Supra-glacier debris cover expansion and recession of glaciers across Himalaya and Karakoram range

Abstract

The Himalaya and the Karakoram Range are intensely glacierized, with large parts covered by debris cover that strongly influences ablation rates. Therefore, monitoring for Supra Glacial Debris (SGD) coverage is highly essential. The current study focuses on 24 debris-covered glaciers (DCG) across these extensive regions, mapping their spatial distribution, morphometric variations, and frontal retreat. We modified the RGI outlines using Standard False Colour Composite satellite imagery and ASTER GDEM data to assess the uncertainty for the mapped outlines. In order to map and monitor SGD, the highly accurate image classification technique of Random Forest was implemented through Google Earth Engine (GEE) - a cloud computing platform. It integrated Landsat TM, OLI, and also OLI-2 high-resolution imagery of the years 1992 and 2022 during peak ablation periods. The result exhibited increasing upward expansion and spatial coverage of SGD across all studied glaciers. All morphometric parameters showed significant changes in dimensions where most glaciers retreated. Our study also analyzed the relationship between various morphometric parameters and established a relationship between the coverage by SGD and the retreat of glaciers. Although the relation is not strong, it establishes a fact that increased coverage by SGD influences the rate of melting. Significantly, glaciers in the Central and Western Himalaya are melting at a faster rate than those in the Karakoram Ranges.