Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes

Gottschalk, Julia; Skinner, Luke C; Lippold, Jörg; Vogel, Hendrik; Frank, Norbert; Jaccard, Samuel L.; Waelbroeck, C.

doi:10.1038/ncomms11539

Cited by 140 publications

(202 citation statements)

References 76 publications

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“…The general idea is that a northward shift of Southern Ocean upwelling leads to reduced CO 2 outgassing and enhanced carbon export to the deep waters, resulting in a deep ocean accumulation of organic matter from the surface and hence a vertical "fractionation" of carbon as well as nutrients as already described by Boyle (1988a) and Boyle (1988b). This general view is also corroborated by recent proxy data findings (for the Southern Ocean by Gottschalk et al, 2016; also for the North Atlantic by Hoogakker et al, 2015). Refined Southern Ocean dynamics could also improve the results of our studies, but we have been limited to the flow fields available.…”

Section: Resultssupporting

confidence: 77%

Ocean carbon cycling during the past 130 000 years – a pilot study on inverse palaeoclimate record modelling

2016

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Abstract. What role did changes in marine carbon cycle processes and calcareous organisms play in glacial-interglacial variation in atmospheric pCO 2 ? In order to answer this question, we explore results from an ocean biogeochemical general circulation model. We attempt to systematically reconcile model results with time-dependent sediment core data from the observations. For this purpose, we fit simulated sensitivities of oceanic tracer concentrations to changes in governing carbon cycle parameters to measured sediment core data. We assume that the time variation in the governing carbon cycle parameters follows the general pattern of the glacial-interglacial deuterium anomaly. Our analysis provides an independent estimate of a maximum mean sea surface temperature drawdown of about 5 • C and a maximum outgassing of the land biosphere by about 430 Pg C at the Last Glacial Maximum as compared to pre-industrial times. The overall fit of modelled palaeoclimate tracers to observations, however, remains quite weak, indicating the potential of more detailed modelling studies to fully exploit the information stored in the palaeoclimatic archive. This study confirms the hypothesis that a decline in ocean temperature and a more efficient biological carbon pump in combination with changes in ocean circulation are the key factors for explaining the glacial CO 2 drawdown. The analysis suggests that potential changes in the export rain ratio POC : CaCO 3 may not have a substantial imprint on the palaeoclimatic archive. The use of the last glacial as an inverted analogue to potential ocean acidification impacts thus may be quite limited.A strong decrease in CaCO 3 export production could potentially contribute to the glacial CO 2 decline in the atmosphere, but this remains hypothetical.

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Section: Resultssupporting

confidence: 77%

Ocean carbon cycling during the past 130 000 years – a pilot study on inverse palaeoclimate record modelling

2016

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“…We therefore conclude that if C. kullenbergi had an endobenthic habitat during glacials, it would have been shallower than that of Uvigerina spp., limiting the possible microhabitat effect, and thus the offset from δ 13 C DIC of the overlying bottom water during these time intervals. A negative bias due to 13 C‐depleted pore water is supported by the observation of lower Holocene C. kullenbergi δ 13 C than modern δ 13 C DIC at the MD07‐3076Q core site (Figure ), which may have been larger during last glacial periods, for instance as a response to enhanced glacial organic carbon fluxes [ Anderson et al ., ; Gottschalk et al ., ]. However, a close match of C. kullenbergi and C. wuellerstorfi δ 13 C during MIS11 (−0.09 ± 0.19, N = 52) suggest that this bias was negligible during some interglacials.…”

Section: Discussionmentioning

confidence: 96%

Carbon isotope offsets between benthic foraminifer species of the genus Cibicides (Cibicidoides) in the glacial sub‐Antarctic Atlantic

et al. 2016

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Epibenthic foraminifer δ13C measurements are valuable for reconstructing past bottom water dissolved inorganic carbon δ13C (δ13CDIC), which are used to infer global ocean circulation patterns. Epibenthic δ13C, however, may also reflect the influence of 13C‐depleted phytodetritus, microhabitat changes, and/or variations in carbonate ion concentrations. Here we compare the δ13C of two benthic foraminifer species, Cibicides kullenbergi and Cibicides wuellerstorfi, and their morphotypes, in three sub‐Antarctic Atlantic sediment cores over several glacial‐interglacial transitions. These species are commonly assumed to be epibenthic, living above or directly below the sediment‐water interface. While this might be consistent with the small δ13C offset that we observe between these species during late Pleistocene interglacial periods (Δδ13C = −0.19 ± 0.31‰, N = 63), it is more difficult to reconcile with the significant δ13C offset that is found between these species during glacial periods (Δδ13C = −0.76 ± 0.44‰, N = 44). We test possible scenarios by analyzing Uvigerina spp. δ13C and benthic foraminifer abundances: (1) C. kullenbergi δ13C is biased to light values either due to microhabitat shifts or phytodetritus effects and (2) C. wuellerstorfi δ13C is biased to heavy values, relative to long‐term average conditions, for instance by recording the sporadic occurrence of less depleted deepwater δ13CDIC. Neither of these scenarios can be ruled out unequivocally. However, our findings emphasize that supposedly epibenthic foraminifer δ13C in the sub‐Antarctic Atlantic may reflect several factors rather than being solely a function of bottom water δ13CDIC. This could have a direct bearing on the interpretation of extremely light South Atlantic δ13C values at the Last Glacial Maximum.

