Variabilities in climate sensitivities and mass balance of four High Mountain Asian glaciers

Abstract

We analyse the mass balance evolution and climate sensitivities of four glaciers of High Mountain Asia (HMA) over the last five decades: Tuyuksu and Sary Tor glaciers (Northern and Central Tien Shan, Central Asia), Chhota Shigri Glacier (Western Himalaya), and an unnamed glacier (Glacier No. 4) (Eastern Himalaya). Using declassified Corona and Hexagon imageries (1960–1980) and recent high-resolution optical satellite data, we estimate mass loss rates of −0.3 ± 0.1 m w.e a⁻¹ (Tuyuksu and Chhota Shigri, 1971–2020), −0.6 ± 0.1 m w.e a⁻¹ (Sary Tor, 1973–2023) and −0.4 ± 0.1 m w.e. a⁻¹ (Glacier No. 4, 1969–2022). A calibrated mass balance model (SnowModel) coupled with an ice dynamics model was used to simulate long-term annual and seasonal mass balance. Sensitivity analysis indicates temperature has a much stronger influence than precipitation, with Glacier No. 4 being most climate sensitive. Even in the most optimistic future climate scenario (SSP126) temperatures are projected to rise by ∼2 °C with a ∼10% increase in precipitation leading to continuous mass loss. Sensitivity based projections suggest losses within a range of 0.8 m w.e. a⁻¹ (Chhota Shigri) and 1.8 m w.e. a⁻¹ (Glacier No. 4), with higher losses under more extreme scenarios. Glacier No. 4 faces the greatest threat due to insufficient precipitation to counterbalance warming. These findings highlight the vulnerability of HMA glaciers and the challenge of maintaining equilibrium under future climate scenarios.