Responses of two branches of Glacier No. 1 to climate change from 1993 to 2005, Tianshan, China

Clear understanding of how alpine glaciers respond to climate change is critical to accurately evaluate water resources and to retrieve climate information from the alpine glaciers. However, different glaciers may have different responses to climate change. This study focuses on two branches of Glacier No. 1 at the head of Urumqi River, Tianshan, China. These two branches, West Branch (WB) and East Branch (EB), have experienced the same pattern of climate warming since their separation in 1993. However, these glaciers have responded differently as observed by fieldwork and analysis of their annual mass balances, lengths, areas, equilibrium line altitudes (ELAs). To illustrate the different responses of climate change (increase in both temperature and precipitation), the glacier length response time (Trl) and climate sensitivity (C) are calculated for the two branches. The length response time and climate sensitivity are 1.89 y and 8.81 for the EB, and 1.63 y and 5.92 for WB. The different responses are interpreted to be controlled by glacial/topographical features with larger slopes and smaller areas, making the WB more sensitive to the recent climate warming.