Characteristics of a partially debris-covered glacier and its response to atmospheric warming in Mt. Tomor, Tien Shan, China

Qingbingtan Glacier No. 72 in Mt. Tomor region is a cirque-valley glacier with complex topography and debris-covered areas. In-situ measurements from 2008 to 2013 revealed that both ice temperature and velocity are obviously higher than in other glaciers in this region. Comparison of digitized earlier topographic maps with recent satellite images indicates that the glacier had been retreating and thinning during the past decades. Between 1964 and 2008, its terminus retreat and area reduction was 41.16 ± 0.6 m a− 1 and 0.034 ± 0.030 × 10− 3 km2 a− 1, respectively, and thickness decreased at an average rate of 0.22 ± 0.14 m a− 1 in the ablation area. The strongest ablation and terminus retreat occurred at the end of the last century and the beginning of this century rather than in most recent years, seeming to be related to increase in the debris coverage and thickness. The debris-covered area was 0.87 km2, of which 0.66 km2 is thicker than the critical thickness of 4 cm, and thus the debris cover on this glacier has an alleviating ablation effect overall. Based on a comprehensive analysis of climate change, glacier response delay, glacial topographic features and debris cover influence, the glacier is likely to continue to retreat in the upcoming decades, yet with a gradually decreasing speed.