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  • 2020-2022  (1)
  • 2010-2014  (75)
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  • 1
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    Copernicus Publications (EGU)
    In:  Climate of the Past, 9 (6). pp. 2595-2614.
    Publication Date: 2020-07-27
    Description: Ice core records demonstrate a glacial–interglacial atmospheric CO2 increase of ~ 100 ppm, while 14C calibration efforts document a strong decrease in atmospheric 14C concentration during this period. A calculated transfer of ~ 530 Gt of 14C-depleted carbon is required to produce the deglacial coeval rise of carbon in the atmosphere and terrestrial biosphere. This amount is usually ascribed to oceanic carbon release, although the actual mechanisms remained elusive, since an adequately old and carbon-enriched deep-ocean reservoir seemed unlikely. Here we present a new, though still fragmentary, ocean-wide Δ14C data set showing that during the Last Glacial Maximum (LGM) and Heinrich Stadial 1 (HS-1) the maximum 14C age difference between ocean deep waters and the atmosphere exceeded the modern values by up to 1500 14C yr, in the extreme reaching 5100 14C yr. Below 2000 m depth the 14C ventilation age of modern ocean waters is directly linked to the concentration of dissolved inorganic carbon (DIC). We propose as a working hypothesis that the modern regression of DIC vs. Δ14C also applies for LGM times, which implies that a mean LGM aging of ~ 600 14C yr corresponded to a global rise of ~ 85–115 μmol DIC kg−1 in the deep ocean. Thus, the prolonged residence time of ocean deep waters may indeed have made it possible to absorb an additional ~ 730–980 Gt DIC, one third of which possibly originated from intermediate waters. We also infer that LGM deep-water O2 dropped to suboxic values of 〈 10 μmol kg−1 in the Atlantic sector of the Southern Ocean, possibly also in the subpolar North Pacific. The deglacial transfer of the extra-aged, deep-ocean carbon to the atmosphere via the dynamic ocean–atmosphere carbon exchange would be sufficient to account for two trends observed, (1) for the increase in atmospheric CO2 and (2) for the 190‰ drop in atmospheric Δ14C during the so-called HS-1 "Mystery Interval", when atmospheric 14C production rates were largely constant
    Type: Article , PeerReviewed
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  • 2
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    Springer
    In:  (In Press / Accepted) International Journal of Earth Sciences .
    Publication Date: 2021-07-30
    Description: Summary of Ilse Seibold's vita Ilse Seibold, née Usbeck, was born May 8, 1925 in Breslau, Silesia, and went to school in Halle/Saale during WW2. She started her studies of geology and paleontology at the University of Halle and at the Humboldt University in Berlin, and later at the University of Tübingen, where she received her doctorate as micropaleontologist in 1951 with Otto Schindewolf as her supervisor. She remained active as productive scientist over many decades. In 1952, she married Dr. Eugen Seibold, who in 1958 became professor at Kiel University, founded one of Europe's most important institutes for marine geology, and later became president of the German Science Foundation (DFG), and subsequently of the European Science Foundation (ESF). Being a scientist herself Ilse Seibold soon evolved to a deeply reflective insider of geological sciences. She followed her husband during his scientific career from his appointments in Tübingen, Bonn, Karlsruhe, Kiel, to Bonn and Strasbourg/Freiburg i.Br. She accompanied Eugen on his sabbatical leave at Scripps Institution of Oceanography in La Jolla, CA. She participated in countless international scientific meetings. Together with Eugen she published many papers that document her independence and autonomy as scientist. She gained deep insights into the origins of the geosciences and their historical evolution, up to the ideas of fine arts. We are happy that she documented in her publications a broad range of her scientific and distinguished-humane impressions.
    Type: Article , NonPeerReviewed
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  • 3
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    Copernicus Publications (EGU)
    In:  Climate of the Past, 8 (1). pp. 79-87.
    Publication Date: 2019-09-23
    Description: Ocean Drilling Program (ODP) Site 982 provided a key sediment section at Rockall Plateau for reconstructing northeast Atlantic paleoceanography and monitoring benthic δ18O stratigraphy over the late Pliocene to Quaternary onset of major Northern Hemisphere glaciation. A renewed hole-specific inspection of magnetostratigraphic reversals and the addition of epibenthic δ18O records for short Pliocene sections in holes 982A, B, and C, crossing core breaks in the δ18O record published for Hole 982B, now imply a major revision of composite core depths. After tuning to the orbitally tuned reference record LR04, the new composite δ18O record results in a hiatus, where the Kaena magnetic subchron might have been lost, and in a significant age reduction for all proxy records by 130 to 20 ky over the time span 3.2–2.7 million years ago (Ma). Our study demonstrates the general significance of reliable composite-depth scales and δ18O stratigraphies in ODP sediment records for generating ocean-wide correlations in paleoceanography. The new concept of age control makes the late Pliocene trends in SST (sea surface temperature) and atmospheric pCO2 at Site 982 more consistent with various paleoclimate trends published from elsewhere in the North Atlantic.
