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  • 2020-2024  (22)
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  • 1
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    Radiocarbon: A key tracer for studying Earth’s dynamo, climate system, carbon cycle, and Sun (2021)
    AAAS (American Association for the Advancement of Science)
    Details
    Publication Date: 2024-02-07
    Description: Radiocarbon (14C), as a consequence of its production in the atmosphere and subsequent dispersal through the carbon cycle, is a key tracer for studying the Earth system. Knowledge of past 14C levels improves our understanding of climate processes, the Sun, the geodynamo, and the carbon cycle. Recently updated radiocarbon calibration curves (IntCal20, SHCal20, and Marine20) provide unprecedented accuracy in our estimates of 14C levels back to the limit of the 14C technique (~55,000 years ago). Such improved detail creates new opportunities to probe the Earth and climate system more reliably and at finer scale. We summarize the advances that have underpinned this revised set of radiocarbon calibration curves, survey the broad scientific landscape where additional detail on past 14C provides insight, and identify open challenges for the future.
    Type: Article , PeerReviewed
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Constraining ventilation and non-ventilation contributions to global mean ocean-atmosphere radiocarbon offsets across the last deglaciation: implications for atmospheric CO and 14C budget closure (2022)
    In:  EPIC3114th International Conference on Paleoceanography, Bergen, Norway, 2022-08-28-2022-09-02
    Details
    Publication Date: 2023-10-19
    Description: Radiocarbon serves as a tracer that provides unique insights into the ocean’s ability to sequester CO2 from the atmosphere. By applying a Bayesian interpolation method to compiled ocean-atmosphere radiocarbon age offsets (B-Atm), we provide global data fields and mean ocean B-Atm estimates for a suite of time-slices across the last deglaciation. These reveal a stepwise and spatially heterogeneous ‘rejuvenation’ of the deep ocean, and confirm that carbon was incrementally released to the atmosphere through two ‘swings’ of a ventilation seesaw, operating between the North Atlantic and Southern Ocean/North Pacific. A suite of numerical model sensitivity tests further demonstrate that the reconstructed changes could account for two thirds of deglacial atmospheric CO2 rise, depending on the mix of processes driving marine and atmospheric radiocarbon change. Our model sensitivity tests also serve to constrain non-ventilation biases that could affect deglacial B-Atm offsets, under the (extreme) hypothesis of a completely passive ocean response to atmospheric radiocarbon variability driven by radiocarbon production or other non-marine processes. By placing quantitative constraints on the closure of the global radiocarbon budget, our findings help to constrain the contribution of ocean ventilation to observed B-atm changes, and to atmospheric CO2 change, and further suggest that glacial radiocarbon production levels are likely underestimated on average by existing reconstructions.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , NonPeerReviewed
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    PAPER (OA)
  • 3
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    Rejuvenating the ocean: mean ocean radiocarbon, CO2 release, and radiocarbon budget closure across the last deglaciation (2023)
    Copernicus GmbH
    In:  EPIC3Climate of the Past, Copernicus GmbH, 19(11), pp. 2177-2202, ISSN: 1814-9332
    Details
    Publication Date: 2023-11-06
