Deglacial carbon cycle changes observed in a compilation of 127 benthic &amp;lt;i&amp;gt;δ&amp;lt;/i&amp;gt;&amp;lt;sup&amp;gt;13&amp;lt;/sup&amp;gt;C time series (20–6 ka)

Peterson, Carlye D.; Lisiecki, L. E.

doi:10.5194/cp-14-1229-2018

Cited by 20 publications

(22 citation statements)

References 126 publications

(216 reference statements)

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“…1; Muglia et al 2018). This is in agreement with results from fewer but higher-resolution deglacial δ 13 C cib timeseries (Peterson and Lisiecki 2018). Complementary to this model run that best fits the δ 13 C cib records (Fig.…”

Section: Ambiguity In Proxy Reconstructionssupporting

confidence: 87%

Benthic foraminiferal stable carbon isotope constraints on deglacial ocean circulation and carbon-cycle changes

2019

PAGES Mag

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Section: Ambiguity In Proxy Reconstructionssupporting

confidence: 87%

Benthic foraminiferal stable carbon isotope constraints on deglacial ocean circulation and carbon-cycle changes

2019

PAGES Mag

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“…S1 in the Supplement (see also Fig. 1 in Peterson et al, 2014). Note that LGM benthic δ 13 C is more 13 C-depleted than that in the Holocene due to the addition of 13 C-depleted terrestrial carbon to the glacial ocean (Shackleton, 1977;Curry et al, 1988;Duplessy et al, 1988), which is not simulated in our model experiments.…”

Section: Observationsmentioning

confidence: 85%

“…Modern data of ocean temperature, oxygen, and nutrients are retrieved from the World Ocean Atlas 2018 (Locarnini et al, 2018;Garcia et al, 2018c, b) We use model-data comparison of benthic δ 13 C to assess the statistical similarity (correlation) between both the model control state and glacial-like state (see Sect. 2.3) to benthic δ 13 C data representing the late Holocene (0-6 ka, HOL) and Last Glacial Maximum (19-23 ka, LGM) (Peterson et al, 2014). Locations of core sites can be seen in Fig.…”

Section: Observationsmentioning

confidence: 99%

“…Proxy records of benthic δ 13 C indicate a change in ocean δ 13 C across the deglaciation. The whole ocean deglacial change has been estimated to ∼ 0.35 ‰ (Peterson et al, 2014;Peterson and Lisiecki, 2018), and the surface-to-deep gradient weakened (shown in numerous studies; see e.g. Curry et al, 1988;Duplessy et al, 1988;Curry and Oppo, 2005;Herguera et al, 2010;Peterson and Lisiecki, 2018, and references therein).…”

Section: What Can We Learn From the Model-datamentioning

confidence: 99%

“…Due to the difference in size between the oceanic, terrestrial, and atmospheric carbon reservoirs, where the oceanic reservoir is by far the largest with > 90 % of their summed carbon contents (reviewed by Ciais et al, 2013), it is likely that most of the CO 2 that was removed from the atmosphere was stored in the glacial ocean. In addition, studies of paleo-proxy records indicate that carbon storage in the glacial terrestrial biosphere was smaller compared to in interglacial climate (Shackleton, 1977;Duplessy et al, 1988;Curry et al, 1988;Crowley, 1995;Adams and Faure, 1998;Ciais et al, 2012;Peterson et al, 2014). During deglaciation, radiocarbon evidence indicates that CO 2 was rapidly released from the ocean back to the atmosphere (Marchitto et al, 2007;Skinner et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Variable C∕P composition of organic production and its effect on ocean carbon storage in glacial-like model simulations

