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ArticleComparing food web structures and dynamics across a suite of global marine ecosystem models(Elsevier, 2013-05-16) Sailley, Sevrine F. ; Vogt, Meike ; Doney, Scott C. ; Aita, M. N. ; Bopp, Laurent ; Buitenhuis, Erik T. ; Hashioka, Taketo ; Lima, Ivan D. ; Le Quere, Corinne ; Yamanaka, YasuhiroDynamic Green Ocean Models (DGOMs) include different sets of Plankton Functional Types (PFTs) and equations, thus different interactions and food webs. Using four DGOMs (CCSM-BEC, PISCES, NEMURO and PlankTOM5) we explore how predator–prey interactions influence food web dynamics. Using each model's equations and biomass output, interaction strengths (direct and specific) were calculated and the role of zooplankton in modeled food webs examined. In CCSM-BEC the single size-class adaptive zooplankton preys on different phytoplankton groups according to prey availability and food preferences, resulting in a strong top-down control. In PISCES the micro- and meso-zooplankton groups compete for food resources, grazing phytoplankton depending on their availability in a mixture of bottom-up and top-down control. In NEMURO macrozooplankton controls the biomass of other zooplankton PFTs and defines the structure of the food web with a strong top-down control within the zooplankton. In PlankTOM5, competition and predation between micro- and meso-zooplankton along with strong preferences for nanophytoplankton and diatoms, respectively, leads to their mutual exclusion with a mixture of bottom-up and top-down control of the plankton community composition. In each model, the grazing pressure of the zooplankton PFTs and the way it is exerted on their preys may result in the food web dynamics and structure of the model to diverge from the one that was intended when designing the model. Our approach shows that the food web dynamics, in particular the strength of the predator–prey interactions, are driven by the choice of parameters and more specifically the food preferences. Consequently, our findings stress the importance of equation and parameter choice as they define interactions between PFTs and overall food web dynamics (competition, bottom-up or top-down effects). Also, the differences in the simulated food-webs between different models highlight the gap of knowledge for zooplankton rates and predator–prey interactions. In particular, concerted effort is needed to identify the key growth and loss parameters and interactions and quantify them with targeted laboratory experiments in order to bring our understanding of zooplankton at a similar level to phytoplankton.
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ArticleNorth Pacific carbon cycle response to climate variability on seasonal to decadal timescales(American Geophysical Union, 2006-07-04) McKinley, Galen A. ; Takahashi, Taro ; Buitenhuis, Erik T. ; Chai, Fei ; Christian, James R. ; Doney, Scott C. ; Jiang, Mingshun ; Lindsay, Keith ; Moore, J. Keith ; Le Quere, Corinne ; Lima, Ivan D. ; Murtugudde, Raghu ; Shi, L. ; Wetzel, PatrickClimate variability drives significant changes in the physical state of the North Pacific, and thus there may be important impacts of climate variability on the upper ocean carbon balance across the basin. We address this issue by considering the response of seven biogeochemical ocean models to climate variability in the North Pacific. The models’ upper ocean pCO2 and air-sea CO2 flux respond similarly to climate variability on seasonal to decadal timescales. Modeled seasonal cycles of pCO2 and its temperature and non-temperature driven components at three contrasting oceanographic sites capture the basic features found in observations [Takahashi et al., 2002, 2006; Keeling et al., 2004; Brix et al., 2004]. However, particularly in the Western Subarctic Gyre, the models have difficulty representing the temporal structure of the total pCO2 cycle because it results from the difference of these two large and opposing components. In all but one model, the airsea CO2 flux interannual variability (1σ) in the North Pacific is smaller (ranges across models from 0.03 to 0.11 PgC/yr) than in the Tropical Pacific (ranges across models from 0.08 to 0.19 PgC/yr), and the timeseries of the first or second EOF of the air-sea CO2 flux has a significant correlation with the Pacific Decadal Oscillation (PDO). Though air-sea CO2 flux anomalies are correlated with the PDO, their magnitudes are small (up to ±0.025 PgC/yr (1σ)). Flux anomalies are damped because anomalies in the key drivers of pCO2 (temperature, dissolved inorganic carbon (DIC) and alkalinity) are all of similar magnitude and have strongly opposing effects that damp total pCO2 anomalies.