    Description: 〈jats:p〉Abstract. Radiocarbon is a tracer that provides unique insights into the ocean's ability to sequester CO2 from the atmosphere. While spatial patterns of radiocarbon in the ocean interior can indicate the vectors and timescales for carbon transport through the ocean, estimates of the global average ocean–atmosphere radiocarbon age offset (B-Atm) place constraints on the closure of the global carbon cycle. Here, we apply a Bayesian interpolation method to compiled B-Atm data to generate global interpolated fields and mean ocean B-Atm estimates for a suite of time slices across the last deglaciation. The compiled data and interpolations confirm a stepwise and spatially heterogeneous “rejuvenation” of the ocean, suggesting that carbon was released to the atmosphere through two swings of a “ventilation seesaw” operating between the North Atlantic and both the Southern Ocean and the North Pacific. Sensitivity tests using the Bern3D model of intermediate complexity demonstrate that a portion of the reconstructed deglacial B-Atm changes may reflect “phase-attenuation” biases that are unrelated to ocean ventilation and that arise from independent atmospheric radiocarbon dynamics instead. A deglacial minimum in B-Atm offsets during the Bølling–Allerød could partly reflect such a bias. However, the sensitivity tests further demonstrate that when correcting for such biases, ocean “ventilation” could still account for at least one-third of deglacial atmospheric CO2 rise. This contribution to CO2 rise appears to have continued through the Younger Dryas, though much of the impact was likely achieved by the end of the Bølling–Allerød, indicating a key role for marine carbon cycle adjustment early in the deglacial process. Our global average B-Atm estimates place further new constraints on the long-standing mystery of global radiocarbon budget closure across the last deglaciation and suggest that glacial radiocarbon production levels are likely underestimated on average by existing reconstructions. 〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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    PAPER (OA)
  • 4
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    Pollen, XRF, biomarkers, charcoal of the COL17c record, Colônia Basin, São Paulo-Brazil (2022)
    PANGAEA
    Details
    Publication Date: 2023-01-30
    Description: The COL17c composite record was analyzed based on pollen, charcoal, the elemental composition of bulk sediment obtained by X-Ray fluorescence scanning (XRF) and biomarkers (branched glycerol dialkyl glycerol tetraethers (brGDGTs), n-Alkanes and Hopanes). We aimed to characterize early states of the Atlantic forest to evaluate the link with southern hemisphere climate variability at orbital scales using a sediment core located at the transition between SASM (South american summer monsoon) and subtropical front influence.
    Keywords: Araucaria; Atlantic forest; Brazil; early Pleistocene; Southern Hemisphere; Subtropical Front
    Type: Dataset
    Format: application/zip, 5 datasets
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    DATA PANGAEA
  • 5
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    Macrocharcoal counts of sediment core COL17c (2022)
    PANGAEA
    Details
    Publication Date: 2023-02-08
    Keywords: Age, tuned to 41kyr; Age model; Araucaria; Atlantic forest; Brazil; COL17c; Colônia Basin, São Paulo, Brazil; COMPCORE; Composite Core; DEPTH, sediment/rock; early Pleistocene; Macrocharcoal; Southern Hemisphere; Subtropical Front
    Type: Dataset
    Format: text/tab-separated-values, 372 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 6
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    Microcharcoal concentration of sediment core COL17c (2022)
    PANGAEA
    Details
    Publication Date: 2023-02-08
    Keywords: Age, tuned to 41kyr; Age model; Araucaria; Atlantic forest; Brazil; COL17c; Colônia Basin, São Paulo, Brazil; COMPCORE; Composite Core; DEPTH, sediment/rock; early Pleistocene; Microcharcoal; Southern Hemisphere; Subtropical Front