et al. 2020

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Abstract. During the four most recent glacial maxima, atmospheric CO2 has been lowered by about 90–100 ppm with respect to interglacial concentrations. It is likely that most of the atmospheric CO2 deficit was stored in the ocean. Changes in the biological pump, which are related to the efficiency of the biological carbon uptake in the surface ocean and/or of the export of organic carbon to the deep ocean, have been proposed as a key mechanism for the increased glacial oceanic CO2 storage. The biological pump is strongly constrained by the amount of available surface nutrients. In models, it is generally assumed that the ratio between elemental nutrients, such as phosphorus, and carbon (C∕P ratio) in organic material is fixed according to the classical Redfield ratio. The constant Redfield ratio appears to approximately hold when averaged over basin scales, but observations document highly variable C∕P ratios on regional scales and between species. If the C∕P ratio increases when phosphate availability is scarce, as observations suggest, this has the potential to further increase glacial oceanic CO2 storage in response to changes in surface nutrient distributions. In the present study, we perform a sensitivity study to test how a phosphate-concentration-dependent C∕P ratio influences the oceanic CO2 storage in an Earth system model of intermediate complexity (cGENIE). We carry out simulations of glacial-like changes in albedo, radiative forcing, wind-forced circulation, remineralization depth of organic matter, and mineral dust deposition. Specifically, we compare model versions with the classical constant Redfield ratio and an observationally motivated variable C∕P ratio, in which the carbon uptake increases with decreasing phosphate concentration. While a flexible C∕P ratio does not impact the model's ability to simulate benthic δ13C patterns seen in observational data, our results indicate that, in production of organic matter, flexible C∕P can further increase the oceanic storage of CO2 in glacial model simulations. Past and future changes in the C∕P ratio thus have implications for correctly projecting changes in oceanic carbon storage in glacial-to-interglacial transitions as well as in the present context of increasing atmospheric CO2 concentrations.

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Carbon cycle responses to changes in weathering and the long-term fate of stable carbon isotopes

Jeltsch-Thömmes

Joos

2022

Preprint

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The causes of the variations in CO 2 of the past million years remain poorly understood. Imbalances between the input of elements from rock weathering and their removal from the atmosphere-ocean-biosphere system to the lithosphere likely contributed to reconstructed changes. We employ the Bern3D Earth system model of intermediate complexity to investigate carbon-climate responses to step-changes in the weathering input of phosphorus, alkalinity, carbon, and carbon isotope ratio (δ 13 C) in simulations extending up to 600,000 years. CO 2 and climate approach a new equilibrium within a few ten thousand years, whereas the equilibration lasts several hundred thousand years for δ 13 C. These timescales represent a challenge for the initialization of sediment-enabled models and unintended drifts may be larger than forced signals in simulations of the last glacial-interglacial cycle. Changes in dissolved CO 2 change isotopic fractionation during marine photosynthesis and δ 13 C of organic matter. This mechanism and changes in the organic matter export cause distinct spatio-temporal perturbations in δ 13 C of dissolved inorganic carbon. A cost-efficient emulator is built with the Bern3D responses and applied in contrasting literature-based weathering histories for the past 800,000 years. Differences between scenarios for carbonate rock weathering reach around a third of the glacial-interglacial CO 2 amplitude, 0.05 exceed reconstructed variations in marine carbonate ion. Plausible input from the decomposition of organic matter on shelves causes variations of up to 10 ppm in CO 2 , 4 mmol m -3 in CO 2-3 , and 0.09δ 13 C. Our results demonstrate that weathering-burial imbalances are important for past climate variations.

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Deglacial carbon cycle changes observed in a compilation of 127 benthic <i>δ</i><sup>13</sup>C time series (20–6 ka)

Cited by 20 publications

References 126 publications

Benthic foraminiferal stable carbon isotope constraints on deglacial ocean circulation and carbon-cycle changes

Benthic foraminiferal stable carbon isotope constraints on deglacial ocean circulation and carbon-cycle changes

Variable C∕P composition of organic production and its effect on ocean carbon storage in glacial-like model simulations

Carbon cycle responses to changes in weathering and the long-term fate of stable carbon isotopes

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