MONGOLIA’S GLACIERS: A CENTURY OF OBSERVATIONS

The glaciers of Mongolia are relatively understudied, and different results about their number and the area they cover have been presented. As a reaction, the Regional Center for Mongolia of the international initiative Global Land Ice Measurements from Space (GLIMS) monitors Mongolia’s ice since 2010. Since then, two inventories have been generated that describe glacial changes from 1989 to 2011, and from 1990 to 2016. They have been derived from analyzing satellite images from Landsat 4, 5, 7 and 8, and Sentinel in combination with SRTM DEM data. Today, glaciers only exist in various ranges within the larger Altai Mountain system. Here, the debris-free glacierized area (the debris-covered area is estimated to be less than 5%) decreased from 515 km² in 1989 to 334 km² in 2016, a reduction of 35% in 27 years; we counted 627 glaciers in total. This glacier recession goes hand-in-hand with an increase in summer temperature of 1 °C from 1965-2015, with an enhanced increase since 1990. In the Turgen Range, repeat photographs from 1910 and 2010 revealed a significant downwasting of the valley glaciers, while the ice/snow cover on the summits appears to be intact. Compared to other mountain ranges worldwide, the glaciers in the extreme continental Mongolian Altai seem to recede at higher rates. This is of particular concern, since glaciers feed into numerous freshwater lakes throughout the region and probably make up 10-15% of the total water resources in Mongolia.