ИСТИНА

The observed increase in summer temperatures and the related glacier downwasting has led to a noticeable decrease of ice water resources in the inner Tien Shan (central Asia), with possible future impacts on the economy of all central Asia countries. Thus, a correct assessment of glacier retreat rates is an extremely important task in a region where water issues have been (and could become) the reason for tensions between neighboring countries. The Ak-Shyirak massif in the inner Tien Shan has one of the largest glacier-covered areas in the region, which feeds the Syrdarya and Sary-Jaz rivers. Whereas glaciers were quasi-stationary during the mid-20th century, they started to retreat in the 1970s. Glaciers of the Ak-Shyirak massif are not only affected by climatic changes, but are also impacted by the open-pit gold mining of the Kumtor Gold Company (KGC); this is why the role of KGC in the downwasting of Ak-Shyirak glaciers has repeatedly been the subject of speculation. The goals of our study include (1) an assessment of Ak-Shyirak glacier area in 2013 and its change with respect to 2003 and (2) better identification of triggers of change by distinguishing KGC vs climate impacts. To estimate change of glacier extent in 2003–2013, we manually delineated glacier outlines using three generations of images, namely Terra ASTER 2003, SPOT-2 2006 and SPOT-5 2013. We determined that, in 2013, glaciers covered 351.2 km2 in the Ak-Shyirak massif, which correpsonds to glacier area losses of ~21.9 km2 or 5.9% with respect to the values obtained for 2003. Glacier downwasting led to termini recession with mean values of 110 m for all Ak-Shyirak glaciers, whereas the direct impact of KGC on Davydov glacier has led to losses of 0.4% of total glacier area in the Ak-Shyirak massif between 2003 and 2013. To assess the indirect influence of KGC on glaciers in the Ak-Shyirak massif, we performed an assessment of the relation between glacier area losses and the distance between the glacier and area of KGC’s main activity. Using statistical analysis of two glaciologically verified samplings, we demonstrate an absence of this type of relation. Thus we argue that the indirect impact of KGC activities on glaciers in the Ak-Shyirak massif is negligible or even absent. We conclude that the rapid increase of summer air temperatures is the main driver of glacier shrinkage in the Ak-Shyirak massif, which has been almost two times larger in 2003–2013 as compared with 1977–2003.