Summer stratification of Andean lakes of Patagonia and Tierra del Fuego. Global warming or ENSO effects?

ISLA, F.I., ESPINOSA, M.A. & BUJALESKI, G.

Revista Geográfica del Sur

Universidad de Concepción

Lugar: Concepción, Chile; Año: 2010 vol. 1 p. 55 - 71

0718-7653

Lakes are traps of water and sediment and therefore they can content the record of past climate variations. High-latitude Andean piedmont lakes only give information of periods free of ice (Interglacials). Climatic studies based on cycles should be based on analogies. In this sense, it should be stated if varves respond to annual changes (summer-winter seasonality) or they are also representing cycles of longer temporal scale (interannual). Sedimentary records can represent trends (glacial advances, retreats or captures), local effects (vulcanism, gravity-dominated phenomena) or episodes. According to their dynamics, glacial lakes vary in relation to the summer stratification of the surface waters (monomic, dimictic or polimictic lakes). Global warming is assumed to produce significant changes in the vertical structure of lakes, and there are some experiments to forecast these variations (Lydersen et al. 2007). Patagonian and fueguian lakes analyzed during the summers of 2001 to 2007 stratified at depths between 10 and 22 m. These depths of the thermocline were shallower than those recorded in the summer of 1984. The lakes from the volcanic district (Neuquén and Chilean Region IX) are recording increases in temperature with depth. In some sectors of certain lakes, turbidity plumes were recognized as conditioning sedimentation rates and therefore the sedimentary record. According to their dynamics, glacial lakes vary in relation to the summer stratification of the surface waters (monomic, dimictic or polimictic lakes). Global warming is assumed to produce significant changes in the vertical structure of lakes, and there are some experiments to forecast these variations (Lydersen et al. 2007). Patagonian and fueguian lakes analyzed during the summers of 2001 to 2007 stratified at depths between 10 and 22 m. These depths of the thermocline were shallower than those recorded in the summer of 1984. The lakes from the volcanic district (Neuquén and Chilean Region IX) are recording increases in temperature with depth. In some sectors of certain lakes, turbidity plumes were recognized as conditioning sedimentation rates and therefore the sedimentary record.