scholarly journals Commercial fishery disturbance of the global ocean biological carbon sink

2021 ◽  
Author(s):  
Emma L. Cavan ◽  
Simeon L. Hill
Keyword(s):  
Carbon Sink ◽  
Global Ocean ◽  
Commercial Fishery

The dire straits of Paratethys: Gateways to the anoxic giant of Eurasia

2021 ◽  
pp. SP523-2021-73
Author(s):  
D. V. Palcu ◽  
W. Krijgsman
Keyword(s):  
Carbon Sink ◽  
Global Climate ◽  
Water Masses ◽  
Source Rocks ◽  
Global Ocean ◽  
Tectonic Processes ◽  
Anoxic Environments ◽  
Geological Evolution ◽  
History Of ◽  
Tethys Ocean

AbstractA complex interplay of palaeoclimatic, eustatic and tectonic processes led to fragmentation and dissipation of the vast Tethys Ocean in Eocene-Oligocene times. The resulting Paratethys Sea occupied the northern Tethys region on Eurasia, grouping water masses of various subbasins, separated from each other and from the open ocean through narrow and shallow gateways and land bridges. Changes in marine gateway configuration and intra-basinal connectivity affected the regional hydrology, shifting most Paratethyan basins to extreme carbon-sink anoxic environments, anomalohaline evaporitic or brackish conditions or even endorheic lakes. Paratethys gateway restriction triggered the onset of a long-lasting (∼20 Myr) giant anoxic sea, characterised by stratified water masses and anoxic bottom water conditions, resulting in thick hydrocarbon source rocks. Here, we review the geological evolution of the “dire straits” of Paratethys that played a crucial role in the Eocene-Oligocene connectivity history of the Central Eurasian seas and we show that the main anoxic phases (Kuma and Maikop) correspond to restricted connectivity with the global ocean and a period of CO2 depletion in the atmosphere. Paratethys represents one of the largest carbon sinks of Earth's history and may thus have played a prominent role in global climate change.

The Southern Ocean carbon sink 1985-2018: first results of the RECCAP2 project

2021 ◽  
Author(s):  
Judith Hauck ◽  
Luke Gregor ◽  
Cara Nissen ◽  
Eric Mortenson ◽  
Seth Bushinsky ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Seasonal Cycle ◽  
Carbon Sink ◽  
Global Ocean ◽  
Biogeochemical Models ◽  
Wide Range ◽  
Data Products ◽  
First Results ◽  
Ocean Carbon ◽  
Indian Sector

<p>The Southern Ocean is the main gateway for anthropogenic CO<sub>2</sub> into the ocean owing to the upwelling of old water masses with low anthropogenic CO<sub>2</sub> concentration, and the transport of the newly equilibrated surface waters into the ocean interior through intermediate, deep and bottom water formation. Here we present first results of the Southern Ocean chapter of RECCAP2, which is the Global Carbon Project’s second systematic study on Regional Carbon Cycle Assessment and Processes. In the Southern Ocean chapter, we aim to assess the Southern Ocean carbon sink 1985-2018 from a wide range of available models and data sets, and to identify patterns of regional and temporal variability, model limitations and future challenges.</p><p>We gathered global and regional estimates of the air-sea CO<sub>2</sub> flux over the period 1985-2018 from global ocean biogeochemical models, surface pCO<sub>2</sub>-based data products, and data-assimilated models. The analysis on the Southern Ocean quantified geographical patterns in the annual mean and seasonal amplitude of air-sea CO<sub>2</sub> flux, with results presented here aggregated to the level of large-scale ocean biomes.</p><p>Considering the suite of observed and modelled estimates, we found that the subtropical seasonally stratified (STSS) biome stands out with the largest air-sea CO<sub>2</sub> flux per area and a seasonal cycle with largest ocean uptake of CO<sub>2</sub> in winter, whereas the ice (ICE) biome is characterized by a large ensemble spread and a pronounced seasonal cycle with the largest ocean uptake of CO<sub>2</sub> in summer. Connecting these two, the subpolar seasonally stratified (SPSS) biome has intermediate flux densities (flux per area), and most models have difficulties simulating the seasonal cycle with strongest uptake during the summer months.</p><p>Our analysis also reveals distinct differences between the Atlantic, Pacific and Indian sectors of the aforementioned biomes. In the STSS, the Indian sector contributes most to the ocean carbon sink, followed by the Atlantic and then Pacific sectors. This hierarchy is less pronounced in the models than in the data-products. In the SPSS, only the Atlantic sector exhibits net CO<sub>2</sub> uptake in all years, likely linked to strong biological production. In the ICE biome, the Atlantic and Pacific sectors take up more CO<sub>2</sub> than the Indian sector, suggesting a potential role of the Weddell and Ross Gyres.</p><p>These first results confirm the global relevance of the Southern Ocean carbon sink and highlight the strong regional and interannual variability of the Southern Ocean carbon uptake in connection to physical and biogeochemical processes.</p>

scholarly journals Seasonal to decadal spatiotemporal variations of the global ocean carbon sink

