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The analysis of satellite images revealed by 25% decrease of the Altai mountains’ glaciation area over last 50 years. In 2008–2017, deglaciation rate increased twice. This tendency is in good agreement with an observed increase in the Katun River flow by 9% in 2008–2017 as compared to 1940–1968 (under invariable total precipitation). The analysis of trends of main meteorological parameters based on weather station data and the ERA-Interim reanalysis demonstrated that statistically significant warming in the region occurs only during the warm season and does not exceed 0.5°С/10 years. For this reason, “atmosphere–glaciers” turbulent heat transfer has increased by 4 W/m2 in last two years, that caused an annual melting layer increase by 100 mm water equivalent (w.e.). However, the main reason for the Altai mountains’ deglaciation is an increase of downward solar radiation flux, which amounted to 5 W/m2 per decade and increased the melting layer by 365 mm w.e. per year. A positive trend in net radiation agrees well with a decrease in cloud amount, which is associated with an increase in the moisture divergence flux and geopotential height and with the weakening of zonal winds in the middle troposphere.

An updated glacier inventory is important for understanding glacier behavior given the accelerating glacier retreat observed around the world. Here, we present data from new glacier inventory at two time periods (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 surface area of 1381.5 ± 58.2 km2. By 2020, glacier surface area had decreased to 1060.9 ± 33.6 km2. Of the 2223 glaciers, fourteen have an area > 10 km2 resulting the 221.9 km2 or 20.9 % of total glacier area in 2020. The Bezingi Glacier with an area of 39.4 ± 0.9 km2 was the largest glacier mapped in 2020 database. Our result represents a 23.2 ± 3.8 % (320.6 ± 45.9 km2) or −1.16 % yr−1 reduction in total glacier surface area over the last twenty years in the Greater Caucasus. Glaciers between 1.0 km2 and 5.0 km2 account for 478.1 km2 or 34.6 % in total area in 2000, while it account 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 two 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.

The results of 20 years of field data (1963–1982) and 50 years of remote observations (1963–2012) on Medvezhy Glacier in the Pamirs by the Institute of Geography, Russian Academy of Sciences, are considered. The prevalence of the influence of climatic factors over internal ones (features of ice deformation) on glacial surges is shown. A conclusion is made about the uniqueness of the surge regime of Medvezhy Glacier connected with the structure of its bed. There are no analogues of this structure of the bed on any of the 82 surging glaciers in the Pamirs.

The new glacier inventory created recently at the Institute of Geography of the Russian Academy of Sciences made it possible to study the current state and recent changes of glacial systems in Russia, where now there are 22 glacial systems. The total area of ​​glaciation on this territory is 54,531 km2 based on Sentinel 2 images obtained mainly in 2016-2019. This area is occupied by 7478 glaciers. The largest glacial system in area is located on the Novaya Zemlya archipelago (22,241.37 km2). It is followed by Severnaya Zemlya (16491.81 km2) and Franz Josef Land (12530.03 km2). The next largest glacial systems are locate on the Caucasus Mountains (1067.13 km2), Kamchatka (682.8 km2) and Altai (523.14 km2). The area of ​​glaciers on the Arctic island of Ushakov (283, 09 km2), in the Suntar Khayata mountains (132, 97 km2) and the Koryak Upland (254.1 km2) occupies a range from 100 to 300 km2.The largest group is small glacial systems, the area of ​​which does not exceed 100 km2. They are located in different glaciological zones: the De Long Islands (65, 2 km2), the Urals (10.45 km2), the Putorana Plateau (11.36 km2), the Byranga Mountains (29.94 km2), the Chersky Ridge (86.37 km2), the Chukotka Upland (15.98 km2). Northeast of the Koryak highlands (42.19 km2), Kodar Ridge (16.22 km2), Eastern Sayan (12.88 km2).The remaining four regions are characterized by the smallest glacial systems. These are the Orulgan ridge (9.82km2) and the Kolyma Upland (6.62 km2), the Kuznetsk Alatau (3.42km2), the Barguzinsky (0.09) and Baikalsky ( 0.65km2) ridges. Despite their small size, these glacial systems are important from indicative point of view, fixing the zone of spatial distribution of glaciation. They indicate the growth points in the event of a change in climatic conditions according to a scenario favorable for glaciers.The glacier area has decreased since the compilation of the USSR glacier Inventory (1965-1982) by 5603.9 km2 or 9.3%. The area of ​​polar glaciers has decreased less than glaciers in mountainous regions. Values ​​range from 5.44% (Novaya Zemlya) to 19.11% (De Longa Islands). Small glaciers were not found in the Khibiny. Glaciers in the Urals have reduced their area by 63%. The subpolar glacier systems of the Orulgan (46.6%), Chersky (44.4%), and Suntar-Khayata (34%) ridges reduced the area a little less. Reduction in the area of ​​glacial systems in the temperate belt ranges from 57% (Eastern Sayan) to 13% (Kodar). The largest glacial systems in the Caucasus, Kamchatka and Altai have reduced their areas by 25, 22 and 39 percent, respectively.The results of our studies confirm the tendencies for the reduction of the glacier area throughout Russia. The exception is the glaciers of the volcanic regions of Kamchatka, which increased their size or remained stationary. The magnitude and rate of changes depend on the local climatic and orographic features.The presentation includes the results obtained in the framework of the following research projects: № 0148-2019-0004 of the Research Plan of the Institute of Geography of RAS, № 18-05-60067 supported by RFBR.

