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This work involving the study of changes in the glacier equilibrium line altitude (ELA) is a continuance of the glaciological parameters of mountain systems investigation. The article explores the possibility of using new generation climate archives (in this case, ERA5–Land) together with weather station data on temperature and precipitation, in order to assess the climate dependence of the glacial system ELA in hard-to-reach and insufficiently studied mountain regions of the Russia Asian part. The ERA5–Land reanalysis reproduces temperature (values, dynamics, and trends) quite well in mountain systems. The use of total precipitation is possible only for assessing their dynamics and trends. The relative error for temperature trend is below 20% in both positive and negative sides, and precipitation is less than 30% in the negative one. Positive temperature trends of different intensity are observed in all mountains of the Russia Asian part with a maximum in the mountain systems of the Arctic zone. Minimal temperature trends are distinctive for coastal mountain regions of temperate latitudes. Summer temperature trends are maximum in inland areas and minimum in coastal mountain areas. The increase in precipitation in such areas occurs mainly at the expense of the cold period. It was revealed there was an increase of the glacial systems ELA from 50 to 800 m in the mountain regions of the Asian North Russia within 1966–2021. The value of the ELA rise coincides with areas of high temperature trends and may not correspond to precipitation negative trends.

Glaciers of the Verkhneangarsky mountain range are discovered in 2017-2018 and require detailed investigation and cataloging. This group of glaciers includes glaciers of the corrie and morphological types, and, according to the sizes, they should be qualified as small forms of glaciation. Four glacial formations were found during field studies of 2017-2018 together with several snow patches and stone glaciers; these four glaciers were measured and described. The temperature of ice in the glaciers of this region was measured during the investigations. Data on the ice temperature close to the temperature of the surface permafrost layer explain one of the conditions for existence of glaciers in the temperate zone at altitudes of 1800-2000 m. The dynamics of some glacial formations is analyzed in comparison with their present-day sizes, obtained as a result of interpretation of images from Bing maps and Sentinel-2 services, as well as with images of the CORONA mission (1967). The relative stability of the local glacial formations under climate change is related to the underlying permafrost as well as to the forms of occurrence in the relief, and a degree of closure by the stone cover.

Three glaciers and other small glacial formations, which are not mentioned in the USSR Catalog of glaciers as well as in any published article, were found in the area of the Verkhneangarsky (upper Angara) Range on satellite images. Earlier, researchers from the Institute of Geography of Siberian Branch of RAS described a group of glaciers on the Baikal Mountains and the Barguzin Range, which together with the above group of the Verkhneangarsky Range are related to the Baikal basin by the climate conditions. Ogdynda-Maskit Glacier has been described on the spot in 2017, while other glaciers and snow patches are to be investigated in situ in 2018. Together with the above Baikal and Barguzin glaciers, new data allow identification of the Baikal Glacial system. The article presents analysis of climate changes in the region. Trends in mean annual temperature range from 1 to 4 °C/50 years, while the same of summer temperatures change from 1 to 3 °C/50 years, but without any evident spatial distribution between them. Another situation takes place in the spatial distribution of precipitation: trends in total precipitation decrease towards the Baikal Lake, while precipitation of the cold period, on the contrary, slightly increases towards the Lake, but with rather small trend – 10–40 mm per 50 years. The last fact confirms the influence of the Baikal basin on the alimentation of glaciers and snow patches on the Verkhneangarsky Range. Currently, glaciers of the Verkhneangarsky Range undergo a slow regression.

A methodical approach is proposed for calculating the equilibrium line altitude HELA of glacier systems (on the example of the Northeastern Russia) on the basis of the characteristics that determine it in time and space: from the archive of temperature and precipitation at the grid points (the UDel archive, Delaware University). This data is used in the equation of mass balance of the glacier systems for the calculation of its components. As a result, the output is the inter-annual series of deviations of HELA from the mean value and the ratio between accumulation and solid precipitation in the regular grids over the glacial systems. By the longterm series of the HELA deviations the periods of minimum and maximum HELA state were revealed for various glacial systems, as well as linear trends of these series. This made us possible to evaluate the HELA trends in the future using the linear regression method. The sensitivity of the method of the initial parameters – the mean values of the summer air temperature, solid precipitation and the HELA value, received independently, have been estimated. Thus, the method allows detailing the HELA changes in space with the resolution of the archive used, and in time for each year of the selected climatic period.

The estimation of glaciers of the Suntar-Khayata Mountains (the Northeastern Siberia) in the context of previously published data is presented. Under the background of current warming the glaciers in this region retreat enough quickly, they decrease not only in a real size, but also by the ice thickness. In this paper the mean summer temperature and solid precipitation of the key factors for glaciation, which indicate unfavorable conditions for the glacier existence at present time are presented as spatial distribution of trends (for 45 years, until 2012). The glaciers of the northern massif of the Suntar-Khayata have a negative ice mass balance as their entire surface is below the equilibrium line altitude. Mean thickness of superimposed ice on the glaciers of this massif was about 17 cm. Based on the assumption of climate variation in the Northern Pacific data it is suggested about the beginning of more favorable climatic conditions for the Suntar-Khayata glaciers.

