Description: 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 fCO(2) 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 +/- 1 sigma. For the year 2022, E-FOS increased by 0.9% relative to 2021, with fossil emissions at 9.9 +/- 0.5 GtC yr(-1) (10.2 +/- 0.5 GtC yr(-1) when the cement carbonation sink is not included), and E-LUC was 1.2 +/- 0.7 GtC yr(-1), for a total anthropogenic CO2 emission (including the cement carbonation sink) of 11.1 +/- 0.8 GtC yr(-1) (40.7 +/- 3.2 GtCO(2) yr(-1)). Also, for 2022, G(ATM) was 4.6 +/- 0.2 GtC yr(-1) (2.18 +/- 0.1 ppm yr(-1); ppm denotes parts per million), S-OCEAN was 2.8 +/- 0.4 GtC yr(-1), and S-LAND was 3.8 +/- 0.8 GtC yr(-1), with a B-IM of 0.1 GtC 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 Cyr(-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.

Description: Wie soll der Mensch den Klimawandel wirkungsvoll begrenzen? Oberste Priorität haben sicherlich Maßnahmen zur Vermeidung von Treibhausgas-Emissionen. Fakt ist mittlerweile aber auch, dass wir der Atmosphäre in den kommenden Jahrzehnten viel Kohlendioxid entnehmen und sicher einlagern müssen. Kann oder sogar muss uns der Ozean bei dieser Aufgabe helfen? Der neue „World Ocean Review“ (WOR Nr. 8) erläutert diese Frage anhand der Rolle des Ozeans im Kohlenstoffkreislauf der Erde und stellt Vorteile, Risiken und Wissenslücken zu den wichtigsten meeresbasierten Verfahren zur Kohlendioxid-Entnahme vor.

Description: 〈jats:p〉Abstract. 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 (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) is estimated with global ocean biogeochemistry models and observation-based fCO2 products. The terrestrial CO2 sink (SLAND) 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 (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 incomplete understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the year 2022, EFOS 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 ELUC 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, GATM was 4.6±0.2 Gt C yr−1 (2.18±0.1 ppm yr−1; ppm denotes parts per million), SOCEAN was 2.8±0.4 Gt C yr−1, and SLAND was 3.8±0.8 Gt C yr−1, with a BIM 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 EFOS 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). 〈/jats:p〉

Description: We present data on distribution of inorganic nitrogen compounds including nitrate (NO2-) and nitrite (NO3-) in the northern Benguela and the Angola-Benguela Front regions between 10°S and 23°S. The fieldwork took place during the cruise No. M120 (Oct. 17th – Nov. 18th, 2015) onboard the R/V METEOR, which encompassed close-coastal and open ocean regions off Angola and Namibia. All nutrient samples were retrieved with the ship's CTD rosette (SBE 9+). Immediately after sampling, a volume of about 40 ml of each sample was filtered through a disposable syringe filter (CA, 0.45 µm) and filled in a pre-rinsed 50 ml PE bottle. The bottles were securely closed and kept frozen at -20°C until further analysis. The concentrations of nutrients were determined photometrically with a Skalar San++ Autoanalyzer following the procedures detailed in Grasshoff et al. (1999). For the quality control, a reference standard was also measured at regular intervals.

Description: Based on direct surface pCO2 observation and a model-based extrapolation technique, we established a regional pCO2 climatology of the Baltic Sea. Observations from June 2003 to Dec. 2021 are obtained from the SOCAT version 2022 data collection and largely based on ICOS DE-SOOP Finnmaid data. The extrapolation technique uses model-based patters of variability to create observational data-constrained, gap- and discontinuity-free mapped fields including local error estimates without the need for or dependence on ancillary data (like, e.g., satellite sea surface temperature maps). Details on the pCO2 climatology and the model-based extrapolation technique are found in Bittig et al. (2023). Here we make the corresponding dataset available with monthly climatological pCO2 value as well as a linear pCO2 time trend for the Baltic Sea domain. Both value and trend are provided with their error estimate and are centered on the 15th of each month. Besides, the long-term trend 2003-2021 in pCO2 as well as its error estimate is given.

