Dispatch from the Cryosphere: Glacier Decrease in the Georgian Caucasus

The Greater Caucasus extend along the northern territory of Georgia for about 750 kilometers. The spatial distribution of modern glaciers in the territory of Georgia is stipulated by the peculiarities of atmospheric processes, morphological-morphometric conditions, and their interaction. The northern slopes and watersheds of the Greater Caucasus contain more glaciers than the southern slopes, which is due to the relatively cold climate, higher relief and extremely partitioned slopes, gorges, and cirque depressions that are associated with the Würm glaciation. Georgian glaciers are concentrated mostly in the southern watersheds, as well as in the sub-ranges of the Greater Caucasus and Kazbegi massif.

The importance of studying Georgia’s glaciers

Regular and detailed observations of alpine glacier behaviour are necessary in regions such as the Georgian Caucasus, where glaciers are an important source of water for agricultural production, and runoff in large glacially fed rivers (Kodori, Enguri, Rioni, Tskhenistskali, Nenskra) supply hydroelectric power stations. In addition, glacier outburst floods and related debris flows are a significant hazard in Georgia and in the Caucasus.

In the last century, some experience was gained in the study of glaciers in Georgia, but after the economic difficulties of the 1990s, glaciological studies stopped. In recent years, though, glaciological research has been restored, and nowadays a glaciological group is studying the glacier variations in the Georgian Caucasus in different river basins.

The latest study

In the scientific work that I have published in The Cryosphere, the changes in the area and number of glaciers in the Georgian Caucasus were examined over the last century by comparing recent Landsat and ASTER images with older topographical maps and images.

Glacier reduction over the last few decades

Chalaati is one of the largest glaciers in Georgia, consisting of two flows and fed by the slopes of the over 4,000-meter-high peaks of Ushba, Chatini, Kavkasi, and Bzhedukhi Mountains. Among the glaciers on the southern slopes of the Greater Caucasus, this glacier has the lowest terminus position for the whole Caucasus region — 1,980 m above sea level and intrudes into the forest zone.

Due to the impact climate change, the area of Chalaati Glacier decreased from about 12.2 square km to 9.2 square km over the last century. It is possible to identify the drastic change of the glacier by comparing of old and modern images.

Chalaati Glacier reduction seen by comparing images from 1890 (left) and 2011 (right) (Source: Levan Tielidze)

Kirtisho is the largest glacier in the Rioni River basin with an area of about 4.4 square km. It is a valley glacier lying in the central section of the Greater Caucasus. This glacier is connected to the firn basin of the Bartui Glacier on the northern slope of the Greater Caucasus. In the years of 1930–1940, its leading edge hung over the ledge in front of it at an elevation of about 2,400 m. Today, the ice tongue terminates at a height of 2,660 m.

Kirtisho Glacier terminus in the 1930s (above) and 2010 (below) (Source: Levan Tielidze)

Gergeti (Ortsveri) is one of the largest glacier in the Tergi (Terek) River basin. It flows down the south-eastern slope of Kazbegi massif (5,047 m). A glacier firn basin is located at about 3,900 m. According to data from the 1960s (Levan Tielidze, 2017), the area of Gergeti Glacier was about 6.8 square km. Its sharply pointed tongue terminated at an elevation of 2,880 m. During the last half century the glacier has diminished by about 0.9 square km.

Using repeat photography, it is possible to depict the dramatic change to the glacier over the last century.

Gergeti Glacier reduction seen in images from the 1890s (above), the 1950s (middle), and 2011 (below) (Source: Levan Tielidze)

Overall, according to my research, the Georgian Caucasus region experienced glacier area loss over the last century at an average annual rate of 0.4 percent with a higher rate in the eastern Caucasus than in the central and western sections. Glacier melt is faster for southern glaciers than northern ones. A combination of topographic factors including glacier geometry and elevation, as well as climatic aspects such as southern aspect and higher radiation input, are related to the observed spatial trends in the glacier change analysis.

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