NOAA/WDS Paleoclimatology - South American Altiplano 70 Year Tree-Ring Oxygen Isotope Data

Hydroclimate variability in tropical South America is strongly regulated by the South American Summer Monsoon (SASM). However, past precipitation changes are poorly constrained due to limited observations and high-resolution paleoproxies. We found that summer precipitation and the El Niño - Southern Oscillation (ENSO) variability are well registered in tree-ring stable oxygen isotopes (d18OTR) of Polylepis tarapacana in the Chilean and Bolivian Altiplano in the Central Andes (18-22S, ~4500 m a.s.l.), with the northern forests having the strongest climate signal. More enriched d18OTR values were found at the southern sites, likely due to the increasing aridity towards the south-west of the Altiplano. The climate signal of P. tarapacana d18OTR is the combined result of moisture transported from the Amazon Basin, modulated by the SASM, ENSO and local evaporation, and emerges as a novel tree-ring proxy for regional and large-scale climate of the tropical Andes.