Changes in ITCZ-related precipitation over NE South America during the penultimate glacial-to-interglacial transition: assessing fluvial discharge via planktonic foraminiferal Ba/Ca

Abstract

Tropical South American hydroclimate sustains the world's largest biodiversity, as well as hundreds of millions of people. Still, its response to climate change remains highly uncertain. A better understanding of past natural climate variability can be a powerful tool in order to reduce these uncertainties. The Intertropical Converge Zone (ITCZ) is one of the most important atmospheric features of tropical South American hydroclimate. Understanding how the ITCZ behaved in the past is extremely important to better predict and deal with South American hydroclimate responses to climate change. The penultimate glacial-to-interglacial transition represents a key case study since it was marked by significant rises in atmospheric CO2 and marked changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC). All these factors being potential drivers of past and future ITCZ changes. The northeastern (NE) portion of South America is a tropical region directly affected by the ITCZ. However, the lack of paleoclimate records with appropriate temporal recovery and resolution for the penultimate glacial-to-interglacial transition hinders a more detailed understanding of ITCZ changes over this region. We will reconstruct changes in NE South America fluvial discharge associated with ITCZ meridional shifts during the penultimate glacial-to-interglacial transition. To accomplish this task, we propose to perform Ba/Ca analyses in planktonic foraminiferal tests from marine sediment core CDH-89, collected under the influence of the Parnaíba River drainage basin discharge, one of the largest drainage basins in NE South America. This marine core is already under investigation within the Post-Doctoral project of the candidate. (AU)