Millennial- to centennial-scale Atlantic ITCZ swings during the penultimate deglaciation

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Campos, Marilia C. ; Chiessi, Cristiano M. ; Nascimento, Rodrigo A. ; Kraft, Laura ; Radionovskaya, Svetlana ; Skinner, Luke ; Dias, Bruna B. ; Pinho, Taina M. L. ; Kochhann, Marcus V. L. ; Crivellari, Stefano ; Mineli, Thays D. ; Mendes, Vinicius R. ; Baker, Paul A. ; Silva, Cleverson G. ; Sawakuchi, Andre O.

• Document type: Journal article
• Source: QUATERNARY SCIENCE REVIEWS; v. 348, p. 12-pg., 2024-11-30.

Abstract

Growing concerns surround the future of the Atlantic Meridional Overturning Circulation (AMOC) and its impacts on tropical regions, particularly due to changes in the dynamics of the Intertropical Convergence Zone (ITCZ). Northeastern Brazil, a tropical region strongly influenced by ITCZ dynamics, exhibits significant biological and social vulnerability to climate change, making it timely to understand how its hydroclimate could be impacted by AMOC changes in the face of anthropogenic global warming. The penultimate deglaciation was marked by a millennial-scale weak AMOC event called Heinrich stadial 11 (HS11; similar to 136-129 ka), providing an instructive target interval for improving our understanding of Northeastern Brazil hydroclimate responses to climate change. Here, we reconstruct paleoclimate changes during HS11 based on a multi-proxy approach applied to a high-resolution marine core from the western equatorial Atlantic. Our results suggest that HS11 was marked by a southward shift of the ITCZ, evidenced by paleoprecipitation records showing increased precipitation over Northeastern Brazil. These changes were concurrent with increased sea surface temperatures and reduced bottom water ventilation in the western equatorial Atlantic, interpreted as consequences of a weak AMOC. Importantly, we identified centennial-scale events within HS11, which are similar in nature but smaller in magnitude than HS11. These events align with North Atlantic climate changes, highlighting the crucial role that not only millennial- but also centennial-scale AMOC variability may play in low latitudes. Our findings raise concerns about the potential future impacts that an AMOC weakening may have on the hydroclimate of Northeastern Brazil and other tropical regions. (AU)

• FAPESP's process: 19/25179-0 - Penultimate glacial-to-interglacial transition in Northeastern South America and the adjacent ocean
• Grantee: Marília de Carvalho Campos Garcia
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 22/06452-0 - The South Atlantic on a 2°C warmer planet
• Grantee: Marília de Carvalho Campos Garcia
• Support Opportunities: Generation Project Research Grant
• FAPESP's process: 23/05764-0 - The South Atlantic on a 2°C warmer planet
• Grantee: Marília de Carvalho Campos Garcia
• Support Opportunities: Scholarships in Brazil - Generation Project
• FAPESP's process: 18/23899-2 - Trans-Amazon Drilling Project: origin and evolution of the forests, climate, and hydrology of the South American tropics
• Grantee: André Oliveira Sawakuchi
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants
• FAPESP's process: 18/15123-4 - Past perspectives on tipping elements of the climate system: the Amazon Rainforest and the Atlantic Meridional Overturning Circulation (PPTEAM)
• Grantee: Cristiano Mazur Chiessi
• Support Opportunities: Research Grants - Research Program on Global Climate Change - Young Investigators - Phase 2
• FAPESP's process: 20/11452-3 - Carbon storage changes in the mid-depth South Atlantic during the penultimate glacial termination and the Anthropocene
• Grantee: Bruna Borba Dias
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 22/02957-0 - Effects of the South Atlantic warming over South American precipitation
• Grantee: Vinícius Ribau Mendes
• Support Opportunities: Research Grants - Initial Project
• FAPESP's process: 19/24349-9 - Assessing the effects of past and future climate change on Amazonian biodiversity (CLAMBIO)
• Grantee: Cristiano Mazur Chiessi
• Support Opportunities: BIOTA-FAPESP Program - Regular Research Grants
• FAPESP's process: 22/01056-9 - The application of neodymium isotopes to reconstruct AMOC variability and its role in the global carbon cycle during the last two glacial terminations
• Grantee: Bruna Borba Dias
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• FAPESP's process: 21/02877-3 - Paleoceanographic evolution of the South Atlantic subtropical gyre over the past 800,000 years based on a multi-proxy approach
• Grantee: Marcus Vinicius Lermen Kochhann
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 22/09822-2 - Improvement of analytical routines and software development for analysis of carbon and oxygen stable isotopes by gas isotope ratio mass spectrometry in single specimens
• Grantee: Stefano Crivellari
• Support Opportunities: Scholarships in Brazil - Technical Training Program - Technical Training
• FAPESP's process: 22/09479-6 - Changes in ITCZ-related precipitation over NE South America during the penultimate glacial-to-interglacial transition: assessing fluvial discharge via planktonic foraminiferal Ba/Ca
• Grantee: Marília de Carvalho Campos Garcia
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor