Caucasus glacier melt area expansion – From a Glaciers Perspective

Ladevali (L), Tsaigmili (T), Baki (B), and Cherinda Glacier (C) in Sentinel false color image from August 30, 2022. Illustrating that each has 10% or less of the glacier surface retaining snowcover.

Several glaciers at the headwaters of the Doira River in the Zemo Svaneti Planned National Park in the Georgian Caucasus have been stripped of snowpack during recent summers. A glacier without a zone a persistent snowcover throughout the year has no accumulation zone and cannot survive (Pelto, 2010). Here we examine Ladevali, Tsaigmili, Baki and Cherinda Glaciers during August of 2016, 2018, 2020 and 2022 using Sentinel imagery. Tielidze and Wheate (2018) completed an inventory of Caucasus glaciers documenting the 1986 glacier surface area at 1482 square kilometers decreasing to 1193 square kilometers by 2014, a 20% decline in this 28 year period. Tielidze et al ( 2022) update this inventory identifying a 23% decline in area from 2000 to 2020, greater than 1% per year.

In 1998 ther Ladvali and Tsaigmili Glacier nearly join at the terminus. Baki Glacier spans the entire upper basin and no lake is evident near Point B. Cherinda Glacier descends a bedrock step to form a lower section. In mid-August of 2018 Baki Glacier has lost nearly all snowcover and a new lake has formed adjancent to Point B. Cherlinda Glacier has a fringe 15% along its upper margin and is no longer connected to lower relict ice below the bedrock step. Ladevali and Tsaigmili Glacier have snow cover above 3200 m covering 15-20% of the glacier and the termini are now separated by ~1 km. At the end of August in 2020 Baki Glacier is snow free. Cherinda has a fringe on its upper maring covering less than 10% of the glacier. Ladevali and Tsaigmili Glacier have snow cover above 3300 m covering ~5% of the glacier. At the end of August 2022 Baki Glacier is again snow free, while Cherinda has a fringe on its upper margin covering 10% of the Glacier. Ladevali and Tsaigmili Glacier have snow cover above 3250 m covering ~10% of the glacier. In 2022 the glaciers also exhibit a lack of retained firn from any recent year, illustrating a consistent lack of retained accumulation. This consistent minimal retained snowcover illustrates that the glaciers cannot survive current climate. A similar situation has been observed further east at Gora Gvandra. The mass balance in the region has continued to decline with a mean annual loss of ~-0.5 m/year from 2000-2019, (Tielidze et al 2022) with 2020-2022 likely even worse

Ladevali (L), Tsaigmili (T), Baki (B), and Cherinda Glacier (C) in Sentinel true color image from August 30, 2020. Illustrating that each has 10% or less of the glacier surface retaining snowcover.

Ladevali (L), Tsaigmili (T), Baki (B), and Cherinda Glacier (C) in Sentinel false color image from August 16, 2018. Illustrating that each has 20% or less of the glacier surface retaining snowcover with several weeks left in the melt season.

Ladevali (L), Tsaigmili (T), Baki (B), and Cherinda Glacier (C) in Landsat image from mid-August 1998. Ladvali and Tsaigmili nearly join in 1998. Baki Glacier expands across the entire basin and Cherlinda descends below a bedrock step.

Dzhikiugankez Glacier in 1985 and 2020 Landsat images with the snowline shown by purple dots. A tributary at Point A has disappeared and tributary at the red arrow has separated. Thinning and marginal retreat is emphasized by blue and green arrows.

Dzhikiugankez Glacier (Frozen Lake) is a large glacier on the northeast side of Mount Elbrus, Caucasus Range. The primary portion of the glacier indicated in the map of the region does not extend to the upper mountain, the adjoining glacier extending to the submit is the Kynchyr Syrt Glacier. The glacier is 5 km long extending from ~4000 m to 3200 m. Shahgedanova et al (2014) examined changes of Elbrus glaciers from 1999-2012 and found a 5% area loss in this short period, with accelerattion retreat from the 1987-2000 period. Of the glaciers on Elbrus over 10 km² in area Dzhikiugankez Glacier experienced a high rate of reduction, the relative loss was 27% between 1960 and 2014 (Tielidze and Wheate, 2018). This is driven by a persistent lack of retained snowcover, here we examine Landsat imagery to illustrate that. This post is inspired by the frequent imagery of Caucasus glacier change posted on Twitter by @LevanTielidze.

In 1985 the glacier connects beneath the subsidiary rock peak at the red arrow, a tongue of ice extends on the east side of the rock rib at the yellow arrow, Point A. The transient snow line is at 3550 m and less than 30% of the glacier is snowcovered. The medial moraine at the blue arrow is just beyond the glacier terminus, green arrow. In 2013 a wide zone of bare rock extends up to the subsidiary peak at the red arrow and the glacier has separated from the western tributary. The medial moraine, blue arrow is exposed all the way to its origin near the red arrow. In 2013 the tongue of ice at Point A, is gone. This glacier is retreating faster on its lateral margins than at the terminus, a 20% reduction between red and yellow arrows from 1985 to 2013. In 2013 the snowline is at 3600 m, with several weeks of the melt season left.

In 2018 the transient snowline near the end of the melt season is at 3900 m, leaving less than 10% of the glacier snowcovered. In 2019 the transient snowline is at 3800 m near the end of the melt season leaving 10-15% of the glacier snowcovered. In mid-July 2020 the transient snowline is already at 3600 m with at least 6 weeks left in the melt season. It is evident from the Landsat images from the 2013 to 2020 period that Dzhikiugankez Glacier consistently has the lowest percent of overall snowcover on Elbrus and too small of an accumulation zone to persist. The limited snowcover and glacier separation in also seen at Azaubashi Glacier on Mount Elbrus