_2018-10-29 and to NOAA ESRL for maintaining this database. We also acknowledge data provided by Hong Kong Observatory, the Japan–Russia Siberia Tall Tower Inland Observation Network and the World Data Centre for Greenhouse Gases. We also thank P. Somkuti for GOSAT SIF data and the broader GOSAT team who provided the L1 data.
The authors declare no competing interests.
Peer review information Nature thanks Sourish Basu, Julia Marshall, Peter Rayner and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended data figures and tables
a, Map showing the location of atmospheric CO2 measurement sites over East Asia used in our numerical experiments. Coloured dots represent individual measurement sites referred to by letter codes (Supplementary Tables 1, 2). Blue dots represent NOAA ObsPack stations, the cyan dot represents the HKG station from WDCGG, brown dots represent Siberia stations and orange dots represent CMA regional background stations. b–g, CO2 mole fraction observations (in parts per million, ppm) at the six sites across China from 2009 to 2017 used in this study. Discrete (weekly) flask air samples, denoted by blue dots, and continuous (hourly) observations, denoted by black dots, are collected and analysed by the China Meteorological Administration. CRDS, cavity ring-down spectrometer. Source data
a, Map showing the subcontinental geographical regions over China where we report a posteriori CO2 fluxes. Colours denote the proportion of each region that falls within mainland China. b–i, Monthly regional a priori and a posteriori biosphere CO2 fluxes (Pg C month−1) over China during 2010–2016. A posteriori fluxes are inferred from data used in the SR-1 and SR-2 inversions (see main text). Vertical bars and the orange envelope denote a priori and a posteriori uncertainties. NWC, northwest China; NC, northern China; NE, northeast China; TP, Tibetan Plateau; CC, central China; EC, eastern China; SW, southwest China; SE, southeast China, as shown in a. Source data
Extended Data Fig. 3 Mean spatial distribution of a priori and a posteriori land biosphere CO2 fluxes from May to September, inferred from in situ and satellite observations of CO2.
a, Our a priori fluxes. b, c, The a posteriori fluxes corresponding to inversions SR-1 and SR-2 (see main text) that use in situ data. d, e, A posteriori fluxes inferred from column observations of CO2 from GOSAT and from NASA’s OCO-2, respectively. Flux estimates reported represent a temporal mean from 2010 to 2015, except for e, which is only for 2015.
Extended Data Fig. 4 Seasonal distribution and magnitude of satellite retrievals of column CO2 from December 2014 to November 2015.
a–d, Data from GOSAT (v7.3 ACOS). e–h, Data from OCO-2 (v8r). See Methods section ‘Data’ for further information.
Extended Data Fig. 5 A priori and a posteriori monthly biosphere CO2 fluxes over China inferred from the GOSAT CO2 column data and in situ data from 2010 to 2016.
We also report a posteriori fluxes inferred from OCO-2 CO2 column from September 2014 to December 2016. Vertical bars and shaded envelopes denote a posteriori uncertainties. Higher annual fluxes inferred from GOSAT and OCO-2 are due mainly to higher a posteriori fluxes during winter months when data coverage is sparse (Extended Data Fig. 4) and the fluxes are more influenced by a priori values. Source data
Extended Data Fig. 6 Changes in forest area, forest stocks and forest coverage over six key forested Chinese provinces and over the whole of China, 1973–2013.
a–f, Values for Heilongjiang, Jilin, Liaoning, Yunnan, Guizhou and Guangxi provinces. g, Values for China. The x-axis labels refer to the National Forest Inventory of China’s State Forestry Administration: 1st (1973–1976), 2nd (1977–1981), 3rd (1984–1988), 4th (1989–1993), 5th (1994–1998), 6th (1999–2003), 7th (2004–2008) and 8th (2009–2013). Source data
a, How land cover changed from 2002 to 2012: 0 (1) denotes non-forest (forest) in both 2002 and 2012, 2 denotes conversion from non-forest to forest between 2002 and 2012, and 3 denotes conversion from forest to non-forest between 2002 and 2012. b, The forest percentage change per grid box from 2002 to 2012. Data are presented on a 0.05° × 0.05° spatial grid.
a, NDVI. b, EVI. c, LAI. d, Solar induced fluorescence (SIF). e, Net photosynthesis (PSN). f, Gross primary production (GPP). g, Above-ground biomass carbon (ABC). See Supplementary Information for details. The mean is over 2010–2012, inclusive, for ABC, and over 2010–2016 for the other data.
Extended Data Fig. 9 Forest area and stock of five forest-stand age groups over six key forested provinces and over the whole of China.
a–f, Forest area for Heilongjiang, Jilin, Liaoning, Yunnan, Guizhou and Guangxi provinces. g, Forest area for China. h–m, Forest stock for Heilongjiang, Jilin, Liaoning, Yunnan, Guizhou and Guangxi provinces. n, Forest stock for China. Forest stands are divided into five age groups: young, mid-aged, near-mature, mature and overmature. Data are taken from the 8th NFI. Source data
This file contains Supplementary Materials, including Supplementary Methods, Supplementary Notes, Supplementary Figures 114, Supplementary Tables 1–7, and Supplementary References.
About this article
Cite this article
Wang, J., Feng, L., Palmer, P.I. et al. Large Chinese land carbon sink estimated from atmospheric carbon dioxide data. Nature 586, 720–723 (2020). https://doi.org/10.1038/s41586-020-2849-9