Peat-based record from southern Patagonia shows centennial-scale variability since 4.2 ka

2021 ◽  
Author(s):  
Julie Loisel ◽  
Kristen Sarna
Keyword(s):  
Water Table ◽  
Atmospheric Carbon Dioxide ◽  
Deep Ocean ◽  
Testate Amoeba ◽  
Peat Core ◽  
Southern Patagonia ◽  
Depth Reconstruction ◽  
Late Twentieth ◽  
Southern Annual Mode ◽  
Carbon Dioxide Co2

<p>Here we present a 4200-year-old high-resolution peat core reconstruction from southern Patagonia. Our detailed carbon isotope (δ13C) record and testate amoeba-inferred water table depth reconstruction point to a progressive wetting of the peatland surface from 4200 to 1500 cal. yr BP, followed by a dry event at 1200-800 cal. yr BP and drier conditions since then. Superimposed on this trend are centennial-scale dips in δ13C values and water table depths that we associate with warm/dry spells. We interpret these shifts, which are akin to positive phases of the Southern Annual Mode (SAM), as reflecting century-scale changes in the Southern Westerly Wind belt during the late Holocene. Other records from southern South America and Tasmania have revealed synchronous changes in local vegetation and fire activity, strengthening our hypothesis. We know that millennial-scale shifts in the Westerly winds influence ocean upwelling in the Southern Ocean, with effects on global atmospheric carbon dioxide (CO2) concentrations. Our study, along with a few others, may help elucidate whether centennial-scale SAM-like shifts could also modulate the global carbon cycle via CO2 degassing from the deep ocean. This is important because instrumental and reanalysis records indicate strengthening and poleward contraction indicate a positive phase of the SAM since the late twentieth century.</p>

scholarly journals Preservation of terrestrial organic carbon in marine sediments off shore Taiwan: mountain building and atmospheric carbon dioxide sequestration

2013 ◽  
Vol 1 (1) ◽  
pp. 177-206
Author(s):  
S.-J. Kao ◽  
R. G. Hilton ◽  
K. Selvaraj ◽  
M. Dai ◽  
F. Zehetner ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Organic Carbon ◽  
Marine Sediments ◽  
Atmospheric Carbon Dioxide ◽  
Climatic Variability ◽  
Deep Ocean ◽  
Sediment Traps ◽  
Terrestrial Biosphere ◽  
Atmospheric Carbon ◽  
Carbon Dioxide Co2

Abstract. Geological sequestration of atmospheric carbon dioxide (CO2) can be achieved by the erosion of organic carbon (OC) from the terrestrial biosphere and its burial in long-lived marine sediments. Rivers on mountain islands of Oceania in the western Pacific have very high rates of OC export to the ocean, yet its preservation offshore remains poorly constrained. Here we use the OC content (Corg, %), radiocarbon (Δ14Corg) and stable isotope (δ13Corg) composition of sediments offshore Taiwan to assess the fate of terrestrial OC. We account for rock-derived fossil OC to assess the preservation of OC eroded from the terrestrial biosphere (non-fossil OC) during flood discharges (hyperpycnal river plumes) and when river inputs are dispersed more widely (hypopycnal). The Corg, Δ14Corg and δ13Corg of marine sediment traps and cores indicate that during flood discharges, terrestrial OC is transferred efficiently to the deep ocean and accumulates offshore with little evidence for terrestrial OC loss. In marine sediments fed by dispersive river inputs, the Corg, Δ14Corg and δ13Corg are consistent with mixing of marine OC and terrestrial OC and suggest that efficient preservation of terrestrial OC (> 70%) is also associated with hypopycnal delivery. Re-burial of fossil OC is pervasive. Our findings from Taiwan suggest that erosion and marine burial of terrestrial non-fossil OC may sequester > 8 TgC yr−1 across Oceania, a significant geological CO2 sink which requires better constraint. We postulate that mountain islands of Oceania provide strong link between tectonic uplift and the carbon cycle, one moderated by the climatic variability that controls terrestrial OC delivery to the ocean.

scholarly journals The importance of Northern Peatlands in global carbon systems during the Holocene