We present new Glacier Inventory of the Russian glaciers based on Sentinel images (2017/2018).The modern reduction in the size of glaciers is accompanied by the activation of natural processes leading to catastrophic consequences, changes in landscapes and prevailing nature management practices. To reduce risks and adapt to the consequences of ongoing changes, relevant data on the state of glacial systems are needed. In Russia, extensive glaciation is present in the Arctic zone, and in its continental part there are 18 mountain-glacial systems. According to the Glacier Inventory of the USSR in the mid-twentieth century in Russia there were 7167 glaciers with a total area of ​​60103, 99 km2. Of these, 685 glaciers with an area of ​​56,127.2 km2 accounted for the Arctic archipelagos. Despite the ever-increasing amount of information from space, and experimental studies in a number of glacial regions, a complete and reliable picture of the state of glaciation in Russia at the beginning of the 21st century has not been available to date.The project aims to develop and create a unified information basis for the study of glacial regions of Russia using geoinformation technologies. The initial data were collected and systematized to assess the current state of Russia's glaciers: data from previous inventories, maps, historical and modern aerial and space images, digital elevation models. A classification of possible catastrophic phenomena of glacial genesis was developed: dynamically unstable glaciers, glacier lakes, icebergs, etc. The structure of the database for the study of Russian glaciers is developed, compatible with world and national data archives. Implementation of the project allowed to gain new knowledge about the state of Russian glaciers.The presentation includes the results obtained in the framework of the following research projects: № 0148-2019-0004 of the Research Plan of the Institute of Geography of the Russian Academy of Sciences, № 05/2019/RGS-RFBR supported by the Russian Geographical Society, № 18-05-60067 supported by RFBR.

This paper reports that in the period of global warming continuing over 150 years, there are the glaciers growing in size.

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 highly dynamic nature of snow requires frequent observations to study its various properties. Keeping this in mind, the present investigation presents results from the analysis of fully polarimetric synthetic aperture radar (POLSAR) parameters for the development of a snow depth (SD) inversion model for SD retrieval. Snow depth retrieved using ground penetrating radar (GPR) at 500 MHz over Austre Gr&oslash, nfjordbreen in the Svalbard region was used to understand the behaviour of certain polarimetric parameters. A significant correlation was found between field-measured SD and POLSAR parameters, namely coherence and normalized volume scattering power (R2 = 0.84 and R2 = 0.73, respectively.) Using the POLSAR scattering powers obtained from the six-component model-based decomposition (6SD), the heterogeneity and anisotropic behaviour in the firn areas are also explained. Further, based on the analyses shown in this work, a polarimetric parameter-based SD inversion algorithm have been proposed and validated. The univariate model with co-polarization coherence has the highest correlation (R2 = 0.84, Root Mean Square Error (RMSE) = 0.18). We have even tested several multivariate models for the same, to conclude that a combination of coherence, normalized volume and double-bounce scattering have a high correlation with SD (R2 = 0.84, RMSE = 0.18). Additionally, temporal and spatial variability in SD was also observed from three polarimetric SAR images acquired between 4 April 2015 and 15 May 2015 over the Western Nordenski&ouml, ld Land region. Increase in snow depth corresponding to snow precipitation events were also detected using the POLSAR data.

Based on systematic surveys and analysis of the satellite images under the GLIMS international project, the rate of glacier shrinkage and the increase in this rate for the past 15 years are estimated.

