Description: © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Earth System Science Data 6 (2014): 235-263, doi:10.5194/essd-6-235-2014.

Description: Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and a methodology to quantify all major components of the global carbon budget, including their uncertainties, based on the combination of a range of data, algorithms, statistics and model estimates and their interpretation by a broad scientific community. We discuss changes compared to previous estimates, consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil-fuel combustion and cement production (EFF) are based on energy statistics, while emissions from land-use change (ELUC), mainly deforestation, are based on combined evidence from land-cover change data, fire activity associated with deforestation, and models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The mean ocean CO2 sink (SOCEAN) is based on observations from the 1990s, while the annual anomalies and trends are estimated with ocean models. The variability in SOCEAN is evaluated for the first time in this budget with data products based on surveys of ocean CO2 measurements. The global residual terrestrial CO2 sink (SLAND) is estimated by the difference of the other terms of the global carbon budget and compared to results of independent dynamic global vegetation models forced by observed climate, CO2 and land cover change (some including nitrogen–carbon interactions). All uncertainties are reported as ±1σ, reflecting the current capacity to characterise the annual estimates of each component of the global carbon budget. For the last decade available (2003–2012), EFF was 8.6 ± 0.4 GtC yr−1, ELUC 0.9 ± 0.5 GtC yr−1, GATM 4.3 ± 0.1 GtC yr−1, SOCEAN 2.5 ± 0.5 GtC yr−1, and SLAND 2.8 ± 0.8 GtC yr−1. For year 2012 alone, EFF grew to 9.7 ± 0.5 GtC yr−1, 2.2% above 2011, reflecting a continued growing trend in these emissions, GATM was 5.1 ± 0.2 GtC yr−1, SOCEAN was 2.9 ± 0.5 GtC yr−1, and assuming an ELUC of 1.0 ± 0.5 GtC yr−1 (based on the 2001–2010 average), SLAND was 2.7 ± 0.9 GtC yr−1. GATM was high in 2012 compared to the 2003–2012 average, almost entirely reflecting the high EFF. The global atmospheric CO2 concentration reached 392.52 ± 0.10 ppm averaged over 2012. We estimate that EFF will increase by 2.1% (1.1–3.1%) to 9.9 ± 0.5 GtC in 2013, 61% above emissions in 1990, based on projections of world gross domestic product and recent changes in the carbon intensity of the economy. With this projection, cumulative emissions of CO2 will reach about 535 ± 55 GtC for 1870–2013, about 70% from EFF (390 ± 20 GtC) and 30% from ELUC (145 ± 50 GtC).

Description: We thank the many researchers and funding agencies responsible for the collection and quality control of the data included in SOCAT, and the support of the International Ocean Carbon Coordination Project (IOCCP), the Surface Ocean Lower Atmosphere Study (SOLAS), and the Integrated Marine Biogeochemistry and Ecosystem Research program (IMBER). The UK Natural Environment Research Council (NERC) provided funding to C. Le Quéré, R. Moriarty and the GCP though their International Opportunities Fund specifically to support this publication (project NE/103002X/1). R. J. Andres and T. A. Boden were supported by the US Department of Energy, Office of Science, Biological and Environmental Research (BER) programs under US Department of Energy contract DE-AC05- 00OR22725. G. P. Peters and R. M. Andrews were supported by the Norwegian Research Council (221355). A. Arneth, A. Omar, C. Le Quéré, J. Schwinger, P. Ciais, P. Friedlingstein, P. Regnier, J. Segschneider, S. Sitch and S. Zaehle were supported by the EU FP7 for funding through projects GEOCarbon (283080), COMBINE (226520), CARBOCHANGE (264879), EMBRACE (GA282672), and LUC4C (GA603542). A. Harper was supported by the NERC Joint Weather and Climate Research Programme. A. K. Jain was supported by the US National Science Foundation (NSF AGS 12-43071) the US Department of Energy, Office of Science and BER programs (DOE DE-SC0006706) and NASA LCLUC program (NASA NNX14AD94G). B. D. Stocker was supported by the Swiss National Science Foundation. A. Wiltshire was supported by the Joint UK DECC/Defra Met Office Hadley Centre Climate Programme (GA01101). E. Kato was supported by the Environment Research and Technology Development Fund (S-10) of the Ministry of Environment of Japan. J. G. Canadell and M. R. Raupach were supported by the Australian Climate Change Science Program. J. I. House was supported by a Leverhulme Research Fellowship. S. C. Doney was supported by the US National Science Foundation (NSF AGS-1048827).

Description: Author Posting. © National Academy of Sciences, 2019. This article is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences 116 (24), (2019):11646-11651, doi:10.1073/pnas.1900371116.

Description: Measurements show large decadal variability in the rate of CO2 accumulation in the atmosphere that is not driven by CO2 emissions. The decade of the 1990s experienced enhanced carbon accumulation in the atmosphere relative to emissions, while in the 2000s, the atmospheric growth rate slowed, even though emissions grew rapidly. These variations are driven by natural sources and sinks of CO2 due to the ocean and the terrestrial biosphere. In this study, we compare three independent methods for estimating oceanic CO2 uptake and find that the ocean carbon sink could be responsible for up to 40% of the observed decadal variability in atmospheric CO2 accumulation. Data-based estimates of the ocean carbon sink from pCO2 mapping methods and decadal ocean inverse models generally agree on the magnitude and sign of decadal variability in the ocean CO2 sink at both global and regional scales. Simulations with ocean biogeochemical models confirm that climate variability drove the observed decadal trends in ocean CO2 uptake, but also demonstrate that the sensitivity of ocean CO2 uptake to climate variability may be too weak in models. Furthermore, all estimates point toward coherent decadal variability in the oceanic and terrestrial CO2 sinks, and this variability is not well-matched by current global vegetation models. Reconciling these differences will help to constrain the sensitivity of oceanic and terrestrial CO2 uptake to climate variability and lead to improved climate projections and decadal climate predictions.

Description: We thank Rebecca Wright and Erik Buitenhuis at University of East Anglia, Norwich, for providing updated runs from the NEMO-PlankTOM5 model. T.D. was supported by NSF Grant OCE-1658392. C.L.Q. thanks the UK Natural Environment Research Council for supporting the SONATA Project (Grant NE/P021417/1). P.L. was supported by the Max Planck Society for the Advancement of Science. J.H. was supported under Helmholtz Young Investigator Group Marine Carbon and Ecosystem Feedbacks in the Earth System (MarESys) Grant VH-NG-1301. S.B. and R.S. were supported by the H2020 project CRESCENDO “Coordinated Research in Earth Systems and Climate: Experiments, Knowledge, Dissemination and Outreach,” which received funding from the European Union’s Horizon 2020 research and innovation program under Grant No 641816. SOCAT is an international effort, endorsed by the International Ocean Carbon Coordination Project, the Surface Ocean-Lower Atmosphere Study, and the Integrated Marine Biosphere Research program, to deliver a uniformly quality-controlled surface ocean CO2 database. The many researchers and funding agencies responsible for the collection of data and quality control are thanked for their contributions to SOCAT.

Description: 2019-11-28