Organic carbon burial forcing of the carbon cycle from Himalayan erosion

Abstract. Several past episodes of rapid carbon cycle and climate change are hypothesised to be the result of the Earth system reaching a tipping point beyond which an abrupt transition to a new state occurs. At the Palaeocene–Eocene Thermal Maximum (PETM) at ∼56 Ma and at subsequent hyperthermal events, hypothesised tipping points involve the abrupt transfer of carbon from surface reservoirs to the atmosphere. Theory suggests that tipping points in complex dynamical systems should be preceded by critical slowing down of their dynamics, including increasing temporal autocorrelation and variability. However, reliably detecting these indicators in palaeorecords is challenging, with issues of data quality, false positives, and parameter selection potentially affecting reliability. Here we show that in a sufficiently long, high-resolution palaeorecord there is consistent evidence of destabilisation of the carbon cycle in the ∼1.5 Myr prior to the PETM, elevated carbon cycle and climate instability following both the PETM and Eocene Thermal Maximum 2 (ETM2), and different drivers of carbon cycle dynamics preceding the PETM and ETM2 events. Our results indicate a loss of “resilience” (weakened stabilising negative feedbacks and greater sensitivity to small shocks) in the carbon cycle before the PETM and in the carbon–climate system following it. This pre-PETM carbon cycle destabilisation may reflect gradual forcing by the contemporaneous North Atlantic Volcanic Province eruptions, with volcanism-driven warming potentially weakening the organic carbon burial feedback. Our results are consistent with but cannot prove the existence of a tipping point for abrupt carbon release, e.g. from methane hydrate or terrestrial organic carbon reservoirs, whereas we find no support for a tipping point in deep ocean temperature.

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Carbon isotope evidence for large methane emissions to the Proterozoic atmosphere

Scientific Reports ◽

10.1038/s41598-020-75100-x ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Pierre Cadeau ◽

Didier Jézéquel ◽

Christophe Leboulanger ◽

Eric Fouilland ◽

Emilie Le Floc’h ◽

...

Keyword(s):

Organic Carbon ◽

Carbon Cycle ◽

Carbon Isotope ◽

Methane Emissions ◽

Unique Combination ◽

Isotopic Signatures ◽

The Earth ◽

Carbon Burial ◽

Organic Carbon Burial ◽

Isotope Evidence

Abstract The Proterozoic Era records two periods of abundant positive carbon isotope excursions (CIEs), conventionally interpreted as resulting from increased organic carbon burial and leading to Earth’s surface oxygenation. As strong spatial variations in the amplitude and duration of these excursions are uncovered, this interpretation is challenged. Here, by studying the carbon cycle in the Dziani Dzaha Lake, we propose that they could be due to regionally variable methane emissions to the atmosphere. This lake presents carbon isotope signatures deviated by ~ + 12‰ compared to the modern ocean and shares a unique combination of analogies with putative Proterozoic lakes, interior seas or restricted epireic seas. A simple box model of its Carbon cycle demonstrates that its current isotopic signatures are due to high primary productivity, efficiently mineralized by methanogenesis, and to subsequent methane emissions to the atmosphere. By analogy, these results might allow the reinterpretation of some positive CIEs as at least partly due to regionally large methane emissions. This supports the view that methane may have been a major greenhouse gas during the Proterozoic Era, keeping the Earth from major glaciations, especially during periods of positive CIEs, when increased organic carbon burial would have drowned down atmospheric CO2.