Description: The high surface productivity triggered by nutrient-rich Benguela upwelled waters results in significant enrichment of organic carbon in the sub-surface waters due to enhanced mineralization in the water column and benthic fluxes. Hence, microbial oxygen-consuming processes are promoted, driving oxygen depletion that favours trace gases i.e. methane (CH4) and nitrous oxide (N2O) production at relatively shallow depths. Also, gas-rich subsurface waters are transported towards the surface waters during upwelling, enhancing trace gas sea-air fluxes. Within the EVAR project, we investigate the variability of these fluxes on seasonal and shorter timescales to understand the intensity of the Benguela upwelling system as the source of these greenhouse gases relative to the atmosphere. The data might serve as a base for projections under a changing climate. The fieldwork took place during the cruise SO283 (March 19th – May 25th, 2021) onboard the R/V SONNE from and to Emden (Germany). The main area of the sampling was the Namibian shelf between 18°S and 25°S which is suggested to represent some regional hotspots of trace gas emissions to the atmosphere, in particular in the vicinity of the upwelling cells. Over 260 discrete water samples were collected from the Niskin bottles at different stations for the determination of the concentrations of CH4, N2O, and dissolved inorganic carbon (DIC). 200ml seawater samples were fixed with 200 µL of saturated HgCl2 solution straight after sampling and trace gas was quantified in return. Dissolved CH4 and N2O were measured by an in-house designed purge and trap system with a dynamic headspace method back on land. In brief, a subsample is purged with an inert ultrapure carrier gas of Helium, and the gases are focused on a cryo-trap operated at about -120°C. The volatile compounds are desorbed by rapid heating and analyzed by a gas chromatograph (GC; Agilent 7890B), equipped with capillary columns and a Deans Switch, which directed the components to the flamenionization detector for CH4 detection and electron capture detector ECD for N2O detection. To explore the carbonate system Dissolved Inorganic Carbon (DIC) was measured in the institute. About 5.00 ml of each fixed discrete sample was acidified by 10 % phosphoric acid, resulting in release of inorganic carbon content of the sample. An automated infra-red inorganic carbon analyzer (AIRICA, Marianda, Tulpenweg 28, D-24145 Kiel) equipped with an infrared detector LICOR 7000 (LI-COR Environmental – GmbH, Homburg, Germany) was used to quantify DIC. A 3-fold measurement of the pH was also carried out in 120 ml of discrete samples directly after sampling using the HydroFIA pH system (4H Jena Engineering, 24148 Kiel, Germany). We calculated the average pH value of the corresponding sample after Müller and Rehder (2018) and corresponding total alkalinity and pCO2 after Dickson et al. (2007).

