The reduction in the area and volume of glaciation in all mountain regions of the Earth has strongly accelerated for the last decades. In this work, we analysed the trends of the main climatic parameters which caused the glacier recession in the Kamchatka Peninsula. It was shown that the glaciers of the northern part of the Sredinny Range decreased by 125 km2 (35.6%) from 1950 to 2016-2017. The average rate of their reduction in the period from 2002 to 2016-2017 (1.45%/year) increased approximately 4.3 times compared to the period 1950-2002 (0.34%/year). The greatest reduction is observed in small glaciers with an area of less than 0.1 km2 and in glaciers with southeastern and southern expositions. On the Kronotsky Peninsula, the glacier area reduction for 1957-2019 was equal to 32.1 km2 (35.6%), and the rates were almost the same in the periods of 1957-2000 (0.61%/year) and 2000-2019 (0.67%/year). According to the data of weather stations and ERA5 reanalysis, it was shown that, in the ablation (summer) period the warming rate was minimal (0.3 degrees C/10 years) and in the accumulation period a significant decrease in precipitation (5%-10%/10 years) was revealed in some areas. At the same time, a significant increase in the radiation balance was revealed in the warm season along with a tendency in downward shortwave radiation increase for the last two decades due to a decrease in cloud amount. These trends are in good agreement with the growth of the geopotential height over the North Pacific during the warm season in the 21st century, and with the growth of velocity divergence in the middle troposphere and the intensification of downward air movements. All this confirms an increase in anticyclone frequency in the warm season, which could be the cause of a radiation balance increase and, consequently, an increase in glacier ablation. Kamchatka glaciers shrank significantly in recent decades: the glacier area of the northern part of the Middle Range (NpMR) and Kronotsky Peninsula (KP) decreased by 35.6% from the middle of the XX century. The most likely reasons for this strong reduction are the winter precipitation decrease and surface radiation balance increase in the warm season (May-September), partly due to the cloud cover decrease, associated with the anticyclone's frequency increase in the North Pacific region at the beginning of the XXI century.image

A study has been made of changes in some characteristics of daily precipitation in Russia for the winter and summer seasons in the 20th and 21st centuries using Coupled Model Intercomparison Project Phase 6 (CMIP6) climate models. In the modern period, model data are compared with data from meteorological stations and ERA5 reanalysis. For winter and summer, changes in mean seasonal precipitation, the number of days with precipitation, and the frequency of extreme precipitation are analyzed. For the modern period 1991–2020, according to empirical data, in winter on the territory of Russia, a significant increase in seasonal precipitation amounts and the frequency of days with extreme precipitation on the Far East coast and in the central part of European Russia (ER) are detected. A decrease in the frequency of days with precipitation at most meteorological stations in Russia by 4–6 days/10 years is also noted. In summer, an increase in precipitation amounts and the frequency of days with precipitation is found in Western Siberia and on the coasts of the Sea of Okhotsk and the Pacific Ocean. A decrease in the amount and frequency of precipitation is obtained for southern ER and the south of Eastern Siberia. Climate models, on average for the ensemble, show an increase in the relative amounts of precipitation and the extreme precipitation frequency over most of the Russia territory in winter, and these trends may intensify in the coming decades. In summer, on the contrary, for southern ER, as a whole, there is a slight decrease in the seasonal precipitation totals and the number of days with precipitation. However, strong intermodel differences, especially in the summer season, do not allow us to draw unambiguous conclusions about changes in precipitation characteristics in Russia in the next 30 years. By the end of the 21st century, changes will become more pronounced. For example, in ER and northern Siberia, a noticeable increase in winter precipitation amounts and the frequency of extreme precipitation may occur. By the end of the 21st century, a slight decrease in the precipitation totals and the number of days with precipitation is possible in summer in ER.

Scenario projections of climate changes in the XXI century in Crimea are presented based on the data of an ensemble of models of the recent generation CMIP6 for aggressive SSP585 and moderate SSP245 scenarios of anthropogenic impact. Variations of season-averaged values of temperature and precipitation for winter and summer, the number of days with extreme anomalies of temperature and precipitation, the rate of precipitation, and the contribution of heavy precipitation to the seasonal total are shown. For the current period, the data of the models are compared with reanalysis data ERA5 and interpolated grid observation data CRUTS4.05. On the average over the model ensemble, the summer temperature is expected to increase by ~6 and 2.5°C by the late XXI century according to scenarios SSP585 and SSP245, respectively. The number of days in summer with extremely high temperature (95% percentile of the distribution function for 1981–2010) will increase 5–6 times as soon as the mid-XXI century and will reach ~40 days by the end of the century, even for a moderate scenario. Strong year-to-year variations are typical of seasonal precipitation, at which statistically insignificant increase in winter can be seen in the models, while the summer precipitation is expected to decrease considerably by ~15 and 40% for scenarios SSP585 and SSP245, respectively. At the same time, no statistically significant decrease is expected in the intensity and extremeness of precipitation. In winter, the proportion of extreme precipitation in its total will increase considerably (from 25 to 35%). It should be noted that the changes forecasted for the nearest two decades are practically independent of the analyzed scenarios of anthropogenic impact. The decrease in precipitation at an increase in the temperature demonstrates the important role of atmospheric dynamics in the future changes in the characteristics of precipitation in the region under study.