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ArticleRecent trends and drivers of regional sources and sinks of carbon dioxide(Copernicus Publications on behalf of the European Geosciences Union, 2015-02-02) Sitch, Stephen ; Friedlingstein, Pierre ; Gruber, Nicolas ; Jones, S. D. ; Murray-Tortarolo, G. ; Ahlstrom, Andreas P. ; Doney, Scott C. ; Graven, Heather ; Heinze, Christoph ; Huntingford, Chris ; Levis, Samuel ; Levy, Peter E. ; Lomas, Mark ; Poulter, Benjamin ; Viovy, Nicolas ; Zaehle, Sonke ; Zeng, Ning ; Arneth, Almut ; Bonan, Gordon B. ; Bopp, Laurent ; Canadell, Josep G. ; Chevallier, Frédéric ; Ciais, Philippe ; Ellis, Richard ; Gloor, Emanuel ; Peylin, Philippe ; Piao, S. L. ; Le Quere, Corinne ; Smith, Benjamin ; Zhu, Zaichun ; Myneni, RangaThe land and ocean absorb on average just over half of the anthropogenic emissions of carbon dioxide (CO2) every year. These CO2 "sinks" are modulated by climate change and variability. Here we use a suite of nine dynamic global vegetation models (DGVMs) and four ocean biogeochemical general circulation models (OBGCMs) to estimate trends driven by global and regional climate and atmospheric CO2 in land and oceanic CO2 exchanges with the atmosphere over the period 1990–2009, to attribute these trends to underlying processes in the models, and to quantify the uncertainty and level of inter-model agreement. The models were forced with reconstructed climate fields and observed global atmospheric CO2; land use and land cover changes are not included for the DGVMs. Over the period 1990–2009, the DGVMs simulate a mean global land carbon sink of −2.4 ± 0.7 Pg C yr−1 with a small significant trend of −0.06 ± 0.03 Pg C yr−2 (increasing sink). Over the more limited period 1990–2004, the ocean models simulate a mean ocean sink of −2.2 ± 0.2 Pg C yr−1 with a trend in the net C uptake that is indistinguishable from zero (−0.01 ± 0.02 Pg C yr−2). The two ocean models that extended the simulations until 2009 suggest a slightly stronger, but still small, trend of −0.02 ± 0.01 Pg C yr−2. Trends from land and ocean models compare favourably to the land greenness trends from remote sensing, atmospheric inversion results, and the residual land sink required to close the global carbon budget. Trends in the land sink are driven by increasing net primary production (NPP), whose statistically significant trend of 0.22 ± 0.08 Pg C yr−2 exceeds a significant trend in heterotrophic respiration of 0.16 ± 0.05 Pg C yr−2 – primarily as a consequence of widespread CO2 fertilisation of plant production. Most of the land-based trend in simulated net carbon uptake originates from natural ecosystems in the tropics (−0.04 ± 0.01 Pg C yr−2), with almost no trend over the northern land region, where recent warming and reduced rainfall offsets the positive impact of elevated atmospheric CO2 and changes in growing season length on carbon storage. The small uptake trend in the ocean models emerges because climate variability and change, and in particular increasing sea surface temperatures, tend to counter\-act the trend in ocean uptake driven by the increase in atmospheric CO2. Large uncertainty remains in the magnitude and sign of modelled carbon trends in several regions, as well as regarding the influence of land use and land cover changes on regional trends.
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ArticleGlobal ocean carbon uptake : magnitude, variability and trends(Copernicus Publications on behalf of the European Geosciences Union, 2013-03-22) Wanninkhof, Rik ; Park, Geun-Ha ; Takahashi, Taro ; Sweeney, Colm ; Feely, Richard A. ; Nojiri, Yukihiro ; Gruber, Nicolas ; Doney, Scott C. ; McKinley, Galen A. ; Lenton, Andrew ; Le Quere, Corinne ; Heinze, Christoph ; Schwinger, Jorg ; Graven, Heather ; Khatiwala, SamarThe globally integrated sea–air anthropogenic carbon dioxide (CO2) flux from 1990 to 2009 is determined from models and data-based approaches as part of the Regional Carbon Cycle Assessment and Processes (RECCAP) project. Numerical methods include ocean inverse models, atmospheric inverse models, and ocean general circulation models with parameterized biogeochemistry (OBGCMs). The median value of different approaches shows good agreement in average uptake. The best estimate of anthropogenic CO2 uptake for the time period based on a compilation of approaches is −2.0 Pg C yr−1. The interannual variability in the sea–air flux is largely driven by large-scale climate re-organizations and is estimated at 0.2 Pg C yr−1 for the two decades with some systematic differences between approaches. The largest differences between approaches are seen in the decadal trends. The trends range from −0.13 (Pg C yr−1) decade−1 to −0.50 (Pg C yr−1) decade−1 for the two decades under investigation. The OBGCMs and the data-based sea–air CO2 flux estimates show appreciably smaller decadal trends than estimates based on changes in carbon inventory suggesting that methods capable of resolving shorter timescales are showing a slowing of the rate of ocean CO2 uptake. RECCAP model outputs for five decades show similar differences in trends between approaches.
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ArticleDecadal trends in the ocean carbon sink(National Academy of Sciences, 2019-05-28) DeVries, Timothy ; Le Quere, Corinne ; Andrews, Oliver D. ; Berthet, Sarah ; Hauck, Judith ; Ilyina, Tatiana ; Landschützer, Peter ; Lenton, Andrew ; Lima, Ivan D. ; Nowicki, Michael ; Schwinger, Jorg ; Séférian, RolandMeasurements 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.