2009 ◽  
Vol 5 (2) ◽  
pp. 1231-1258 ◽  
Author(s):  
Y. Wang ◽  
N. T. Roulet ◽  
S. Frolking ◽  
L. A. Mysak
Keyword(s):  
Atmospheric Carbon Dioxide ◽  
Ice Cores ◽  
Deep Ocean ◽  
Interglacial Period ◽  
The Holocene ◽  
The Past ◽  
C Cycle ◽  
Carbon Dioxide Co2 ◽  
Northern Peatlands ◽  
Global Carbon

Abstract. We applied an inverse model to simulate global carbon (C) cycle dynamics during the Holocene period using atmospheric carbon dioxide (CO2) concentrations reconstructed from Antarctic ice cores and prescribed C accumulation rates of Northern Peatlands (NP) as inputs. Previous studies indicated that different sources could contribute to the 20 parts per million by volume (ppmv) atmospheric CO2 increase over the past 8000 years. These sources of C include terrestrial release of 40–200 petagram C (PgC, 1 petagram=1015 gram), deep oceanic adjustment to a 500 PgC terrestrial biomass buildup early in this interglacial period, and anthropogenic land-use and land-cover changes of unknown magnitudes. Our study shows that the prescribed peatland C accumulation significantly modifies our previous understanding of Holocene C cycle dynamics. If the buildup of the NP is considered, the terrestrial pool becomes the C sink of about 160–280 PgC over the past 8000 years, and the only C source for the terrestrial and atmospheric C increases is presumably from the deep ocean due to calcium carbonate compensation. Future studies need to be conducted to constrain the basal times and growth rates of the NP C accumulation in the Holocene. These research endeavors are challenging because they need a dynamically-coupled peatland simulator to be constrained with the initiation time and reconstructed C reservoir of the NP. Our results also suggest that the huge reservoir of deep ocean C explains the major variability of the glacial-interglacial C cycle dynamics without considering the anthropogenic C perturbation.

scholarly journals The importance of Northern Peatlands in global carbon systems during the Holocene

2009 ◽  
Vol 5 (4) ◽  
pp. 683-693 ◽  
Author(s):  
Y. Wang ◽  
N. T. Roulet ◽  
S. Frolking ◽  
L. A. Mysak
Keyword(s):  
Atmospheric Carbon Dioxide ◽  
Ice Cores ◽  
Deep Ocean ◽  
Interglacial Period ◽  
The Holocene ◽  
The Past ◽  
C Cycle ◽  
Carbon Dioxide Co2 ◽  
Northern Peatlands ◽  
Global Carbon

Abstract. We applied an inverse model to simulate global carbon (C) cycle dynamics during the Holocene period using atmospheric carbon dioxide (CO2) concentrations reconstructed from Antarctic ice cores and prescribed C accumulation rates of Northern Peatlands (NP) as inputs. Previous studies indicated that different sources could contribute to the 20 parts per million by volume (ppmv) atmospheric CO2 increase over the past 8000 years. These sources of C include terrestrial release of 40–200 petagram C (PgC, 1 petagram=1015 gram), deep oceanic adjustment to a 500 PgC terrestrial biomass buildup early in this interglacial period, and anthropogenic land-use and land-cover changes of unknown magnitudes. Our study shows that the prescribed peatland C accumulation significantly modifies our previous understanding of Holocene C cycle dynamics. If the buildup of the NP is considered, the terrestrial pool becomes the C sink of about 160–280 PgC over the past 8000 years, and the only C source for the terrestrial and atmospheric C increases is presumably from the deep ocean due to calcium carbonate compensation. Future studies need to be conducted to constrain the basal times and growth rates of the NP C accumulation in the Holocene. These research endeavors are challenging because they need a dynamically-coupled peatland simulator to be constrained with the initiation time and reconstructed C reservoir of the NP. Our results also suggest that the huge reservoir of deep ocean C explains the major variability of the glacial-interglacial C cycle dynamics without considering the anthropogenic C perturbation.

scholarly journals The Exploitation of Local Vitis vinifera L. Biodiversity as a Valuable Tool to Cope with Climate Change Maintaining Berry Quality

