Regional Climate Reconstructions across the Andes in South America: A contribution from the LOTRED-SA Initiative

RICARDO VILLALBA; MASIOKAS, M.; LARA, A.; RIVERA, A.; GROSJEAN, M.; MORALES, M.; CHRISTIE, D.; URRUTIA, R.; DELGADO, S.; LUCKMAN, B.; BONINSEGNA, J.A.; PRIETO, M.R.; ESPIZUA, L.; ARAVENA, J.C.; LE QUESNE, C.

Tilcara, Jujuy

Encuentro; IAI CRN 2047: Documenting, understanding and projecting changes in the hydrological cycle in the American Cordillera. Program with Abstracts, Final Science Meeting,; 2011

IANIGLA - CONICET

Recent reviews in the LOTRED-SA Special Issue (Palaeo 3, 2009) show that there is a wealthof data sets available from a large variety of high-resolution archives across the Andes ofSouth America. Based on this information, we provide regional syntheses of climatevariations for the southern tropics (Altiplano), subtropical Andes (Central Chile andArgentina), and the northern and southern sectors of the Patagonian Andes during the last fourcenturies. Consistency among different proxy records provide confidence about the majorclimate changes recorded at regional scales. Humid conditions in the Bolivian Altiplano andthe subtropical Andes inferred from tree rings during the 17th and 19th centuries are consistentwith glacier advances in both regions during the Little Ice Age (LIA, ca. AD 1600-1850).Across Patagonia, most glaciers also reached their peak LIA advances between the 17th and19th centuries followed by an accelerated loss of ice during the past century. Glacier retreathas been particularly pronounced in the northern Patagonian Andes since the mid-1970s,where tree-ring based temperature estimates have been the warmest of the past 400 years.This warming has been concurrent with a marked negative trend in regional precipitation.Comparisons of long-term climate variations in the four selected Andean regions suggest theexistence of coupled interactions between tropical and extratropical modes of climatevariability. The wet periods in the southern tropics and the subtropical Andes around AD1650 and AD 1820 could be dynamically associated with a weakening of the Hadley Cell anda northward shift of the Westerlies, respectively. Northward locations of the Westerlies duringthe same intervals might have enhanced Antarctic influences across Patagonia, consistent withthe two coldest periods reconstructed for the north and south Patagonian Andes during thepast four centuries.