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Net carbon emissions from African biosphere dominate pan-tropical atmospheric CO2 signal.

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journal contribution
posted on 16.08.2019, 14:30 by PI Palmer, L Feng, D Baker, F Chevallier, H Bösch, P Somkuti
Tropical ecosystems are large carbon stores that are vulnerable to climate change. The sparseness of ground-based measurements has precluded verification of these ecosystems being a net annual source (+ve) or sink (-ve) of atmospheric carbon. We show that two independent satellite data sets of atmospheric carbon dioxide (CO2), interpreted using independent models, are consistent with the land tropics being a net annual carbon emission of [Formula: see text] [Formula: see text] and [Formula: see text] petagrams (PgC) in 2015 and 2016, respectively. These pan-tropical estimates reflect unexpectedly large net emissions from tropical Africa of [Formula: see text] PgC in 2015 and [Formula: see text] PgC in 2016. The largest carbon uptake is over the Congo basin, and the two loci of carbon emissions are over western Ethiopia and western tropical Africa, where there are large soil organic carbon stores and where there has been substantial land use change. These signals are present in the space-borne CO2 record from 2009 onwards.


P.I.P., L.F., and H.B. acknowledge support from the UK National Centre for Earth Observation (NCEO). The Natural Environment Research Council provides national capability funding for NCEO (grant # PR140015). P.I.P. also acknowledges his Royal Society Research Merit Award, and discussions with Chris O’Dell (CSU), the wider OCO-2 science team, Bertrand Guenet (LSCE), Ian Baker (CSU), Seifu Kebede (Addis Ababa University), David Mattey (Royal Holloway, U. London), and Tom Pugh (U. Birmingham) on the results reported. F.C. was funded by the Copernicus Atmosphere Monitoring Service, implemented by the European Centre for Medium-Range Weather Forecasts (ECMWF) on behalf of the European Commission, and was granted access to the HPC resources of TGCC under the allocation A0030102201. H.B. also acknowledges funding from the Copernicus Climate Change Service C3S. We thank Jasdeep Anand for processing the University of Leicester GOSAT L2 data, distributed via the C3S and ESA CCI projects. We gratefully acknowledge all CO2 ground observations contributors to the ObsPack and to NOAA ESRL for maintaining this database. We gratefully acknowledge the NASA MODIS, OMI, and GRACE teams for providing their L2 data. We also thank the broader GOSAT team who provided their L1 data. The ACOS GOSAT and OCO-2 data were produced by the ACOS and OCO-2 projects at the Jet Propulsion Laboratory, California Institute of Technology. The ACOS/GOSAT data were obtained from the JPL website, co2.jpl.nasa.gov, while the OCO-2 data were obtained from the OCO-2 data archive maintained at the NASA Goddard Earth Science Data and Information Services Center. The spectra used to develop the ACOS/GOSAT product were provided by the GOSAT project team in Japan. The authors thank the ORCHIDEE development team for sharing their detailed simulation results.



Nature Communications, 2019, volume 10, Article number: 3344

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/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy


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Supplementary Information accompanies this paper at https://doi.org/10.1038/s41467-019-11097-w.



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