Dynamic process simulation of a glacier on Qilian Mountain based on a thermo-mechanically coupled model

Abstract

As a climate-sensitive region, the glacier on Qilian Mountain is changing rapidly, and climate change can rapidly increase glacier flow instabilities through movement and ablation. We used the thermo-mechanically-coupled-with-full-Stokes code with the Elmer method to perform a steady-state diagnostic simulation of the Shuiguan River Glacier No. 3 (SG3) in the eastern Qilian Mountains, and to predict and analyze future changes of the glacier in combination with historical elevation data. The results showed that the average ice temperature was above −1.5 °C, that the hydrological process inside and under the ice was complex, and that the high ice temperature at the bottom would make the glacier fragile in the future. Because of the small thickness of the glacier and the small stress in the ice, the stress of the ice flow caused no great damage to the glacier. The development of cracks and melting holes under the ice was mainly caused by the melting of the glacier. Prognostic simulation under two climate models (RCP 4.5 and RCP 8.5) revealed that the area of SG3 changed evenly at first, and then retreated at an accelerated rate, whereas the volume consistently presented a state of accelerated reduction. Although our study confirmed that climatic warming was the main reason for glacial retreat, it was also found that the altitude of the glacier, the topography of the bedrock under the ice and the accumulation area would greatly affect the response of the glacier to climatic change. For these reasons, our study also profoundly elucidated why different glaciers with the same scale and under the same climatic conditions could exhibit different changes in area and terminal position.