Abstract

An updated glacier inventory is important for understanding glacier behavior given the accelerating glacier retreat observed around the world. Here, we present data from new glacier inventory at two time periods (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 surface area of 1381.5 ± 58.2 km2. By 2020, glacier surface area had decreased to 1060.9 ± 33.6 km2. Of the 2223 glaciers, fourteen have an area > 10 km2 resulting the 221.9 km2 or 20.9 % of total glacier area in 2020. The Bezingi Glacier with an area of 39.4 ± 0.9 km2 was the largest glacier mapped in 2020 database. Our result represents a 23.2 ± 3.8 % (320.6 ± 45.9 km2) or −1.16 % yr−1 reduction in total glacier surface area over the last twenty years in the Greater Caucasus. Glaciers between 1.0 km2 and 5.0 km2 account for 478.1 km2 or 34.6 % in total area in 2000, while it account 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 two 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, Sentinel-2, SPOT 6/7) in combination with digital elevation models (DEMs) along with the observed changes

  • Based on Landsat data from 2000 we have identified and mapped 2186 glaciers larger than 0.01 km2 with a total area of 1381.5±58.2 km2 from 53 river basins in the Greater Caucasus (Table S2)

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Summary

Introduction

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 glacier-specific information. Glaciers are an important source of fresh water in countries of the Caucasus region and runoff in large glacier-fed rivers supplies several hydroelectric power stations They are important reservoirs of water for the population living downstream, often providing meltwater during seasonal droughts

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