Precipitation changes over the eastern Bolivian Andes inferred from speleothem (delta O-18) records for the last 1400 years

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Apaestegui, James ^{[1, 2]} ; Cruz, Francisco William ^[3] ; Vuille, Mathias ^[4] ; Fohlmeister, Jens ^{[5, 6]} ; Carlo Espinoza, Jhan ^[1] ; Sifeddine, Abdelfettah ^[7] ; Strikis, Nicolas ^[8] ; Guyot, Jean Loup ^[9] ; Ventura, Roberto ^[10] ; Cheng, Hai ^{[11, 12]} ; Edwards, R. Lawrence ^[12]

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^[1] Inst Geofis Peru, Lima - Peru

^[2] Pontificia Univ Catolica Peru, Inst Cient Agua, Lima - Peru

^[3] Univ Sao Paulo, Inst Geociencias, Sao Paulo - Brazil

^[4] SUNY Albany, Albany, NY 12222 - USA

^[5] Univ Potsdam, Inst Earth & Environm Sci, Potsdam - Germany

^[6] GFZ German Res Ctr Geosci, Sect Climate Dynam & Landscape Dev 5 2, Potsdam - Germany

^[7] MNHN, CNRS, UPMC, UMR LOCEAN, IRD, Paris - France

^[8] Univ Fed Fluminense, Dept Geoquim, Niteroi, RJ - Brazil

^[9] OMP, UPS, IRD, CNRS, UMR GET IRD Geosci Environm Toulouse, Toulouse - France

^[10] Univ Brasilia, Inst Geociencias, Brasilia, DF - Brazil

^[11] Xi An Jiao Tong Univ, Inst Global Environm Change, Xian, Shaanxi - Peoples R China

^[12] Univ Minnesota Twin Cities, Dept Geol & Geophys, Minneapolis, MN - USA

• Tipo de documento: Artigo Científico
• Fonte: Earth and Planetary Science Letters; v. 494, p. 124-134, JUL 15 2018.
• Citações Web of Science: 8

Resumo

Here we present high-resolution delta O-18 records obtained from speleothems collected in the eastern Bolivian Andes. The stable isotope records are related to the regional- to large-scale atmospheric circulation over South America and allow interpreting changes in delta O-18 during the last 1400 yr as a function of changes in precipitation regimes over the southern tropical Andes. Two distinct phases with more negative delta O-18 values, interpreted as periods of increased convective activity over the eastern Andean Cordillera in Bolivia are observed concomitantly with periods of global climate anomalies during the last millennium, such as the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) respectively. Changes in the Bolivian delta O-18 record during the LIA are apparently related to a southward displacement of the Intertropical Convergence Zone (ITCZ), which acts as a main moisture driver to intensify convection over the tropical continent. During the MCA, however, the increased convective activity observed in the Bolivian record is likely the result of a different mechanism, which implies moisture sourced mainly from the southern tropical Atlantic. This interpretation is consistent with paleoclimate records further to the north in the tropical Andes that show progressively drier conditions during this time period, indicating a more northerly position of the ITCZ. The transition period between the MCA and the LIA shows a slight tendency toward increased delta O-18 values, indicating weakened convective activity. Our results also reveal a non-stationary anti-phased behavior between the delta O-18 reconstructions from Bolivia and northeastern Brazil that confirms a continental-scale east-west teleconnection across South America during the LIA. (C) 2018 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 13/50297-0 - Dimensions US-BIOTA São Paulo: integrando disciplinas para a predição da biodiversidade da Floresta Atlântica no Brasil
• Beneficiário: Cristina Yumi Miyaki
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Temático
• Processo FAPESP: 12/50260-6 - Estruturação e evolução da biota amazônica e seu ambiente: uma abordagem integrativa
• Beneficiário: Lúcia Garcez Lohmann
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOTA - Temático