Large‐scale climatic factors driving glacier recession in the Greater Caucasus, 20th–21st century

Abstract

Over the past 30 years, there has been a catastrophic reduction of the glacierized area in the mountains of the Greater Caucasus, with the values reaching 0.69% per year. Physical mechanisms accountable for such intense melting are investigated in this study. The main trends in the temperature‐moisture regime of the Caucasus and adjacent areas for the period 1982–2015 were recovered based on instrumental data and the ERA‐Interim data reanalysis. It is demonstrated that there is statistically significant warming for the summer season in the region as a whole. No statistically significant changes were detected in the precipitation regime, despite the increase in the integral moisture content of the atmosphere and in the potential convective energy. The integral moisture content growth is compensated by the increase in the moisture divergence. This happens due to the intensification of large‐scale descending atmospheric motions. As a result, the seasonal and annual precipitation amounts do not change significantly. Such effects are possibly the consequence of the global process of “widening of the tropics.” This process is most clearly manifested in the expansion of the Hadley cell and the northward shift of its descending branch. This process can lead to an increased frequency of anticyclones over the southern regions of Europe during the warm part of the year. This, in turn, leads to a negative cloud cover trend as well as an increase in the closely related radiation balance. Apparently, this process is the cause of the intensive reduction of the glaciation area in the North Caucasus.

Volume Changes of Elbrus Glaciers From 1997 to 2017

“…The intensified Elbrus glacier recession reflects the pronounced increase in summer temperatures, especially since 1995, which is accompanied by nearly consistent precipitation rates Rototaeva et al, 2019;Tashilova et al, 2019. The average summer temperature in the high-altitude regions of the Caucasus over the past 30 years has increased by 0.5-0.7 • C (Toropov et al, 2019). It is possible that the increase in incoming shortwave radiation, noted since the 1980s, also played a significant role in the accelerated mass loss of glaciers in recent years (Toropov et al, 2016).…”

“…It is possible that the increase in incoming shortwave radiation, noted since the 1980s, also played a significant role in the accelerated mass loss of glaciers in recent years (Toropov et al, 2016). The increasing trend of 10 W m −2 per decade in the shortwave radiation balance in the high-altitude regions of the Caucasus is related to the negative trend of general and lower cloud cover, which in turn is caused by increasing frequency of anticyclones during the warm season (Toropov et al, 2019).…”

The Holocene paleoenvironmental history of Western Caucasus (Russia) reconstructed by multi-proxy analysis of the continuous sediment sequence from Lake Khuko

“…The Holocene paleoenvironmental history of Western Caucasus (Russia) reconstructed by multi-proxy analysis of the continuous sediment sequence from Lake Khuko and high biodiversity, which places it in one of Earth's 25 biodiversity hotspots (Myers, 2000). The region experienced a dramatic decline in glacier cover over the last decades (Shahgedanova et al, 2014;Solomina et al, 2015Solomina et al, , 2016aSolomina et al, , 2016bTielidze et al, 2020;Toropov et al, 2019). The high-altitude zone of the Caucasus is largely free of direct human impact and therefore it is well suited to study present and past natural environmental changes.…”

Modeling of Extreme Hydrological Events in the Baksan River Basin, the Central Caucasus, Russia

“…An increasing rate of glacier downwasting is reported for most mountain areas [2,3]. The same situation is observed in the Central Caucasus, Russia [4][5][6][7]. There is also high confidence that the number and area of glacier lakes will continue to increase in most regions in the coming decades, and new lakes will develop closer to steep and potentially unstable mountain walls where lake outbursts can be more easily triggered by the impact of landslides [8][9][10][11][12][13].…”