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“…Over 50 years' (1966–2019) worth of data have been compiled to create the global thorium database ( n = 1,167) presented here (Adkins et al, ; Anderson et al, , Anderson et al, , Anderson et al, , Anderson et al, ; Bausch, ; Böhm et al, ; Bohrmann, ; Borole, ; Bradtmiller et al, , , ; Broecker, ; Broecker et al, ; Brunelle et al, , ; Causse & Hillaire‐Marcel, ; Chase et al, , ; Chong et al, ; Costa, McManus, & Anderson, ; Costa & McManus, ; Crusius et al, ; Dekov, ; Denis et al, ; Dezileau et al, , ; Durand et al, ; Fagel et al, ; Francois et al, , Francois et al, ; Frank, Eisenhauer, Bonn, et al, , Frank, Eisenhauer, Kubik, et al, , ; Fukuda et al, ; Galbraith et al, ; Geibert et al, ; Gherardi et al, , ; Gottschalk et al, ; Hickey, ; Hillaire‐Marcel et al, ; Hoffmann et al, , ; Jaccard et al, , ; Jacobel et al, ; Jonkers et al, ; Kienast et al, ; Ku & Broecker, ; Kumar et al, ; Lam et al, ; Lamy et al, ; Lao et al, ; Lippold et al, , Lippold et al, , Lippold et al, , Lippold et al, ; Loubere et al, ; Loveley et al, ; Lund et al, ; Mangini & Dominik, ; Marcantonio et al, , Marcantonio et al, ...…”

Section: Background: the Marine Geochemistry Of 230thunclassified

²³⁰Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean

Costa

Hayes

Anderson

et al. 2020

Paleoceanog and Paleoclimatol

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230Th normalization is a valuable paleoceanographic tool for reconstructing high‐resolution sediment fluxes during the late Pleistocene (last ~500,000 years). As its application has expanded to ever more diverse marine environments, the nuances of 230Th systematics, with regard to particle type, particle size, lateral advective/diffusive redistribution, and other processes, have emerged. We synthesized over 1000 sedimentary records of 230Th from across the global ocean at two time slices, the late Holocene (0–5,000 years ago, or 0–5 ka) and the Last Glacial Maximum (18.5–23.5 ka), and investigated the spatial structure of 230Th‐normalized mass fluxes. On a global scale, sedimentary mass fluxes were significantly higher during the Last Glacial Maximum (1.79–2.17 g/cm2kyr, 95% confidence) relative to the Holocene (1.48–1.68 g/cm2kyr, 95% confidence). We then examined the potential confounding influences of boundary scavenging, nepheloid layers, hydrothermal scavenging, size‐dependent sediment fractionation, and carbonate dissolution on the efficacy of 230Th as a constant flux proxy. Anomalous 230Th behavior is sometimes observed proximal to hydrothermal ridges and in continental margins where high particle fluxes and steep continental slopes can lead to the combined effects of boundary scavenging and nepheloid interference. Notwithstanding these limitations, we found that 230Th normalization is a robust tool for determining sediment mass accumulation rates in the majority of pelagic marine settings (>1,000 m water depth).

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Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes

Cited by 140 publications

References 76 publications

Ocean carbon cycling during the past 130 000 years – a pilot study on inverse palaeoclimate record modelling

Ocean carbon cycling during the past 130 000 years – a pilot study on inverse palaeoclimate record modelling

Carbon isotope offsets between benthic foraminifer species of the genus Cibicides (Cibicidoides) in the glacial sub‐Antarctic Atlantic

²³⁰Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean

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Biological and physical controls in the Southern Ocean on past millennial-scale atmospheric CO2 changes

Cited by 140 publications

References 76 publications

Ocean carbon cycling during the past 130 000 years – a pilot study on inverse palaeoclimate record modelling

Ocean carbon cycling during the past 130 000 years – a pilot study on inverse palaeoclimate record modelling

Carbon isotope offsets between benthic foraminifer species of the genus Cibicides (Cibicidoides) in the glacial sub‐Antarctic Atlantic

230Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean

Contact Info

Product

Resources

About

Ocean carbon cycling during the past 130 000 years – a pilot study on inverse palaeoclimate record modelling

Ocean carbon cycling during the past 130 000 years – a pilot study on inverse palaeoclimate record modelling

²³⁰Th Normalization: New Insights on an Essential Tool for Quantifying Sedimentary Fluxes in the Modern and Quaternary Ocean