Glacier Fluctuations since the "Little Ice Age" in the Andes of Mendoza, Argentina.

LYDIA ESPIZUA

Roma

Workshop; Climate Change and Glaciers: Impacts in Water Resources, Sea Level Rise and Mountain Environments; 2007

Embassy of Chile in Italy; Ente per le Nuove tecnologie, l´Energia; e l´Ambiente; Centro de Estudios Científicos; Comitato Glaciologico Italiano, Instituto Antártico Chileno.

Abstract The most recent episode of glacier growth of the Holocene glacier fluctuations occurred during the “Little Ice Age” (LIA), which was a global, well documented phenomenon in nearly all glaciated regions. Nevertheless, in the Central Andes of Argentina between 31º-35ºS, very scarce studies have been carried out about the LIA maximum advance and the information of glacier variations deal manly with the time period from the beginning of the 20th century or from the end of the 19th century to the present. This study is thus relevant for paleoclimate reconstructions in South America. El Azufre and El Peñón valleys at 35ºS latitude and Las Damas and Las Choicas valleys at 34º55´S latitude in the headwater of the Rio Grande basin were studied since the maximum “Little Ice Age” (LIA) to the present. Based on morphological characteristics, the proximity to the active glaciers, and radiocarbon ages, the LIA advance begun around 1450 and the maximum was reached about 1660, and a later stage occurred around 1720-1820. The ELA during the LIA maximum in EL Azufre and El Peñón glaciers was 105 and 110 m lower than the present levels. The fluctuations of Las Vacas and Güssfeldt glaciers at 33ºS, and El Azufre and El Peñón glaciers, have been studied between 1894 and 2005, through the use of historical data, topographic maps, aerial photographs, satellite images (TM) of different years, and GPS measurements in the field. During this period the glacier length trend of advanced during 1980s and 1990s, then retreated until 2004 and remained near stationary. The Glaciar Güssfeldt retreated until 1999 and then remained practically stationary between 1999-2005. In Las Vacas, El Azufre and El Peñón glaciers, the advance during the 1980s and 1990s could be related with the ENSO events. The position of the modern snow-line (or equilibrium-line altitude; ELA) in El Azufre and El Peñón glaciers was estimated from the median altitude of the glaciers and lies at 3225 m and 3375±50 m, respectively.