CONICET | Buscador de Institutos y Recursos Humanos

Size fluctuations inendorheic lakes in northwestern Argentina (NWA) and southwestern Bolivia (SWB)are very sensitive to basin hydrological balances, and consequently, veryvulnerable to deleterious effects from climatic changes. In this study, wepresent a multi-century reconstruction of past lake-area fluctuations in NWAand SWB. The evidence used to develop and validate this reconstruction includessatellite images and a century-long tree-ring record from P. tarapacana. Inter-annual fluctuations in lake area of nine lakeswere quantified based on Landsat satellite images over the interval 1975 to2009. A regional P. tarapacanatree-ring chronology, composite from two sampling sites, was used as predictorsin a regression model to reconstruct the mean annual (January-December) lakearea from the nine lakes. The reconstruction model captures 62% of the totalvariance in lake-area fluctuations and shows adequate levels ofcross-validation. This high-resolution reconstruction covers the past 601 yrand characterized the occurrence of annual to multi-decadal lake areafluctuations and its main oscillation modes of variability. Our reconstruction points out that the latetwenty century decrease in lake area was exceptional over the period 1407?2007;a persistent negative trend in lake area is clear in the reconstruction andconsistent with glacier retreat and other climate proxies from the Altiplanoand the tropical Andes. Throughout the 601 yr, the reconstruction provides valuableinformation about spatial and temporal stabilities of the relationships betweenchanges in lake area, ENSO, and PDO, highlighting the Pacific influence overmost modes of lake area variability. Global and regional climate models for theAltiplano project a marked reduction in precipitation to the end of the 21stcentury, exacerbating presently dry conditions. These results provide abaseline for the historical range of variability in water resources in theCentral Andes.