ИСТИНА

A long series of observations on the glaciers located on the southern slope of Mount Elbrus reflects the change of two climatic periods in the Caucasus high mountains. The first period 1982-1997 was relatively cold and snowy. During this time, a layer of ice with a thickness of 0.8 m w.e. accumulated on the surface of the glacier. The second period 1998-2018 is characterized by increases of summer air temperatures and catastrophic melting. Repeatability of extensive anticyclones over the southern part of the European part of Russia and the North Caucasus has increased in the last ten years. Summer temperatures in the Elbrus region rose almost to the level of the 1950s, the hottest decade of the 20th century. The duration of the summer season increased on glaciers. Large firn areas in the main part of the accumulation area disappeared at altitudes of 3800-4000 m, and an open ice of the ablation zone appeared. The former areas of the temperate firn zone, where up to 35 % of thawed water was retained in the 20-meter firn layer, were replaced by the firn-ice zone. The glacier runoff increased. The supply of the glacier is currently deteriorating, its tongue receding with increasing speed. New rocks and entire lava ridges appear from under the ice at different altitude levels. Ablation intensity determines interannual fluctuations of the glacier mass balance. Over 36 years of observation the reduction of glacier mass led to a loss of 0.05 km3 of volume, 0.51 km2 of area, and 11.4 m w.e. layer of ice.