Facies control on carbonate δ13C on the Great Bahama Bank

Geology ◽  
2021 ◽  
Author(s):  
Emily C. Geyman ◽  
Adam C. Maloof
Keyword(s):  
Global Carbon Cycle ◽  
Global Ocean ◽  
Seawater Chemistry ◽  
Great Bahama Bank ◽  
The Past ◽  
Carbon Isotopic ◽  
Lime Mud ◽  
Stratigraphic Record ◽  
Vital Effects ◽  
Global Carbon

The carbon isotopic (δ13C) composition of shallow-water carbonates often is interpreted to reflect the δ13C of the global ocean and is used as a proxy for changes in the global carbon cycle. However, local platform processes, in addition to meteoric and marine diagenesis, may decouple carbonate δ13C from that of the global ocean. We present new δ13C measurements of benthic foraminifera, solitary corals, calcifying green algae, ooids, coated grains, and lime mud from the modern Great Bahama Bank. We find that vital effects, cross-shelf seawater chemistry gradients, and meteoric diagenesis produce carbonate with δ13C variability rivaling that of the past two billion years of Earth history. Leveraging Walther’s Law, we illustrate how these local δ13C signals can find their way into the stratigraphic record of bulk carbonate.

The morphology of experimentally produced charcoal distinguishes fuel types in the Arctic tundra

The Holocene ◽  
2020 ◽  
Vol 30 (7) ◽  
pp. 1091-1096 ◽  
Author(s):  
Eleanor MB Pereboom ◽  
Richard S Vachula ◽  
Yongsong Huang ◽  
James Russell
Keyword(s):  
Arctic Tundra ◽  
Global Carbon Cycle ◽  
Fire Frequency ◽  
The Arctic ◽  
Fuel Type ◽  
The Past ◽  
Primary Means ◽  
Forested Ecosystems ◽  
Global Carbon ◽  
Tundra Ecosystems

Wildfires in the Arctic tundra have become increasingly frequent in recent years and have important implications for tundra ecosystems and for the global carbon cycle. Lake sediment–based records are the primary means of understanding the climatic influences on tundra fires. Sedimentary charcoal has been used to infer climate-driven changes in tundra fire frequency but thus far cannot differentiate characteristics of the vegetation burnt during fire events. In forested ecosystems, charcoal morphologies have been used to distinguish changes in fuel type consumed by wildfires of the past; however, no such approach has been developed for tundra ecosystems. We show experimentally that charcoal morphologies can be used to differentiate graminoid (mean = 6.77; standard deviation (SD) = 0.23) and shrub (mean = 2.42; SD = 1.86) biomass burnt in tundra fire records. This study is a first step needed to construct more nuanced tundra wildfire histories and to understand how wildfire will impact the region as vegetation and fire change in the future.

Modelling the global carbon cycle for the past and future evolution of the earth system

1999 ◽  
Vol 159 (1-4) ◽  
pp. 305-317 ◽  
Author(s):  
Siegfried Franck ◽  
Konrad Kossacki ◽  
Christine Bounama
Keyword(s):  
Carbon Cycle ◽  
Global Carbon Cycle ◽  
Earth System ◽  
Future Evolution ◽  
The Past ◽  
The Earth ◽  
Global Carbon

The stable carbon isotopic composition of organic material in platform derived sediments: implications for reconstructing the global carbon cycle

Sedimentology ◽  
2011 ◽  
Vol 59 (1) ◽  
pp. 319-335 ◽  
Author(s):  
AMANDA M. OEHLERT ◽  
KATHRYN A. LAMB-WOZNIAK ◽  
QUINN B. DEVLIN ◽  
GRETA J. MACKENZIE ◽  
JOHN J. G. REIJMER ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Isotopic Composition ◽  
Organic Material ◽  
Carbon Isotopic Composition ◽  
Global Carbon Cycle ◽  
Stable Carbon ◽  
Carbon Isotopic ◽  
Global Carbon

Influence of Southern Ocean dynamics on Antarctic temperatures and on the global carbon cycle over the past two millennia.