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The carbon cycle and associated redox processes through time

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2006.1840 ◽

2006 ◽

Vol 361 (1470) ◽

pp. 931-950 ◽

Cited By ~ 274

Author(s):

John M Hayes ◽

Jacob R Waldbauer

Keyword(s):

Organic Carbon ◽

Carbon Cycle ◽

Organic Materials ◽

Methanogenic Bacteria ◽

Carbonate Minerals ◽

Carbon Isotopic ◽

Carbon Burial ◽

Organic Carbon Burial ◽

Oxidizing Power ◽

Sedimentary Carbonate

Earth's biogeochemical cycle of carbon delivers both limestones and organic materials to the crust. In numerous, biologically catalysed redox reactions, hydrogen, sulphur, iron, and oxygen serve prominently as electron donors and acceptors. The progress of these reactions can be reconstructed from records of variations in the abundance of 13 C in sedimentary carbonate minerals and organic materials. Because the crust is always receiving new CO 2 from the mantle and a portion of it is being reduced by photoautotrophs, the carbon cycle has continuously released oxidizing power. Most of it is represented by Fe 3+ that has accumulated in the crust or been returned to the mantle via subduction. Less than 3% of the estimated, integrated production of oxidizing power since 3.8 Gyr ago is represented by O 2 in the atmosphere and dissolved in seawater. The balance is represented by sulphate. The accumulation of oxidizing power can be estimated from budgets summarizing inputs of mantle carbon and rates of organic-carbon burial, but levels of O 2 are only weakly and indirectly coupled to those phenomena and thus to carbon-isotopic records. Elevated abundances of 13 C in carbonate minerals ca 2.3 Gyr old, in particular, are here interpreted as indicating the importance of methanogenic bacteria in sediments rather than increased burial of organic carbon.

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A diurnal carbon engine explains 13C-enriched carbonates without increasing the global production of oxygen

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1908783116 ◽

2019 ◽

Vol 116 (49) ◽

pp. 24433-24439 ◽

Cited By ~ 6

Author(s):

Emily C. Geyman ◽

Adam C. Maloof

Keyword(s):

Organic Carbon ◽

Carbon Cycle ◽

Shallow Water ◽

Dissolved Inorganic Carbon ◽

The Past ◽

Carbon Isotopic ◽

Oxygen Paradox ◽

Carbon Burial ◽

Continental Shelves ◽

Organic Carbon Burial

In the past 3 billion years, significant volumes of carbonate with high carbon-isotopic (δ13C) values accumulated on shallow continental shelves. These deposits frequently are interpreted as records of elevated global organic carbon burial. However, through the stoichiometry of primary production, organic carbon burial releases a proportional amount of O2, predicting unrealistic rises in atmospheric pO2 during the 1 to 100 million year-long positive δ13C excursions that punctuate the geological record. This carbon–oxygen paradox assumes that the δ13C of shallow water carbonates reflects the δ13C of global seawater-dissolved inorganic carbon (DIC). However, the δ13C of modern shallow-water carbonate sediment is higher than expected for calcite or aragonite precipitating from seawater. We explain elevated δ13C in shallow carbonates with a diurnal carbon cycle engine, where daily transfer of carbon between organic and inorganic reservoirs forces coupled changes in carbonate saturation (ΩA) and δ13C of DIC. This engine maintains a carbon-cycle hysteresis that is most amplified in shallow, sluggishly mixed waters with high rates of photosynthesis, and provides a simple mechanism for the observed δ13C-decoupling between global seawater DIC and shallow carbonate, without burying organic matter or generating O2.

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Past climate variations recorded in needle-like aragonites correlate with organic carbon burial efficiency as revealed by lake sediments in Croatia

Scientific Reports ◽

10.1038/s41598-021-87166-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ivan Razum ◽

Petra Bajo ◽

Dea Brunović ◽

Nikolina Ilijanić ◽

Ozren Hasan ◽

...

