Portillon Glacier, French Pyrenees- Retreating and Disappearing

Portillon Glacier is in the Luchon-Bagneres region of the French Pyrenees, just north of the border with Spain. This currently small, and becoming smaller glacier drains into Lac du Portillon, which has a dam impounding it for hydroelectric generation. Like the nearby Aneto Glacier, Portillon Glacier has been thinning, retreating and separating. First a comparison of photographs from 1900 and 2013. In 1900 the glacier fills most of the cirque and nearly reaches the shore of the lake. The lake level is lower at this time also. By 2013 the glacier occupies a few small niches near the head of the cirque.

portillon lac 1900
1900 image from the Lakes of the Pyrenees web forum

portillon 2013
2013 image from Julien Lacrampe

By 2006 Google Earth imagery indicates a glacier with an area of 0.12 square kilometers, red dots indicate the terminus of the glacier. Section 3 of the glacier has separated from the main section, 2. Section 1 is a narrow avalanche fed fringe beneath the cliffs. This section is too steep to retain good snow. In the 2008 image The glacier also is notably thin with few crevasses, and several bedrock outcrops amidst the thinning ice. Both the 2006 and 2008 image indicate the lack of snowcover on the glacier. This has exposed up to 75 annual layers in a closeup transect from head to terminus of the glacier. There are only a few crevasses on this relatively steep glacier, indicating the lack of movement, which can only come from thin ice on a steep slope.

The lack of persistent snowcover at the end of the melt season indicates a glacier,, like the Aneto and Maladeta Glacier, that will not survive current climate (Pelto, 2010). Its area is much less than Aneto Glacier, and it will disappear sooner. As SOER (2010) indicates more than 80% of the area of glaciers in the Pyrenees has been lost since the start of the 20th century. The color of Lac du Portillon and the loss of glacier in the basin reminds me of the Milk Lake Glacier, Washington that I watched disappear recently.
portillon glacier 2006
Google Earth image

portillong glacier best
2008 Digital Globe image

portillon annual layers

Glacier de la Girose Retreat, France

Glacier de la Grirose (Girose) is one of the most travelled glaciers in the Alps. It is part of the Les 2 Alpes ski resort, used primarily for summer skiing. The main glacier serviced by a lift is Glacier Mantel just to the west of Girose. 2alpes_plan-de-pistes Despite the frequent visits to the glacier by skiers it has not been the focus of much study. The glacier is smaller than often visited but seldom skied Mer De Glace, similar to Glacier Blanc 15 km south and larger than the Grande Motte at Tignes ski area. Here we examine changes from 1984-2012 using Landsat images, Google Earth images and two photographs. Girose has three termini from west to east labelled A-C. The 1985 terminus location is marked by red arrows, the 2003 terminus is indicated by a purple line, the 2009 terminus by an orange line adn the lip of a key icefall here the middle branch (B) separates from the main branch (C). In 1985 this icefall lip is 500 m above the terminus. The two western termini A and B both extend well below the main icefield of Girose in 1985, by 2012 the tongues barely extend beyond the main glacier. The views of the terminus are in order a 1984 photograph, a 1985 Landsat, 2003 Google Earth, 2010 Google Earth and 2012 Landsat image. They are all viewed from the north. Retreat from 1985 to 2010 has been 420 m at terminus a, 500 m at terminus B and 350 m at terminus C. The overall rate is 15 meters/ year. girose glacier 1984

girose glacier 1985

glacier girose terminus 2003

girose glacier terminus 2010

girose glacier 2012

Of greater concern is the expansion of outcrops amidst the accumulation zone of the glacier from 2003 to 2010. This indicates thinning in the accumulation zone, which indicates the lack of a persistent snowcover even for many regions high on the glacier. The two images below identify three locations, at A and B the expansion of bedrock is evident. The scale is the same, at point A the rock outcrop is no longer a narrow linear feature. At Point B the rock outcrop is much longer. At point C there is a sharp reduction in crevassing, and the glacier surface is quite dark colored, this is not a rock amidst the glacier, instead the dark area indicates a portion of the glacier surface that has persistently lost its snowcover and where dirt at the surface has been preferentially enriched. This helps speed thinning, but in the former accumulation zone is a sign it is no longer an accumulation zone. The ski season is supposed to extend from mid- June to Sept. 1 for Les 2 Alpes on the glaciers, in many recent years the season is cut short on Girose. girose glacier acc zone 2003

girose glacier acc zone 2010

Saint Sorlin Glacier Retreat, France

The Saint Sorlin glacier above the resort of Saint-Sorlin d’Arves has lost over 50% of its surface area since 1870. The mass balance of the glacier is measured and reported annually to the World Glacier Monitoring Service, since 1980 the glacier’s cumulative mass balance is -28 meters water equivalent, equivalent to an average loss of over 30 meters in thickness The glacier is measured as part of the GLACIOCLIM program by the Laboratory of Glaciology and Geophysics of the Environment (LGGE) at the Université Grenoble. The LGGE has applied a glacier model that forecasts the disappearance of the glacier before 2100. The glacier retreat and accumulation zone thinning from 2002 to 2006 are evident in Google Earth Imagery. The average retreat during the four years is 60 meters, the red line in both images is the 2002 terminus position. More worrisome for the glacier is the expansion of bare rock areas high on the glacier, green lines outline the bare rock margins in 2006, which cross significant glacial ice just four years previous. . A view of the glacier from the hut beyond the terminus, from Lakiki, affords a view of both the thinning terminus (blue arrow) and rock outcrops emerging on the upper glacier (red arrows) that are a sign of a glacier that is thinning in its former accumulation zone. This is not a sign of a glacier that can survive (Pelto, 2010).