Influence of debris cover on glacier response to climate change: insights from Koxkar glacier using dynamic simulation

Abstract

The response of debris-covered glaciers to climate change is more heterogeneous and complex than that of debris-free glaciers. The debris has a significant effect on glacier dynamic characteristics, which causes uneven mass balance changes, and then affects the change of glacier geometry evolves in response to climate. In our study, both energy balance and a two-dimensional mass and momentum conservation equation were used to simulate the ice temperature and velocity respectively at the main stream line of Koxkar glacier. The influence of the debris on ice temperature was described in the model. The ice velocity simulation was coupled with a description of ice viscosity under the influence of ice temperature. Our simulation results showed that the debris could increase the ice velocity and ablation in the middle of the glacier. Especially in the surface from 3200 to 3400 m.a.s.l, where the debris had great influence for ice velocity and temperature. From simulation results, we inferred that the ice thickness in this region would change obviously. Comparing with the measured thickness changes by ground-penetrating radar (GPR) between 1981 and 2008, the simulation result is consistent with measured results. Therefore, supraglacial lakes are easily developed in this region because of the high ice temperature and uneven ice surface. And the Landsat 8 remote-sensing image had verified this conclusion.