Global Carbon Sinks and Their Variability Inferred from Atmospheric O2 and 13C

Science ◽  
2000 ◽  
Vol 287 (5462) ◽  
pp. 2467-2470 ◽  
Author(s):  
M. Battle
Keyword(s):  
Carbon Sinks ◽  
Global Carbon

scholarly journals Global carbon budgets estimated from atmospheric O<sub>2</sub>/N<sub>2</sub> and CO<sub>2</sub> observations in the western Pacific region over a 15-year period

2019 ◽  
Author(s):  
Yasunori Tohjima ◽  
Hitoshi Mukai ◽  
Toshinobu Machida ◽  
Yu Hoshina ◽  
Shin-Ichiro Nakaoka
Keyword(s):  
Mole Fraction ◽  
Temporal Trends ◽  
Heat Content ◽  
Western Pacific ◽  
Global Ocean ◽  
Carbon Sinks ◽  
Increasing Trend ◽  
Carbon Project ◽  
Global Carbon ◽  
The Western Pacific

Abstract. Time series of atmospheric O2/N2 ratio and CO2 mole fraction of flask samples obtained from NIES’s flask sampling network are presented. The network includes two ground sites, Hateruma Island (HAT, 24.05 °N, 123.81 °E) and Cape Ochiishi (COI, 43.17 °N, 145.50 °E), and cargo ships regularly sailing in the western Pacific. Based on temporal changes in fossil fuel-derived CO2 emissions, global atmospheric CO2 burden, and atmospheric potential oxygen (APO), which were calculated from the observed O2/N2 ratio and CO2 mole fraction according to APO = O2 + 1.1 × CO2, we estimated the global carbon sinks of the ocean and land biosphere for a period of more than 15 years. In this carbon budget calculation, we adopted a correction for the time-varying ocean O2 outgassing effect with an average of 0.43 PgC yr−1 for 2000–2016. The outgassing effect, attributed to global ocean warming, was evaluated under the assumption that the net ocean gas flux is proportional to the change in the ocean heat content for the 0–2000 m layer. The resulting oceanic and land biotic carbon sinks were 2.5 ± 0.6 PgC yr−1 and 1.6 ± 0.8 PgC yr−1, respectively, for a 17-year period (2000–2016) and 2.3 ± 0.6 PgC yr−1 and 2.0 ± 0.8 PgC yr−1, respectively, for a 14-year period (2003–2016). Despite the independent approaches, these sink values of this study agreed with those estimated by the Global Carbon Project (GCP) within a difference of about ±0.3 PgC yr−1. We examined the carbon sinks for an interval of five years to assess the temporal trends. The pentad (5-year) ocean sinks showed an increasing trend at a rate of 0.09 ± 0.02 PgC yr−2 during 2001–2014, while the pentad land sinks showed an increasing trend at a rate of 0.23 ± 0.03 PgC yr−2 for 2001–2009 and a decreasing trend at a rate of − 0.23 ± 0.05 PgC yr−2 during 2009–2014. Although there is good agreement in the trends of the pentad sinks between this study and that of GCP, the increasing rate of the pentad ocean sinks of this study was about two times larger than that of GCP.

scholarly journals Regional CO<sub>2</sub> fluxes from 2010 to 2015 inferred from GOSAT XCO<sub>2</sub> retrievals using a new version of the Global Carbon Assimilation System

2021 ◽  
Vol 21 (3) ◽  
pp. 1963-1985
Author(s):  
Fei Jiang ◽  
Hengmao Wang ◽  
Jing M. Chen ◽  
Weimin Ju ◽  
Xiangjun Tian ◽  
...  
Keyword(s):  
Carbon Assimilation ◽  
Carbon Fluxes ◽  
Atmospheric Co2 ◽  
Interannual Variations ◽  
Carbon Sinks ◽  
Area Index ◽  
Spatial Coverage ◽  
The Impact ◽  
Global Carbon ◽  
Assimilation System

Abstract. Satellite retrievals of the column-averaged dry air mole fractions of CO2 (XCO2) could help to improve carbon flux estimation due to their good spatial coverage. In this study, in order to assimilate the GOSAT (Greenhouse Gases Observing Satellite) XCO2 retrievals, the Global Carbon Assimilation System (GCAS) is upgraded with new assimilation algorithms, procedures, a localization scheme, and a higher assimilation parameter resolution. This upgraded system is referred to as GCASv2. Based on this new system, the global terrestrial ecosystem (BIO) and ocean (OCN) carbon fluxes from 1 May 2009 to 31 December 2015 are constrained using the GOSAT ACOS (Atmospheric CO2 Observations from Space) XCO2 retrievals (Version 7.3). The posterior carbon fluxes from 2010 to 2015 are independently evaluated using CO2 observations from 52 surface flask sites. The results show that the posterior carbon fluxes could significantly improve the modeling of atmospheric CO2 concentrations, with global mean bias decreases from a prior value of 1.6 ± 1.8 ppm to −0.5 ± 1.8 ppm. The uncertainty reduction (UR) of the global BIO flux is 17 %, and the highest monthly regional UR could reach 51 %. Globally, the mean annual BIO and OCN carbon sinks and their interannual variations inferred in this study are very close to the estimates of CarbonTracker 2017 (CT2017) during the study period, and the inferred mean atmospheric CO2 growth rate and its interannual changes are also very close to the observations. Regionally, over the northern lands, the strongest carbon sinks are seen in temperate North America, followed by Europe, boreal Asia, and temperate Asia; in the tropics, there are strong sinks in tropical South America and tropical Asia, but a very weak sink in Africa. This pattern is significantly different from the estimates of CT2017, but the estimated carbon sinks for each continent and some key regions like boreal Asia and the Amazon are comparable or within the range of previous bottom-up estimates. The inversion also changes the interannual variations in carbon fluxes in most TransCom land regions, which have a better relationship with the changes in severe drought area (SDA) or leaf area index (LAI), or are more consistent with previous estimates for the impact of drought. These results suggest that the GCASv2 system works well with the GOSAT XCO2 retrievals and shows good performance with respect to estimating the surface carbon fluxes; meanwhile, our results also indicate that the GOSAT XCO2 retrievals could help to better understand the interannual variations in regional carbon fluxes.

