Centennial-scale precipitation anomalies in the southern Altiplano (18° S) suggest an extratropical driver for the South American summer monsoon during the late Holocene

Ignacio A. Jara, Antonio Maldonado, Leticia González, Armand Hernández, Alberto Sáez, Santiago Giralt, Roberto Bao, Blas Valero-Garcés

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Modern precipitation anomalies in the Altiplano, South America, are closely linked to the strength of the South American summer monsoon (SASM), which is influenced by large-scale climate features sourced in the tropics such as the Intertropical Convergence Zone (ITCZ) and El Niño-Southern Oscillation (ENSO). However, the timing, direction, and spatial extent of precipitation changes prior to the instrumental period are still largely unknown, preventing a better understanding of the long-term drivers of the SASM and their effects over the Altiplano. Here we present a detailed pollen reconstruction from a sedimentary sequence covering the period between 4500 and 1000&thinsp;cal&thinsp;yr&thinsp;BP in Lago Chungará (18<span classCombining double low line"inline-formula">ĝ </span>&thinsp;S; 4570&thinsp;m&thinsp;a.s.l.), a high-elevation lake on the southwestern margin of the Altiplano where precipitation is delivered almost exclusively during the mature phase of the SASM over the austral summer. We distinguish three well-defined centennial-scale anomalies, with dry conditions between 4100-3300 and 1600-1000&thinsp;cal&thinsp;yr&thinsp;BP and a conspicuous humid interval between 2400 and 1600&thinsp;cal&thinsp;yr&thinsp;BP, which resulted from the weakening and strengthening of the SASM, respectively. Comparisons with other climate reconstructions from the Altiplano, the Atacama Desert, the tropical Andes, and the southwestern Atlantic coast reveal that - unlike modern climatological controls - past precipitation anomalies at Lago Chungará were largely decoupled from north-south shifts in the ITCZ and ENSO. A regionally coherent pattern of centennial-scale SASM variations and a significant latitudinal gradient in precipitation responses suggest the contribution of an extratropical moisture source for the SASM, with significant effects on precipitation variability in the southern Altiplano.

Original languageEnglish (US)
Pages (from-to)1845-1859
Number of pages15
JournalClimate of the Past
Volume15
Issue number5
DOIs
StatePublished - 2019

Bibliographical note

Funding Information:
Acknowledgements. This investigation was funded by Fondecyt grant 1181829 and International Cooperation Grant PI20150081. The Spanish Ministry of Science and Innovation funded this research through the projects ANDESTER (BTE2001-3225), Complementary Action (BTE2001-5257-E), LAVOLTER (CGL2004-00683/BTE), GEOBILA (CGL2007-60932/BTE), and CON-SOLIDER Ingenio 2010 GRACCIE (CSD2007-00067). In addition, we acknowledge funding from the Spanish government through the MEDLANT project. BV-G is grateful for the support of project CGL2016-76215-R/BTE. IAJ would like to thank David López from CEAZA for his assistance in the drawing of Figs. 1–2 and Andrew BH Rees from Victoria University of Wellington, New Zealand, for his aid with the multivariate statistics. IAJ was supported by Fondecyt postdoctoral grant no. 3190181. AH was supported by a Beatriu de Pinós–Marie Curie COFUND contract within the framework of the FLOODES2k (2016 BP 00023) project.

Funding Information:
Financial support. This research has been supported by the Go-bierno Español (MEDLANT Project).

Publisher Copyright:
© 2019. This work is distributed under the Creative Commons Attribution 4.0 License.

Copyright:
Copyright 2019 Elsevier B.V., All rights reserved.

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