V. Popovnin

Recent glacier retreat in the Caucasus Mountains, Russia, and associated increase in supraglacial debris cover and supra-/proglacial lake development

Abstract This paper reports changes in supraglacial debris cover and supra-/proglacial lake development associated with recent glacier retreat (1985–2000) in the central Caucasus Mountains, Russia. Satellite imagery (Landsat TM and ETM+) was used to map the surface area and supraglacial debris cover on six neighbouring glaciers in the Adylsu valley through a process of manual digitizing on a false-colour composite of bands 5, 4, 3 (red, green, blue). The distribution and surface area of supraglacial and proglacial lakes was digitized for a larger area, which extended to the whole Landsat scene. We also compare our satellite interpretations to field observations in the Adylsu valley. Supraglacial debris cover ranges from <5% to >25% on individual glaciers, but glacier retreat between 1985 and 2000 resulted in a 3–6% increase in the proportion of each glacier covered by debris. The only exception to this trend was a very small glacier where debris cover did not change significantly and remote mapping proved more difficult. The increase in debris cover is characterized by a progressive up-glacier migration, which we suggest is being driven by focused ablation (and therefore glacier thinning) at the up-glacier limit of the debris cover, resulting in the progressive exposure of englacial debris. Glacier retreat has also been accompanied by an increase in the number of proglacial and supraglacial lakes in our study area, from 16 in 1985 to 24 in 2000, representing a 57% increase in their cumulative surface area. These lakes appear to be impounded by relatively recently lateral and terminal moraines and by debris deposits on the surface of the glacier. The changes in glacier surface characteristics reported here are likely to exert a profound influence on glacier mass balance and their future response to climate change. They may also increase the likelihood of glacier-related hazards (lake outbursts, debris slides), and future monitoring is recommended.

Geodetic mass balance of Azarova glacier, Kodar mountains, eastern Siberia, and its links to observed and projected climatic change

Abstarct The Kodar mountains in eastern Siberia accommodate 30 small, cold-based glaciers with a combined surface area previously estimated at ~19 km2. Very little is known about these glaciers, which were first surveyed in the late 1950s. In this paper, we use terrestrial photogrammetry to calculate changes in the surface area, elevation, volume and geodetic mass balance of Azarova glacier between 1979 and 2007 and relate these to meteorological data from nearby Chara weather station (1938–2007). The glacier surface area declined by 20±6.9% and the surface lowered by an average of 20±1.8m (mean thinning 0.71 ma–1), resulting in a strongly negative cumulative and average mass balance of –18±1.6mw.e. and –640±60mm w.e. a–1, respectively. The July–August air temperature increased at a rate of 0.036˚Ca–1 between 1979 and 2007, and the 1980–2007 period was on average ~1˚C warmer than 1938–79. In comparison to the 1961–90 period, regional climate projections for the A2 and B2 CO2 emission scenarios developed using the PRECIS regional climate model indicate that summer temperatures will increase by 2.6–4.7˚C and 4.9–6.2˚C, respectively, during the 2071–2100 period. The annual total of solid precipitation will increase by 20% under the B2 scenario but is projected to decline by 3% under the A2 scenario. Azarova glacier exhibits high sensitivity to climatic warming due to its low elevation and exposure to comparatively high summer temperatures. Further summer warming and a decline in solid precipitation projected under the A2 scenario will force Azarova glacier to retreat further, but the impact of an increase in solid precipitation projected under the B2 scenario is more uncertain and requires further investigation before a more conclusive prediction can be made.

Long-term change, interannual and intra-seasonal variability in climate and glacier mass balance in the central Greater Caucasus, Russia

Abstract Long-term trends, interannual and intra-seasonal variability in the mass-balance record from Djankuat glacier, central Greater Caucasus, Russia, are related to local climate change, synoptic and large-scale anomalies in atmospheric circulation. A clear warming signal emerged in the central Greater Caucasus in the early 1990s, leading to a strong increase in ablation. In the absence of a compensating change in winter accumulation, the net mass balance of Djankuat has declined. The highest value of seasonal ablation on record was registered in the summer of 2000. At the beginning of the 21st century these trends reversed. Ablation was below average even in the summer of 2003, which was unusually warm in western Europe. Precipitation and winter accumulation were high, allowing for a partial recovery of net mass balance. The interannual variability in the components of mass balance is weakly related to the North Atlantic Oscillation (NAO) and the Scandinavian teleconnection patterns, but there is a clear link with the large-scale circulation anomalies represented by the Rossby pattern. Five synoptic categories have been identified for the ablation season of 2005, revealing a strong separation between components of radiation budget, air temperature and daily melt. Air temperature is the main control over melt. The highest values of daily ablation are related to the strongly positive NAO which forces high net radiation, and to the warm and moist advection from the Black Sea.