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ArticlePhytoplankton competition during the spring bloom in four plankton functional type models(Copernicus Publications on behalf of the European Geosciences Union, 2013-11-02) Hashioka, Taketo ; Vogt, Meike ; Yamanaka, Yasuhiro ; Le Quere, Corinne ; Buitenhuis, Erik T. ; Aita, M. N. ; Alvain, S. ; Bopp, Laurent ; Hirata, T. ; Lima, Ivan D. ; Sailley, Sevrine F. ; Doney, Scott C.We investigated the mechanisms of phytoplankton competition during the spring bloom, one of the most dramatic seasonal events in lower-trophic-level ecosystems, in four state-of-the-art plankton functional type (PFT) models: PISCES, NEMURO, PlankTOM5 and CCSM-BEC. In particular, we investigated the relative importance of different ecophysiological processes on the determination of the community structure, focusing both on the bottom-up and the top-down controls. The models reasonably reproduced the observed global distribution and seasonal variation of phytoplankton biomass. The fraction of diatoms with respect to the total phytoplankton biomass increases with the magnitude of the spring bloom in all models. However, the governing mechanisms differ between models, despite the fact that current PFT models represent ecophysiological processes using the same types of parameterizations. The increasing trend in the percentage of diatoms with increasing bloom magnitude is mainly caused by a stronger nutrient dependence of diatom growth compared to nanophytoplankton (bottom-up control). The difference in the maximum growth rate plays an important role in NEMURO and PlankTOM5 and determines the absolute values of the percentage of diatoms during the bloom. In CCSM-BEC, the light dependency of growth plays an important role in the North Atlantic and the Southern Ocean. The grazing pressure by zooplankton (top-down control), however, strongly contributes to the dominance of diatoms in PISCES and CCSM-BEC. The regional differences in the percentage of diatoms in PlankTOM5 are mainly determined by top-down control. These differences in the mechanisms suggest that the response of marine ecosystems to climate change could significantly differ among models, even if the present-day ecosystem is reproduced to a similar degree of confidence. For further understanding of plankton competition and for the prediction of future change in marine ecosystems, it is important to understand the relative differences in each physiological rate and life history rate in the bottom-up and the top-down controls between PFTs.
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ArticleGlobal carbon budget 2017(Copernicus Publications on behalf of the European Geosciences Union, 2018-03-12) Le Quere, Corinne ; Andrew, Robbie M. ; Friedlingstein, Pierre ; Sitch, Stephen ; Pongratz, Julia ; Manning, Andrew C. ; Korsbakken, Jan Ivar ; Peters, Glen P. ; Canadell, Josep G. ; Jackson, Robert B. ; Boden, Thomas A. ; Tans, Pieter P. ; Andrews, Oliver D. ; Arora, Vivek K. ; Bakker, Dorothee ; Barbero, Leticia ; Becker, Meike ; Betts, Richard A. ; Bopp, Laurent ; Chevallier, Frédéric ; Chini, Louise Parsons ; Ciais, Philippe ; Cosca, Catherine E. ; Cross, Jessica N. ; Currie, Kim I. ; Gasser, Thomas ; Harris, Ian ; Hauck, Judith ; Haverd, Vanessa ; Houghton, Richard A. ; Hunt, Christopher W. ; Hurtt, George ; Ilyina, Tatiana ; Jain, Atul K. ; Kato, Etsushi ; Kautz, Markus ; Keeling, Ralph F. ; Klein Goldewijk, Kees ; Körtzinger, Arne ; Landschützer, Peter ; Lefèvre, Nathalie ; Lenton, Andrew ; Lienert, Sebastian ; Lima, Ivan D. ; Lombardozzi, Danica ; Metzl, Nicolas ; Millero, Frank J. ; Monteiro, Pedro M. S. ; Munro, David R. ; Nabel, Julia E. M. S. ; Nakaoka, Shin-ichiro ; Nojiri, Yukihiro ; Padin, X. Antonio ; Peregon, Anna ; Pfeil, Benjamin ; Pierrot, Denis ; Poulter, Benjamin ; Rehder, Gregor ; Reimer, Janet ; Rödenbeck, Christian ; Schwinger, Jorg ; Séférian, Roland ; Skjelvan, Ingunn ; Stocker, Benjamin D. ; Tian, Hanqin ; Tilbrook, Bronte ; Tubiello, Francesco N. ; van der Laan-Luijkx, Ingrid T. ; van der Werf, Guido R. ; van Heuven, Steven ; Viovy, Nicolas ; Vuichard, Nicolas ; Walker, Anthony P. ; Watson, Andrew J. ; Wiltshire, Andrew J. ; Zaehle, Sonke ; Zhu, DanAccurate 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 (EFF) are based on energy statistics and cement production data, respectively, while emissions from land-use change (ELUC), 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 (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 (2007–2016), EFF was 9.4 ± 0.5 GtC yr−1, ELUC 1.3 ± 0.7 GtC yr−1, GATM 4.7 ± 0.1 GtC yr−1, SOCEAN 2.4 ± 0.5 GtC yr−1, and SLAND 3.0 ± 0.8 GtC yr−1, with a budget imbalance BIM of 0.6 GtC yr−1 indicating overestimated emissions and/or underestimated sinks. For year 2016 alone, the growth in EFF was approximately zero and emissions remained at 9.9 ± 0.5 GtC yr−1. Also for 2016, ELUC was 1.3 ± 0.7 GtC yr−1, GATM was 6.1 ± 0.2 GtC yr−1, SOCEAN was 2.6 ± 0.5 GtC yr−1, and SLAND was 2.7 ± 1.0 GtC yr−1, with a small BIM of −0.3 GtC. GATM continued to be higher in 2016 compared to the past decade (2007–2016), reflecting in part the high fossil emissions and the small SLAND 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 EFF 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).
