Garabashi glacier (Caucasus) mass changes estimated from glaciological and geodetic mass balance measurements

The ice-covered Europe's largest volcanic massif Elbrus (5,642 m) is a unique object for studying the reaction of mountain glaciers to climate changes. Elbrus glacial system contains more than 10% of the total ice volume in the Greater Caucasus. Elbrus glaciers influence on the recreation development. The rivers runoff from the Elbrus glaciers irrigates agricultural lands on steppe plains of the North Caucasus.

The rate of glacier reduction in the late XX - early XXI centuries has increased significantly and in 1997-2017 Elbrus have lost 23% of its volume. Despite a number of glacier studies the mechanisms and quantitative characteristics surface mass exchange on Elbrus are still uncertain. Mass balance calculations were based on limited data. In particular, amount and distribution of snow accumulation, mass balance sensitivity to meteorological parameters under dramatic climate changes and other parameters remained unknown.

Here we present the results of the detailed analysis of Garabashi glacier mass changes in 1982-2019 using glaciological and geodetic methods. Based on the new data of snow and ablation distribution the mass balance measurement system of Garabashi glacier was improved in 2018-2019. The mass balance over the studied period was also modelled using both temperature-index and distributed energy mass balance models calibrated by in situ measurements and albedo estimates from the remote sensing.

The mass balance of the Garabashi glacier was close to zero or slightly positive in 1982-1997 and the cumulative mass balance was 1 m w.e. in this period. In 1997-2017 Garabashi glacier lost 12.58 m w.e. and 12.92 ± 0.95 m w.e. (−0.63 and −0.65 ± 0.05 m w.e. a−1) estimated by glaciological and geodetic method, respectively. Additional -1.7 m w.e. were lost in 2018-2019. This resulted in an area reduction by 14% and a loss of 27% of glacier volume. The observed glacier recession is driven by the pronounced increase in summer temperatures, especially since 1995, which is accompanied by nearly consistent precipitation rates The increase in incoming shortwave radiation, also played a significant role in the accelerated mass loss of glaciers in Caucasus. This study was supported by the RFBR grant 18-05-00838 a