Drought variability across the Andes during the last millennia and its linkage to Pacific Ocean climate variability

CHRISTIE, D; BARICHIVICH, J; MORALES, MS; COOK, ER; LE QUESNE, C; VILLALBA, R; ALVAREZ, C.A; SILVA J.S; MUÑOZ, A; MELVIN, T.M; BRIFFA, K.R; PACAJES, J; SAMANIEGO, H

Valdivia

Conferencia; II International Symposium Reconstructing Climate Variations in South America and the Antartic Peninsula over the last 2000 years; 2010

PAGES Past Global changes

Since the second half of the 20th century the Andes Cordillera has experienceda positive warming trend, an increase in elevation of the 0ºC isotherm, rapidmelting of ice caps, and a sustained shrinkage of glaciers. These climate andenvironmental changes have occurred in conjunction with a growing demandfor hydrological resources as a result of population increases and industrialdevelopment. Given the short span of instrumental hidroclimate records forthis region, longer records are needed to understand the nature of climatevariability and how the dominant interannual modes of climate variabilityhave evolved under changes in long-term background conditions. We developa field reconstruction of summer Palmer Drought Severity Index (PDSI) sinceAD 1200 from 10°S to 40°S latitude based on a multi species network of treeringchronologies from both flanks of the Andes. Our results show two dominantspatio-temporal modes, the first centered in the Altiplano region andthe second in the Central Andes of Chile and Argentina (CCha). Both modesshow an intermittent anti-phase relationship among themselves at high spectralfrequencies and an increase in interannual variability within the ENSOband since the late XIX century. Sea surface temperatures from the centralPacific Ocean results negatively (positive) correlated with Altiplano (CChA)summer PDSI.