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ArticleGlobal Carbon Budget 2016(Copernicus Publications, 2016-11-14) Le Quere, Corinne ; Andrew, Robbie M. ; Canadell, Josep G. ; Sitch, Stephen ; Korsbakken, Jan Ivar ; Peters, Glen P. ; Manning, Andrew C. ; Boden, Thomas A. ; Tans, Pieter P. ; Houghton, Richard A. ; Keeling, Ralph F. ; Alin, Simone R. ; Andrews, Oliver D. ; Anthoni, Peter ; Barbero, Leticia ; Bopp, Laurent ; Chevallier, Frédéric ; Chini, Louise Parsons ; Ciais, Philippe ; Currie, Kim I. ; Delire, Christine ; Doney, Scott C. ; Friedlingstein, Pierre ; Gkritzalis, Thanos ; Harris, Ian ; Hauck, Judith ; Haverd, Vanessa ; Hoppema, Mario ; Klein Goldewijk, Kees ; Jain, Atul K. ; Kato, Etsushi ; Körtzinger, Arne ; Landschützer, Peter ; Lefèvre, Nathalie ; Lenton, Andrew ; Lienert, Sebastian ; Lombardozzi, Danica ; Melton, Joe R. ; Metzl, Nicolas ; Millero, Frank J. ; Monteiro, Pedro M. S. ; Munro, David R. ; Nabel, Julia E. M. S. ; Nakaoka, Shin-ichiro ; O'Brien, Kevin ; Olsen, Are ; Omar, Abdirahman M. ; Ono, Tsuneo ; Pierrot, Denis ; Poulter, Benjamin ; Rödenbeck, Christian ; Salisbury, Joseph E. ; Schuster, Ute ; Schwinger, Jorg ; Séférian, Roland ; Skjelvan, Ingunn ; Stocker, Benjamin D. ; Sutton, Adrienne J. ; Takahashi, Taro ; Tian, Hanqin ; Tilbrook, Bronte ; van der Laan-Luijkx, Ingrid ; van der Werf, Guido R. ; Viovy, Nicolas ; Walker, Anthony P. ; Wiltshire, Andrew J. ; Zaehle, SonkeAccurate 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 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 and consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuels and industry (EFF) are based on energy statistics and cement production data, respectively, 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 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. We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. 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 (2006–2015), EFF was 9.3 ± 0.5 GtC yr−1, ELUC 1.0 ± 0.5 GtC yr−1, GATM 4.5 ± 0.1 GtC yr−1, SOCEAN 2.6 ± 0.5 GtC yr−1, and SLAND 3.1 ± 0.9 GtC yr−1. For year 2015 alone, the growth in EFF was approximately zero and emissions remained at 9.9 ± 0.5 GtC yr−1, showing a slowdown in growth of these emissions compared to the average growth of 1.8 % yr−1 that took place during 2006–2015. Also, for 2015, ELUC was 1.3 ± 0.5 GtC yr−1, GATM was 6.3 ± 0.2 GtC yr−1, SOCEAN was 3.0 ± 0.5 GtC yr−1, and SLAND was 1.9 ± 0.9 GtC yr−1. GATM was higher in 2015 compared to the past decade (2006–2015), reflecting a smaller SLAND for that year. The global atmospheric CO2 concentration reached 399.4 ± 0.1 ppm averaged over 2015. For 2016, preliminary data indicate the continuation of low growth in EFF with +0.2 % (range of −1.0 to +1.8 %) based on national emissions projections for China and USA, and projections of gross domestic product corrected for recent changes in the carbon intensity of the economy for the rest of the world. In spite of the low growth of EFF in 2016, the growth rate in atmospheric CO2 concentration is expected to be relatively high because of the persistence of the smaller residual terrestrial sink (SLAND) in response to El Niño conditions of 2015–2016. From this projection of EFF and assumed constant ELUC for 2016, cumulative emissions of CO2 will reach 565 ± 55 GtC (2075 ± 205 GtCO2) for 1870–2016, about 75 % from EFF and 25 % from ELUC. This living data update documents changes in the methods and data sets used in this new carbon budget compared with previous publications of this data set (Le Quéré et al., 2015b, a, 2014, 2013). All observations presented here can be downloaded from the Carbon Dioxide Information Analysis Center (doi:10.3334/CDIAC/GCP_2016).
