Carbon storage changes in the mid-depth South Atlantic during the penultimate glacial termination and the Anthropocene

Abstract

Changes in the Atlantic Meridional Overturning Circulation (AMOC) are thought to play an important role in the carbon cycle by regulating atmospheric carbon dioxide (CO2) levels and the carbon storage in the deep ocean, particularly during glacial terminations. During the beginning of glacial terminations, the AMOC weakened substantially and the mid-depth Atlantic showed reduced ventilation, a process that favored carbon storage before the AMOC recovered to its interglacial mode. Although the efforts made to understand the AMOC control over mid-depth carbon storage, this process is still poorly constrained beyond the last glacial termination. New sedimentological records from past glacial terminations are necessary to elucidate the exact moment of deep circulation reactivation and carbon storage changes. Therefore, we propose to perform stable carbon and oxygen isotopic (13C and 18O) and radiogenic neodymium isotopic (Nd) analyses in foraminifera in order to (i) calibrate a circulation proxy based on preindustrial and Anthropocene samples, and (ii) to reconstruct the deep circulation in the Brazilian Margin during the penultimate glacial termination. This proposal will not only validate a proxy for deep circulation reconstruction, but also provide reconstructions with precise age control to define the timing of AMOC recovery, changes in carbon storage and atmospheric CO2 levels during the penultimate deglaciation.