Reduction of glaciation in the Suntar-Khayata Mountains from the mid-20th century to 2018

Abstract

New data on the state of the Suntar-Khayata Mountains glaciers in 2018 are presented and changes in the area of glaciers in the second half of the 20th and early 21st centuries are estimated. In 2018, the glaciation of the Suntar-Khayata Mountains was represented by 251 glaciers with a total area of about 133±10 km2. Among the morphological types in this region, the corrie and corrie-hanging glaciers predominate. The largest areas are occupied by valley and compound valley glaciers. The main part (82.7%) of the total area of glaciers is concentrated in the altitude range of 2200–2600 m. The changes in the glaciation area were analyzed over three periods: 1) from 1944–1947 to 2018; 2) from 1944–1947 to 2003; and 3) from 2003 to 2018. During the first one, the area of the glaciers registered in the Glacier Inventory of the USSR decreased from 199 to 132±10 km2, that is, by 67 km2 (33.6%). Of these, 28 km2 was lost in the period from 1944–1947 to 2003, and another 39 km2 in 2003–2018. By 2018, the largest reduction of the area occurred in small glaciers with an area of less than 0.1 km2 (more than 80%), the smallest – in large glaciers with an area exceeding 2 km2 (less than 21%). The glaciers with western aspect were the most reduced (39.9%), and with south–western aspect – the least (25.0%). As compared to the previous period, the significant increase in the rate of the area reduction was found in 2003–2018 – from 0.24% to 1.52% per year. At the beginning of the 21st century, the activation of the process of disintegration of glaciers into smaller fragments was recorded. Thus, the average size of the studied glaciers decreased from 1.03 km2 in 1944–1947 to 0.88 km2 in 2003 and to 0.59 km2 in 2018. The increase in the rate of the area reduction in the Suntar-Khayata Mountains noted in the early 21st century agrees with a stable positive anomaly of summer air temperatures observed from 2007 to 2018. The mean summer air temperature during this period was 12.2 °C, which was by 1 °C higher its average value for 1981– 2010; in 2008 and 2009, the difference reached 2 °C. In combination with the ongoing decrease in winter precipitation, this may be one of the main reasons for the increase in the rate of glacier reduction

Keywords

• mountain glaciers
• area reduction
• morphological types
• altitude distribution
• suntar-khayata