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ArticleMagnitude, trends, and variability of the global ocean carbon sink from 1985‐2018(American Geophysical Union, 2023-09-11) DeVries, Tim ; Yamamoto, Kana ; Wanninkhof, Rik ; Gruber, Nicolas ; Hauck, Judith ; Muller, Jens Daniel ; Bopp, Laurent ; Carroll, Dustin ; Carter, Brendan ; Chau, Thi-Tuyet-Trang ; Doney, Scott C. ; Gehlen, Marion ; Gloege, Lucas ; Gregor, Luke ; Henson, Stephanie A. ; Kim, Ji-Hyun ; Iida, Yosuke ; Ilyina, Tatiana ; Landschutzer, Peter ; Le Quere, Corinne ; Munro, David R. ; Nissen, Cara ; Patara, Lavinia ; Perez, Fiz F. ; Resplandy, Laure ; Rodgers, Keith B. ; Schwinger, Jorg ; Seferian, Roland ; Sicardi, Valentina ; Terhaar, Jens ; Trinanes, Joaquin ; Tsujino, Hiroyuki ; Watson, Andrew J. ; Yasunaka, Sayaka ; Zeng, JiyeThis contribution to the RECCAP2 (REgional Carbon Cycle Assessment and Processes) assessment analyzes the processes that determine the global ocean carbon sink, and its trends and variability over the period 1985–2018, using a combination of models and observation-based products. The mean sea-air CO2 flux from 1985 to 2018 is −1.6 ± 0.2 PgC yr−1 based on an ensemble of reconstructions of the history of sea surface pCO2 (pCO2 products). Models indicate that the dominant component of this flux is the net oceanic uptake of anthropogenic CO2, which is estimated at −2.1 ± 0.3 PgC yr−1 by an ensemble of ocean biogeochemical models, and −2.4 ± 0.1 PgC yr−1 by two ocean circulation inverse models. The ocean also degasses about 0.65 ± 0.3 PgC yr−1 of terrestrially derived CO2, but this process is not fully resolved by any of the models used here. From 2001 to 2018, the pCO2 products reconstruct a trend in the ocean carbon sink of −0.61 ± 0.12 PgC yr−1 decade−1, while biogeochemical models and inverse models diagnose an anthropogenic CO2-driven trend of −0.34 ± 0.06 and −0.41 ± 0.03 PgC yr−1 decade−1, respectively. This implies a climate-forced acceleration of the ocean carbon sink in recent decades, but there are still large uncertainties on the magnitude and cause of this trend. The interannual to decadal variability of the global carbon sink is mainly driven by climate variability, with the climate-driven variability exceeding the CO2-forced variability by 2–3 times. These results suggest that anthropogenic CO2 dominates the ocean CO2 sink, while climate-driven variability is potentially large but highly uncertain and not consistently captured across different methods.
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ArticleGlobal Carbon Budget 2015(Copernicus Publications, 2015-12-07) Le Quere, Corinne ; Moriarty, Roisin ; Andrew, Robbie M. ; Canadell, Josep G. ; Sitch, Stephen ; Korsbakken, Jan Ivar ; Friedlingstein, Pierre ; Peters, Glen P. ; Andres, Robert J. ; Boden, Thomas A. ; Houghton, Richard A. ; House, Jo I. ; Keeling, Ralph F. ; Tans, Pieter P. ; Arneth, Almut ; Bakker, Dorothee C. E. ; Barbero, Leticia ; Bopp, Laurent ; Chang, J. ; Chevallier, Frédéric ; Chini, Louise Parsons ; Ciais, Philippe ; Fader, Marianela ; Feely, Richard A. ; Gkritzalis, Thanos ; Harris, Ian ; Hauck, Judith ; Ilyina, Tatiana ; Jain, Atul K. ; Kato, Etsushi ; Kitidis, Vassilis ; Klein Goldewijk, Kees ; Koven, Charles ; Landschutzer, Peter ; Lauvset, Siv K. ; Lefevre, N. ; Lenton, Andrew ; Lima, Ivan D. ; Metzl, Nicolas ; Millero, Frank J. ; Munro, David R. ; Murata, Akihiko ; Nabel, Julia E. M. S. ; Nakaoka, Shin-ichiro ; Nojiri, Yukihiro ; O'Brien, Kevin ; Olsen, Are ; Ono, Tsuneo ; Perez, Fiz F. ; Pfeil, Benjamin ; Pierrot, Denis ; Poulter, Benjamin ; Rehder, Gregor ; Rodenbeck, C. ; Saito, Shu ; Schuster, Ute ; Schwinger, Jorg ; Seferian, Roland ; Steinhoff, Tobias ; Stocker, Benjamin D. ; Sutton, Adrienne J. ; Takahashi, Taro ; Tilbrook, Bronte ; van der Laan-Luijkx, I. T. ; van der Werf, Guido R. ; van Heuven, Steven ; Vandemark, Douglas ; Viovy, Nicolas ; Wiltshire, Andrew J. ; Zaehle, Sonke ; Zeng, NingAccurate 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 as well as consistency within and among components, alongside methodology and data limitations. CO2 emissions from fossil fuels and industry (EFF) are based on energy statistics and cement production data, 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 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). We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. 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 (2005–2014), EFF was 9.0 ± 0.5 GtC yr−1, ELUC was 0.9 ± 0.5 GtC yr−1, GATM was 4.4 ± 0.1 GtC yr−1, SOCEAN was 2.6 ± 0.5 GtC yr−1, and SLAND was 3.0 ± 0.8 GtC yr−1. For the year 2014 alone, EFF grew to 9.8 ± 0.5 GtC yr−1, 0.6 % above 2013, continuing the growth trend in these emissions, albeit at a slower rate compared to the average growth of 2.2 % yr−1 that took place during 2005–2014. Also, for 2014, ELUC was 1.1 ± 0.5 GtC yr−1, GATM was 3.9 ± 0.2 GtC yr−1, SOCEAN was 2.9 ± 0.5 GtC yr−1, and SLAND was 4.1 ± 0.9 GtC yr−1. GATM was lower in 2014 compared to the past decade (2005–2014), reflecting a larger SLAND for that year. The global atmospheric CO2 concentration reached 397.15 ± 0.10 ppm averaged over 2014. For 2015, preliminary data indicate that the growth in EFF will be near or slightly below zero, with a projection of −0.6 [range of −1.6 to +0.5] %, based on national emissions projections for China and the USA, and projections of gross domestic product corrected for recent changes in the carbon intensity of the global economy for the rest of the world. From this projection of EFF and assumed constant ELUC for 2015, cumulative emissions of CO2 will reach about 555 ± 55 GtC (2035 ± 205 GtCO2) for 1870–2015, about 75 % from EFF and 25 % from ELUC. This living data update documents changes in the methods and data sets used in this new carbon budget compared with previous publications of this data set (Le Quéré et al., 2015, 2014, 2013). All observations presented here can be downloaded from the Carbon Dioxide Information Analysis Center (doi:10.3334/CDIAC/GCP_2015).
