Ocean circulation and carbon cycle dynamics in the Pacific Southern Ocean during Late Pleistocene interglacials

The Southern Ocean is a key component of the global ocean overturning circulation, enabling water mass exchange between ocean basins, driving Antarctic Bottom Water and Antarctic Intermediate Water formation and providing the major return path of Circumpolar Deep Water (CDW) to the ocean surface. The Pacific Ocean is the largest aquatic carbon reservoir and having a strong leverage on atmospheric CO2 concentration upon upwelling of carbon-rich CDW and subsequent CO2 release in the Pacific sector of the Southern Ocean, it is an important component regulating global climate. However, it remains one of the most unstudied regions regarding its carbon cycle dynamics, particularly for past warmer-than-present interglacial periods. This thesis takes advantage of high-resolution sediment material, retrieved during International Ocean Discovery Program Expedition 383 in the Pacific Southern Ocean at Sites U1540, U1542 and U1543, studying deep ocean upwelling and its impact on the marine carbon cycle as well as the West Antarctic Ice Sheet stability during Pleistocene interglacial periods that are often considered analogs for the current interglacial period. Applying a multi-proxy approach, this thesis investigates CDW upwelling dynamics using planktic and benthic foraminiferal δ13C, bottom water oxygenation using foraminiferal U/Mn ratios, bottom water temperature using benthic foraminiferal Mg/Ca ratios, sea surface temperatures using Neogloboquadrina pachyderma abundances, water mass provenance using Nd isotopes, nutrient concentrations using benthic foraminiferal Cd/Ca ratios, carbon storage variations using benthic foraminiferal B/Ca ratios and changes in productivity using sedimentary opal content during Marine Isotope Stage 11, 19 and 31. The thesis provides important constraints on the ocean-ice sheet-atmospheric system in the southern high latitudes, relevant for our understanding of the future climate system.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Christian-Albrechts-Universität zu Kiel

Year

2026

Author dc:creator

• Jebasinski, Lena

Contributors dc:contributor

• Gottschalk, Julia
• Frank, Martin

• Paleoceanography
• Paleoclimate
• Carbon cycle
• Southern Ocean
• Foraminifera
• Late Pleistocene

Repository record source_url

https://macau.uni-kiel.de/receive/macau_mods_00008078

OAI identifier oai:identifier

oai:macau.uni-kiel.de:macau_mods_00008078