Accurate assessment of anthropogenic carbon dioxide (CO₂) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical 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 (E_FOS) are based on energy statistics and cement production data, while emissions from land-use change (E_LUC), 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 (G_ATM) is computed from the annual changes in concentration. The ocean CO₂ sink (S_OCEAN) is estimated with global ocean biogeochemistry models and observation-based f CO₂ products. The terrestrial CO₂ sink (S_LAND) is estimated with dynamic global vegetation models. Additional lines of evidence on land and ocean sinks are provided by atmospheric inversions, atmospheric oxygen measurements, and Earth system models. The resulting carbon budget imbalance (B_IM), 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 incomplete understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the year 2022, E_FOS increased by 0.9 % relative to 2021, with fossil emissions at 9.9±0.5 Gt C yr⁻¹ (10.2±0.5 Gt C yr⁻¹ when the cement carbonation sink is not included), and E_LUC was 1.2±0.7 Gt C yr⁻¹, for a total anthropogenic CO₂ emission (including the cement carbonation sink) of 11.1±0.8 Gt C yr⁻¹ (40.7±3.2 Gt CO₂ yr⁻¹). Also, for 2022, G_ATM was 4.6±0.2 Gt C yr⁻¹ (2.18±0.1 ppm yr⁻¹; ppm denotes parts per million), S_OCEAN was 2.8±0.4 Gt C yr⁻¹, and S_LAND was 3.8±0.8 Gt C yr⁻¹, with a B_IM of −0.1 Gt C yr⁻¹ (i.e. total estimated sources marginally too low or sinks marginally too high). The global atmospheric CO₂ concentration averaged over 2022 reached 417.1±0.1 ppm. Preliminary data for 2023 suggest an increase in E_FOS relative to 2022 of +1.1 % (0.0 % to 2.1 %) globally and atmospheric CO₂ concentration reaching 419.3 ppm, 51 % above the pre-industrial level (around 278 ppm in 1750). Overall, the mean of and trend in the components of the global carbon budget are consistently estimated over the period 1959–2022, with a near-zero overall budget imbalance, although discrepancies of up to around 1 Gt C yr⁻¹ persist for the representation of annual to semi-decadal variability in CO₂ fluxes. Comparison of estimates from multiple approaches and observations shows the following: (1) a persistent large uncertainty in the estimate of land-use changes emissions, (2) a low agreement between the different methods on the magnitude of the land CO₂ flux in the northern extra-tropics, and (3) a discrepancy between the different methods on the strength of the ocean sink over the last decade. This living-data update documents changes in methods and data sets applied to this most recent global carbon budget as well as evolving community understanding of the global carbon cycle. The data presented in this work are available at https://doi.org/10.18160/GCP-2023 (Friedlingstein et al., 2023).

Accurate assessment of anthropogenic carbon dioxide (CO₂) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere in a changing climate is critical to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe and synthesize datasets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO₂ emissions (E_FOS) are based on energy statistics and cement production data, while emissions from land-use change (E_LUC), 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 (G_ATM) is computed from the annual changes in concentration. The ocean CO₂ sink (S_OCEAN) is estimated with global ocean biogeochemistry models and observation-based data products. The terrestrial CO₂ sink (S_LAND) is estimated with dynamic global vegetation models. The resulting carbon budget imbalance (B_IM), 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 first time, an approach is shown to reconcile the difference in our E_LUC estimate with the one from national greenhouse gas inventories, supporting the assessment of collective countries' climate progress. For the year 2020, E_FOS declined by 5.4 % relative to 2019, with fossil emissions at 9.5 ± 0.5 GtC yr⁻¹ (9.3 ± 0.5 GtC yr⁻¹ when the cement carbonation sink is included), and E_LUC was 0.9 ± 0.7 GtC yr⁻¹, for a total anthropogenic CO₂ emission of 10.2 ± 0.8 GtC yr⁻¹ (37.4 ± 2.9 GtCO₂). Also, for 2020, G_ATM was 5.0 ± 0.2 GtC yr⁻¹ (2.4 ± 0.1 ppm yr⁻¹), S_OCEAN was 3.0 ± 0.4 GtC yr⁻¹, and S_LAND was 2.9 ± 1 GtC yr⁻¹, with a B_IM of −0.8 GtC yr⁻¹. The global atmospheric CO₂ concentration averaged over 2020 reached 412.45 ± 0.1 ppm. Preliminary data for 2021 suggest a rebound in E_FOS relative to 2020 of +4.8 % (4.2 % to 5.4 %) globally. Overall, the mean and trend in the components of the global carbon budget are consistently estimated over the period 1959–2020, but discrepancies of up to 1 GtC yr⁻¹ persist for the representation of annual to semi-decadal variability in CO₂ fluxes. Comparison of estimates from multiple approaches and observations shows (1) a persistent large uncertainty in the estimate of land-use changes emissions, (2) a low agreement between the different methods on the magnitude of the land CO₂ flux in the northern extra-tropics, and (3) a discrepancy between the different methods on the strength of the ocean sink over the last decade. This living data update documents changes in the methods and datasets used in this new global carbon budget and the progress in understanding of the global carbon cycle compared with previous publications of this dataset (Friedlingstein et al., 2020, 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-2021 (Friedlingstein et al., 2021).

