August 29, 2017
Saleina Glacier comparison in 1985 and 2015 Landsat images. The red arrow is the 1985 terminus, the yellow arrow the 2015 terminus and the purple dots the transient snow line in these August images.
Saleina Glacier is south of Trient Glacier descending a steep eastward oriented valley from Aiguille d’Argentiere on the northern end of the Mount Blanc Range. The Swiss Monitoring Network has maintained annual observations of the glacier front since 1878. After a sustained retreat during the first half of the 20th century, the glacier advanced 215 m from 1964-1988. From 1990 to 2015 the glacier retreated 640 m.
Here we use Landsat imagery from 1985-2017 and Google Earth images to identify ongoing changes. In 1985 the glacier extended down valley to an elevation of 1850 m, just before the valley turns east. After 2000 the lower 800 m of the glacier became debris covered, but up to at least 2009 remained crevassed indicating activity. By 2015 this section of the glacier no longer has crevassing or glacier ice exposed at the surface and has essentially collapsed and is no longer part of the main glacier. This is illustrated in a comparison of Google Earth images from 2011 and 2015. Points A,B and C represent the same bedrock locations adjacent to the glacier. The green arrows indicate a medial moraine on active ice in 2009 and what has become an ice cored moraine ridge without adjacent active ice in 2015. In 2009 the blue arrows indicate areas of crevassing indicating active ice. In 2015 the purple arrows indicate buried ice cored moraine as indicated by meltwater wetting the sediments. The total retreat of the active front from 1985 to 2015 is 1250 m, with the active front at 2300 m. The retreat has been driven by a rise in the end of melt season snowline. This amount of retreat is similar to that of adjacent Glacier du Tour.
In 1985 the snow line in mid-August was at 2900 m, in 2015 in late August the snowline was at 3075 m and in late August of 2017 the snowline is at 3150 m. The summer of 2003 is when the highest snowlines were reported across the western Alps (Rabatel et al 2013). That summer of 2003 in mid-August the snowline on Saleina Glacier was at 3050 m in an August snowline comparison of Mont Blanc glaciers. This years snowline will likely end the year as high or higher than 2003, the extensive negative mass balance will drive further retreat.
The 2016 inventory of Swiss glaciers noted several with significant retreats due to separation of stagnant ice areas and active ice. Saleina Glacier warrants being in this category.
Saleina Glacier in 2017 Landsat image. The red arrow is the 1985 terminus, the yellow arrow the 2015 terminus and the purple dots the transient snow line on 8/26/2017.
Points A,B and C represent the same bedrock locations adjacent to the glacier in the 2009 and 2015 Google Earth images. The green arrows indicate a medial moraine on active ice in 2009 and an ice cored moraine ridge without adjacent active ice in 2015. In 2009 the blue arrows indicate areas of crevassing. In 2015 the purple arrows indicate buried ice cored moraine as indicated by meltwater wetting the sediments.
Yellow arrows mark the end of the active ice in 2015 on Saleina Glacier.