Abstract
Abstract. Ice Apron (IA) is a poorly studied ice feature, commonly existing in all the world’s major mountain regions. This study aims to map the locations of the IAs in the Mont Blanc massif (MBM), making use of the very high-resolution optical satellite images from 2001, 2012 and 2019. 423 IAs were identified and accurately delineated in the MBM on the images from 2019, and their topographic characteristics were studied. We generated our own Digital Elevation Model (DEM) at 4 m resolution since the freely available products predominantly suffer from significant inconsistencies, especially in steep mountain areas. Results show that most IAs exist at elevations above the regional Equilibrium Line Altitude (ELA), on steep slopes, on concave surfaces, on northern and southern aspects and on the most rugged terrains. They are also commonly associated with steep slope glaciers as 85% of them occur on these glaciers’ headwalls. A comparison between 2001 and 2019 shows that IAs have lost around 29% of their area over a period of 18 years. This is significant and the rate of area loss is very alarming in comparison with the larger glacier bodies. We also studied the effect of topographic parameters on the area loss. We found that topographic factors like slope, aspect, curvature, elevation and Terrain Ruggedness Index (TRI) strongly influence the rate of area loss of IAs.
Highlights
The impacts of climate change on mountain environments are of great concern to the scientific community
Since we have already restricted our criteria for selecting Ice Apron (IA) to steep slopes (>40◦) We observed that most IAs in Mont-Blanc massif (MBM) exist on mean slopes between 53 − 65◦ (Figure. 4c.)
A majority of IAs lie on concave surfaces, as compared to convex surfaces. (Figure. 4d.) To understand the topographic locations of IAs in the MBM, we made a final comparison with the Topographic Ruggedness Index (TRI)
Summary
The impacts of climate change on mountain environments are of great concern to the scientific community. Like other mountain terrains in the world, the Mont-Blanc massif (MBM) has experienced a general trend of glacier retreat since the end of the Little Ice Age (LIA) despite small re-advances culminating in 1890, the 1920s and 1980s (Bauder et al, 2007). In the MBM, the loss of glacier surface area as recorded from 1985 to 2007 is more than 7% (109.5 km in 1985 to 102.4 km in 2007) in relation to the ELA (Rabatel et al, 2013). The recorded loss of glacier surface area was 24% of the total area from the end of the LIA to 2008 (Gardent et al, 2014). The surface of Talefre glacier lowered by 5-10 m between an altitude of 3000 – 3500 m a.s.l from 1979 to 2003 (Berthier, 2007). The presence of IAs is considered as a necessary condition for
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