Strong acceleration of glacier area loss in the Greater Caucasus between 2000 and 2020

An updated glacier inventory is important for understanding glacier behaviour given the accelerating glacier retreat observed around the world. Here, we present data from a new glacier inventory for two points in time (2000, 2020) covering the entire Greater Caucasus (Georgia, Russia, and Azerbaijan). Satellite imagery (Landsat, Sentinel, SPOT) was used to conduct a remote-sensing survey of glacier change. The 30m resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM; 17 November 2011) was used to determine aspect, slope, and elevations, for all glaciers. Glacier margins were mapped manually and reveal that in 2000 the mountain range contained 2186 glaciers with a total glacier area of 1381.5 +/- 58.2 km(2). By 2020, the area had decreased to 1060.9 +/- 33.6 km(2) a reduction of 23.2 +/- 3.8% (320.6 +/- 45.9 km(2)) or 1.16% yr 1 over the last 20 years in the Greater Caucasus. Of the 2223 glaciers, 14 have an area > 10 km(2), resulting in the 221.9 km(2) or 20.9% of total glacier area in 2020. The Bezengi Glacier with an area of 39.4 +/- 0.9 km(2) was the largest glacier mapped in the 2020 database. Glaciers between 1.0 and 5.0 km(2) accounted for 478.1 km(2) or 34.6% in total area in 2000, while they accounted for 354.0 km(2) or 33.4% in total area in 2020. The rates of area shrinkage and mean elevation vary between the northern and southern and between the western, central, and eastern Greater Caucasus. Area shrinkage is significantly stronger in the eastern Greater Caucasus (1.82% yr(-1)), where most glaciers are very small. The observed increased summer temperatures and decreased winter precipitation along with increased Saharan dust deposition might be responsible for the predominantly negative mass balances of Djankuat and Garabashi glaciers with long-term measurements. Both glacier inventories are available from the Global Land Ice Measurements from Space (GLIMS) database and can be used for future studies.

Automated summary

An updated glacier inventory reveals a significant reduction in glacier area in the Greater Caucasus region over the past 20 years. The study compares glacier data from 2000 to 2020 and finds a 23.2% decrease in total glacier area. The research also highlights variations in glacier shrinkage and mean elevation across different regions.