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ArticleOn the Southern Ocean CO2 uptake and the role of the biological carbon pump in the 21st century(John Wiley & Sons, 2015-09-23) Hauck, Judith ; Volker, Chrisoph ; Wolf-Gladrow, Dieter A. ; Laufkötter, Charlotte ; Vogt, Meike ; Aumont, Olivier ; Bopp, Laurent ; Buitenhuis, Erik T. ; Doney, Scott C. ; Dunne, John P. ; Gruber, Nicolas ; Hashioka, Taketo ; John, Jasmin G. ; Le Quere, Corinne ; Lima, Ivan D. ; Nakano, Hideyuki ; Seferian, Roland ; Totterdell, Ian J.We use a suite of eight ocean biogeochemical/ecological general circulation models from the Marine Ecosystem Model Intercomparison Project and Coupled Model Intercomparison Project Phase 5 archives to explore the relative roles of changes in winds (positive trend of Southern Annular Mode, SAM) and in warming- and freshening-driven trends of upper ocean stratification in altering export production and CO2 uptake in the Southern Ocean at the end of the 21st century. The investigated models simulate a broad range of responses to climate change, with no agreement on a dominance of either the SAM or the warming signal south of 44°S. In the southernmost zone, i.e., south of 58°S, they concur on an increase of biological export production, while between 44 and 58°S the models lack consensus on the sign of change in export. Yet in both regions, the models show an enhanced CO2 uptake during spring and summer. This is due to a larger CO2(aq) drawdown by the same amount of summer export production at a higher Revelle factor at the end of the 21st century. This strongly increases the importance of the biological carbon pump in the entire Southern Ocean. In the temperate zone, between 30 and 44°S, all models show a predominance of the warming signal and a nutrient-driven reduction of export production. As a consequence, the share of the regions south of 44°S to the total uptake of the Southern Ocean south of 30°S is projected to increase at the end of the 21st century from 47 to 66% with a commensurable decrease to the north. Despite this major reorganization of the meridional distribution of the major regions of uptake, the total uptake increases largely in line with the rising atmospheric CO2. Simulations with the MITgcm-REcoM2 model show that this is mostly driven by the strong increase of atmospheric CO2, with the climate-driven changes of natural CO2 exchange offsetting that trend only to a limited degree (∼10%) and with negligible impact of climate effects on anthropogenic CO2 uptake when integrated over a full annual cycle south of 30°S.
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ArticleDrivers and uncertainties of future global marine primary production in marine ecosystem models(Copernicus Publications on behalf of the European Geosciences Union, 2015-12-07) Laufkötter, Charlotte ; Vogt, Meike ; Gruber, Nicolas ; Aita-Noguchi, M. ; Aumont, Olivier ; Bopp, Laurent ; Buitenhuis, Erik T. ; Doney, Scott C. ; Dunne, John P. ; Hashioka, Taketo ; Hauck, Judith ; Hirata, Takafumi ; John, Jasmin G. ; Le Quere, Corinne ; Lima, Ivan D. ; Nakano, Hideyuki ; Seferian, Roland ; Totterdell, Ian J. ; Vichi, Marcello ; Volker, ChrisophPast model studies have projected a global decrease in marine net primary production (NPP) over the 21st century, but these studies focused on the multi-model mean rather than on the large inter-model differences. Here, we analyze model-simulated changes in NPP for the 21st century under IPCC's high-emission scenario RCP8.5. We use a suite of nine coupled carbon–climate Earth system models with embedded marine ecosystem models and focus on the spread between the different models and the underlying reasons. Globally, NPP decreases in five out of the nine models over the course of the 21st century, while three show no significant trend and one even simulates an increase. The largest model spread occurs in the low latitudes (between 30° S and 30° N), with individual models simulating relative changes between −25 and +40 %. Of the seven models diagnosing a net decrease in NPP in the low latitudes, only three simulate this to be a consequence of the classical interpretation, i.e., a stronger nutrient limitation due to increased stratification leading to reduced phytoplankton growth. In the other four, warming-induced increases in phytoplankton growth outbalance the stronger nutrient limitation. However, temperature-driven increases in grazing and other loss processes cause a net decrease in phytoplankton biomass and reduce NPP despite higher growth rates. One model projects a strong increase in NPP in the low latitudes, caused by an intensification of the microbial loop, while NPP in the remaining model changes by less than 0.5 %. While models consistently project increases NPP in the Southern Ocean, the regional inter-model range is also very substantial. In most models, this increase in NPP is driven by temperature, but it is also modulated by changes in light, macronutrients and iron as well as grazing. Overall, current projections of future changes in global marine NPP are subject to large uncertainties and necessitate a dedicated and sustained effort to improve the models and the concepts and data that guide their development.
