Reconstruction of changes in the South Atlantic Subtropical Gyre during Termination V and the MIS11: a multi-proxy approach

Abstract

The subtropical gyres are the main routes for redistributing energy between the low and high latitudes (intra-hemispheres), playing a crucial role in the global climate system. In recent decades, observational data has recorded a southward shift of the South Atlantic Subtropical Gyre. This phenomenon has been linked to the weakening of the Atlantic meridional overturning cell (AMOC), which causes heat accumulation in the Southern Hemisphere and the consequent southward shift of (sub)tropical climatic belts, such as the South Atlantic Subtropical Gyre. However, the lack of long-term monitoring data prevents an in-depth understanding of the trends of such changes. Paleoceanographic records obtained from the western tropical Atlantic offer a unique opportunity to investigate migrations of this gyre on longer time scales, since this region is influenced by the northern boundary of the South Atlantic Subtropical Gyre. The termination that occurred around 400,000 years ago, also called Termination V, culminated in an interglacial (i.e. Marine Isotope Stage 11, MIS11), during which the Earth recorded a global average temperature 2°C warmer than pre-industrial. Thus, Termination V and MIS11 are ideal periods to investigate changes in the South Atlantic Subtropical Gyre under global warming climate conditions. This Master's project aims to investigate changes in the position of the northern boundary of the South Atlantic Subtropical Gyre during the Termination V and MIS11. To this end, stable oxygen isotopic analyses will be carried out on two species of planktonic foraminifera, as well as paleoecological and morphometric analyses of planktonic foraminifera in a marine sediment core collected in the western tropical Atlantic.