Projected evolution of the Qiyi Glacier in the Qilian Mountains using the PyGEM with the calibration of glaciological mass balance

Owing to glacial retreat and associated future runoff variations, major concerns have been raised over the sustainability of water resources in the Qilian Mountains. Based on the Python Glacier Evolution Model, we present projections of the Qiyi glacier for shared socioeconomic pathways (SSPs) calibrated with the glaciological mass balance. The results indicate the air temperature as the dominant factor in the continuous mass loss of the Qiyi Glacier in the future. Glacier area and volume are projected to decline to 0.16 ± 0.11 km 2 (6.4% ± 4.4%, relative to 2015) and 0.0023 ± 0.0006 km³ (2.1% ± 1.5%, relative to 2015), respectively, by 2100, for SSP1-2.6. For SSP5-8.5, the glacier will disappear by 2088. The mass loss of the Qiyi Glacier will accelerate before 2050 for all SSPs but will decelerate after 2050 for SSP1-2.6 and SSP2-4.5. The peak water of glacier runoff will occur between 2034 and 2045, with the duration of high water from 7 to 18 years. Thereafter, the runoff will rapidly decline till 2070–2080 and remain low afterward. Compared with the existing projections, the present projections indicate that the Qiyi Glacier will experience more drastic shrinkage and ice loss in the coming decades. Finally, the glacier runoff is expected to reach its peak water earlier with a shorter duration of high water.