2021 ◽  
Author(s):  
Min Zhang ◽  
Yangyan Cheng ◽  
Ying Bao ◽  
Chang Zhao ◽  
Gang Wang ◽  
...  
Keyword(s):  
Carbon Sink ◽  
Global Ocean ◽  
Spatiotemporal Variations ◽  
Ocean Carbon

Sailing meets Science

2021 ◽  
Author(s):  
Peter Landschützer ◽  
Toste Tanhua ◽  
Stefan Raimund ◽  
Keyword(s):  
High Performance ◽  
Carbon Sink ◽  
Vital Role ◽  
Global Ocean ◽  
Quality Data ◽  
Sensor Technology ◽  
Sink Strength ◽  
Low Weight ◽  
First Results ◽  
Ocean Carbon

<p>The surface partial pressure of carbon dioxide (pCO2) is one of the main quantitates determining the ocean sink strength for CO2 and knowledge of surface ocean pCO2 plays a vital role in monitoring the global carbon budget. However, measuring pCO2 via infrared absorption requires repeated calibration and drift corrections, and therefore ships are still the major platform for these measurements. Given the limited number and availability of pCO2 observations, scientists have fostered collaborations with industrial partners, participating in the Ships of Opportunity (SOOP) program, to collect valuable pCO2 measurements. One fleet, however, has thus far been largely overlooked: sailing yachts. Modern sensor technology to-date allows for low weight and low energy consumption equilibrator systems that can be successfully mounted on recreational and high-performance sailing yachts with good quality data. Here we present the first results from 3 years of autonomous measurements aboard two IMOCA yachts, Seaexplorer -Yacht Club de Monaco (previously Malizia) and Newrest –Art & Fenêtres using a SubCtech flat membrane equilibrator system. First results indicate that sailing yachts provide crucial high frequency measurements to study open and coastal ocean systems, are well suited to study mesoscale variations in the ocean carbon sink and provide measurements beyond industrial shipping routes (e.g. the Southern Ocean). In summary, sail yachts are a promising way forward in order to complement the current observing system for the global ocean carbon cycle in a changing climate.</p>

scholarly journals Decadal variations and trends of the global ocean carbon sink

2016 ◽  
Vol 30 (10) ◽  
pp. 1396-1417 ◽  
Author(s):  
Peter Landschützer ◽  
Nicolas Gruber ◽  
Dorothee C. E. Bakker
Keyword(s):  
Carbon Sink ◽  
Global Ocean ◽  
Decadal Variations ◽  
Ocean Carbon

scholarly journals Recent variability of the global ocean carbon sink

2014 ◽  
Vol 28 (9) ◽  
pp. 927-949 ◽  
Author(s):  
P. Landschützer ◽  
N. Gruber ◽  
D. C. E. Bakker ◽  
U. Schuster
Keyword(s):  
Carbon Sink ◽  
Global Ocean ◽  
Ocean Carbon

scholarly journals Harmonization of global surface ocean pCO<sub>2</sub> mapped products and their flux calculations; an improved estimate of the ocean carbon sink

2021 ◽  
Author(s):  
Amanda R. Fay ◽  
Luke Gregor ◽  
Peter Landschützer ◽  
Galen A. McKinley ◽  
Nicolas Gruber ◽  
...  
Keyword(s):  
Carbon Sink ◽  
Global Ocean ◽  
Average Error ◽  
Co2 Uptake ◽  
Surface Ocean ◽  
Spatial Coverage ◽  
Net Flux ◽  
Carbon Dioxide Co2 ◽  
Global Carbon ◽  
Global Mean

