Snow Cover, Permafrost, Forest, and
Climate in Siberia

	The taiga near Yakutsk in spring. High albedo in non-forest site.

In Siberia, there exists permafrost since the annual mean air temperature is less than 0°C. There, the area is covered by snow in cold season and large forest called taiga grows. These typical surface components have strong influence on the climate formation of this area, which has very complex mechanism.

Change of snow cover and frozen ground due to global warming and their feedback to the climate system are important subjects we should keep our eyes on. Existence of the frozen ground is an important climate factor to confine the water flow to the surface, and alter the water cycle and subsequently the energy cycle. In the southern part, it is already said that the ground temperature is increasing due to the global warming and as a result, area of permafrost is decreasing. Such change will lead to drying of the ground surface, decreasing of the vegetation, and changing of the water resources condition. It is said that degradation of snow cover will act as a positive feedback to the climate system, and accelerate the global warming. Yet the mechanism and the intensity of its effect need further evaluation.

Forest is one of the important climate components. A result by the Atmospheric General Circulation Model (AGCM) calculated by one researcher suggests that if there were no forest, the temperature will decrease by 8-12°C and there will be "extremely cold Siberia", which will affect not only this area, but also the southern area as well as Japan. The reason is that, without forest in Siberia, the surface albedo (reflectivity of solar radiation at surface) will be nearly 80%, absorbing only 20% of solar radiation. Yet currently, due to dark color of the forest, the surface albedo is kept as low as 30%, absorbing 70% of solar radiation, keeping the ground surface warm. If deforestation occurs due to logging, forest fire, and other causes, climate will become close to "extremely cold Siberia." On the other hand, climate will become warm if forested area increases by aforestation, and so forth. Both cases will have certain effect on carbon cycle, and therefore, we have to have a holistic evaluation on the direction of this Planet including aforementioned changes and effects of this area.

Since Siberia dominates large part of Eurasian continent, its change will have effects on the surrounding regions. Therefore, it is necessary to understand the various processes, monitor the change and discuss the variability using models. Based on such backgrounds, Land-Surface Hydrological Cycle and Processes group has established observation network for the process and long-term variation study of water/energy cycle in the eastern Siberian region and northern Mongolia, and implementing multi-scale and interdisciplinary observational research.