Projections of Elbrus glaciers, proglacial lakes and dead ice areas.

Mt Elbrus being the highest peak in Europe (5642 m a.s.l.) is an inactive volcano currently covered by nearly thirty glaciers. Glaciated area is 112.20 ± 0.58 km³ and 5.03 ± 0.85 km³ in volume as revealed by Kutuzov et al., (2019) for the year of 2017. Current and future deglaciation of the Caucasus in general and of the Elbrus glacial massif in particular can be the reason for various negative consequences for the local economy and environment. Therefore, relevant prognostic studies are of great value both for the academicians and for the policymakers. In this research, we consider probable scenarios of Elbrus glacier change in the 21st century. We mostly focus at the phenomena accompanying degradation of glaciation, such as the formation of glacial lakes and areas of “dead” ice buried under the moraine, which is relevant for predicting Glacial Lake Outburst Floods (GLOFs). Future climate projections, based on SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5 scenarios, were employed. Surface mass balance is calculated using temperature-index method (Huss and Hock, 2015). Glacier dynamics is emulated in 1-D global glacier model GloGEMflow (Zekollari et al., 2019) updated by incorporation of the module responsible for the description of debris cover evolution (Postnikova et al., 2023). Model adaptation for Elbrus involves the model transition from colluvial (e.g. slope erosion) to exarational (e.g. emergence of subglacial sediments) debris-cover sources, which aligns with the region's geological setting. These two modes of modelling the debris cover transformation in time are compared. While model validation reveals a slight underestimation of mass loss in the early 21st century, it accurately reproduces general mass loss patterns. Under the warmest climate change scenarios, almost all of the remaining ice mass in the Central Caucasus will be concentrated on Elbrus. At the same time, Elbrus glaciers are anticipated to retreat above the 4000 m elevation by 2100. In case of moderate warming the position of glacier fronts may stabilize at an altitude of 3600-3700 m. According to our estimates, glacier retreat may lead to the formation of up to 17 new proglacial lakes. Under a moderate warming scenario (SSP1-2.6), up to 8 proglacial lakes may appear. The largest of them is expected to form at the terminus of the Djikaughenkioz ice plateau dammed by debris-covered dead ice in the 2030s-2040s assuming no sufficiently effective runoff channels are established. This study was funded by the RSF grant number 23-27-00050.