Abstract. Air-sea flux of carbon dioxide (CO2) is a critical component of the global carbon cycle and the climate system with the ocean removing about a quarter of the CO2 emitted into the atmosphere by human activities over the last decade. A common approach to estimate this net flux of CO2 across the air-sea interface is the use of surface ocean CO2 observations and the computation of the flux through a bulk parameterization approach. Yet, the details for how this is done in order to arrive at a global ocean CO2 uptake estimate varies greatly, unnecessarily enhancing the uncertainties. Here we reduce some of these uncertainties by harmonizing an ensemble of products that interpolate surface ocean CO2 observations to near global coverage. We propose a common methodology to fill in missing areas in the products and to calculate fluxes and present a new estimate of the net flux. The ensemble data product, SeaFlux (Fay et al. (2021), doi.org/10.5281/zenodo.4133802, https://github.com/luke-gregor/SeaFlux), accounts for the diversity of the underlying mapping methodologies. Utilizing six global observation-based mapping products (CMEMS-FFNN, CSIR-ML6, JENA-MLS, JMA-MLR, MPI-SOMFFN, NIES-FNN), the SeaFlux ensemble approach adjusts for methodological inconsistencies in flux calculations that can result in an average error of 15 % in global mean flux estimates. We address differences in spatial coverage of the surface ocean CO2 between the mapping products which ultimately yields an increase in CO2 uptake of up to 19 % for some products. Fluxes are calculated using three wind products (CCMPv2, ERA5, and JRA55). Application of an appropriately scaled gas exchange coefficient has a greater impact on the resulting flux than solely the choice of wind product. With these adjustments, we derive an improved ensemble of surface ocean pCO2 and air-sea carbon flux estimates. The SeaFlux ensemble suggests a global mean uptake of CO2 from the atmosphere of 1.92 +/- 0.35 PgC yr-1. This work aims to support the community effort to perform model-data intercomparisons which will help to identify missing fluxes as we strive to close the global carbon budget.

The Variable Southern Ocean Carbon Sink

2019 ◽  
Vol 11 (1) ◽  
pp. 159-186 ◽  
Author(s):  
Nicolas Gruber ◽  
Peter Landschützer ◽  
Nicole S. Lovenduski
Keyword(s):  
Southern Ocean ◽  
Carbon Sink ◽  
Global Ocean ◽  
The Pacific ◽  
Southward Shift ◽  
Storage Rate ◽  
The Pacific Ocean ◽  
Ocean Models ◽  
Ocean Carbon ◽  
Decadal Predictions

The CO2uptake by the Southern Ocean (<35°S) varies substantially on all timescales and is a major determinant of the variations of the global ocean carbon sink. Particularly strong are the decadal changes characterized by a weakening period of the Southern Ocean carbon sink in the 1990s and a rebound after 2000. The weakening in the 1990s resulted primarily from a southward shift of the westerlies that enhanced the upwelling and outgassing of respired (i.e., natural) CO2. The concurrent reduction in the storage rate of anthropogenic CO2in the mode and intermediate waters south of 35°S suggests that this shift also decreased the uptake of anthropogenic CO2. The rebound and the subsequent strong, decade-long reinvigoration of the carbon sink appear to have been driven by cooling in the Pacific Ocean, enhanced stratification in the Atlantic and Indian Ocean sectors, and a reduced overturning. Current-generation ocean models generally do not reproduce these variations and are poorly skilled at making decadal predictions in this region.

scholarly journals Downscaling CMIP6 Global Solutions to Regional Ocean Carbon Model: Connecting the Mississippi, Gulf of Mexico, and Global Ocean

2021 ◽  
Author(s):  
Le Zhang ◽  
Z. George Xue
Keyword(s):  
Gulf Of Mexico ◽  
Carbon Sink ◽  
Biological Activities ◽  
Global Ocean ◽  
Biogeochemical Model ◽  
Spatial And Temporal Patterns ◽  
Saturation State ◽  
Biogeochemical Models ◽  
Ocean Carbon ◽  
Carbon System

