June 8, 2017

Sabbione Glacier, Italy Retreat & Fragmentation

Posted by Mauri Pelto

Sabbione Glacier in 1999, 2001 and 2016 Landsat images.  Red arrow is 1999 terminus location, red arrow the 2016 terminus location and the purple area new rock outcrops emerging in the midst of the glacier.

Sabbione Glacier is on the Swiss-Itlaian border.  The glacier drains into Lago Sabbione an artificial lake that in turn drains into Lago Morasco, which is a 29MW hydropower facility. The lake also has good fishing. This glacier in 1988 reached the shore of Lago Sabbione. Today glacier retreat has changed its nature dramatically.  It is not as close to disappearance as nearby Cavagnoli Glacier or Careser Glacier.  Huss and Fischer (2016) indicate that the majority of the small alpine glaciers, less than 0.5 square kilometers will disappear in the next 25 years.
In a series of Landsat images from 1999, 2001 and 2016 and a picture from Lago Sabbione in 2007, the retreat from the lake is evident. The 1988 terminus in an image below is indicated by a red arrow, the 2010 terminus by a yellow arrow, the new outcrop in the midst of the glacier by a magenta arrow. The retreat from 1988 to 1999 is 240 m, there is no rock outcrops emerging in 1999 or 2001. The glacier is 2.5 km long beginning at 3200 m and terminating at 2550 m in 1999. By 2007 image below the rock outcrop has become apparent. By 2016 the glacier has retreated 950 m from the lake and 700 m since 1999 and is now less than 2 km long.  The outcrop in the glacier center is 200 m wide. Of greater concern for the future of the glacier than retreat is the emergence of rock outcrops in the midst of the middle portion of the glacier, and smaller ones on the upper glacier. In 2016 the glacier only has 15% snow cover in this late August image, much less than the 50-60% needed for equilibrium balance. This indicates a glacier that is not in equilibrium lacks a persistent accumulation zone, indicating it will not survive current climate  (Pelto, 2010). In the most recent survey published by the Italian Glacier Commission indicates all glaciers in this region of Italy retreated in 2015.

Google Earth image of Sabbione Glacier and Lago Sabbione.

1988 Landsat image of Sabbione Glacier