In accordance with the International Convention to Combat Desertification (CCD; United Nations 1994) desertification is defined as land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variation and human activities. Following this definition, 90% of Mongolian territory can be regarded as vulnerable to desertification. These areas are almost exclusively used as rangelands, supporting about 30 million heads of livestock and numerous populations of wild animals. At resent time there is no consensus among scientists on climate variations, particularly on presence or absence of the aridization of Inner Asia and Mongolia. The coastal formations of many lakes in this area and number of other examples are characteristic for lakes with fluctuating water levels. Now there are certain indications of lake level rises (for instance, Ubsu-Nuur, Uureg-Nuur in Great Lakes areas of Mongolia). At the same time it is necessary to note that this fact might have some relation to the increase in glacial river flow due to global warming. Desertification of a territory is usually reflected first of all by dynamics of sand massifs, which can indicate aridization processes. Sand massifs are the typical landscape elements in the majority of inter mountainous depressions of Inner Asia. The deflation cells and basins among fixed sands are particularly evident in the basin of Ubsu-Nuur (Largest lake in Mongolia 3423 km2) where eolian processes are becoming active. There is evidence of increased moisture resources during the last three centuries. The annual precipitation shows steady tendency to growth from the first half of the 19th century (Dagvadorj et al. 1994). In this regard not only mere climatic variation, but also sharp continental climate condition and impact of human activities should be considered as the most important factors of ecosystem vulnerability and desertification risk in Mongolia.