Changes of the 0°C isotherm and the equilibrium line altitude in central Chile during the last quarter of the 20th century

An overall retreat of glaciers has been observed in the Andes of central Chile during the last similar to 100 years. Precipitation is mainly of frontal origin and concentrates in winter months. Analysis of precipitation data shows a decrease until 1976, an increase thereafter north of 34 degrees S and a decrease south of 34 degrees S, but overall no significant trends during the last quarter of the 20th century. Analysis of radiosonde data of central Chile shows ruid-tropospheric warming with an elevation increase of the 0 degrees C isotherm of 122 +/- 8 in and 200 +/- 6 m in winter and summer, respectively, during the 27-year period between 1975 and 2001. The results point to a snowline elevation increase in the region during the last quarter of the 20th century and a concurrent rise of the equilibrium line altitude (ELA) and suggest that mid-troposphere warming is the main cause for glacier retreat in central Chile.