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Global carbon budget 2020

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Friedlingstein, P and O'Sullivan, M and Jones, MW and Andrew, RM and Hauck, J and Olsen, A and Peters, GP and Peters, W and Pongratz, J and Sitch, S and Le Quere, C and Canadell, JG and Ciais, P and Jackson, RB and Alin, S and Aragao, LEOC and Arneth, A and Arora, V and Bates, NR and Becker, M and Benoit-Cattin, A and Bittig, HC and Bopp, L and Bultan, S and Chandra, N and Chevallier, F and Chini, LP and Evans, W and Florentie, L and Forster, PM and Gasser, T and Gehlen, M and Gilfillan, D and Gkritzalis, T and Gregor, L and Gruber, N and Harris, I and Hartung, K and Haverd, V and Houghton, RA and Ilyina, T and Jain, AK and Joetzjer, E and Kadono, K and Kato, E and Kitidis, V and Korsbakken, JI and Landschutzer, P and Lefevre, N and Lenton, A and Lienert, S and Liu, Z and Lombardozzi, D and Marland, G and Metzl, N and Munro, DR and Nabel, JEMS and Nakaoka, SI and Niwa, Y and O'Brien, K and Ono, T and Palmer, PI and Pierrot, D and Poulter, B and Resplandy, L and Robertson, E and Rodenbeck, C and Schwinger, J and Seferian, R and Skjelvan, I and Smith, AJP and Sutton, AJ and Tanhua, T and Tans, PP and Tian, H and Tilbrook, B and Van Der Werf, G and Vuichard, N and Walker, AP and Wanninkhof, R and Watson, AJ and Willis, D and Wiltshire, AJ and Yuan, W and Yue, X and Zaehle, S, Global carbon budget 2020, Earth System Science Data, 12, (4) pp. 3269-3340. ISSN 1866-3508 (2020) [Refereed Article]


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DOI: doi:10.5194/essd-12-3269-2020

Abstract

Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate – the "global carbon budget" – is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO2 emissions (EFOS) are based on energy statistics and cement production data, while emissions from land-use change (ELUC), mainly deforestation, are based on land use and land-use change data and bookkeeping models. Atmospheric CO2 concentration is measured directly and its growth rate (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) and terrestrial CO2 sink (SLAND) are estimated with global process models constrained by observations. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the last decade available (2010–2019), EFOS was 9.6 ± 0.5 GtC yr−1 excluding the cement carbonation sink (9.4 ± 0.5 GtC yr−1 when the cement carbonation sink is included), and ELUC was 1.6 ± 0.7 GtC yr−1. For the same decade, GATM was 5.1 ± 0.02 GtC yr−1 (2.4 ± 0.01 ppm yr−1), SOCEAN 2.5 ±  0.6 GtC yr−1, and SLAND 3.4 ± 0.9 GtC yr−1, with a budget imbalance BIM of 0.1 GtC yr−1 indicating a near balance between estimated sources and sinks over the last decade. For the year 2019 alone, the growth in EFOS was only about 0.1 % with fossil emissions increasing to 9.9 ± 0.5 GtC yr−1 excluding the cement carbonation sink (9.7 ± 0.5 GtC yr−1 when cement carbonation sink is included), and ELUC was 1.8 ± 0.7 GtC yr−1, for total anthropogenic CO2 emissions of 11.5 ± 0.9 GtC yr−1 (42.2 ± 3.3 GtCO2). Also for 2019, GATM was 5.4 ± 0.2 GtC yr−1 (2.5 ± 0.1 ppm yr−1), SOCEAN was 2.6 ± 0.6 GtC yr−1, and SLAND was 3.1 ± 1.2 GtC yr−1, with a BIM of 0.3 GtC. The global atmospheric CO2 concentration reached 409.85 ± 0.1 ppm averaged over 2019. Preliminary data for 2020, accounting for the COVID-19-induced changes in emissions, suggest a decrease in EFOS relative to 2019 of about 7 % (median estimate) based on individual estimates from four studies of 6 %, 7 %, 7 % (3 % to 11 %), and 13 %. Overall, the mean and trend in the components of the global carbon budget are consistently estimated over the period 1959–2019, but discrepancies of up to 1 GtC yr−1 persist for the representation of semi-decadal variability in CO2 fluxes. Comparison of estimates from diverse approaches and observations shows (1) no consensus in the mean and trend in land-use change emissions over the last decade, (2) a persistent low agreement between the different methods on the magnitude of the land CO2 flux in the northern extra-tropics, and (3) an apparent discrepancy between the different methods for the ocean sink outside the tropics, particularly in the Southern Ocean. This living data update documents changes in the methods and data sets used in this new global carbon budget and the progress in understanding of the global carbon cycle compared with previous publications of this data set (Friedlingstein et al., 2019; Le Quéré et al., 2018b, a, 2016, 2015b, a, 2014, 2013). The data presented in this work are available at https://doi.org/10.18160/gcp-2020 (Friedlingstein et al., 2020).

Item Details

Item Type:Refereed Article
Keywords:global carbon budget, carbon dioxide, climate change, CO2 emissions
Research Division:Earth Sciences
Research Group:Climate change science
Research Field:Greenhouse gas inventories and fluxes
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Global effects of climate change (excl. Australia, New Zealand, Antarctica and the South Pacific) (excl. social impacts)
UTAS Author:Tilbrook, B (Dr Bronte Tilbrook)
ID Code:150545
Year Published:2020
Web of Science® Times Cited:466
Deposited By:Sustainable Marine Research Collaboration
Deposited On:2022-06-20
Last Modified:2022-06-20
Downloads:0

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