We distinguished 32 regional glacier systems in continental Eurasia. We found that 80% of the glacier area and 90% of the glacier volume are concentrated in

Recent decades are characterized by progressively increasing cosmic information on glacier sizes. The effectively used satellite images obtained by the LANDSAT/TM, SPOT/HRV, JERS/OPS, and ASTER systems [1] are now supplemented with high� resolution satellite information: Ikonos, QuickBird, EROS, OrbVie, WorldView, ALOS, Cartosat, and Tet�

Historical surveys and recent satellite imagery are used to map and assess glacier recession in the eastern Pamir over the last three decades. For this study we used topographic maps of 1 : 100 000 scales published in 1943 and 1970; air photos from 1978 and 1990; space images: from Russian satellites in 1972, 1978, 1980, and 1990 and ASTER data for 2001. Climatic records from the “Fedtchenko” glacier station (4156 m a.s.l., 38.83°N, 72.22°E) and “Murgab” meteorological station (3576 m a.s.l., 38.17°N, 73.97°E) are used for analysis of the climate conditions in the region. Changes in the area of 5 glaciers and terminus positions of 44 glaciers in the eastern Pamir reveal an accelerating trend since the end of the 1970s through 2001, as a continuation of glacier wastage and retreat since, at least, the end of the Little Ice Age. The glacier area decreased 7.8% during 1978–1990, and 11.6% in 1990–2001. This corresponds with documented changes in other mountain and subpolar regions in the Northern Hemisphere and specifically in Central Asia. Glacier changes in the eastern Pamir are a response to increasing summer temperatures. We find decreases in glacier area and retreat of glacier fronts, increased debris-covered area and the appearance of new lakes.

We describe an investigation that combines space-based observations of glacier parameters with histor- ical glaciological data derived by traditional means to predict changes in ice extent and volume for the Ak-shirak Range in the interior Tien Shan of Central Asia. A variety of geographic information systems and photogrammetric tools are used to extract glacier outlines, derive of a digital elevation model, and compute area versus elevation distribution functions from data acquired by the Advanced Spaceborne Thermal Emission and Re- flection radiometer. These products are then used in a glaciological methodology that can predict the response of glacier systems to changes in local climate.

[1] Global analysis of glacier regimes reveals widespread wastage since the late 1970s, with a marked acceleration in the late 1980s. We investigate changes in the heavily glacierized Ak-shirak Range, central Tien Shan plateau (43°N, 75°E) using air photo mapping surveys (1943 and 1977), an ASTER imagery (2001), and long term glaciological and meteorological observations. The wasting of the Ak-shirak glacier system features a decrease in average glacier size, and an increase in the area of outcrops. A small shrinkage during 1943–1977 was followed by a greater than 20% reduction during 1977–2001 in response to increases in summer and annual air temperature and decreases in annual precipitation.

Glaciers are widely recognized as key indicators of climate change. Recent evidence suggests an acceleration of glacier mass loss in several key mountain regions. Glacier recession implies landscape changes in the glacial zone, the origin of new lakes and activation of natural disaster processes, catastrophic mudflows, ice avalanches, outburst floods, etc. The absence or inadequacy of such information results in financial and human losses. A more comprehensive evaluation of glacier changes is imperative to assess ice contributions to global sea level rise and the future of water resources from glacial basins. One of the urgent steps is a full inventory of all ice bodies and their changes. The first estimation of glacier state and glacier distribution on the territory of the former Soviet Union has been done in the USSR Glacier Inventory (UGI) published in 1965‐1982. The UGI is based on topographic maps and air photos and reflects the status of the glaciers in the 1940s‐1970s. There is information about 28 884 glaciers with an area of 7830.75 km 2 in the inventory. It covers 25 glacier systems in Northern Eurasia. In the 1980s the UGI has been transformed into digital form as a part of the World Glacier Inventory (WGI). Recent satellite data provide a unique opportunity to look again at these glaciers and to evaluate changes in glacier extent for the second part of the 20th century. About 15 000 glacier outlines for the Caucasus, Polar Urals, Pamir Alay, Tien Shan, Altai, Kamchatka and Russian Arctic have been derived from ASTER and Landsat imagery and can be used for glacier change evaluation. Results of the analysis indicate the steady trend in glacier shrinkage in all mountain regions for the second part of the 20th century. Glacier area loss for the studied regions varies from 13% (Tien Shan) to 22.3% (Polar Urals). The common driver, most likely, is an increase in summer air temperature. There is also a very large variability in the degree of individual glacier degradation, very much depending on the morphology and local meteorological conditions.

Analysis of current and historical data demonstrates that the cryosphere component are very sensitive to the climate change thus proving its role as the climate indicator. In the process of this a pattern of the changes clearly reflect regional climate characteristics. International cryospheric community works very hard for efficient organization of observations of the cryosphere components and specific features of its development against background of changing climate. Geophysical, geochemical, space and other methods are used for solution of this problem.