Hydrological Changes in the South American Altiplano During the Last Millennium

DUNCAN A. CHRISTIE; MARIANO S. MORALES; RICARDO VILLALBA; MATHIAS VUILLE

Melburne

Conferencia; 9th International Conference on Dendrochronology; 2014

Throughout the second half of the 20th century, the Central Andes has experienced significant climatic and environmental changes characterized by a persistent warming trend, an increase in elevation of the 0º C isotherm. Given the short span of instrumental hydroclimatic records in this region, longer time span records are needed to understand the nature of climate variability in the South American Altiplano (SAA). In this study we present a tree-ring based precipitation reconstruction for the SAA, and we evaluate the possibility of a multiproxy reconstruction of the Titicaca lake levels based on tree-rings and ice cores. This precipitation reconstruction is based on the Polylepis tarapacana tree-ring series. This reconstruction covers 707 yr and provides a unique record characterizing the occurrence of extreme events and consistent oscillations in precipitation. It also allows an assessment of the spatial and temporal stabilities of the teleconnections between rainfall in the Altiplano and hemispheric forcings such as El Niño-Southern Oscillation. Since the 1930s to present, a persistent negative trend in precipitation has been recorded in the reconstruction. The reconstruction contains a clear ENSO-like pattern at interannual to multidecadal time scales, which determines inter-hemispheric linkages between our reconstruction and other precipitation sensitive records modulated by ENSO in North America. We points out that century scale dry periods are a recurrent feature in the Altiplano climate. Otherwise, the robustness and consistency exhibited by the tree-rings and ice cores records provide the opportunity to develop hydroclimatic multiproxy reconstructions in this region as indicated by the Lake Titicaca example.