    Type: Dataset
    Format: text/tab-separated-values, 414 data points
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    DATA PANGAEA
  • 7
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    Biomarkers of sediment core COL17c (2022)
    PANGAEA
    Details
    Publication Date: 2023-02-08
    Keywords: Age, tuned to 41kyr; Age model; Araucaria; Atlantic forest; Branched and isoprenoid tetraether index; Brazil; COL17c; Colônia Basin, São Paulo, Brazil; COMPCORE; Composite Core; DEPTH, sediment/rock; early Pleistocene; Hopane; n-Alkane C24-C35; Southern Hemisphere; Subtropical Front; Sum branched glycerol dialkyl glycerol tetraether, IIIa/Sum Branched glycerol dialkyl glycerol tetraether, IIa ratio; Sum brGDGT IIIa, IIa, Iabc; Temperature, air, annual mean; Temperature anomaly
    Type: Dataset
    Format: text/tab-separated-values, 1054 data points
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    DATA PANGAEA
  • 8
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    Biomarker indices and concentrations and biomarker-based temperature estimates from Iberian Margin cores MD99-2331, MD95-2040 and MD95-2042 (2021)
    PANGAEA
    Details
    Publication Date: 2023-07-20
    Description: Biomarker metadata and data for cores MD99-2331, MD95-2040, and MD95-2042: depth, age, summed OH-GDGT, iGDGT, and di-unsaturated and tri-unsaturated C37 alkenone concentrations, OH-GDGT-based, iGDGT-based, and alkenone-based paleothermometric indices, GDGT-2/GDGT-3 ratio, and biomarker-based sea surface temperature (SST) and 0‐ to 200‐m sea temperature (subT; gamma function probability distribution for target temperatures with a = 4.5 and b = 15) estimates. The 1σ analytical uncertainties are 0.008 (0.5 °C) for RI-OH, 0.007 (0.2 °C) for RI-OH′, 0.003 (0.1 °C) for TEX86, 0.263 for GDGT-2/GDGT-3, and 0.010 (0.26 °C) for UK′37. RI-OH′-SST estimates are from the following global calibration: SST = (RI-OH′ + 0.029)/0.0422 (Fietz et al., 2020). RI-OH-SST estimates are from the following global calibration: SST = (RI-OH − 1.11)/0.018 (Lü et al., 2015). TEX86H-SST estimates are from the following regional paleocalibration: SST = 68.4 × TEX86H + 33.0 (Darfeuil et al., 2016). UK′37-SST estimates are from the following global calibration: SST = 29.876 × UK′37 − 1.334 (Conte et al., 2006). Bayesian calibrations were also used for TEX86-SST and TEX86-subT estimates (BAYSPAR; Tierney & Tingley, 2014, 2015) and for UK′37-SST estimates (BAYSPLINE; Tierney & Tingley, 2018). Core MD95-2040 UK′37 and summed di-unsaturated and tri-unsaturated C37 alkenone concentration data are from Pailler and Bard (2002). Core MD95-2042 UK′37 and summed di-unsaturated and tri-unsaturated C37 alkenone concentration data covering the 70–45 ka BP period are from Darfeuil et al. (2016). GDGT data for core MD95-2042 samples with TEX86 values below 0.4 are deemed anomalous and are thus excluded from any description and analysis. MIS, Marine Isotope Stage; DO, Dansgaard–Oeschger event; GS, Greenland stadial; H, Heinrich event; GDGT, glycerol dialkyl glycerol tetraether; and N/A, not available.
    Keywords: Alkenones; GDGTs; Iberian margin; IMAGES; International Marine Global Change Study; RI-OH; Sea surface temperature; TEX86; UK'37
    Type: Dataset
    Format: application/zip, 3 datasets
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 9
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    Pollen, spore and algae counts of sediment core COL17c (2022)
    PANGAEA
    Details
    Publication Date: 2024-03-06
