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  • 1
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    Technical note: Late Pliocene age control and composite depths at ODP Site 982, revisited (2012)
    Copernicus Publications (EGU)
    In:  Climate of the Past, 8 (1). pp. 79-87.
    Details
    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
    Format: text
    Format: text
    DOI: 10.5194/cp-8-79-2012
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Did North Atlantic cooling and freshening from 3.65–3.5 Ma precondition Northern Hemisphere ice sheet growth? (2020)
    Elsevier
    Details
    Publication Date: 2023-02-08
    Description: Highlights • Prominent North Atlantic sea surface cooling and freshening of ~3.5 °C and ~0.7‰ during ~3.65–3.5 Ma. • Surface cooling and freshening inline with a decrease of benthic δ13C records from South Atlantic Ocean sites. • Surface cooling and freshening at the same time as sea ice extension in the Arctic Ocean. Abstract The North Atlantic Current (NAC) as part of the Atlantic Meridional Overturning Circulation (AMOC) is the major supplier of heat into the northern North Atlantic. Pliocene changes of AMOC strength were speculated to either have amplified or diminished the Northern Hemisphere Glaciation (NHG) 2.7 million years ago (Ma). However, from the North Atlantic, little evidence is known about AMOC changes at around 3.6 Ma. At this time the intensification of NHG started and culminated in the first major glacial M2 event at 3.3 Ma. To elaborate the climatic effects of variations in the NAC during this early stage of NHG, we here present millennial-scale resolved records from Deep Sea Drilling (DSDP) Site 610A in the northern North Atlantic. Our data of planktic foraminiferal Mg/Ca-based sea surface temperatures (SSTMg/Ca) and ice volume corrected salinity approximations (δ18OIVC-seawater) span the critical time period 4–3.3 Ma. From 3.65 to 3.5 Ma, we observe a distinct ~3.5 °C cooling and ~0.7‰ freshening of the sea surface, which we interpret to reflect a weakened NAC. At the same time Arctic sea ice grew and benthic δ13C in the South Atlantic suggest a weakened AMOC. We conclude that the weakened NAC in response to a sluggish AMOC fostered sea ice formation in the Arctic Ocean and high-latitude North Atlantic, which might have preconditioned the climate for subsequent continental glaciations.
    Type: Article , PeerReviewed
    Format: text
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Expert assessment of future vulnerability of the global peatland carbon sink (2021)
    Nature Research
    Details
    Publication Date: 2024-02-07
    Description: The carbon balance of peatlands is predicted to shift from a sink to a source this century. However, peatland ecosystems are still omitted from the main Earth system models that are used for future climate change projections, and they are not considered in integrated assessment models that are used in impact and mitigation studies. By using evidence synthesized from the literature and an expert elicitation, we define and quantify the leading drivers of change that have impacted peatland carbon stocks during the Holocene and predict their effect during this century and in the far future. We also identify uncertainties and knowledge gaps in the scientific community and provide insight towards better integration of peatlands into modelling frameworks. Given the importance of the contribution by peatlands to the global carbon cycle, this study shows that peatland science is a critical research area and that we still have a long way to go to fully understand the peatland–carbon–climate nexus.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Sea-surface temperature evolution across Aptian Oceanic Anoxic Event 1a (2016)
    Geological Society of America (GSA)
    In: Geology
    Details
    Publication Date: 2016-10-19
    Description: Atmospheric CO 2 possibly doubled during Oceanic Anoxic Event (OAE) 1a, likely in response to submarine volcanic outgassing. Despite being important for our understanding of the consequences of carbon cycle perturbations, the response of the climate system to this increase in greenhouse forcing is poorly constrained. Here we provide a new sea-surface temperature (SST) record from the mid-latitude proto–North Atlantic based on the organic geochemical TEX 86 paleothermometer. Using different calibrations, including the newly developed Bayesian Spatially-varying Regression (BAYSPAR) deep-time analogue approach, we demonstrate that SSTs increased by ~2–4 °C during OAE 1a and decreased by ~4–6 °C at its end, both simultaneous with changes in 13 C org , which we argue reflects changes in p CO 2 . We demonstrate that a clear latitudinal SST gradient prevailed during OAE 1a, contrary to the generally accepted view that a nearly flat SST gradient existed during OAE 1a and the Early Cretaceous. These results are more consistent with climate model simulations of the Cretaceous that have failed to produce flat SST gradients.
    Print ISSN: 0091-7613
    Electronic ISSN: 1943-2682
    Topics: Geosciences
    Published by Geological Society of America (GSA)
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    PAPER CURRENT
  • 5
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    Dansgaard-Oeschger forcing of sea surface temperature variability in the midlatitude North Atlantic between 500 and 400 ka (MIS 12) (2014)
    In:  EPIC3Paleoceanography, 29(11), pp. 1024-1030, ISSN: 08838305
    Details
    Publication Date: 2016-11-06
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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    PAPER (OA)
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