The recent evolution of an Alpine glacier used for summer skiing (Vedretta Piana, Stelvio Pass, Italy)

The use of glaciers for ski activities is a relatively recent phenomenon and it seems now spreading in spite of the matter roused much controversy. In Europe, the Stelvio Pass (2757 m a.s.l) glacier area is a popular zone for this activity; summer skiing has been practiced there since the beginning of the 20th century. The effects of human impact on this kind of glacier is poorly known up to now such as its answer to climate variations. In this paper, variations in a sample glacier volume and thickness were quantified (Vedretta Piana, Stelvio Pass) through a comparison of large-scale maps (1955-1981) and field surveys (by GPS, RTK technique summers 1999, 2000 and 2001). A thickness increase on the larger part of the glacier profile was evident from 1955 to 1981, maximum value of + 10 in. In the subsequent period (1981-1999), a strong reduction was evident, maximum of about -30 m. The field surveys performed on two following summer seasons allowed also to calculate the glacier volume variations resulted equal, for summer 1999 to -442,000 m(3) (mean thickness variation of about -0.8 m) and for the summer 2000, to -606,000 m(3) (mean thickness variation of about - I m). On this glacier, geophysical surveys by GPR techniques have also been performed allowing the calculation of the ice thickness and of the glacier ice volume (72.5 x 10(6) m(3)). Attention has been paid also to the glacier historical evolution by analyzing in the time the number of infrastructures located on the glacier (especially lifts and their capacity) and the number of customers (largely skiers) using the lifts during the 2000 and 2001 summers, trying to relate these data with glacier seasonal surface evolution (crevasses presence and snow cover persistence and distribution) and with the summer climate trends. These results underline that the climate conditions of summer of 2001 was more favorable for summer ski activities owing to the extension of the snow cover and its persistence and also to the reduced number of open crevasses. An increase in the number of skiers is in fact evident for the 2001 summer (+21%); this datum is an exception respect to the general Italian trend of the last decade which underline an uninterrupted decline of Alpine skiers (-35% in the year 2004 respect the year 1997). (c) 2005 Elsevier B.V. All rights reserved.