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ArticleGlobal carbon budget 2014(Copernicus Publications, 2015-05-08) Le Quere, Corinne ; Moriarty, Roisin ; Andrew, Robbie M. ; Peters, Glen P. ; Ciais, Philippe ; Friedlingstein, Pierre ; Jones, S. D. ; Sitch, Stephen ; Tans, Pieter P. ; Arneth, Almut ; Boden, Thomas A. ; Bopp, Laurent ; Bozec, Yann ; Canadell, Josep G. ; Chini, Louise Parsons ; Chevallier, Frédéric ; Cosca, Catherine E. ; Harris, Ian ; Hoppema, Mario ; Houghton, Richard A. ; House, Jo I. ; Jain, Atul K. ; Johannessen, T. ; Kato, Etsushi ; Keeling, Ralph F. ; Kitidis, Vassilis ; Klein Goldewijk, Kees ; Koven, Charles ; Landa, C. S. ; Landschutzer, Peter ; Lenton, Andrew ; Lima, Ivan D. ; Marland, G. ; Mathis, Jeremy T. ; Metzl, Nicolas ; Nojiri, Yukihiro ; Olsen, Are ; Ono, Tsuneo ; Peng, S. ; Peters, W. ; Pfeil, Benjamin ; Poulter, Benjamin ; Raupach, Michael R. ; Regnier, P. ; Rodenbeck, C. ; Saito, Shu ; Salisbury, Joseph E. ; Schuster, Ute ; Schwinger, Jorg ; Seferian, Roland ; Segschneider, J. ; Steinhoff, Tobias ; Stocker, Benjamin D. ; Sutton, Adrienne J. ; Takahashi, Taro ; Tilbrook, Bronte ; van der Werf, Guido R. ; Viovy, Nicolas ; Wang, Y.-P. ; Wanninkhof, Rik ; Wiltshire, Andrew J. ; Zeng, NingAccurate 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 and cement production data, respectively, 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 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). We compare the mean land and ocean fluxes and their variability to estimates from three atmospheric inverse methods for three broad latitude bands. 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 (2004–2013), EFF was 8.9 ± 0.4 GtC yr−1, ELUC 0.9 ± 0.5 GtC yr−1, GATM 4.3 ± 0.1 GtC yr−1, SOCEAN 2.6 ± 0.5 GtC yr−1, and SLAND 2.9 ± 0.8 GtC yr−1. For year 2013 alone, EFF grew to 9.9 ± 0.5 GtC yr−1, 2.3% above 2012, continuing the growth trend in these emissions, ELUC was 0.9 ± 0.5 GtC yr−1, GATM was 5.4 ± 0.2 GtC yr−1, SOCEAN was 2.9 ± 0.5 GtC yr−1, and SLAND was 2.5 ± 0.9 GtC yr−1. GATM was high in 2013, reflecting a steady increase in EFF and smaller and opposite changes between SOCEAN and SLAND compared to the past decade (2004–2013). The global atmospheric CO2 concentration reached 395.31 ± 0.10 ppm averaged over 2013. We estimate that EFF will increase by 2.5% (1.3–3.5%) to 10.1 ± 0.6 GtC in 2014 (37.0 ± 2.2 GtCO2 yr−1), 65% above emissions in 1990, based on projections of world gross domestic product and recent changes in the carbon intensity of the global economy. From this projection of EFF and assumed constant ELUC for 2014, cumulative emissions of CO2 will reach about 545 ± 55 GtC (2000 ± 200 GtCO2) for 1870–2014, about 75% from EFF and 25% from ELUC. This paper documents changes in the methods and data sets used in this new carbon budget compared with previous publications of this living data set (Le Quéré et al., 2013, 2014). All observations presented here can be downloaded from the Carbon Dioxide Information Analysis Center (doi:10.3334/CDIAC/GCP_2014).