Plants ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 71
Author(s):  
María Carmen Antolín ◽  
María Toledo ◽  
Inmaculada Pascual ◽  
Juan José Irigoyen ◽  
Nieves Goicoechea
Keyword(s):  
Climate Change ◽  
Fruit Quality ◽  
Atmospheric Carbon Dioxide ◽  
Antioxidant Properties ◽  
Co2 Concentration ◽  
Soluble Solids ◽  
Vitis Vinifera L ◽  
Grape Quality ◽  
Berry Quality ◽  
Carbon Dioxide Co2

(1) Background: The associated increase in global mean surface temperature together with raised atmospheric carbon dioxide (CO2) concentration is exerting a profound influence on grapevine development (phenology) and grape quality. The exploitation of the local genetic diversity based on the recovery of ancient varieties has been proposed as an interesting option to cope with climate change and maintaining grape quality. Therefore, this research aimed to characterize the potential fruit quality of genotypes from seven local old grapevine varieties grown under climate change conditions. (2) Methods: The study was carried out on fruit-bearing cuttings (one cluster per plant) that were grown in pots in temperature gradient greenhouses (TGG). Two treatments were applied from fruit set to maturity: (1) ambient CO2 (400 ppm) and temperature (T) (ACAT) and (2) elevated CO2 (700 ppm) and temperature (T + 4 °C) (ECET). (3) Results: Results showed that some of the old genotypes tested remained quite stable during the climate change conditions in terms of fruit quality (mainly, total soluble solids and phenolic content) and of must antioxidant properties. (4) Conclusion: This research underlines the usefulness of exploiting local grapevine diversity to cope with climate change successfully, although further studies under field conditions and with whole plants are needed before extrapolating the results to the vineyard.

scholarly journals The Influence of Ocean Thermocline Temperatures on the Earth’s Surface Climate

2005 ◽  
Vol 18 (13) ◽  
pp. 2222-2246 ◽  
Author(s):  
Robert J. Oglesby ◽  
Monica Y. Stephens ◽  
Barry Saltzman
Keyword(s):  
Carbon Dioxide ◽  
Mixed Layer ◽  
General Circulation ◽  
Atmospheric Carbon Dioxide ◽  
Deep Ocean ◽  
High Latitudes ◽  
Surface Climate ◽  
Low Latitudes ◽  
Atmospheric Carbon ◽  
The Impact

Abstract A coupled mixed layer–atmospheric general circulation model has been used to evaluate the impact of ocean thermocline temperatures (and by proxy those of the deep ocean) on the surface climate of the earth. Particular attention has been devoted to temperature regimes both warmer and cooler than at present. The mixed layer ocean model (MLOM) simulates vertical dynamics and thermodynamics in the upper ocean, including wind mixing and buoyancy effects, and has been coupled to the NCAR Community Climate Model (CCM3). Simulations were made with globally uniform thermocline warmings of +2°, +5°, and +10°C, as well as a globally uniform cooling of −5°C. A simulation was made with latitudinally varying changes in thermocline temperature such that the warming at mid- and high latitudes is much larger than at low latitudes. In all simulations, the response of surface temperature over both land and ocean was larger than that expected just as a result of the imposed thermocline temperature change, largely because of water vapor feedbacks. In this respect, the simulations were similar to those in which only changes in atmospheric carbon dioxide were imposed. In fact, when carbon dioxide was explicitly changed along with thermocline temperatures, the results were not much different than if only the thermocline temperatures were altered. Land versus ocean differences are explained largely by latent heat flux differences: the ocean is an infinite evaporative source, while land can be quite dry. The latitudinally varying case has a much larger response at mid- to high latitudes than at low latitudes; the high latitudes actually appear to effectively warm the low latitudes. Simulations exploring scenarios of glacial inception suggest that the deep ocean alone is not likely to be a key trigger but must operate in conjunction with other forcings, such as reduced carbon dioxide. Moist upland regions at mid- and high latitudes, and land regions adjacent to perennial sea ice, are the preferred locations for glacial inception in these runs. Finally, the model combination equilibrates very rapidly, meaning that a large number of simulations can be made for a fairly modest computational cost. A drawback to this is greatly reduced sensitivity to parameters such as atmospheric carbon dioxide, which requires a full response of the ocean. Thus, this approach can be considered intermediate between fixing, or prescribing, sea surface temperatures and a fully coupled modeling approach.

