Simulated isotopic fingerprint of the Atlantic Multidecadal Oscillation over South America and its relation to the Little Ice Age

Autor(es)

Maksic, Jelena ; Shimizu, Marilia Harumi ; Sampaio, Gilvan ; Chiessi, Cristiano M. ; Prange, Matthias ; Vuille, Mathias ; Utida, Giselle ; Cruz, Francisco W. ; Lemes, Murilo Ruv

• Tipo de documento: Artigo Científico
• Fonte: PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY; v. 659, p. 11-pg., 2024-12-10.

Resumo

Linkages have been established between the Atlantic Multidecadal Oscillation (AMO) and surface air temperature variations, low-level jet streams, and precipitation trends in both northeastern Brazil and southeastern South America. Previous studies have discerned distinct wet-season (March-May) precipitation responses in northeastern Brazil, with cold (warm) AMO phases triggering increased (decreased) precipitation. Findings from various records indicate that the AMO's variability extends for thousands of years. A recent reconstruction suggests a significant AMO role in the shift from the Medieval Climate Anomaly (MCA) to the Little Ice Age (LIA) and reveals the LIA as the longest period with a persistent cold anomaly in the North Atlantic over the past similar to 3 millennia. Stable oxygen isotope records from South America show typical AMO periodicities (similar to 65 years), however, despite increased paleo precipitation data, the AMO's role in South American precipitation during the LIA and MCA remains unclear. In this study, the influence of AMO phases on atmospheric dynamics, precipitation patterns, and stable oxygen isotope composition (delta 18O) of precipitation over South America is assessed using the water isotope-enabled version of the Community Earth System Model version 1.2 (iCESM1.2). This research sheds light on the connection between AMO-induced precipitation anomalies and isotopic signals observed in paleoclimate records and emphasizes the significance of isotope-enabled climate models in unraveling the mechanisms behind past variations. The analysis involves comparing delta 18O simulations with published reconstructions from South America. By utilizing climate models that incorporate isotopes, we can delve deeper into understanding the impact of the AMO on precipitation patterns and isotopic ratios. Contrary to expectations, the simulated delta O-18(p) signal differ from speleothem records over the western Amazon and Andes during the LIA. That is, the simulated significant total precipitation amounts change over the western Amazon and Andes are not reflected in delta O-18(p) depletion. (AU)

• Processo FAPESP: 18/23522-6 - Simulação da Monção da América do Sul no último milênio: à variabilidade multidecadal e interanual e mecanismos de atuação
• Beneficiário: Jelena Maksic
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto
• Processo FAPESP: 19/24349-9 - Avaliando os efeitos das mudanças climáticas do passado e do futuro na biodiversidade amazônica (CLAMBIO)
• Beneficiário: Cristiano Mazur Chiessi
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Regular
• Processo FAPESP: 18/15123-4 - Perspectivas pretéritas sobre limiares críticos do sistema climático: a Floresta Amazônica e a célula de revolvimento meridional do Atlântico (PPTEAM)
• Beneficiário: Cristiano Mazur Chiessi
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Jovens Pesquisadores - Fase 2