Accurate assessment of anthropogenic carbon dioxide (CO₂) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere – 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 data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. Fossil CO₂ emissions (E_FF) are based on energy statistics and cement production data, while emissions from land use change (E_LUC), 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 (G_ATM) is computed from the annual changes in concentration. The ocean CO₂ sink (S_OCEAN) and terrestrial CO₂ sink (S_LAND) are estimated with global process models constrained by observations. The resulting carbon budget imbalance (B_IM), 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 (2009–2018), E_FF was 9.5±0.5 GtC yr⁻¹, E_LUC 1.5±0.7 GtC yr⁻¹, G_ATM 4.9±0.02 GtC yr⁻¹ (2.3±0.01 ppm yr⁻¹), S_OCEAN 2.5±0.6 GtC yr⁻¹, and S_LAND 3.2±0.6 GtC yr⁻¹, with a budget imbalance B_IM of 0.4 GtC yr⁻¹ indicating overestimated emissions and/or underestimated sinks. For the year 2018 alone, the growth in E_FF was about 2.1 % and fossil emissions increased to 10.0±0.5 GtC yr⁻¹, reaching 10 GtC yr⁻¹ for the first time in history, E_LUC was 1.5±0.7 GtC yr⁻¹, for total anthropogenic CO₂ emissions of 11.5±0.9 GtC yr⁻¹ (42.5±3.3 GtCO₂). Also for 2018, G_ATM was 5.1±0.2 GtC yr⁻¹ (2.4±0.1 ppm yr⁻¹), S_OCEAN was 2.6±0.6 GtC yr⁻¹, and S_LAND was 3.5±0.7 GtC yr⁻¹, with a B_IM of 0.3 GtC. The global atmospheric CO₂ concentration reached 407.38±0.1 ppm averaged over 2018. For 2019, preliminary data for the first 6–10 months indicate a reduced growth in E_FF of +0.6 % (range of −0.2 % to 1.5 %) based on national emissions projections for China, the USA, the EU, and India and projections of gross domestic product corrected for recent changes in the carbon intensity of the economy for the rest of the world. Overall, the mean and trend in the five components of the global carbon budget are consistently estimated over the period 1959–2018, but discrepancies of up to 1 GtC yr⁻¹ persist for the representation of semi-decadal variability in CO₂ fluxes. A detailed comparison among individual estimates and the introduction of a broad range of 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 underestimation of the CO₂ variability by ocean models outside the tropics. 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 (Le Quéré et al., 2018a, b, 2016, 2015a, b, 2014, 2013). The data generated by this work are available at https://doi.org/10.18160/gcp-2019 (Friedlingstein et al., 2019).

Accurate assessment of anthropogenic carbon dioxide (CO₂) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere – 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 data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. CO₂ emissions from fossil fuels and industry (E_FF) are based on energy statistics and cement production data, respectively, while emissions from land-use change (E_LUC), mainly deforestation, are based on land-cover change data and bookkeeping models. The global atmospheric CO₂ concentration is measured directly and its rate of growth (G_ATM) is computed from the annual changes in concentration. The ocean CO₂ sink (S_OCEAN) and terrestrial CO₂ sink (S_LAND) are estimated with global process models constrained by observations. The resulting carbon budget imbalance (B_IM), 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 (2007–2016), E_FF was 9.4 ± 0.5 GtC yr⁻¹, E_LUC 1.3 ± 0.7 GtC yr⁻¹, G_ATM 4.7 ± 0.1 GtC yr⁻¹, S_OCEAN 2.4 ± 0.5 GtC yr⁻¹, and S_LAND 3.0 ± 0.8 GtC yr⁻¹, with a budget imbalance B_IM of 0.6 GtC yr⁻¹ indicating overestimated emissions and/or underestimated sinks. For year 2016 alone, the growth in E_FF was approximately zero and emissions remained at 9.9 ± 0.5 GtC yr⁻¹. Also for 2016, E_LUC was 1.3 ± 0.7 GtC yr⁻¹, G_ATM was 6.1 ± 0.2 GtC yr⁻¹, S_OCEAN was 2.6 ± 0.5 GtC yr⁻¹, and S_LAND was 2.7 ± 1.0 GtC yr⁻¹, with a small B_IM of −0.3 GtC. G_ATM continued to be higher in 2016 compared to the past decade (2007–2016), reflecting in part the high fossil emissions and the small S_LAND consistent with El Niño conditions. The global atmospheric CO₂ concentration reached 402.8 ± 0.1 ppm averaged over 2016. For 2017, preliminary data for the first 6–9 months indicate a renewed growth in E_FF of +2.0 % (range of 0.8 to 3.0 %) based on national emissions projections for China, USA, and India, and projections of gross domestic product (GDP) corrected for recent changes in the carbon intensity of the economy for the rest of the world. This living data update documents changes in the methods and data sets used in this new global carbon budget compared with previous publications of this data set (Le Quéré et al., 2016, 2015b, a, 2014, 2013). All results presented here can be downloaded from https://doi.org/10.18160/GCP-2017 (GCP, 2017).