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ArticleThe Southern Ocean Carbon Cycle 1985–2018: Mean, Seasonal Cycle, Trends, and Storage(American Geophysical Union, 2023-11-10) Hauck, Judith ; Gregor, Luke ; Nissen, Cara ; Patara, Lavinia ; Hague, Mark ; Mongwe, Precious ; Bushinsky, Seth ; Doney, Scott C. ; Gruber, Nicolas ; Le Quere, Corinne ; Manizza, Manfredi ; Mazloff, Matthew R. ; Monteiro, Pedro M. S. ; Terhaar, JensWe assess the Southern Ocean CO2 uptake (1985–2018) using data sets gathered in the REgional Carbon Cycle Assessment and Processes Project Phase 2. The Southern Ocean acted as a sink for CO2 with close agreement between simulation results from global ocean biogeochemistry models (GOBMs, 0.75 ± 0.28 PgC yr−1) and pCO2-observation-based products (0.73 ± 0.07 PgC yr−1). This sink is only half that reported by RECCAP1 for the same region and timeframe. The present-day net uptake is to first order a response to rising atmospheric CO2, driving large amounts of anthropogenic CO2 (Cant) into the ocean, thereby overcompensating the loss of natural CO2 to the atmosphere. An apparent knowledge gap is the increase of the sink since 2000, with pCO2-products suggesting a growth that is more than twice as strong and uncertain as that of GOBMs (0.26 ± 0.06 and 0.11 ± 0.03 Pg C yr−1 decade−1, respectively). This is despite nearly identical pCO2 trends in GOBMs and pCO2-products when both products are compared only at the locations where pCO2 was measured. Seasonal analyses revealed agreement in driving processes in winter with uncertainty in the magnitude of outgassing, whereas discrepancies are more fundamental in summer, when GOBMs exhibit difficulties in simulating the effects of the non-thermal processes of biology and mixing/circulation. Ocean interior accumulation of Cant points to an underestimate of Cant uptake and storage in GOBMs. Future work needs to link surface fluxes and interior ocean transport, build long overdue systematic observation networks and push toward better process understanding of drivers of the carbon cycle.
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ArticleA synthesis of global coastal ocean greenhouse gas fluxes(American Geophysical Union, 2024-01-20) Resplandy, Laure ; Hogikyan, Allison ; Muller, Jens Daniel ; Najjar, Raymond G. ; Bange, Hermann W. ; Bianchi, Daniele ; Weber, Thomas ; Cai, Wei-Jun ; Doney, Scott C. ; Fennel, Katja ; Gehlen, Marion ; Hauck, Judith ; Lacroix, Fabrice ; Landschutzer, Peter ; Le Quere, Corinne ; Roobaert, Alizee ; Schwinger, Jorg ; Berthet, Sarah ; Bopp, Laurent ; Chau, Thi Tuyet Trang ; Dai, Minhan ; Gruber, Nicolas ; Ilyina, Tatiana ; Kock, Annette ; Manizza, Manfredi ; Lachkar, Zouhair ; Laruelle, Goulven G. ; Liao, Enhui ; Lima, Ivan D. ; Nissen, Cara ; Rodenbeck, Christian ; Seferian, Roland ; Toyama, Katsuya ; Tsujino, Hiroyuki ; Regnier, PierreThe coastal ocean contributes to regulating atmospheric greenhouse gas concentrations by taking up carbon dioxide (CO2) and releasing nitrous oxide (N2O) and methane (CH4). In this second phase of the Regional Carbon Cycle Assessment and Processes (RECCAP2), we quantify global coastal ocean fluxes of CO2, N2O and CH4 using an ensemble of global gap-filled observation-based products and ocean biogeochemical models. The global coastal ocean is a net sink of CO2 in both observational products and models, but the magnitude of the median net global coastal uptake is ∼60% larger in models (−0.72 vs. −0.44 PgC year−1, 1998–2018, coastal ocean extending to 300 km offshore or 1,000 m isobath with area of 77 million km2). We attribute most of this model-product difference to the seasonality in sea surface CO2 partial pressure at mid- and high-latitudes, where models simulate stronger winter CO2 uptake. The coastal ocean CO2 sink has increased in the past decades but the available time-resolving observation-based products and models show large discrepancies in the magnitude of this increase. The global coastal ocean is a major source of N2O (+0.70 PgCO2-e year−1 in observational product and +0.54 PgCO2-e year−1 in model median) and CH4 (+0.21 PgCO2-e year−1 in observational product), which offsets a substantial proportion of the coastal CO2 uptake in the net radiative balance (30%–60% in CO2-equivalents), highlighting the importance of considering the three greenhouse gases when examining the influence of the coastal ocean on climate.
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ArticleGlobal carbon budget 2013(Copernicus Publications., 2014-06-17) Le Quere, Corinne ; Peters, Glen P. ; Andres, Robert J. ; Andrew, Robbie M. ; Boden, Thomas A. ; Ciais, Philippe ; Friedlingstein, Pierre ; Houghton, Richard A. ; Marland, G. ; Moriarty, Roisin ; Sitch, Stephen ; Tans, Pieter P. ; Arneth, Almut ; Arvanitis, A. ; Bakker, Dorothee C. E. ; Bopp, Laurent ; Canadell, Josep G. ; Chini, Louise Parsons ; Doney, Scott C. ; Harper, Anna B. ; Harris, Ian ; House, Jo I. ; Jain, Atul K. ; Jones, S. D. ; Kato, Etsushi ; Keeling, Ralph F. ; Klein Goldewijk, Kees ; Kortzinger, A. ; Koven, Charles ; Lefevre, N. ; Maignan, F. ; Omar, A. ; Ono, Tsuneo ; Park, Geun-Ha ; Pfeil, Benjamin ; Poulter, Benjamin ; Raupach, Michael R. ; Regnier, P. ; Rodenbeck, C. ; Saito, Shu ; Schwinger, Jorg ; Segschneider, J. ; Stocker, Benjamin D. ; Takahashi, Taro ; Tilbrook, Bronte ; van Heuven, Steven ; Viovy, Nicolas ; Wanninkhof, Rik ; Wiltshire, Andrew J. ; Zaehle, SonkeAccurate 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).