A new tree-ring δ18O precipitation reconstruction for the South American Altiplano (1700-2013 CE) highlights decadal hydroclimate teleconnections

MILAGROS RODRIGUEZ CATON; LAIA ANDREU-HAYLES; MARIANO MORALES; MUKUND PALAT RAO; TROY NIXON; JUAN ANTONIO RIVERA; VALERIE DAUX; DUNCAN CHRISTIE; EUGENIA FERRERO; ROSE OELKERS; ARIANNA MARIE VARUOLO-CLARKE; MATHIAS VUILLE; RICARDO VILLALBA

San Francisco

Conferencia; AGU 2023 Fall Meeting; 2023

American Geophysical Union

Paleoclimate records are key to characterizing present-day climate conditions in the context of the past. Stable oxygen isotopes (δ18O) measured in tree rings can be used as high-resolution proxies to estimate climate variability for the past centuries to millennia. In this study, we present the first precipitation reconstruction based on tree-ring δ18O for the South American Altiplano. Our annually resolved precipitation reconstruction is derived from a 314-year tree-ring δ18O chronology of Polylepis tarapacana, a tree species growing at the highest elevations in the world, in the southern tropical Andes. This reconstruction explains 56% of the interannual variability in observed December–March precipitation, coincident with the mature phase of the South American Summer Monsoon. It also shows good spatial agreement with Altiplano precipitation and its related atmospheric circulation patterns. Spectral analysis reveals interannual (2-5 years) and decadal (~11 years) oscillations in our record, similar to frequencies observed in instrumental precipitation (~2.3 year) and tropical Pacific sea surface temperature in the Niño 3.4 and Niño 4 regions (2-7 years). The decadal frequency is also remarkably consistent with 9-14-year peaks in ice-core δ18O from the Central Andes and coral δ18O from the central tropical Pacific. These results highlight the shared properties of δ18O proxies and their importance as records of decadal-scale atmospheric teleconnections modulated by the El Niño Southern Oscillation. In addition, we find strong agreement between our tree-ring δ18O based precipitation reconstruction and independent paleoclimatic reconstructions of the Palmer Drought Severity Index from the gridded South American Drought Atlas over the last 300 years. The δ18O record from the southern Altiplano provides a skillful reconstruction of past hydroclimate changes at local and regional scales, and represents a valuable tool for water management, lending a centennial-scale perspective of precipitation variability. Due to its teleconnections with tropical Pacific hydroclimate, this record may also be useful for larger-scale tropical climate reconstructions.