THE REACTION OF FISHT GLACIER (WESTERN CAUCASUS) TO CURRENT CLIMATE CHANGE

Abstract

We have generalized observation data on Fisht Glacier – the most western glacier in the Caucasus located at elevation 2450–2750 m asl. Considering location of Fisht Glacier we might сonsider it one of the most sensitive to climate change glaciers in the Caucasus. We used the following materials: sketch map (1909), aerial photos (1954), topographic map (1957), detailed map (1:5000, 1982), LIDAR survey data (2010) and finally UAV data (2015). We have noted considerable shrinkage of glacier area from 0.9±0.1 to 0.5±0.01 km2 in 1909–2015, retreat of glacier termini was assessed as 200±20 m (eastern snout) and 350±20 m (western snout). We consider that during 1982–2010 the glacier was close to equilibrium, but during 2010–2015 the glacier surface elevation lowering up to 15–20 m was accompanied by an abrupt decrease of glacier area at about 15 %. Rapid glacier downwashing in 2010–2015 could be explained by a significant decrease of October-May (accumulation season) precipitation and snow thickness accompanied by an increase of June-September (ablation season) air temperature in comparison to 1982–2010. During 2010– 2015 mean ablation was about 800 mm w.e. more than during 1982–2010. Basing on geodetical data on glacier change in 1982–2010 and ablation values assessed using DDF (4600 mm w.e.) we have roughly estimated mean accumulation at Fisht Glacier as 4500 mm w.e. In 2010–2015 mean accumulation was at least 600 mm w.e. lower than in 1982–2010. As a result in 2010–2015 Fisht Glacier lost at least 1500 mm w.e. more than in 1982–2010.Basing on obtained results we could adjust regional pattern of the glacier response to climate change in the Caucasus. Rarely applied in Russia both LIDAR and UAV techniques are recognized as precise tools for mapping glacier surface in high mountains.

Keywords

• climate changes
• glacier dynamics
• LIDAR
• UAV
• Western Caucasus