II glacialismo del Livignasco (Alpi lombarde): variazioni recenti e relazioni con il clima

The glaciers of the Livigno area (Lombardy Alps); recent variations and relations with the climate

Abstract

The glacier variations of the Livigno area (Lombardy Alps) of the last sixty years have been studied, analyzing both the length and area reductions. It results a strong glacier area reduction (almost 30% between 1941 and 2002) coupled with a noticeable increase in the terminus altitudes (from the 2,693 m medium value to the 2,746 m medium value for six glaciers). The elaboration of the terminus glaciers data obtained from the publications of the Italian Glaciological Committee showed a length reduction of 230 m from 1940 to 2002 for the Ghiacciaio Settentrionale di Campo and a length reduction of 140 m in 20 years (1941-1961) for the Mine Glacier. Their dynamic was however discontinuous and saw phases of strong reductions and of small advances as the one occurred between 1977 and 1985, which left evident deposits in the proglacial area. The above mentioned glacier variations have been correlated to the Bormio meteorological station's data, which allow to point out a reduction in the mean summer temperatures of almost 1 °C (-0.95 compared to the average of the 1922-1995 period), occurred between 1968 and 1990, and a concomitant increase in winter precipitation of about 100 mm (always compared to the full series average). This type of glacial dynamic is well connected to the alpine glaciers recent variation phase which, after a continuous regression up to 1950, saw a short and small global increasing phase between years 60' and 80' of the XX Century followed by a restart of an intense and very strong reduction.