Precipitation extremes are widely thought to intensify with global warming due to an exponential growth following the Clausius–Clapeyron (C–C) equation which links the atmosphere water vapor saturation pressure with air temperature. However, a number of recent studies based on station and reanalyzes data for the contemporary period showed that scaling rates between extreme precipitation and temperature strongly depend on temperature range, moisture availability, and a region of interest. Being performed for some regions, such estimates, however, lack for Northern Eurasia, where prominent temperature changes and rapid shift from large-scale to convective precipitation are observed. Here, we examine the scaling between daily precipitation extremes and surface air temperature (SAT) over Russia for 1966–2017 using meteorological station data and for 1979–2020 using ERA5 reanalysis. The precipitation-temperature relation is examined for total precipitation and, separately, for convective and large-scale precipitation types. In winter, we reveal a general increase in extreme precipitation of all precipitation types according to the C–C relationship. For the Russian Far East region, the stratiform precipitation extremes scale with SAT following even super C–C rates, about two times as fast as C–C. However, in summer we find a peak-like structure of the precipitation-temperature scaling, especially for the convective precipitation in the southern regions. Extreme precipitation reaches their peak values at the temperature range between 15 °C and 20 °C. At higher temperatures, the negative scaling prevails. Analyzed data show a pronounced decrease in relative humidity with increasing surface temperatures beyond the 15 °C–20 °C threshold. This indicates that moisture availability is the major factor for the peak-shaped relationship between extreme precipitation and temperature revealed by our analysis.

The relationship between the daily precipitation intensity and daily temperature conditions were studied for the 1961- 2017 period using meteorological stations data and ERA-Interim reanalysis. Most of the datasets show a statistically significant relationship between the intensity of extreme precipitation and temperature. In winter and autumn, the extreme precipitation intensity tends to be higher at warmer daily mean temperatures. For the warmer seasons (spring and summer) the most typical type of scaling is non-monotonous, where the increase of extreme precipitation stops at very high temperatures. For example, typical temperature threshold values for summer are 15-20°C. A strong precipitation decrease was observed only in the summer period at the southern part of European Russia.

The analysis of satellite images revealed by25% decrease of the Altai mountains’ glaciation area over last 50 years.In 2008–2017, deglaciation rate increased twice. This tendency is ingood agreement with an observed increase in the Katun River flow by 9%in 2008–2017 as compared to 1940–1968 (under invariable totalprecipitation). The analysis of trends of main meteorological parametersbased on weather station data and the ERA-Interim reanalysisdemonstrated that statistically significant warming in the region occursonly during the warm season and does not exceed 0.5°С/10 years. For thisreason, “atmosphere–glaciers” turbulent heat transfer has increased by 4W/m2 in last two years, that caused an annual melting layerincrease by 100 mm water equivalent (w.e.). However, the main reason forthe Altai mountains’ deglaciation is an increase of downward solarradiation flux, which amounted to 5 W/m2 per decade andincreased the melting layer by 365 mm w.e. per year. A positive trend innet radiation agrees well with a decrease in cloud amount, which isassociated with an increase in the moisture divergence flux andgeopotential height and with the weakening of zonal winds in the middletroposphere.

Variations of the frequency of extreme daily precipitation events in winter and summer in the Russian Federation were studied for the 1961-2013 period using meteorological stations data. Future changes were estimated using data of the global climate models from CMIP5 model ensemble. In winter, there is a slight increase in the extreme precipitation frequency throughout Russia except for the Far East. By the end of the twenty-first century, models predict an overall strengthening of this trend. In summer, current changes are less significant and characterized by strong spatial heterogeneity. According to the CMIP5 models, the frequency of extreme precipitation will decrease in western and southern parts of Russia by the end of the 21st century and will increase in the northern and eastern regions.

ИССЛЕДОВАНИЕ РОЛИ ГЛОБАЛЬНЫХ И РЕГИОНАЛЬНЫХ ФАКТОРОВ В ИЗМЕНЕНИИ ЭКСТРЕМАЛЬНОСТИ ЛЕТНИХ ОСАДКОВ НА ЧЕРНОМОРСКОМ ПОБЕРЕЖЬЕ

