No significant mass loss in the glaciers of Astore Basin (North-Western Himalaya), between 1999 and 2016

Sher Muhammad,Lide Tian,Marcus Nüsser

doi:10.1017/jog.2019.5

Abstract

ABSTRACTAlthough glaciers in High Mountain Asia produce an enormous amount of water used by downstream populations, they remain poorly observed in the field. This study presents a geodetic mass balance of the glaciers in the Astore Basin (with differential GPS (dGPS) measurements on Harcho glacier) between 1999 and 2016. Changes near the terminus of Harcho glacier (below 3800 m a.s.l.) featured heterogeneous surface elevation changes, whereas the middle section shows the most negative changes. The surface elevation changes were positive above 4200 m a.s.l. The average annual mass balance was −0.08 ± 0.07 m w.e. a−1 derived from a dGPS and DEM comparison whereas Advanced Spaceborne Thermal Emission and Reflection Radiometer DEM-based results show a slightly positive, that is 0.03 ± 0.24 m w.e. a−1 in the same period. In contrast, the terminus indicates a substantial retreat of ~368 m (4.5 m a−1) between 1934 and 2016. The average mass balance of 19 glaciers (>2 km2) covering ~60% of the total glaciers in the Basin exhibit no net mass loss in the period of 2000−2016 and follow a pattern similar to adjacent Karakoram glaciers.

Highlights

The temperature rise over the past few decades (Stocker and others, 2013) is alarming for glacial health globally including High Mountain Asia (HMA) (Bolch and others, 2012; Gardelle and others, 2013)
We present mass-balance data for Harcho glacier and compare/validate these results with glaciers in the Astore Basin (≥2 km2 area), derived by Brun and others (2017), using ASTER DEM data from the same observation period
A general negative surface elevation change characterizes the debris-covered ablation zone, whereas positive changes occur in the clean ice portions of the glacier

Summary

Introduction

The temperature rise over the past few decades (Stocker and others, 2013) is alarming for glacial health globally including High Mountain Asia (HMA) (Bolch and others, 2012; Gardelle and others, 2013). Accelerated warming could affect glacier mass balances at high altitudes and intensify glacier melting (Mountain Research Initiative, Elevation Dependent Warming Working Group, 2015). Such changes would impact future water availability; hydrological and cryospheric projections require precise glacier mass-balance measurements (Lutz and others, 2016). The valley glaciers in western Himalaya and Karakoram are mostly avalanche-fed, with no distinctive equilibrium line altitude (ELA) or accumulation zones (Hewitt, 2007, 2011). These glaciers share similar morphologies and have extensive debris coverage (Shroder and others, 2000), making it difficult to determine their mass balance using most ground-based methods

Results

Discussion

Conclusion