Climate Change, Glacier Retreat, and Water Availability in the Caucasus Region

The paper discusses the observed and projected warming in the Caucasus region and its implications for glacier melt, water availability and potential hazards. A strong positive trend in summer air temperatures of 0.05 degrees C year(-1) is observed in the high-altitude areas (above 2000 m) providing for a strong glacier melt. A widespread glacier retreat has also been reported between 1985 and 2000, with an average rate of 8 m year(-1). A warming of 5-7 degrees C is projected for the Sum mer months in the 2071-2100 period under the A2 emission group of scenarios, Suggesting that enhanced glacier melt and a changing water balance can be expected.

Using isotope methods to study alpine headwater regions in the Northern Caucasus and Tien Shan

High mountain areas provide water resources for a large share of the world’s population. The ongoing deglaciation of these areas is resulting in great instability of mountainous headwater regions, which could significantly affect water supply and intensify dangerous hydrological processes.The hydrological processes in mountains are still poorly understood due to the complexity of the natural conditions, great spatial variation and a lack of observation. A knowledge of flow-forming processes in alpine areas is essential to predict future possible trends in hydrological conditions and to calculate river runoff characteristics. The goal of this study is to gain detailed field data on various components of natural hydrological processes in the alpine areas of the North Caucasus and Central Tien Shan, and to investigate the possibility that the isotopic method can reveal important regularities of river flow formation in these regions. The study is based on field observations in representative alpine river basins in the North Caucasus (the Dzhankuat river basin) and the Central Tien Shan (the Chon-Kyzyl-Suu river basin) during 2013–2015. A mixing-model approach was used to conduct river hydrograph separation. Isotope methods were used to estimate the contribution of different nourishment sources in total runoff and its regime. d18О, dD and mineralization were used as indicators. Two equation systems for the study sites were derived: in terms of water routing and runoff genesis. The Dzhankuat and Chon-Kyzyl-Suu river hydrographs were separated into 4 components: liquid precipitation/meltwaters, surface routed/subsurface routed waters.

Djankuat Glacier Station in the North Caucasus, Russia: A Database of complex glaciological, hydrological, meteorological observations and stable isotopes sampling results during 2007-2017

The study presents a dataset on long-term complex glaciological, hydrological, meteorological observations and isotopes sampling in an extremely underreported alpine zone of the North Caucasus. The Djankuat research basin is of 9.1 km2, situated on elevations between 2500 – 4000 m, and covered with glaciers by 30%. The largest in the basin, the Djankuat 20 glacier, was chosen as representative of the central North Caucasus during the International Hydrological Decade and is one of 30 ‘reference’ glaciers in the world which have annual mass balance series longer than 50 years (Zemp et al., 2009). The dataset reported here covers 2007–2017 and contains the result of yearly measurements of snow depth and density; dynamics of snow and ice melting; measurements of water runoff, conductivity, turbidity, temperature, δ18O, δD at the main gauging station (844 samples in sum) with a one-hour or several-hours’ time step depending on the parameter; data on δ18O and δ2H 25 sampling of liquid precipitation, snow, ice, firn, groundwater in different parts of the watershed taken regularly in time during melting season (485 samples in sum); precipitation amount, air temperature, relative humidity, shortwave incoming and reflected radiation, longwave downward and upward radiation, atmospheric pressure, wind speed and direction – measured at several automatic weather stations within the basin with 15 min to one-hour step; gradient meteorological measurements to estimate turbulent fluxes of heat and moisture, measuring three components of wind speed at a frequency of 10 hertz to estimate 30 the impulse of turbulent fluxes of sensible and latent heat over the glacier surface by the eddy covariance method. All the observations were done during the ablation period (June–September) and were interrupted in winter. The dataset was published on knb.ecoinformatics.org long-term repository (doi:10.1594/PANGAEA.894807) and will be further updated. The dataset can be useful for developing and verifying hydrological, glaciological and meteorological models for high elevation territories,

Erratum to: Using isotope methods to study alpine headwater regions in the Northern Caucasus and Tien Shan

The original version of this article unfortunately contained a mistake. The spelling of the Yu.K. VASILCHUK’s name was incorrect. The correct name is given below. Yu.K. VASIL’CHUK