Unraveling AMOC-CO2 feedbacks during the warmer-than-present Last Interglacial

Informations projet

MIS-5e

N° de convention de subvention: 101109166

DOI

10.3030/101109166

Date de signature de la CE 10 Mai 2023

Date de début 1 Septembre 2023

Date de fin 31 Août 2026

Financé au titre de

• Marie Skłodowska-Curie Actions (MSCA)

Coût total

Aucune donnée

Contribution de l’UE

€ 289 407,84

Coordonné par

HELMHOLTZ-ZENTRUM FUR OZEANFORSCHUNG KIEL (GEOMAR)
Germany

Periodic Reporting for period 1 - MIS-5e (Unraveling AMOC-CO2 feedbacks during the warmer-than-present Last Interglacial)

Période du rapport: 2023-09-01 au 2025-08-31

Résumé du contexte et des objectifs généraux du projet

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.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

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.

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

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