Abstract
Abstract. 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 30 m 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 km2. By 2020, the area had decreased to 1060.9 ± 33.6 km2 a reduction of 23.2 ± 3.8 % (320.6 ± 45.9 km2) or −1.16 % yr−1 over the last 20 years in the Greater Caucasus. Of the 2223 glaciers, 14 have an area > 10 km2, resulting in the 221.9 km2 or 20.9 % of total glacier area in 2020. The Bezengi Glacier with an area of 39.4 ± 0.9 km2 was the largest glacier mapped in the 2020 database. Glaciers between 1.0 and 5.0 km2 accounted for 478.1 km2 or 34.6 % in total area in 2000, while they accounted for 354.0 km2 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.
Highlights
Glaciers are retreating and losing mass in most regions of the world, largely in response to the ongoing atmospheric warming (Hock et al, 2019; Zemp et al, 2019; Hugonnet et al, 2021)
In this study we present two new glacier inventories for the Greater Caucasus region derived from multi-temporal optical satellite images (Landsat, Sentinel2, SPOT 6/7) in combination with digital elevation models (DEMs) along with the observed changes
931.6 ± 37.7 km2 or 67.4 % of the total glacier area was found in Russia, 446.6 ± 19.9 km2 or 32.3 % in Georgia, and 3.4 ± 0.3 km2 or 0.3 % in Azerbaijan (Table 1)
Summary
Glaciers are retreating and losing mass in most regions of the world, largely in response to the ongoing atmospheric warming (Hock et al, 2019; Zemp et al, 2019; Hugonnet et al, 2021). This knowledge can only be obtained when a baseline dataset (a glacier inventory) is available to calculate glacierspecific information. Complete and accurate glacier inventories provide the information required for various hydrological and climate modelling applications (Vaughan et al, 2013) as well as change assessment. Tielidze et al.: The new Caucasus glacier inventory gies in response to the impact of climate changes on future glacier development (Pfeffer et al, 2014; Huss et al, 2017)
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