Deglacial and Holocene sea-ice and climate dynamics in the Bransfield Strait, northern Antarctic Peninsula

• Published in: Climate of the Past
• Main Authors: Vorrath, Maria-Elena, Müller, Juliane, Cárdenas, Paola, Opel, Thomas, Mieruch, Sebastian, Esper, Oliver, Lembke-Jene, Lester, Etourneau, Johan, Vieth-Hillebrand, Andrea, Lahajnar, Niko, Lange, Carina B, Leventer, Amy, Evangelinos, Dimitris, Escutia, Carlota, Mollenhauer, Gesine
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Copernicus Publications 2023
• Subjects: Antarctic; Southern Ocean; The Antarctic; Antarctic Peninsula; East Antarctica; Bransfield Strait; Antarc*; Antarctica; ice core; Ice Sheet; Sea ice
• Online Access: https://epic.awi.de/id/eprint/59203/; https://doi.org/10.5194/cp-19-1061-2023; https://hdl.handle.net/10013/epic.083b6247-7c07-4a3f-9924-25079a3a1b2b

The reconstruction of past sea-ice distribution in the Southern Ocean is crucial for an improved understanding of ice-ocean-Atmosphere feedbacks and the evaluation of Earth system and Antarctic ice sheet models. The Antarctic Peninsula (AP) has been experiencing a warming since the start of regular monitoring of the atmospheric temperature in the 1950s. The associated decrease in sea-ice cover contrasts the trend of growing sea-ice extent in East Antarctica. To reveal the long-Term sea-ice history at the northern Antarctic Peninsula (NAP) under changing climate conditions, we examined a marine sediment core from the eastern basin of the Bransfield Strait covering the last Deglacial and the Holocene. For sea-ice reconstructions, we focused on the specific sea-ice biomarker lipid IPSO25, a highly branched isoprenoid (HBI), and sea-ice diatoms, whereas a phytoplankton-derived HBI triene (C25:3) and warmer open-ocean diatom assemblages reflect predominantly ice-free conditions. We further reconstruct ocean temperatures using glycerol dialkyl glycerol tetraethers (GDGTs) and diatom assemblages and compare our sea-ice and temperature records with published marine sediment and ice core data. A maximum ice cover is observed during the Antarctic Cold Reversal 13ĝ€¯800-13ĝ€¯000 years before present (13.8-13ĝ€¯ka), while seasonally ice-free conditions permitting (summer) phytoplankton productivity are reconstructed for the late Deglacial and the Early Holocene from 13 to 8.3ĝ€¯ka. An overall decreasing sea-ice trend throughout the Middle Holocene coincides with summer ocean warming and increasing phytoplankton productivity. The Late Holocene is characterized by highly variable winter sea-ice concentrations and a sustained decline in the duration and/or concentration of spring sea ice. Overall diverging trends in GDGT-based TEX86L and RI-OH' subsurface ocean temperatures (SOTs) are found to be linked to opposing spring and summer insolation trends, respectively.