2021 ◽  
Author(s):  
Hugues Goosse ◽  
Zhiqiang Lyu ◽  
Laurie Menviel ◽  
Katrin Meissner ◽  
Anne Mouchet
Keyword(s):  
Carbon Cycle ◽  
Southern Ocean ◽  
Ocean Circulation ◽  
Global Carbon Cycle ◽  
Ocean Dynamics ◽  
Temperature History ◽  
Joint Analysis ◽  
The Past ◽  
Reconstructed Temperature ◽  
Global Carbon

<p>Reconstructions of Antarctic surface temperature covering the past millennia display a large centennial variability that is not synchronous with fluctuations recorded on other continents and which is generally not well simulated by models. Many processes can be at the origin of these temperature variations such as teleconnections with tropical oceans and changes in the Southern Ocean. The focus here will be on the latter, in particular on the influence of westerly winds that have a large impact on the exchange of heat and carbon between the ocean and atmosphere. Changes in the Southern Ocean circulation and stratification also influence the carbon cycle at global scale. It is generally suggested that atmospheric CO<sub>2</sub> variations over the past two millennia were mainly controlled by land processes but the Southern Ocean might have also played a role. We will thus test whether the joint analysis of Antarctic temperature and atmospheric CO<sub>2</sub> concentration fluctuations can inform us on the origin of the observed changes over this period. In this purpose, we use the climate model LOVECLIM which includes a representation of the global carbon cycle. Experiments over the last two millennia will address the sensitivity to realistic perturbations of the wind stress. Finally, experiments with data assimilation will allow assessing what constraints are needed for model results to better reproduce the atmospheric CO<sub>2</sub> concentration and reconstructed temperature history.</p>

Mineral dust coupled with climate-carbon cycle on orbital timescales over the past 4 Ma

2021 ◽  
Author(s):  
Mengmeng Cao ◽  
Zhixiang Wang ◽  
Ze Zhang ◽  
Anguo Xiao
Keyword(s):  
Carbon Cycle ◽  
Deep Sea ◽  
Mineral Dust ◽  
Ice Sheet ◽  
Global Carbon Cycle ◽  
The Arctic ◽  
The Past ◽  
Dust Flux ◽  
Arctic Ice ◽  
Global Carbon

<p>Mineral dust is one of the environmental component for forcing the global climatic change, and not only influences the amount of solar radiation incoming the earth surface, but affects atmospheric CO<sub>2</sub> concentrations in the past through wind transport to ocean and subsequent biological pumping. Mineral dust is one of the important driving factors for variations of atmospheric CO<sub>2 </sub>content in Quaternary glacial-interglacial cycles. Here, we reconstruct the interaction between the Asian dust flux (as a representative of the global dust flux), the cryosphere system (δ<sup>1</sup><sup>8</sup>O<sub>benthic</sub>), and the global carbon cycle since 4 Ma using phase analysis, power decomposition analysis, obliquity sensitivity calculation and evolutionary spectral analysis. The evolutionary spectra show that orbital-scale variability of mineral dust, δ<sup>1</sup><sup>8</sup>O<sub>benthic</sub> and δ<sup>13</sup>C<sub>benthic</sub> are very similar over the past 4 Ma, except the interval time of 3-2 Ma that shows higher obliquity energy (higher O/T values) of the δ<sup>1</sup><sup>8</sup>O<sub>benthic</sub> and δ<sup>13</sup>C<sub>benthic</sub> data. Therefore, we suggest that the Asian and/or global dust is acted as a transmitter transporting the periodic signals stored in the Arctic ice sheet to deep-sea δ<sup>13</sup>C<sub>benthic</sub>. This is why δ<sup>13</sup>C<sub>benthic</sub> data have very similar changes with the Arctic ice sheets on the orbital scale. Sharp increase of global dust flux after 1.6 Ma resulted in a significant weakening of the 405 kyr long eccentricity power of δ<sup>13</sup>C<sub>benthic</sub> series because Arctic ice sheet signals strongly inhibit the influences of low-latitude solar insolation variations on deep-sea δ<sup>13</sup>C<sub>benthic</sub> system. In addition, we suggest that strengthened global drought and increases of dust fluxes since late Miocene probably forced the anti-phase relationship between δ<sup>1</sup><sup>8</sup>O<sub>benthic</sub> and δ<sup>13</sup>C<sub>benthic</sub> around 6 Ma, rather than the expansion of Arctic ice sheet. Our results highlight the close coupling between dust fluxes and the global carbon cycle, with deeply influencing marine productivity and land surface processes.</p><p><strong>Keywords: </strong>mineral dust; deep sea oxygen isotope (δ<sup>18</sup>O<sub>benthic</sub> ); deep sea carbon isotope(δ<sup>13</sup>C<sub>benthic</sub>); orbital  periods ; inland Asia</p>

Are response function representations of the global carbon cycle ever interpretable?

Tellus B ◽  
2009 ◽  
Vol 61 (2) ◽  
Author(s):  
Sile Li ◽  
Andrew J. Jarvis ◽  
David T. Leedal
Keyword(s):  
Carbon Cycle ◽  
Response Function ◽  
Global Carbon Cycle ◽  
Global Carbon
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