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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 km 2 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 km 2 , of which 0.66 km 2 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. [ABSTRACT FROM AUTHOR]

Abstract: Glaciological and geodetic measurements are two methods to determine glacier mass balances. The mass balance of Urumqi Glacier No. 1 has been measured since 1959 by the glaciological method using ablation stakes and snow pits, except during the period 1967–1979 when the observations were interrupted. Moreover, topographic surveys have been carried out at various time intervals since the beginning of the glacier observations. Therefore, glacier volume changes are calculated by comparing topographic maps of different periods during nearly 50 years. Between 1962 and 2009, Urumqi Glacier No. 1 lost an ice volume of 29.51×106 m3, which corresponds to a cumulative ice thickness loss of 8.9m and a mean annual loss of 0.2m. The results are compared with glaciological mass balances over the same time intervals. The differences are 2.3%, 2.8%, 4.6%, 4.7% and 5.9% for the period 1981–1986, 1986–1994, 1994–2001, 2001–2006 and 2006–2009, respectively. For the mass balance measured with the glaciological method, the systematic errors accumulate linearly with time, whereas the errors are random for the geodetic mass balance. The geodetic balance is within the estimated error of the glaciological balance. In conclusion, the geodetic and glaciological mass balances are of high quality, and therefore, there is no need to calibrate the mass balance series of Urumqi Glacier No. 1. [Copyright &y& Elsevier]