    Keywords: Abatia; Acaena/Polylepis; Acalypha; Aegiphila; Age, tuned to 41kyr; Age model; Alchornea; Aloysia; Alternanthera; Amaioua; Anacardiaceae; Anadenanthera; Anemia; Antidaphne; Apiaceae; Araucaria; Arecaceae; Aspidosperma; Asplenium-type; Atlantic forest; Baccharis; Bauhinia; Begoniaceae; Bignoniaceae; Blechnum; Borreria; Botryococcus; Bougainvillea spectabilis; Brassicaceae; Brazil; Bromeliaceae; Bunchosia; Caryocar; Casearia sylvestris; Cecropia; Cedrela; Celtis; Centrolobium; Chenopodium; Cissus-type; Citharexylum; Clematis; Clusia-type; COL17c; Colônia Basin, São Paulo, Brazil; Commelina-type; COMPCORE; Composite Core; Convolvulaceae; Copaifera; Counting, palynology; Croton; Cuphea; Cyathea; Cybianthus; Cyperaceae; Dalechampia; Daphnopsis; DEPTH, sediment/rock; Diploon cuspidatum; Diplopterys; Doliocarpus; early Pleistocene; Ephedra; Ericaceae; Eriocaulon; Eriotheca; Euphorbiaceae; Gomphrena; Guazuma; Heteropterys; Humiriastrum; Huperzia; Hyeronima-type; Hymenophyllum; Ilex; Isoetes; Juncus; Justicia; Lamanonia; Lantana-type; Laplacea fruticosa; Licania; Lippia; Lobelia; Lophosoria; Lycopodium (added); Lycopodium (counted); Lycopodium clavatum; Mandibles; Maprounea; Mauritia; Maytenus; Melastomataceae; Mikania; Mimosa; Moraceae/Urticaceae; Myriophyllum; Myroxylon; Myrsine; Myrtaceae; Nothofagus aff. dombeyi; Onagraceae; Ophioglossum; Orthomene; Palicourea; Passifloraceae; Paullinia; Pereskia-type; Phyllanthus; Piperaceae; Piptocarpha; Poaceae; Podocarpus; Pollen; Pollen richness; Polygalaceae; Polypodiaceae; Potamogeton; Pouteria; Prockia; Protium; Pseudopiptadenia; Psittacanthus; Pteris; Ramisia; Rhamnaceae; Roupala; Sapium; Sauvagesia erecta; Schefflera; Sebastiania; Selaginella; Senna; Sida; Simarouba; Sloanea; Solanaceae; Southern Hemisphere; Sphagnum; Stifftia; Stigmaphyllon; Struthanthus; Subtropical Front; Symplocos; Tetraploa; Tovomita; Trema; Trichomanes-type; Trigonia-type; Tripodanthus; Urvillea; Utricularia; Vernonanthura; Virola; Vochysiaceae; Volume; Wahlenbergia; Waltheria; Weinmannia; Xylosma; Zanthoxylum; Zollernia
    Type: Dataset
    Format: text/tab-separated-values, 21112 data points
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    DATA PANGAEA
  • 10
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    Biomarkers of sediment core MD95-2040 (2021)
    PANGAEA
    Details
    Publication Date: 2024-01-19
    Keywords: AGE; Alkenone, C37:2+C37:3; Alkenone, unsaturation index UK'37; Alkenones; Calculated according to Lü et al. (2015); Calculated according to Schouten et al. (2002); Calculated from C37 alkenones (Prahl & Wakeham, 1987); CALYPSO; Calypso Corer; Comment; Defined by synchronization to the Chinese speleothem record by Cheng et al. (2016); DEPTH, sediment/rock; Dicyclic glycerol dialkyl glycerol tetraether/Tricyclic glycerol dialkyl glycerol tetraether ratio; GDGTs; Hydroxylated acyclic glycerol dialkyl glycerol tetraether; Hydroxylated glycerol dialkyl glycerol tetraethers; Hydroxylated monocyclic glycerol dialkyl glycerol tetraether + hydroxylated dicyclic glycerol dialkyl glycerol tetraether; Iberian margin; IMAGES; IMAGES I; International Marine Global Change Study; Isoprenoid glycerol dialkyl glycerol tetraethers; Marine isotope stage; Marion Dufresne (1995); MD101; MD952040; MD95-2040; Porto Seamount; Ring index of hydroxylated glycerol dialkyl glycerol tetraethers; RI-OH; Sea surface temperature; Sea surface temperature, annual mean; SST, from Ri OH-GDGTs, Fietz et al. (2020); SST, from Ri OH-GDGTs, Lü et al. (2015); SST, from TEXH86, BAYSPAR (BAYesian SPAtially-varying Regression) (Tierney and Tingley, 2014, 2015); SST, from TEXH86, Darfeuil et al. (2016); SST, from UK'37, BAYSPLINE (Tierney and Tingley, 2018); SST, from UK'37 (Conte et al., 2006); Taylor et al. (2013); Temperature, water, annual mean; Tetraether index of 86 carbon atoms; Tetraether index of 86 carbon atoms of isoprenoid glycerol dialkyl glycerol tetraether; TEX86; UK'37
    Type: Dataset
    Format: text/tab-separated-values, 2996 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
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