Abstract. Coupled physical-biogeochemical models can significantly reduce uncertainties in estimating the spatial and temporal patterns of the ocean carbon system. Challenges of applying a coupled physical-biogeochemical model in the regional ocean include the reasonable prescription of carbon model boundary conditions, lack of in situ observations, and the oversimplification of certain biogeochemical processes. In this study, we applied a coupled physical-biogeochemical model (Regional Ocean Modelling System, ROMS) to the Gulf of Mexico (GoM) and achieved an unprecedented 20-year high-resolution (5 km, 1/22°) hindcast covering the period of 2000–2019. The model’s biogeochemical cycle is driven by the Coupled Model Intercomparison Project 6-Community Earth System Model 2 products (CMIP6-CESM2) and incorporates the dynamics of dissolved organic carbon (DOC) pools as well as the formation and dissolution of carbonate minerals. Model outputs include generally interested carbon system variables, such as pCO2, pH, aragonite saturation state (ΩArag), calcite saturation state (ΩCalc), CO2 air-sea flux, carbon burial rate, etc. The model’s robustness is evaluated via extensive model-data comparison against buoy, remote sensing-based Machine Learning (ML) predictions, and ship-based measurements. Model results reveal that the GoM water has been experiencing an ~ 0.0016 yr−1 decrease in surface pH over the past two decades, accompanied by a ~ 1.66 µatm yr−1 increase in sea surface pCO2. The air-sea CO2 exchange estimation confirms that the river-dominated northern GoM is a substantial carbon sink. The open water of GoM, affected mainly by the thermal effect, is a carbon source during summer and a carbon sink for the rest of the year. Sensitivity experiments are conducted to evaluate the impacts from river inputs and the global ocean via model boundaries. Our results show that the coastal ocean carbon cycle is dominated by enormous carbon inputs from the Mississippi River and nutrient-stimulated biological activities, and the carbon system condition of the open ocean is primarily driven by inputs from the Caribbean Sea via Yucatan Channel.

scholarly journals The continued accumulation of anthropogenic carbon in the global ocean during the 2010s

2021 ◽  
Author(s):  
Jens Daniel Müller ◽  
Donghe Zhu ◽  
Luke Gregor ◽  
Are Olsen ◽  
Nico Lange ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Dissolved Inorganic Carbon ◽  
Carbon Sink ◽  
Synthetic Data ◽  
Uncertainty Assessment ◽  
Global Ocean ◽  
Coupled Analysis ◽  
Biogeochemical Model ◽  
Linear Regression Models ◽  
The Past

&lt;p&gt;Surface ocean pCO&lt;sub&gt;2&lt;/sub&gt;-based estimates and models indicate that the ocean sink for anthropogenic CO&lt;sub&gt;2&lt;/sub&gt; (C&lt;sub&gt;ant&lt;/sub&gt;) has continued to increase unabatedly over the past decade. However, the most recent global and observation-based estimate of the accumulation of C&lt;sub&gt;ant&lt;/sub&gt; in the ocean interior by Gruber et al. (2019) does not extend beyond 2007, preventing an independent assessment of this increase in the magnitude of the sink.&lt;/p&gt;&lt;p&gt;Here, we exploit about 50,000 additional observations of dissolved inorganic carbon (DIC) and other relevant biogeochemical parameters, to extend the Gruber et al. analysis based on the eMLR(C*) method to the 2010s. These data were collected from all major ocean basins over the past decade by GO-SHIP and associated programs, and assembled through GLODAPv2.2020 into an internally consistent data product. We refine the eMLR(C*) method in three ways to achieve the updated storage estimates: (1) the uncertainty assessment is improved, based on a coupled analysis of observations and synthetic data generated from an ocean biogeochemical model, (2) the robustness of the multiple linear regression models is increased, using more stringent predictor and model selection procedures, and (3) the mapping of the C&lt;sub&gt;ant&lt;/sub&gt; fields relies on a MLR ensemble approach that takes into account co-occurring temporal changes of the predictor variables salinity, temperature and oxygen.&lt;/p&gt;&lt;p&gt;&lt;br&gt;Initial results show that the ocean has continued to act as a strong C&lt;sub&gt;ant&lt;/sub&gt; sink with an average uptake rate of 2.8 &amp;#177; 0.3 Pg C yr&lt;sup&gt;-1&lt;/sup&gt; between the reference years 2007 and 2015. This represents a small increase in rate compared to 2.6 &amp;#177; 0.3 Pg C yr&lt;sup&gt;-1&lt;/sup&gt; determined for the 1994 through 2007 period. This increase is slightly smaller than expected on the basis of the growth of atmospheric CO&lt;sub&gt;2&lt;/sub&gt; over the period, but associated uncertainties are too large to make a conclusive statement about whether the ocean carbon sink is slowing down. Initial analyses of the synthetic data indicate that variable ocean circulation and limited sampling, especially the small number of cruises in the Indian Ocean, represent the biggest sources of uncertainty for the eMLR(C*)-based estimate. However, our preliminary sink estimate is in good agreement with recent air-sea CO&lt;sub&gt;2&lt;/sub&gt; flux-based uptake estimates, based on an ensemble of surface pCO&lt;sub&gt;2&lt;/sub&gt; interpolation techniques once these fluxes are adjusted for the river carbon input driven outgassing of natural CO&lt;sub&gt;2&lt;/sub&gt;.&lt;/p&gt;

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