Are old forests underestimated as global carbon sinks?

2001 ◽  
Vol 7 (4) ◽  
pp. 339-344 ◽  
Author(s):  
Eileen V. Carey ◽  
Anna Sala ◽  
Robert Keane ◽  
Ragan M. Callaway
Keyword(s):  
Carbon Sinks ◽  
Global Carbon

scholarly journals Carbon Fluxes and Stocks by Mexican Tropical Forested Wetland Soils: A Critical Review of Its Role for Climate Change Mitigation

2020 ◽  
Vol 17 (20) ◽  
pp. 7372
Author(s):  
Sergio Zamora ◽  
Luis Carlos Sandoval-Herazo ◽  
Gastón Ballut-Dajud ◽  
Oscar Andrés Del Ángel-Coronel ◽  
Erick Arturo Betanzo-Torres ◽  
...  
Keyword(s):  
Climate Change ◽  
Soil Carbon ◽  
Carbon Sink ◽  
Carbon Stocks ◽  
Response Strategy ◽  
Forested Wetland ◽  
Wetland Soils ◽  
Carbon Sinks ◽  
Tropical Regions ◽  
Global Carbon

Wetland soils are important stores of soil carbon (C) in the biosphere, and play an important role in global carbon cycles in the response strategy to climate change. However, there areknowledge gaps in our understanding of the quantity and distribution in tropical regions. Specifically, Mexican wetlands have not been considered in global carbon budgets or carbon balances for a number of reasons, such as: (1) the lack of data, (2) Spanish publications have not been selected, or (3) because such balances are mainly made in the English language. This study analyzes the literature regarding carbon stocks, sequestration and fluxes in Mexican forested wetlands (Forest-W). Soil carbon stocks of 8, 24.5 and 40.1 kg cm−2 were detected for flooded palms, mangroves, and freshwater or swamps (FW) wetland soils, respectively, indicating that FW soils are the Forest-W with more potential for carbon sinks (p = 0.023), compared to mangroves and flooded palm soils. While these assessments of carbon sequestration were ranged from 36 to 920 g-C m−2 year−1, C emitted as methane was also tabulated (0.6–196 g-C m−2 year−1). Subtracting the C emitted of the C sequestered, 318.2 g-C m−2 year−1 were obtained. Such data revealed that Forest-W function is mainly as carbon sink, and not C source. This review can help to inform practitioners in future decisions regarding sustainable projects, restoration, conservation or creation of wetlands. Finally, it is concluded that Forest-W could be key ecosystems in strategies addressing the mitigation of climate change through carbon storage. However, new studies in this research line and public policies that protect these essential carbon sinks are necessary in order to, hopefully, elaborate global models to make more accurate predictions about future climate.

scholarly journals Impacts of land cover and climate data selection on understanding terrestrial carbon dynamics and the CO<sub>2</sub> airborne fraction

2011 ◽  
Vol 8 (8) ◽  
pp. 2027-2036 ◽  
Author(s):  
B. Poulter ◽  
D. C. Frank ◽  
E. L. Hodson ◽  
N. E. Zimmermann
Keyword(s):  
Land Cover ◽  
Carbon Emissions ◽  
Net Primary Production ◽  
Carbon Fluxes ◽  
Positive Trend ◽  
Carbon Sinks ◽  
Climate Data ◽  
Terrestrial Carbon ◽  
Dynamic Global Vegetation Model ◽  
Global Carbon

Abstract. Terrestrial and oceanic carbon cycle processes remove ~55 % of global carbon emissions, with the remaining 45 %, known as the "airborne fraction", accumulating in the atmosphere. The long-term dynamics of the component fluxes contributing to the airborne fraction are challenging to interpret, but important for informing fossil-fuel emission targets and for monitoring the trends of biospheric carbon fluxes. Climate and land-cover forcing data for terrestrial ecosystem models are a largely unexplored source of uncertainty in terms of their contribution to understanding airborne fraction dynamics. Here we present results using a single dynamic global vegetation model forced by an ensemble experiment of climate (CRU, ERA-Interim, NCEP-DOE II), and diagnostic land-cover datasets (GLC2000, GlobCover, MODIS). For the averaging period 1996–2005, forcing uncertainties resulted in a large range of simulated global carbon fluxes, up to 13 % for net primary production (52.4 to 60.2 Pg C a−1) and 19 % for soil respiration (44.2 to 54.8 Pg C a−1). The sensitivity of contemporary global terrestrial carbon fluxes to climate strongly depends on forcing data (1.2–5.9 Pg C K−1 or 0.5 to 2.7 ppmv CO2 K−1), but weakening carbon sinks in sub-tropical regions and strengthening carbon sinks in northern latitudes are found to be robust. The climate and land-cover combination that best correlate to the inferred carbon sink, and with the lowest residuals, is from observational data (CRU) rather than reanalysis climate data and with land-cover categories that have more stringent criteria for forest cover (MODIS). Since 1998, an increasing positive trend in residual error from bottom-up accounting of global sinks and sources (from 0.03 (1989–2005) to 0.23 Pg C a−1 (1998–2005)) suggests that either modeled drought sensitivity of carbon fluxes is too high, or that carbon emissions from net land-cover change is too large.

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