Periodic Reporting for period 1 - MIS-5e (Unraveling AMOC-CO2 feedbacks during the warmer-than-present Last Interglacial)
Reporting period: 2023-09-01 to 2025-08-31
The MIS-5e project investigates climate instability in the North Atlantic during the last interglacial period (129,000 to 115,000 years ago), which is widely regarded as one of the most relevant analogues for the projected global climate at the end of this century. The project seeks to understand the feedback mechanisms between ocean circulation variability, particularly the Atlantic Meridional Overturning Circulation (AMOC), and carbon cycling during this time.
The project focuses on paleoceanographic and paleoclimate reconstructions based on high-resolution geochemical data. In collaboration with scientists from GEOMAR and WHOI, I am analyzing multiple sediment cores and fossil corals from the North Atlantic using a suite of geochemical proxies to reconstruct past ocean and climate conditions. Isotopic data (δ¹³C, εNd, δ¹¹B) are used to assess changes in water mass chemistry and circulation patterns, while elemental ratios (Cd/Ca, B/Ca) provide insights into past nutrient levels and carbonate ion concentrations. The overarching goal is to fully leverage the last interglacial period as a natural experiment for understanding ocean-climate feedbacks under warmer-than-present conditions, offering valuable context for future climate projections.
The project focuses on paleoceanographic and paleoclimate reconstructions based on high-resolution geochemical data. In collaboration with scientists from GEOMAR and WHOI, I am analyzing multiple sediment cores and fossil corals from the North Atlantic using a suite of geochemical proxies to reconstruct past ocean and climate conditions. Isotopic data (δ¹³C, εNd, δ¹¹B) are used to assess changes in water mass chemistry and circulation patterns, while elemental ratios (Cd/Ca, B/Ca) provide insights into past nutrient levels and carbonate ion concentrations. The overarching goal is to fully leverage the last interglacial period as a natural experiment for understanding ocean-climate feedbacks under warmer-than-present conditions, offering valuable context for future climate projections.
As part of research on the AMOC during the last interglacial period, I conducted extensive geochemical and isotopic analyses at WHOI. This included trace element analyses, neodymium (Nd) isotope analysis and stable isotope analyses (δ¹³C and δ¹⁸O) on marine sediment cores. Sample preparation involved washing, sieving, and microscopic picking of foraminifera, followed by clay removal, dissolution, column chemistry, reductive and oxidative cleaning protocols, and ICP-MS measurements.
Key achievements:
- Developed end-member constraints for AMOC source waters during the last interglacial period.
- Reconstructed AMOC variability at a high resolution, providing a dataset suitable for validation and improvement of paleo-climate models.
- Prepared a comprehensive dataset to the PANGAEA data repository.
- First-author publication currently in preparation.
Key achievements:
- Developed end-member constraints for AMOC source waters during the last interglacial period.
- Reconstructed AMOC variability at a high resolution, providing a dataset suitable for validation and improvement of paleo-climate models.
- Prepared a comprehensive dataset to the PANGAEA data repository.
- First-author publication currently in preparation.
The project results will directly address a critical knowledge gap in the ocean–climate nexus by significantly advancing our understanding of the ocean’s role in regulating atmospheric CO2 levels. However, continued work at GEOMAR (Work Packages 3 and 4), as outlined in the Description of Action (DoA), remains essential to fully achieve these objectives