Fluctuation of glaciers in the southeast Russian Altai and northwest Mongolia Mountains since the Little Ice Age maximum

Abstract

The present state and dynamics (since the maximum of the LIA) of the glaciers of southeast Russian and north Mongolian Altai have been studied. Data were obtained from 15 areas of glaciation. The research is based on multiyear in situ observations and analysis of aerial photos of mid-1960s and high resolution space imagery; 553 modern glaciers with total area 313.4 km2 have been mapped and put down into catalogues, including glaciated areas and glaciers that have not been studied before. Glacial complexes with united accumulation zone and flat-summit glaciers in the center and valley glaciers on the sides are typical for the area of research. The firn line level rises from 3200–3300 m in the west to 3600–3700 m in the east. This tendency reflects the reduction of nourishment of the glaciers in this direction due to decrease of precipitation. The largest valley glaciers exist on the northeastern leeward slopes as a result of two to threefold concentration of snow. The last glacial advance in the maximum of LIA, according to dendrological data, finished in the first half of the 19th century. From the maximum of the LIA, the glaciation of the region lost about 51 %, ELA average uplift was 89 m. On the background of general trend of glacial retreat, there were several periods of stabilization of glacial fronts, the most distinct in mid-1960s. In the last 50 years, there were two warm and dry intervals: 1972–1981 and 1992–2008; and three cool and moist intervals: prior to 1972, during 1982–1994 and subsequent to 2009. It caused fluctuations of firn line altitude with about 300 m range and abrupt changes of glacial area. Maximal changes were observed between 1995 and 2008, when areas of the glaciers decreased with average rate 1–2 % year. Determination of retreat of glacial snouts after the LIA by geomorphic features is described by VI-phase scheme.