Glaciers of the Levaya Sygykta River watershed, Kodar Ridge, southeastern Siberia, Russia: modern morphology, climate conditions and changes over the past decades

Kodar Ridge (57°N, 118°E), southeastern Siberia, is a glaciarized mountain area of inner Asia. Here we have studied areal changes of glaciers and mid-summer snow cover in the Levaya Sygykta River watershed (area ~650 km², 60 % of total ice cover). We used 1:50,000–1:100,000 topographic maps, Landsat TM (1995), ETM + (2001–2002), high-resolution Cartosat-1 (2009) and WorldView-2 (2013) imagery, two digital elevation models (DEMs) and field survey data to quantify the areal changes of the glaciers since the end of the Little Ice Age (LIA) to 2013. In 2013, the exposed area of 18 small glaciers (from 0.02 to 0.88 km²) in the study area was 3.917 ± 0.064 km², and volume ~255 × 10⁶ m³. Between the LIA maximum and 2013, the area has been decreased by 61 % with rate of 0.377 % a⁻¹. The data available today suggest the areal shrinkage of Kodar glaciers from the LIA seems to be larger than elsewhere in Siberia. The rate of area decrease in 1995–2001 was five times greater than in 1850–2013, and in 1850–1995, 1.7 times less than in 1850–2013. Using regional climatic data we have found that climate conditions obviously stimulated glacier mass loss over the past at least 60 years. The increased variability of absolute and relative changes in 1995–2013 was due to influence of local factors on the overall climate-driven deglaciation trend. Comparison of two DEMs has showed that between 1970 and 2009, ice surfaces of 12 tested glacier tongues have been lowered, on average, by 29 ± 15 m with a rate of 0.75 m a⁻¹.