Glacier extent changes and possible causes in the Hala Lake Basin of Qinghai-Tibet Plateau

Glacier is a common sensitivity indicator of environmental and global climate change. Examining the relationship between glacier area and climate change will help reveal glacier change mechanisms and future trends. Glacier changes are also of great significance to the regulation of regional water resources. This study selected the Hala Lake Basin in the northeastern Qinhai-Tibet Plateau as a study area, and examined the relationships between the temporal and spatial change of glaciers in the northeastern Qinghai-Tibet Plateau and climate change based on remote sensing imagery, climatological data, and topographic data during the past 30 years. Results showed that glacier area in the Hala Lake basin fluctuated and decreased from 106.24 km(2) in 1986 to 78.84 km(2) in 2015, with a decreasing rate of 0.94 km(2)yr(-1). The number of glacier patches, mean patch area, and largest patch index all decreased from 1986 to 2015, while the splitting index increased from 1986 to 2015, indicating that the landscape fragmentation of glacier in the Hala Lake Basin was increasing significantly during the study period. Glacier area change was mainly concentrated in the slopes >25 degrees with an altitude of 4500-5000 m, and the retreating rate of glacier of sunny slope was obviously higher than that of shady slope. Geometric center of glacier in the basin moved from southwest to northeast towards high altitude. Results of the response of glacier extent to climate change showed that temperature was the dominant factor affecting glacier area dynamic change in the Hala Lake Basin. It is predicted that in future several years, the glacier area will decrease and fragment continually as a result of global warming on the Tibetan Plateau