scholarly journals Using airborne HIAPER Pole-to-Pole Observations (HIPPO) to evaluate model and remote sensing estimates of atmospheric carbon dioxide

2016 ◽  
Author(s):  
C. Frankenberg ◽  
S. S. Kulawik ◽  
S. Wofsy ◽  
F. Chevallier ◽  
B. Daube ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Atmospheric Carbon Dioxide ◽  
Correlation Coefficients ◽  
Added Value ◽  
Total Carbon ◽  
Accuracy And Precision ◽  
Atmospheric Carbon ◽  
Carbon Dioxide Co2 ◽  
Global Carbon ◽  
Comparable Quality

Abstract. In recent years, space-borne observations of atmospheric carbon-dioxide (CO2) have become increasingly used in global carbon-cycle studies. In order to obtain added value from space-borne measurements, they have to suffice stringent accuracy and precision requirements, with the latter being less crucial as it can be reduced by just enhanced sample size. Validation of CO2 column averaged dry air mole fractions (XCO2) heavily relies on measurements of the Total Carbon Column Observing Network TCCON. Owing to the sparseness of the network and the requirements imposed on space-based measurements, independent additional validation is highly valuable. Here, we use observations from the HIAPER Pole-to-Pole Observations (HIPPO) flights from January 2009 through September 2011 to validate CO2 measurements from satellites (GOSAT, TES, AIRS) and atmospheric inversion models (CarbonTracker CT2013B, MACC v13r1). We find that the atmospheric models capture the XCO2 variability observed in HIPPO flights very well, with correlation coefficients (r2) of 0.93 and 0.95 for CT2013B and MACC, respectively. Some larger discrepancies can be observed in profile comparisons at higher latitudes, esp. at 300 hPa during the peaks of either carbon uptake or release. These deviations can be up to 4 ppm and hint at misrepresentation of vertical transport. Comparisons with the GOSAT satellite are of comparable quality, with an r2 of 0.85, a mean bias μ of −0.06 ppm and a standard deviation σ of 0.45 ppm. TES exhibits an r2 of 0.75, μ of 0.34 ppm and σ of 1.13 ppm. For AIRS, we find an r2 of 0.37, μ of 1.11 ppm and σ of 1.46 ppm, with latitude-dependent biases. For these comparisons at least 6, 20 and 50 atmospheric soundings have been averaged for GOSAT, TES and AIRS, respectively. Overall, we find that GOSAT soundings over the remote pacific ocean mostly meet the stringent accuracy requirements of about 0.5 ppm for space-based CO2 observations.

scholarly journals Possible source of ancient carbon in phytolith concentrates from harvested grasses

2012 ◽  
Vol 9 (5) ◽  
pp. 1873-1884 ◽  
Author(s):  
G. M. Santos ◽  
A. Alexandre ◽  
J. R. Southon ◽  
K. K. Treseder ◽  
R. Corbineau ◽  
...  
Keyword(s):  
Plant Tissue ◽  
Atmospheric Carbon Dioxide ◽  
Energy Dispersive Spectrometer ◽  
Nutrient Acquisition ◽  
Published Data ◽  
Plant Nutrient ◽  
Before Present ◽  
Sem Images ◽  
Carbon Dioxide Co2 ◽  
Scanning Electron

