Characteristics of an avalanche-feeding and partially debris-covered glacier and its response to atmospheric warming in Mt. Tomor, Tian Shan, China

Abstract. Qingbingtan Glacier No. 72 in Mt. Tomor region is a small cirque-valley glacier with complex topography and debris-covered areas. Investigating its variation process will provide meaningful information for understanding the response of debris-covered glaciers existing broadly to climate change. The glacier accumulation area is characterized by receiving large amounts of precipitation and experiencing frequent snow/ice avalanches; temperature and flow regimes are analogous to a temperate or a monsoonal maritime glacier. Data from in-situ observations since 2008 and digitized earlier maps indicate the glacier has been in retreat and experienced thinning during the past 50 years. Between 1964 and 2008, its terminus retreat was 41 m a⁻¹, area reduction was 0.034 km² a⁻¹, and its thickness decreased at an average rate of 0.6 m a⁻¹ in the ablation area. With the melting enhancing, the proportion of the debris-covered area and thickness increased as well as inhibition of debris cover to melting. Thus, despite the persistent atmospheric warming during the last several decades, the strongest ablation and most significant terminus retreat and area reduction of the glacier occurred at the end of the last century and the beginning of this century rather than in most recent years. Based on a comprehensive analysis of climate change, glacier response delay, glacial topographic features and debris-cover influence, the glacier will continue to retreat in the upcoming decades, yet with a gradually decreasing speed. Then it will stabilize after its terminus retreats to an elevation of approximately 4000 m a.s.l.