Freshwater discharge from Amazon Basin and sea surface temperature variability in the western equatorial Atlantic during the last 60 thousand years

• Grant number: 25/23092-5
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: March 01, 2026
• End date: August 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Geosciences
• Principal Investigator: Cristiano Mazur Chiessi
• Grantee: Júlia Grigolato Iani
• Supervisor: Aline Govin
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Laboratoire Des Sciences Du Climat Et De L'Environnement, France
• Associated to the scholarship: 24/06541-8 - Changes in Amazon River freshwater and sediment discharge during Heinrich Stadials of the last 250 kyr, BP.DR

Abstract

Anthropogenic climate change is contributing to a slowdown of the Atlantic Meridional Overturning Circulation (AMOC), a key component of global ocean circulation that regulates heat distribution and influences regional climates such as that of the Amazon Basin. Understanding the link between AMOC variability and Amazon precipitation is essential given the ecological relevance of the Amazon rainforest. Past AMOC weakening events, such as Heinrich Stadials (HSs), provide the ideal situation to assess these connections. However, Amazon rainfall responses during HSs were spatially and temporally heterogeneous, with variations between and within stadials influenced by sea surface temperature anomalies in the western equatorial Atlantic and eastern equatorial Pacific. This project aims to investigate precipitation changes in the Amazon Basin during HSs over the last 60 thousand years. For this purpose, marine sediment cores MD23-3652Q and MD23-3653, retrieved from the French Guiana continental margin under the influence of the Amazon River discharge, will be analyzed. Stable oxygen isotopes (d18O) and trace element ratios (Ba/Ca, Mg/Ca) in Globigerinoides ruber white will be used to reconstruct variations in Amazon River freshwater discharge and western equatorial Atlantic sea surface temperatures, shedding light on the relationship between AMOC dynamics and Amazon climate. (AU)