Reduction in ventilation at mid-depths of the equatorial Atlantic during the abrupt and cold millennial-scale events of the last glacial period

• Grant number: 24/22324-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2025
• End date: March 31, 2026
• Field of knowledge: Interdisciplinary Subjects
• Principal Investigator: Cristiano Mazur Chiessi
• Grantee: Jaqueline Teixeira Alves
• Host Institution: Escola de Artes, Ciências e Humanidades (EACH). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 18/15123-4 - Past perspectives on tipping elements of the climate system: the Amazon Rainforest and the Atlantic Meridional Overturning Circulation (PPTEAM), AP.PFPMCG.JP2

Abstract

During the last glacial period, abrupt and cold millennial-scale events in the Northern Hemisphere weakened the Atlantic Meridional Overturning Circulation (AMOC) due to freshwater input from ice melting in regions of North Atlantic Deep Water (NADW) formation. These AMOC changes are commonly reconstructed using stable carbon isotope (¿13C) analyses in epibenthic foraminifera, which indicate that rapid negative ¿13C excursions in mid-depth Atlantic waters are linked to reduced ventilation and increased concentrations of remineralized nutrients in NADW. To better understand the ocean circulation responses to these events, a novel ¿13C record from epibenthic foraminifera in sediment core MD23-3652Q, retrieved from the equatorial Atlantic margin, is being developed to identify periods of reduced ventilation during the last glacial period. Increasing the resolution of this ¿13C record is crucial for a more detailed reconstruction of AMOC weakening and associated ventilation changes. This Scientific Initiation project aims to investigate mid-depth circulation changes in the equatorial Atlantic during the last glacial period (60-11.7 ka). To achieve this, a high-resolution ¿13C record will be generated from epibenthic foraminifera in sediment core MD23-3652Q, collected in the equatorial Atlantic.