Glaciares de Chile


"Climate changes and glacier responses during recent decades in the Chilean Lake District"

Bown, F. & A. Rivera (2007) : «Climate changes and glacier responses during recent decades in the Chilean Lake District» Global and Planetary Change, 59, 79-86.

Resumen / Abstract.

Atmospheric temperatures measured at the Chilean Lake District (38° – 42°S) showed contrasting trends during the second half of the 20th century. The surface cooling detected at several meteorological stations ranged from – 0.014 to – 0.021 °C a-1, whilst upper troposphere (850 – 300 gpm) records at radiosonde of Puerto Montt (41°26’S/73°07’W) revealed warming between 0.019 and 0.031 °C a-1. Regional rainfall data collected from 1961 to 2000 showed the overall decrease with a maximum rate of – 15 mm a-2 at Valdivia st. (39°38’S/73°05’W). These ongoing climatic changes, especially the precipitation reduction, seem to be related to El Niño–Southern Oscillation (ENSO) phenomena which has been more frequent after 1976. Glaciers within the Chilean Lake District have significantly retreated during recent decades, in an apparent out-of-phase response to the regional surface cooling.Moreover, very little is known about upper troposphere changes and how they can enhance the glacier responses. In order to analyse their behaviour in the context of the observed climate changes, Casa Pangue glacier (41°08’S/71°52’W) has been selected and studied by comparing Digital ElevationModels (DEMs) computed at three different dates throughout the last four decades. This approach allowed the determination of ice elevation changes between 1961 and 1998, yielding a mean thinning rate of -2.3±0.6 m a-1. Strikingly, when ice thinning is computed for the period between 1981 and 1998, the resulting rate is 50%higher (-3.6±0.6ma-1).