    Type: Article , PeerReviewed
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  • 4
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: PANGAEA Documentation , notRev
    Format: application/pdf
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  • 5
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    PANGAEA
    In:  EPIC3Bremerhaven, PANGAEA
    Publication Date: 2014-10-28
    Repository Name: EPIC Alfred Wegener Institut
    Type: PANGAEA Documentation , notRev
    Format: application/pdf
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  • 6
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    PANGAEA
    In:  Supplement to: Rae, James W B; Sarnthein, Michael; Foster, Gavin L; Ridgwell, Andy; Grootes, Pieter Meiert; Elliott, Tim (2014): Deep water formation in the North Pacific and deglacial CO2 rise. Paleoceanography, 29(6), 645-667, https://doi.org/10.1002/2013PA002570
    Publication Date: 2023-01-13
    Description: Deep water formation in the North Atlantic and Southern Ocean is widely thought to influence deglacial CO2 rise and climate change; here we suggest that deep water formation in the North Pacific may also play an important role. We present paired radiocarbon and boron isotope data from foraminifera from sediment core MD02-2489 at 3640 m in the North East Pacific. These show a pronounced excursion during Heinrich Stadial 1, with benthic-planktic radiocarbon offsets dropping to ~350 years, accompanied by a decrease in benthic d11B. We suggest this is driven by the onset of deep convection in the North Pacific, which mixes young shallow waters to depth, old deep waters to the surface, and low-pH water from intermediate depths into the deep ocean. This deep water formation event was likely driven by an increase in surface salinity, due to subdued atmospheric/monsoonal freshwater flux during Heinrich Stadial 1. The ability of North Pacific Deep Water (NPDW) formation to explain the excursions seen in our data is demonstrated in a series of experiments with an intermediate complexity Earth system model. These experiments also show that breakdown of stratification in the North Pacific leads to a rapid ~30 ppm increase in atmospheric CO2, along with decreases in atmospheric d13C and D14C, consistent with observations of the early deglaciation. Our inference of deep water formation is based mainly on results from a single sediment core, and our boron isotope data are unavoidably sparse in the key HS1 interval, so this hypothesis merits further testing. However we note that there is independent support for breakdown of stratification in shallower waters during this period, including a minimum in d15N, younging in intermediate water 14C, and regional warming. We also re-evaluate deglacial changes in North Pacific productivity and carbonate preservation in light of our new data, and suggest that the regional pulse of export production observed during the Bølling-Allerød is promoted by relatively stratified conditions, with increased light availability and a shallow, potent nutricline. Overall, our work highlights the potential of NPDW formation to play a significant and hitherto unrealized role in deglacial climate change and CO2 rise.
    Type: Dataset
    Format: application/zip, 7 datasets
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  • 7
    Publication Date: 2023-06-27
    Keywords: AGE; Chlorine; DEPTH, sediment/rock; Giant piston corer; GPC; IMAGES; IMAGES VII - WEPAMA; International Marine Global Change Study; Marion Dufresne (1995); MD012378; MD01-2378; MD122; Timor Sea
    Type: Dataset
    Format: text/tab-separated-values, 31 data points
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  • 8
    Publication Date: 2023-06-27
    Keywords: Age, 14C AMS; Age, calculated calendar years; Age, comment; Age, dated; Age, dated standard deviation; Age model; Calculated, see reference(s); DEPTH, sediment/rock; Giant piston corer; GPC; IMAGES; IMAGES VII - WEPAMA; International Marine Global Change Study; Marion Dufresne (1995); MD012378; MD01-2378; MD122; Reservoir effect/correction; Sedimentation rate; Timor Sea
    Type: Dataset
    Format: text/tab-separated-values, 379 data points
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  • 9
    Publication Date: 2023-06-27
    Keywords: AGE; DEPTH, sediment/rock; Giant piston corer; Globigerinoides ruber, δ18O; GPC; IMAGES; IMAGES VII - WEPAMA; International Marine Global Change Study; Marion Dufresne (1995); MD012378; MD01-2378; MD122; Timor Sea
    Type: Dataset
    Format: text/tab-separated-values, 170 data points
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  • 10
    Publication Date: 2023-06-27
    Keywords: AGE; Calculated from Mg/Ca ratios; DEPTH, sediment/rock; Giant piston corer; GPC; IMAGES; IMAGES VII - WEPAMA; International Marine Global Change Study; Marion Dufresne (1995); MD012378; MD01-2378; MD122; Sea surface temperature; Temperature, difference; Thermocline water temperature; Timor Sea
    Type: Dataset
    Format: text/tab-separated-values, 488 data points
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