INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Regional climate reconstructions across the Andes in South America: a contribution from the LOTRED-SA initiative
VILLALBA, R; MASIOKAS, M; LARA, A; RIVERA, A; GROSJEAN, M; MORALES, MS
Encuentro; Documenting, understanding and projecting changes in the hydrological cycle in the American Cordillera. IAI Collaborative Research Network 2047; 2011
Recent reviews in the LOTRED-SA Special Issue (Palaeo 3, 2009) show that there is a wealth of data sets available from a large variety of high-resolution archives across the Andes of South America. Based on this information, we provide regional syntheses of climate variations for the southern tropics (Altiplano), subtropical Andes (Central Chile and Argentina), and the northern and southern sectors of the Patagonian Andes during the last four centuries. Consistency among different proxy records provide confidence about the major climate changes recorded at regional scales. Humid conditions in the Bolivian Altiplano and the subtropical Andes inferred from tree rings during the 17th and 19th centuries are consistent with glacier advances in both regions during the Little Ice Age (LIA, ca. AD 1600-1850). Across Patagonia, most glaciers also reached their peak LIA advances between the 17th and 19th centuries followed by an accelerated loss of ice during the past century. Glacier retreat has been particularly pronounced in the northern Patagonian Andes since the mid-1970s, where tree-ring based temperature estimates have been the warmest of the past 400 years. This warming has been concurrent with a marked negative trend in regional precipitation. Comparisons of long-term climate variations in the four selected Andean regions suggest the existence of coupled interactions between tropical and extratropical modes of climate variability. The wet periods in the southern tropics and the subtropical Andes around AD 1650 and AD 1820 could be dynamically associated with a weakening of the Hadley Cell and a northward shift of the Westerlies, respectively. Northward locations of the Westerlies during the same intervals might have enhanced Antarctic influences across Patagonia, consistent with the two coldest periods reconstructed for the north and south Patagonian Andes during the past four centuries.