Current Glaciation of Inner-Continental Mountain Areas within Mongolian Altai and the Baikal Rift Zone

Abstract

Global climatic changes in recent decades cause changes in the dynamics of mountain geosystems. Of interest is the response of nival-glacial inland geosystems, which is different from those in the pre-Oceanic regions. In 2013, the authors substantiated the expediency of separating the nival-glacial mountain range geosystems within the Baikal Rift Zone and Mongolian Altai into a meridional research transect, within which it is possible to establish latitudinal patterns of modern intracontinental glacier functioning. Over the past decade of ongoing studies of glacial forms within the transect, many new data have been collected and analyzed. The present article based on systematic generalizations of these materials.

The analysis of the state of mountain glaciation in the south of Eastern Siberia and Mongolia in the last decades has revealed a number of peculiarities. The deglaciation that began in the 1970s–1980s continues in all the mountain systems under consideration. It is a reaction to global climatic changes. The greatest reduction is experienced by the near-slope glaciers and flattop glaciers and to a lesser extent by the cirque ice glaciers. They have a significant volume loss due to thinning, while changes in the area of such glaciers are less significant. This is the main difference between the intracontinental glaciers and the preoceanic glaciers. In general, many nival-glacial geosystems of transitional forms are formed.

Quantitative characteristics are based on the calculation of the volume of the East Sayan glaciers measured by geophysical radar. Thus, over 120 years, the Peretolchina (northern) Glacier has decreased in length by a factor of 1.75, in area by a factor of 2.9, and in volume by a factor of 3.71. During the same period, the area of the neighboring Radde Glacier decreased from 0.43 to 0.09 km²; its thickness by 30 m; and, accordingly, its volume by 3 times. The warming of air temperature for Western Mongolia is 0.03–0.29°C/10 years and, for the Baikal region, 0.2–0.5°C/10 years. Warming of air temperatures in the ridges of the Mongolian Altai is noted up to 48° N, and southward the trend is unstable.