December 28, 2015
Lex Blanche Glacier Recession, Mont Blanc Massif, Italy
Posted by Mauri Pelto
Lex Blanche Glacier (Lb) comparison in a 1990 and 2015 Landsat image. Red arrow indicates 1990 terminus, yellow arrow the 2015 terminus and the purple arrow a separated tributary. Debris covered Miage Glacier (M) is adjacent.
Lex Blanche Glacier descends from 3500 m on the southeast flank the Aiguille de Glaciers of the Mont Blanc Massif into the Vale Veny of Italy. The glacier is adjacent to Miage Glacier (M). The glacier advanced over 700 m from 1970 to 1990. In 1990 the glacier extended to the base of a steep slope and turned north to terminate at 1980 m. By 2001 the glacier has retreated up a steep slope to near where the 1970’s advance had begun. By 2009 and 2011 further retreat has left the terminus just above a particularly steep bedrock slope. By 2015 the glacier has retreated 1100 m and terminates at 2450 m remaining on a relatively steep slope. The glacier is heavily crevassed a short distance above the terminus suggesting the period of rapid retreat should be ending. A tributary from the north has detached from the main glacier at the purple arrow. In recent warm summers the glacier has retained snowcover above 3150 m. The mass balance noted in Figure 8 (see below) of a paper by Berthier et al (2014) indicates the thinning is glacier wide but most prominent on glacier tongue. Berthier et al (2014) used the Pléiades satellites to identify a negative region wide mass balances of glaciers in the Mont-Blanc area of -1.04 m/year for the 2003-2012 period. The meltwater runoff from this glacier feeds the Dora Baltea River and then the Po River. Both rivers feature extensive hydropower including the Champagne and Nus hydropower plant on the Dora Baltea that produce 41 MW. The retreat of this glacier mirrors that of other glaciers of Mont Blanc including Taconnaz, Bionnassay, Mer de Glace and Tour Glacier.
Figure 8 from Berthier et al (2014) on glacier wide mass change with thinning in browns, and darker browns greater thinning.
Google Earth image from 2001 indicating the 1990 terminus at red arrow and 2001 terminus at yellow arrow.
Google Earth image from 2009 indicating the 1990 terminus at red arrow and 2009 terminus at yellow arrow.
Google Earth image from 2011 indicating the 1990 terminus at red arrow and 2011 terminus at yellow arrow. Blue arrow indicates the lowest heavily crevassed region.