SummaryPaper presents the results of interpretation of space images (from Landsat and World View-2), which made possible to estimate the areal extent of glaciers ofMeynypilgynskyRange, North-East of Koryak Upland, in the early 2000's. Assessments of glaciers were analyzed in comparison with the Glacier Inventory of the region, compiled by R.V. Sedov (2001), as a whole and for groups of glaciers belonging to the selected six glacial systems. After dozens of years since the compilation of the Inventory (1985) and from some glacier data referred to 1967, the glaciers ofMeynypilgynskyRangelost about 30% of the area, mainly due to drying that accompanies climate warming. The analysis of glaciers, which had retreated, was conducted for the groups by the same morphological type, and the same aspect. The largest retreat and area reduction is relevant to valley-corrie and hanging glaciers of eastern aspect. Glaciers facing north less suffered. As a result of application of the developed methodology for assessing the evolution of glacier systems under given climate scenario, the parameters for the state of the glacier systems ofMeynypilgynskyRangeup to the time span 2049–2060 were obtained. The AOGCM–ECHAM 5 (B1) was used as a scenario; it is the optimal for theNorthern Eurasia. It turned out that the glaciers reduction would be catastrophic (about 90%), but nevertheless they would not completely disappeared.

The Koryak Upland, located in Russian Far East, has so far been poorly studied in terms of glaciology. The information contained in the USSR Glacier Inventory (1982) was obtained by analysis of topographic maps and aerial photography. On the publication date, the Inventory of Koryak Upland included 715 glaciers. To study of the current state of Koryak glaciers, we used satellite imageries – Landsat, Terra /Aqua (EOS AM-1) and ASTER. Deciphering the scenes showed that a significant portion of the glaciers melted away since the mid-1970's until now. We have found only 237 glaciers. Some glaciers are appeared to be rock glaciers, filled with detrital material, cemented by ice in a single body. They might be taken for real glaciers while categorization. The analysis of the retreat (reduction in area) of Koryak glaciers by groups with the same morphological type and the same aspect was conducted. The total retreat of the glaciers of this region varied from 40 (for those measured in situ) to 70% (mean total) as compared to aerial photography surveys (1950). This is the most intense reduction among the studied glacier systems of the Russian Subarctic. It can be explained by the changes in atmospheric circulation due to climate change, the Koryak Upland dries out while the increasing of annual air temperatures. Significant reduction of the glacier area was an incentive for us to undertake a work to assess the evolution of the glaciers in the near future. We used a GCM – ECHAM5 (B1) as the climatic scenario. The projection method has got further development: we have estimated the evolution of glacier systems in which the prevailing type is corries (relatively small circus glacier). The results show a diverse picture of glacier reduction by area, but in general the glacierization will not disappear for the period 2049–2060, reducing the extent by only 17% of the contemporary state.

The paper compares remotely sensed glacier inventories of the Byrranga, Suntar-Khayata, and Chersky ranges (2003), Koryak Highland and Chukotka mountains (2008) with data from the Inventory of Glaciers of the USSR (1945–1985). We studied changes in glacier area since the Inventory, which was primarily based on aerial photos and field research. The glaciers have been classified by orientation (aspect) and morphological type. Overall the glacierization of the Chersky Range (1970–2003), Suntar-Khayata (1945–2003), Byrranga (1967–2003), Koryak Highland (1950–2003) and Meynypilginsky Range (1984–2008) reduced by about 30, 20, 15, 60 (debatable value) and 25% respectively due to summer temperature rise. Calculation of glacier volumes for the dates indicated in the USSR Glacier Inventory and satellite imagery: during this period in sum for 5 studied glacier regions the area, covered by ice, has decreased by 225.2 km², and ice volume – by 8.7 Gtg. Construction of spatial patterns (maps) of current ELA for 3 different by climate mountain regions – the Suntar-Khayata Mountains– Chersky Range, and Meynypilgynsky Range ( North Far East), showed that despite of retreat of the glaciers, the mean ELA change for the first studied region is not large compared with the data from the Glacier Inventory (100 m ), and significant for the second (100–150 m).

We studied contrasting glacier systems in continental (Orulgan, Suntar-Khayata and Chersky) mountain ranges, located in the region of the lowest temperatures in the Northern Hemisphere at the boundary of Atlantic and Pacific influences – and maritime ones (Kamchatka Peninsula) – under Pacific influence. Our purpose is to present a simple projection method to assess the main parameters of these glacier regions under climate change. To achieve this, constructed vertical profiles of mass balance (accumulation and ablation) based both on meteorological data for the 1950–1990s (baseline period) and ECHAM4 for 2049–2060 (projected period) are used, the latter – as a climatic scenario. The observations and scenarios were used to define the recent and future equilibrium line altitude and glacier terminus altitude level for each glacier system as well as areas and balance components. The altitudinal distributions of ice areas were determined for present and future, and they were used for prediction of glacier extent versus altitude in the system taking into account the correlation between the ELA and glacier-terminus level change. We tested two hypotheses of ice distribution versus altitude in mountain (valley) glaciers – "linear" and "non-linear". The results are estimates of the possible changes of the areas and morphological structure of northeastern Asia glacier systems and their mass balance characteristics for 2049–2060. Glaciers in the southern parts of northeastern Siberia and those covering small ranges in Kamchatka will likely disappear under the ECHAM4 scenario; the best preservation of glaciers will be on the highest volcanic peaks of Kamchatka. Finally, we compare characteristics of the stability of continental and maritime glacier systems under global warming.