Description: The high surface productivity triggered by nutrient-rich Benguela upwelled waters results in significant enrichment of organic carbon in the sub-surface waters due to enhanced mineralization in the water column and benthic fluxes. Hence, microbial oxygen-consuming processes are promoted, driving oxygen depletion that favours trace gas i.e. methane (CH4) and nitrous oxide (N2O) production at relatively shallow depths. Also, gas-rich subsurface waters are transported towards sea surface during upwelling, enhancing trace gas sea-air fluxes. Within the EVAR project, we investigate the variability of these fluxes on seasonal and shorter timescales to understand the intensity of the Benguela upwelling system as the source of the greenhouse gases relative to the atmosphere. The data might serve as a base for projections under a changing climate. The fieldwork took place during the cruise MSM105 (January 11th – February 23rd, 2022) onboard the R/V MARIA S. MERIAN, which encompassed close-coastal and open ocean regions between Mindelo (Cape Verde) and Walvis Bay. The working area of the cruise MSM105 was the Namibian shelf between 18°S and 27°S which are suggested to represent some regional hotspots of trace gas emissions to the atmosphere, in particular in the vicinity of the upwelling cells. Over 260 discrete water samples were collected from the Niskin bottles at different stations for the determination of dissolved CH4, N2O, and dissolved inorganic carbon (DIC). 200ml seawater samples were fixed with 200 µL of saturated HgCl2 solution straight after sampling and dissolved trace gas was quantified in return. The dissolved gases were measured by an in-house designed purge and trap system with a dynamic headspace method back on land. In brief, a subsample is purged with an inert ultrapure carrier gas of Helium, and the gases are focused on a cryo-trap operated at about -120°C. The volatile compounds are desorbed by rapid heating and analyzed by a gas chromatograph (GC; Agilent 7890B), equipped with capillary columns and a Deans Switch, which directed the components to the flamenionization detector for CH4 detection and electron capture detector ECD for N2O detection. To explore the carbonate system, Dissolved Inorganic Carbon (DIC) was measured on board by an automated infra-red inorganic carbon analyzer (AIRICA, Marianda, Tulpenweg 28, D-24145 Kiel) equipped with an infrared detector LICOR 7000 (LI-COR Environmental – GmbH, Homburg, Germany. A 3-fold measurement of the pH was also carried out in 120 ml of discrete samples directly after sampling using the HydroFIA pH system (4H Jena Engineering, 24148 Kiel, Germany). We calculated the average pH value of the corresponding sample after Müller and Rehder (2018) and corresponding total alkalinity and pCO2 after Dickson et al. (2007).

Description: The high surface productivity triggered by nutrient-rich Benguela upwelled waters results in significant enrichment of organic carbon in the sub-surface waters due to enhanced mineralization in the water column and benthic fluxes. Hence, microbial oxygen consuming processes are promoted, driving oxygen depletion that favors trace gases i.e. methane (CH4) and nitrous oxide (N2O) production at relatively shallow depths. During upwelling, gas-rich subsurface waters are also transported towards the surface waters, enhancing trace gas sea-air fluxes. We investigate the variability of these fluxes on seasonal and shorter timescales to understand the intensity of the Benguela upwelling system in gas emissions. The data might serve as a base for projections under a changing climate. The fieldwork took place during the cruise MSM105 (January 11th – February 23rd, 2022) onboard the R/V MARIA S. MERIAN, which encompassed close-coastal and open ocean regions between Mindelo (Cape Verde) and Walvis Bay. The working area of the cruise MSM105 was the Namibian shelf between 18°S and 27°S which are suggested to represent some regional hotspots of trace gas emissions to the atmosphere.The underway mesurement of partial pressures of CH4, N2O, and CO2 in sea surface and atmosphere were determined using IOW's self-built Mobile Equilibrator Sensor System (MESS). The system was described in details elsewhere (Sabbaghzadeh et al., 2021) but in brief, it consists of a custom-built equilibrator (combined shower-head/bubble type) and a control unit lined up with two Los Gatos Research off-axis laser absorption spectroscopy (oa-ICOS) analyzers. In this study, a Model # 908-0011-0001(CO2/CH4/H2O) and a Model # 908-0014-0000 (N2O/CO/H2O) were used. To quantify sea-air gas fluxes, the atmospheric concentration of studied trace gases was measured at several positions during the cruise using a tube with the inlet positioned at front of the bow to minimize ship contamination. All other ancillary parameters out of the MESS system were synchronized with D-ship data with a simultaneous data reduction to one-minute intervals.