This study presents a dataset on long-term multidisciplinary glaciological, hydrological, and meteorological observations and isotope sampling in a sparsely monitored alpine zone of the North Caucasus in the Djankuat research basin. The Djankuat glacier, which is the largest in the basin, was chosen as representative of the central North Caucasus during the International Hydrological Decade and is one of 30 “reference” glaciers in the world that have annual mass balance series longer than 50 years (Zemp et al., 2009). The dataset features a comprehensive set of observations from 2007 to 2017 and contains yearly measurements of snow depth and density; measurements of dynamics of snow and ice melting; measurements of water runoff, conductivity, turbidity, temperature, δ18O, δD at the main gauging station (844 samples in total) with an hourly or sub-daily time step depending on the parameter; data on δ18O and δ2H sampling of liquid precipitation, snow, ice, firn, and groundwater in different parts of the watershed taken regularly during melting season (485 samples in total); measurements of precipitation amount, air temperature, relative humidity, shortwave incoming and reflected radiation, longwave downward and upward radiation, atmospheric pressure, and wind speed and direction – measured at several automatic weather stations within the basin with 15 min to 1 h time steps; gradient meteorological measurements to estimate turbulent fluxes of heat and moisture, measuring three components of wind speed at a frequency of 10 Hz to estimate the impulse of turbulent fluxes of sensible and latent heat over the glacier surface by the eddy covariance method. Data were collected during the ablation period (June–September). The observations were halted in winter. The dataset is available from PANGAEA (https://doi.org/10.1594/PANGAEA.894807, Rets et al., 2018a) and will be further updated. The dataset can be useful for developing and verifying hydrological, glaciological, and meteorological models for alpine areas, to study the impact of climate change on hydrology of mountain regions using isotopic and hydrochemical approaches in hydrology. As the dataset includes the measurements of hydrometeorological and glaciological variables during the catastrophic proglacial lake outburst in the neighboring Bashkara valley in September 2017, it is a valuable contribution to study lake outbursts.

Over the past 30 years, there has been a catastrophic reduction of the glacierized area in the mountains of the Greater Caucasus, with the values reaching 0.69% per year. Physical mechanisms accountable for such intense melting are investigated in this study. The main trends in the temperature-moisture regime of the Caucasus and adjacent areas for the period 1982-2015 were recovered based on instrumental data and the ERA-Interim data reanalysis. It is demonstrated that there is statistically significant warming for the summer season in the region as a whole. No statistically significant changes were detected in the precipitation regime, despite the increase in the integral moisture content of the atmosphere and in the potential convective energy. The integral moisture content growth is compensated by the increase in the moisture divergence. This happens due to the intensification of large-scale descending atmospheric motions. As a result, the seasonal and annual precipitation amounts do not change significantly. Such effects are possibly the consequence of the global process of "widening of the tropics." This process is most clearly manifested in the expansion of the Hadley cell and the northward shift of its descending branch. This process can lead to an increased frequency of anticyclones over the southern regions of Europe during the warm part of the year. This, in turn, leads to a negative cloud cover trend as well as an increase in the closely related radiation balance. Apparently, this process is the cause of the intensive reduction of the glaciation area in the North Caucasus.

Based on ERA-Interim reanalysis data and observations, the main trends in the temperature-humidity regime of the Black Sea-Caspian-Sea region (BCR) for the period of 1982–2014 were revealed. The statistically significant summer warming is associated with increasing surface sea temperature (SST) and radiation balance. Despite the growth of the total moisture content in the atmosphere and the potential convective energy no statistically significant changes in precipitation mode were revealed. The growth of total moisture content is compensated by increasing divergence of moisture due to the intensification of large-scale downward movements in the troposphere. As a result the seasonal and annual precipitation amounts show just minor changes. Perhaps this effect is a consequence of increasing frequency of summer anticyclones over the BCR. This process triggers the increase of the radiation balance due to lesser cloudiness, which leads to the increase in SST and surface air temperature.

Variations of the frequency and intensity of extreme daily precipitation in summer in the southeast of the Far East Federal District of the Russian Federation, - in region with high risks of extreme seasonal floods, were studied for the period 1970-2015 using data of 54 meteorological stations. Future changes for the period 2041-2060 were estimated using data of the global climate models HadGEM and MPI-ESM. It is shown that the observed and projected changes in frequency extreme daily precipitation events in summer are diverse and statistically insignificant when averaged for the whole study area. However, a growth of extreme daily precipitation intensity in the north of the study area and in the south of Sakhalin island is found in observations for the recent period 2000-2015 being relative to 1970-1999. Such a tendency is projected by the middle of the 21st century according to the HadGEM and MPI-ESM models.

Резюме.Анализируются данные о температурном режиме у поверхности Земного шара в 2017 году и его изменчивости за 1901-2017 гг.Рассматриваются аномалии приповерхностной температуры и ее тренды на различных временных и пространственных масштабах -от глобального до локального, на континентах и акваториях океанов.Показано, что в целом по Земному шару и в Северном полушарии 2017 г. вошел в тройку самых теплых лет в истории наблюдений (вместе с лидирующими 2016 и 2015 гг.).В Южном полушарии 2017 г. оказался первым (самым теплым) по температуре приземного воздуха над сушей, но по температуре