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An updated glacier inventory is important for understanding glacier behaviour given the accelerating glacier retreat observed around the world. Here, we present data from a new glacier inventory for two points in time (2000, 2020) covering the entire Greater Caucasus (Georgia, Russia, and Azerbaijan). Satellite imagery (Landsat, Sentinel, SPOT) was used to conduct a remote-sensing survey of glacier change. The 30 m resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM; 17 November 2011) was used to determine aspect, slope, and elevations, for all glaciers. Glacier margins were mapped manually and reveal that in 2000 the mountain range contained 2186 glaciers with a total glacier area of 1381.5 ± 58.2 km2. By 2020, the area had decreased to 1060.9 ± 33.6 km2 a reduction of 23.2 ± 3.8 % (320.6 ± 45.9 km2) or −1.16 % yr−1 over the last 20 years in the Greater Caucasus. Of the 2223 glaciers, 14 have an area > 10 km2, resulting in the 221.9 km2 or 20.9 % of total glacier area in 2020. The Bezengi Glacier with an area of 39.4 ± 0.9 km2 was the largest glacier mapped in the 2020 database. Glaciers between 1.0 and 5.0 km2 accounted for 478.1 km2 or 34.6 % in total area in 2000, while they accounted for 354.0 km2 or 33.4 % in total area in 2020. The rates of area shrinkage and mean elevation vary between the northern and southern and between the western, central, and eastern Greater Caucasus. Area shrinkage is significantly stronger in the eastern Greater Caucasus (−1.82 % yr−1), where most glaciers are very small. The observed increased summer temperatures and decreased winter precipitation along with increased Saharan dust deposition might be responsible for the predominantly negative mass balances of Djankuat and Garabashi glaciers with long-term measurements. Both glacier inventories are available from the Global Land Ice Measurements from Space (GLIMS) database and can be used for future studies.

Changes of the glacier areas were analyzed. Rates of the area reduction of glaciers and glacier systems were compared over the course of the past 160 years as well as during shorter time intervals for the same period. On average for the whole period, the glacier areas decreased by a few tenths of a percent from the original in a year. Note, that this value was formed by rates for periods of the glacier retreating and advancing which were comparable by their intensities with rates from tenths of a percent to several percents of area in a year. In the first and the last thirds of the 20th century, when a rise of the air temperature decelerated, a number of advancing glaciers increased in both hemispheres. During these periods the same glaciers advanced (up to 25% of the total quantity of the investigated glaciers in the Alps). The second third of the 20th and the begin‑ ning of the 21st century were characterized by intensification of the temperature rise, and as the consequence of that, the number of advancing glaciers decreased, and rates of the area reductions increased over the whole globe. This dynamics was in a good agreement with the sea ice fluctuations in both, the Arctic and Antarctic regions, where the ice coverage increased in the 1960–1970 and in the second tenth of XXI century. So, decel‑ eration of the climate warming in that time was followed by increasing of the Arctic and Antarctic sea ice coverage and by deceleration of the area reduction of the mountain glacierization in some regions.

The history of studies of ten mountain glacier systems in Russian Subarctic is analyzed in the paper (Fig. 1). The intensity of these systems reduction and the vertical extent of glaciers during last 150 and 50 years are compared with the climate warming in this part of Russia, the map of accumulation–ablation on glaciers of this region is given (Fig. 3). Very quick reaction of the glacier surface to climatic changes is shown. The precision of glaciers’ size during 1960–1980 and 2000 are estimated and suggestion for future monitoring of glaciers size is made.

This paper examines changes in surface area and terminus retreat of glaciers in the Greater Caucasus Mountains between 2001 and 2010 using ASTER imagery. The use of consistent high-resolution imagery such as ASTER significantly reduces uncertainties in measurements of glacier shrinkage and retreat and enables assessments at decadal intervals which are important for both scientists and regional decision-makers. Two ASTER images acquired on 15 September 2001 and 29 September 2010 covering central sector of the Greater Caucasus Ridge and the Elbrus glaciated massif were used for glacier mapping. Outlines of 179 glaciers were mapped of which 108 glaciers are located on the northern macroslope of the Greater Caucasus and on Mt Elbrus in the Baksan River catchment (Russia) and 71 are located on the southern macroslope in the Inguri River catchment (Georgia). In total, glaciers lost 5% of their area. Glacier wastage was higher in the Inguri catchment at 5.6%; in the Baksan catchment, glaciers lost 4.3% of their area. Termini positions of 28 valley glaciers were measured on ASTER and aerial photographs to compare rates of glacier retreat in 2001–2010 and 1987–2001.The rate of this recession increased, this fact confirmed by field studies in Baksan basin. Glacier mass balance observations at Garabashi glacier indicate strong reduction in cumulative mass balance since 1998 providing further evidence on glacier wastage. The observed shrinkage of Caucasus glaciers is mainly connected with increasing in summer temperatures.Increase in precipitation has not compensated for an increase in temperature between 1987–2001 and 2001–2010 periods.

The paper examines changes in the area and volume of the Katun river basin glaciers, North and South Chu glaciers of the Altai Mountains since the beginning of the USSR glaciers inventarization to the present. For this purpose, we used USSR Glaciers Inventory data, space imagery – CORONA-1968, ALOS PRISM-2008, Landsat and ASTER 2000–2012. In total, glaciers have lost 172.4 km2 (27.4%) of its area.