Description: The high surface productivity triggered by nutrient-rich Benguela upwelled waters results in significant enrichment of organic carbon in the sub-surface waters due to enhanced mineralization in the water column and benthic fluxes. Hence, microbial oxygen demand processes are promoted, driving oxygen depletion that favors trace gas production at relatively shallow depths. During upwelling, gas-rich subsurface waters are transported towards the surface waters, enhancing trace gas sea-air fluxes. We investigate the variability of these fluxes on seasonal and shorter timescales to understand the intensity of the Benguela upwelling system in gas emissions. The data might serve as a base for projections under a changing climate. The fieldwork took place during the cruise MSM105 (January 11th – February 23rd, 2022) onboard the R/V MARIA S. MERIAN, which encompassed close-coastal and open ocean regions between Mindelo (Cape Verde) and Walvis Bay. The working area of the cruise MSM105 was the Namibian shelf between 18°S and 27°S which is suggested to represent some regional hotspots of trace gas emissions to the atmosphere. The partial pressures of CH4, N2O, and CO2 in the sea surface and atmosphere were determined using IOW's self-built Mobile Equilibrator Sensor System (MESS). The system was described in detail elsewhere (Sabbaghzadeh et al., 2021) but in brief, it consists of a custom-built equilibrator (combined shower-head/bubble type) with a water flow rate of about 5 l min-1 and an airflow rate of ~ 4.00 - 5.00 L min-1. The system is linked to two off-axis integrated cavity output laser spectrometers (oa-ICOS, Los Gatos Instruments) for the detection of CH4 / CO2 and N2O / CO. To operate the system, seawater was supplied by a deep-well pump (CAPRARI Desert E4XP30-4 with CAPRARI XPBM1 control unit, ~ 100 L min-1, Italy), installed in the moon-pool at ∼ 6.00 m water depth on board of the R/V MARIA S. MERIAN. All gas analyzers were calibrated against three standard gasses at the beginning and end of each survey daily for data recalibration and drift correction. In addition, one "zero" gas (i.e. Nitrogen 5.00, LINDE) was measured infrequently throughout the survey to check any system deficiency like leakage detection. To quantify sea-air gas fluxes, the atmospheric concentration of studied trace gas was measured at several positions during the cruise using a tube with the inlet positioned at the front of the bow to minimize ship contamination. All other ancillary parameters were synchronized with D-ship data with a simultaneous data reduction to one-minute intervals.

Description: Upwelling systems are significant sources of atmospheric nitrous oxide (N₂O). The Benguela Upwelling System is one of the most productive regions worldwide and a temporally variable source of N₂O. Strong O₂ depletions above the shelf are favoring periodically OMZ formations. We aimed to assess underlying N₂O production and consumption processes on different temporal and spatial scales during austral winter in the Benguela Upwelling System, when O₂⁻deficiency in the water column is relatively low. The fieldwork took place during the cruise M157 (August 4ᵗʰ – September 16ᵗʰ 2019) onboard the R/V METEOR. This expedition included four close-coastal regions around Walvis Bay at 23°S, which presented the lowest O₂ concentrations near the seafloor and thus may provide hotspots of N₂O production. Seawater was collected in 10 L free-flow bottles by using a rosette system equipped with conductivity-temperature-depth (CTD) sensors (SBE 911plus, Seabird-electronics, USA).Seawater samples were collected from 10 L free-flow bottles bubble-free, filled into 200 mL serum bottles and immediately fixed with saturated mercury chloride (HgCl₂). Concentrations of dissolved N₂O were measured by a purge and trap system using a dynamic headspace (Sabbaghzadeh et al., 2021). The N₂O gas saturation (N₂Oₛₐₜ in %) was calculated from the concentration ratio between the seawater sample and seawater equilibrated with the atmosphere. ∆N₂O (N₂O saturation disequilibrium in nmol L⁻¹) was calculated as the difference between the measured N₂O concentration and the atmospheric equilibrium N₂O concentration using Bunsen solubility coefficient (Weiss and Price, 1980). AOU (apparent oxygen utilization in µmol L⁻¹) expresses the O₂ consumption by microbial respiration and was calculated as the difference between the equilibrated O₂ and observed O₂ concentration with the same physico-chemical properties (Weiss and Price, 1980).