Glacier Recession in the Altai Mountains after the LIA Maximum

Abstract

The study aims to reconstruct the Altai glaciers at the maximum of the LIA, to estimate the reduction of the Altai glaciers from the LIA maximum to the present, and to analyze glacier reduction rates on the example of the Tavan Bogd mountain range. Research was based on remote sensing and field data. The recent glaciation in the southern part of the Altai is estimated (1256 glaciers with the total area of 559.15 ± 31.13 km2), the area of the glaciers of the whole Altai mountains is estimated at 1096.55 km2. In the southern part of Altai, 2276 glaciers with a total area of 1348.43 ± 56.16 km2 were reconstructed, and the first estimate of the LIA glacial area for the entire Altai mountain system was given (2288.04 km2). Since the LIA, the glaciers decrease by 59% in the southern part of Altai and by 47.9% for the whole Altai. The average increase in ELA in the southern part of Altai was 106 m. The larger increase of ELA in the relatively humid areas was probably caused by a decrease in precipitation. Glaciers in the Tavan Bogd glacial center degraded with higher rates after 1968 relative to the interval between 1850–1968. One of the intervals of fast glacier shrinkage in 2000–2010 was caused by a dry and warm interval between 1989 and 2004. However, the fast decrease in glaciers in 2000–2010 was mainly caused by the shrinkage or disappearance of the smaller glaciers, and large valley glaciers started a fast retreat after 2010. The study results present the first evaluation of the glacier recession of the entire Altai after the LIA maximum.

Timing and extent of glaciation since the Last Glacial Maximum in the upper Kalguty basin, Russian Altai Mountains

“…Mean monthly temperature at Akkem station (2056 m asl) was −18°C in January and +11°C in July for the period 1952–2004; mean summer (JJA) temperature increased by 0.1°C a −1 from 1985 to 2004 (Shahgedanova et al, 2010) and from 12 to 14.5°C over the period 1985–2015 at Kosh‐Agach (1759 m asl, Figure 1; Ganyushkin et al, 2022). Too far north to be affected by the summer East Asian monsoon, the Russian Altai Mountains are today exposed to the westerlies (Benn & Owen, 1998).…”

“…B). Altai Mountains glaciers covered 2288 km 2 during the Little Ice Age (Ganyushkin et al, 2022), and 1096 ± 53 km 2 in 2020 (Chang et al, 2022;Ganyushkin et al, 2022), representing presently c. 50% of the glacierized area of North Asia (RGI Region 10; Earl & Gardner, 2016). In the Russian Altai Mountains, glaciers are mainly located at present in the Katun (185 km 2 ), North (129 km 2 ) and South Chuya (135 km 2 ) Ranges, mainly on their north side, and on the Tavan Bogd north side (23.5 km 2 ), totalling 483.5 km 2 (RGI Consortium, 2017; Figure 1).…”

“…Mean ELA (equilibrium-line altitude) was 3184 m over the 1962-2012 period at Maliy Aktru Glacier (North Chuya Range; WGMS, 2021), and c. 3500 m over the 1980-2018 period at Potanin Glacier (Tavan Bogd east side, Mongolia; Khalzan et al, 2022). Modelled recent ELA for the Altai Mountains shows a NW-SE gradient, from 2600 m in the north-west to 2900-3000 m in the Katun Range (Lehmkuhl et al, 2004;Lehmkuhl, 2008), 3300-3350 m in the South Chuya Range (Lehmkuhl et al, 2011), and 3358 m in the Tavan Bogd Massif (Ganyushkin et al, 2022).…”

“…For instance, a mean ELA of 3390 m asl (3335 m asl) on the north side of Tavan Bogd Massif in 2010 (2015) resulted from 16 observed glacier ELAs ranging from 3110 to 3695 m (Ganyushkin et al, 2017;2018b). Lehmkuhl et al (2011) proposed a mean ELA of 3400 m too but for the entire Tavan Bogd Massif, for which Ganyushkin et al (2018bGanyushkin et al ( , 2022 calculated a mean ELA of 3285 and 3358 m in 2010 and 2006-2020, respectively.…”

“…B). Altai Mountains glaciers covered 2288 km 2 during the Little Ice Age (Ganyushkin et al, 2022), and 1096 ± 53 km 2 in 2020 (Chang et al, 2022; Ganyushkin et al, 2022), representing presently c . 50% of the glacierized area of North Asia (RGI Region 10; Earl & Gardner, 2016).…”