Glacial-interglacial climate dynamics in the Subantarctic Eastern South Pacific since the late Miocene – high-resolution temperature reconstructions during the last 8 Ma – ClimPact

• Applicant: Dr. Antje Wegwerth
• Subject Area: Geology
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 574760954

The Antarctic Circumpolar Current (ACC) is the world’s strongest zonal current system and connects all three major ocean basins thereby strongly affecting global climate variability. Prior knowledge of the Neogene paleoclimate in the Southern Ocean comes from sediment cores in the South Atlantic, Indian Ocean and Western South Pacific, whereas palaeoclimate archives from the Eastern South Pacific covered not more than 700 kyrs in spite of a key role in modulating Drake Passage throughflow along the ACC affecting global MOC and Earth climate. Within the project ClimPact, we aim to improve our understanding of late Miocene to Holocene (last 8 Ma) atmosphere-ocean-cryosphere dynamics in the Eastern South Pacific and their role for regional and global climate by reconstructing biomarker-based sea-surface temperatures (SST) from a unique sediment core drilled during IODP Expedition 383 in the northern ACC system. During previous studies, we obtained a SST-record mainly on a 25 kyr timescale reflecting the Late Miocene to Pleistocene cooling, 400-kyr eccenticity cycles of cooling coinciding with enhanced meridional SST gradients and ACC intensity as well as pronounced dynamics of the Patagonian Ice Sheet. During the proposed project, our goal will be to produce a continuous 3.5 kyr resolution SST record to further (i) estimate the role of changes in zonal and meridional SST gradients on ACC strength during glacial-interglacial cycles. It will help to understand the impact of latitudinal frontal dynamics and zonal Southern Westerly Wind strength on ACC intensity during glacial-interglacial cycles. With this objective, we intend to solve the question, why ACC strength was enhanced during short-term interglacial warming at least during the last ~1 Ma and during long-term 400 kyr cooling periods since the Late Miocene. It will also show, whether ACC intensified during interglacials beyond the Pleistocene. By the help of additional biomarker proxies, we will (ii) reconstruct the glacial-interglacial variability in Patagonian Ice Sheet dynamics and its role for regional productivity. Finally, we will (iii) perform time series analyses to assess the coupling of orbital cycles of climate and environmental conditions in the ocean-atmosphere-continent system. This objective will provide important information on synchronicity of climate and environmental changes in the South Pacific Ocean and Patagonia.

• DFG Programme: Research Grants
• Co-Investigators: Professor Dr. Helge W. Arz; Dr. Jerome Kaiser; Dr. Frank Lamy