Blending historical and limnogeological records of the Little Ice Age in Southern South America.

PIOVANO, E.; CIOCCALE, M.; ARIZTEGUI, D.; ZANOR, G.; CÓRDOBA, F.

Malargue

Simposio; ?Reconstructing Past Regional Climate Variations in South America over the late Holocene: A new PAGES iniciative?; 2006

PAGES - Past Global Change

The clear paucity of complete and well-dated paleoclimate archives covering the LIA across Southern South America has been a major difficulty for depicting the regional environmental variability during this interval. Although the precise timing of the LIA is still a matter of debate, our contribution is focused on the comparison of hydrological balances southward the Tropic of Capricorn (23.5° S) up to ca. 52° S. We reviewed the most significant published limnogeological and historical records, blending both climate archives for enlarging the environmental reconstructions for this time-window. Paleoclimate records were selected throughout a wide geographical range and climate regimes: a) Pampean plains; b) Andean Altiplano and Puna; c) Central and Southern Chile; and d) Northern Andean Patagonia and Extra Andean Southern Patagonia.  SSA climate archives show a complex pattern of timing and climate variability during the LIA. There is, however, a noticeable antiphased hydrological balance at both sides of the Arid Diagonal. Numerous paleohydrological reconstructions suggest wet conditions during the LIA, southward and westward of the Diagonal Arida (i.e., Patagonia, central and southern Chile) as well as part of Puna. Conversely, this cold climate phase in the Pampean plains and Altiplano, was represented by pervasive draught. The antiphased cold-wet vs. cold-dry hydrological conditions at different latitudes in SSA reveal that increased rainfall triggered by intensified Westerlies are synchronous with dry conditions resulting from a diminished monsoonal activity.  Several forcing factors determine the increase or decrease of moisture transport from the tropics into the Pampean plains. Ongoing limnogeological studies in Salinas de Ambargasta (29° S - 64° W) and lagunas Mar Chiquita (30° S - 62° W), Melincué (33° S - 61°W) and Encadenadas del Oeste de Buenos Aires (37 °S - 62°W) may help to disentangle the mechanisms behind the most recent and past climate variability in the subtropics of South America.