Abstract. Plants absorb and transport silicon (Si) from soil, and precipitation of Si within the living plants results in micrometric amorphous biosilica particles known as phytoliths. During phytolith formation, a small amount of carbon (<2%) can become occluded in the silica structure (phytC) and therefore protected from degradation by the environment after plant tissue decomposition. Since the major C source within plants is from atmospheric carbon dioxide (CO2) via photosynthesis, the current understanding is that the radiocarbon (14C) content of phytC should reflect the 14C content of atmospheric CO2 at the time the plant is growing. This assumption was recently challenged by 14C data from phytoliths extracted from living grasses that yielded ages of several thousand years (2–8 kyr BP; in radiocarbon years "Before Present" (BP), "Present" being defined as 1950). Because plants can take up small amounts of C of varying ages from soils (e.g., during nutrient acquisition), we hypothesized that this transported C within the plant tissue could be attached to or even embedded in phytoliths. In this work, we explore this hypothesis by reviewing previously published data on biosilica mineralization and plant nutrient acquisition as well as by evaluating the efficiency of phytolith extraction protocols from scanning electron microscope (SEM) images and energy dispersive spectrometer (EDS) analyses from harvested grasses phytolith concentrates. We show that current extraction protocols are inefficient since they do not entirely remove recalcitrant forms of C from plant tissue. Consequently, material previously measured as "phytC" may contain at least some fraction of soil-derived C (likely radiocarbon-old) taken up by roots. We also suggest a novel interpretation for at least some of the phytC – which enters via the root pathway during nutrient acquisition – that may help to explain the old ages previously obtained from phytolith concentrates.

The rate of dissolution of calcium carbonate from the surface of deep-ocean turbidite sediments

1990 ◽  
Vol 331 (1616) ◽  
pp. 41-49 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Atmospheric Carbon Dioxide ◽  
Bottom Water ◽  
Natural Radionuclide ◽  
Carbon Dioxide Concentration ◽  
Deep Ocean ◽  
Sediment Surface ◽  
Carbonate Sediments ◽  
Sedimentary Record ◽  
Atmospheric Carbon

It is known that past periods of high atmospheric carbon dioxide concentration are associated with poor carbonate preservation in the deep-ocean sedimentary record. Bottom water can become more aggressive towards carbonate sediments during such periods. To interpret the sedimentary record more exactly, and to predict future atmospheric carbon dioxide levels, it is necessary to know the rate of solution of carbonate for a given degree of bottom-water undersaturation. In parts of the Atlantic Ocean, turbidite sedimentation mechanisms have emplaced carbonate-rich material in contact with undersaturated bottom water. The time of the emplacement event can be determined from natural radionuclide distributions, and the degree of carbonate dissolution in this time can be measured. This provides a direct measurement of dissolution rate from a natural sediment surface at a known degree of undersaturation. The range of applicability of the method is explored with a mathematical model, and field data from a 5430 m depth Atlantic site are presented.

scholarly journals Does ocean acidification induce an upward flux of marine aggregates?

2008 ◽  
Vol 5 (4) ◽  
pp. 1023-1031 ◽  
Author(s):  
X. Mari
Keyword(s):  
Ocean Acidification ◽  
Atmospheric Carbon Dioxide ◽  
New Caledonia ◽  
Seawater Acidification ◽  
Seawater Ph ◽  
Biogenic Carbon ◽  
Marine Aggregates ◽  
Atmospheric Carbon ◽  
Carbon Dioxide Co2 ◽  
Sedimentation Processes

Abstract. The absorption of anthropogenic atmospheric carbon dioxide (CO2) by the ocean provokes its acidification. This acidification may alter several oceanic processes, including the export of biogenic carbon from the upper layer of the ocean, hence providing a feedback on rising atmospheric carbon concentrations. The effect of seawater acidification on transparent exopolymeric particles (TEP) driven aggregation and sedimentation processes were investigated by studying the interactions between latex beads and TEP precursors collected in the lagoon of New Caledonia. A suspension of TEP and beads was prepared and the formation of mixed aggregates was monitored as a function of pH under increasing turbulence intensities. The pH was controlled by addition of sulfuric acid. Aggregation and sedimentation processes driven by TEP were drastically reduced when the pH of seawater decreases within the expected limits imposed by increased anthropogenic CO2 emissions. In addition to the diminution of TEP sticking properties, the diminution of seawater pH led to a significant increase of the TEP pool, most likely due to swollen structures. A diminution of seawater pH by 0.2 units or more led to a stop or a reversal of the downward flux of particles. If applicable to oceanic conditions, the sedimentation of marine aggregates may slow down or even stop as the pH decreases, and the vertical flux of organic carbon may reverse. This would enhance both rising atmospheric carbon and ocean acidification.

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