Glacier changes in the Sikeshu River basin, Tienshan Mountains

Glaciers are widely recognized as sensitive indicators for regional climate change. This study reports changes of glaciers in the Sikeshu River basin, Tienshan Mountains, northwest China, between 1964 and 2004. Analysis of satellite images showed that the glaciated area decreased by about 15.4% (0.38% y−1) from 114.6 to 96.9 km2. The average glacier front retreat amounts to 195.3 m (4.9 m y−1) during the last four decades. Data from the Jilede hydro-meteorological station in the Sikeshu River basin showed increases in both the annual mean air temperature and annual precipitation during 1964–2004. This indicates that the glacier shrinkage in the Sikeshu River basin over the last 40 years was largely due to regional climate warming that enhanced glacier ablation and overcompensated for the effects of increased precipitation on the glacier mass balance. Glaciers smaller than 0.5 km2 in area experienced the strongest retreat, whereas glaciers larger than 2 km2 in area experienced gentle recession but may be the main contributors in the future to river runoff. Glacial shrinkage in the Sikeshu River basin is likely to continue with the temperature increase expected in coming decades.