The assessment of the recent mass balance anomaly of Adishi glacier in the Central Caucasus by satellite altimetry

Abstract

Glacier mass balance is a key indicator of climate change, with most glaciers worldwide exhibiting negative trends due to rising temperatures. However, Adishi Glacier in the Central Caucasus presents an anomaly published by earlier studies. This research uses Ice, Clouds and Land Elevation Satellite-2 altimetry data (2018-2024) and the Shuttle Radar Topography Mission Digital Elevation Model to assess recent elevation changes and mass balance variations. ERA5 reanalysis data were used to examine potential climatic drivers. Results show persistent thinning in lower glacier regions, while the accumulation area demonstrates sustained elevation gains. The equilibrium line altitude shows a slight upward trend (+3.07 m/year), consistent with global patterns. Notably, Adishi Glacier exhibited a positive mass balance of 0.05 +/- 0.17 m w.e. a(-1) in 2021 and 0.03 +/- 0.06 m w.e. a(-1) in 2024, but the mean for 2018-2024 remains negative at -0.31 +/- 0.09 m w.e. a(-1). This suggests that, despite short-term gains, the anomaly is not sustained. Compared to the neighbouring glaciers-Bezengi, Khalde, Tsaneri North and South - which show continuous negative mass balances, Adishi's stability stands out. Regional warming (+0.19 degrees C/year) based on ERA5 reanalysis contributes to ablation zone losses, but glacier hypsometry, with an extensive accumulation area above 4,000 m a.s.l., and orographic effect of snowfall on windward slopes support temporary gains. These favourable conditions, however, are insufficient to maintain a long-term positive mass balance under ongoing climate change.