Abstract

Tropical South American climate is influenced by the South American Summer Monsoon and the El Ni & ntilde;o Southern Oscillation. However, assessing natural hydroclimate variability in the region is hindered by the scarcity of long-term instrumental records. Here we present a tree-ring delta O-18-based precipitation reconstruction for the South American Altiplano for 1700-2013 C.E., derived from Polylepis tarapacana tree rings. This record explains 56% of December-March instrumental precipitation variability in the Altiplano. The tree-ring delta O-18 chronology shows interannual (2-5 years) and decadal (similar to 11 years) oscillations that are remarkably consistent with periodicities observed in Altiplano precipitation, central tropical Pacific sea surface temperatures, southern-tropical Andean ice core delta O-18 and tropical Pacific coral delta O-18 archives. These results demonstrate the value of annual-resolution tree-ring delta O-18 records to capture hydroclimate teleconnections and generate robust tropical climate reconstructions. This work contributes to a better understanding of global oxygen-isotope patterns, as well as atmospheric and oceanic processes across the tropics.