Keyword(s):

Organic Carbon ◽

Stable Carbon Isotope ◽

Climate Variations ◽

Before Present ◽

Stable Carbon ◽

Climate Trends ◽

Geochemical Proxies ◽

Carbon Burial ◽

Organic Carbon Burial ◽

Burial Efficiency

AbstractThe drivers of organic carbon (OC) burial efficiency are still poorly understood despite their key role in reliable projections of future climate trends. Here, we provide insights on this issue by presenting a paleoclimate time series of sediments, including the OC contents, from Lake Veliko jezero, Croatia. The Sr/Ca ratios of the bulk sediment are mainly derived from the strontium (Sr) and calcium (Ca) concentrations of needle-like aragonite in Core M1-A and used as paleotemperature and paleohydrology indicators. Four major and six minor cold and dry events were detected in the interval from 8.3 to 2.6 calibrated kilo anno before present (cal ka BP). The combined assessment of Sr/Ca ratios, OC content, carbon/nitrogen (C/N) ratios, stable carbon isotope (δ13C) ratios, and modeled geochemical proxies for paleoredox conditions and aeolian input revealed that cold and dry climate states promoted anoxic conditions in the lake, thereby enhancing organic matter preservation and increasing the OC burial efficiency. Our study shows that the projected future increase in temperature might play an important role in the OC burial efficiency of meromictic lakes.

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Organic carbon burial rates across the Arctic Ocean from the 1994 Arctic Ocean Section expedition

Deep Sea Research Part II Topical Studies in Oceanography ◽

10.1016/s0967-0645(97)00065-9 ◽

1997 ◽

Vol 44 (8) ◽

pp. 1705-1723 ◽

Cited By ~ 11

Author(s):

Ray E. Cranston

Keyword(s):

Organic Carbon ◽

Arctic Ocean ◽

The Arctic ◽

Carbon Burial ◽

Organic Carbon Burial ◽

The Arctic Ocean ◽

Burial Rates

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Climate influence on organic carbon burial efficiency as revealed from a multi-proxy lake sediment record in Croatia

10.1002/essoar.10504565.1 ◽

2020 ◽

Author(s):

Ivan Razum ◽

Petra Bajo ◽

Dea Brunović ◽

Nikolina Ilijanić ◽

Ozren Hasan ◽

...

Keyword(s):

Organic Carbon ◽

Lake Sediment ◽

Sediment Record ◽

Carbon Burial ◽

Organic Carbon Burial ◽

Burial Efficiency

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Long-term Aptian marine osmium isotopic record of Ontong Java Nui activity

Geology ◽

10.1130/g48863.1 ◽

2021 ◽

Author(s):

Hironao Matsumoto ◽

Rodolfo Coccioni ◽

Fabrizio Frontalini ◽

Kotaro Shirai ◽

Luigi Jovane ◽

...

Keyword(s):

Organic Carbon ◽

Volcanic Eruptions ◽

Hydrothermal Activity ◽

Published Data ◽

Isotopic Data ◽

Oceanic Plateaus ◽

Carbon Burial ◽

Organic Carbon Burial ◽

Isotopic Records

The early to mid-Aptian was punctuated by episodic phases of organic-carbon burial in various oceanographic settings, which are possibly related to massive volcanism associated with the emplacement of the Ontong Java, Manihiki, and Hikurangi oceanic plateaus in the southwestern Pacific Ocean, inferred to have formed a single plateau called Ontong Java Nui. Sedimentary osmium (Os) isotopic compositions are one of the best proxies for determining the timing of voluminous submarine volcanic episodes. However, available Os isotopic records during the age are limited to a narrow interval in the earliest Aptian, which is insufficient for the reconstruction of long-term hydrothermal activity. We document the early to mid-Aptian Os isotopic record using pelagic Tethyan sediments deposited in the Poggio le Guaine (Umbria-Marche Basin, Italy) to precisely constrain the timing of massive volcanic episodes and to assess their impact on the marine environment. Our new Os isotopic data reveal three shifts to unradiogenic values, two of which correspond to black shale horizons in the lower to mid-Aptian, namely the Wezel (herein named) and Fallot Levels. These Os isotopic excursions are ascribed to massive inputs of unradiogenic Os to the ocean through hydrothermal activity. Combining the new Os isotopic record with published data from the lowermost Aptian organic-rich interval in the Gorgo a Cerbara section of the Umbria-Marche Basin, it can be inferred that Ontong Java Nui volcanic eruptions persisted for ~5 m.y. during the early to mid-Aptian.

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