Scientists of the Chinese Academy of Sciences calls attention to how climate change ovechaet on permafrost in the west of the country phenomenon has become an unexpected turn.
Beijing, January 10. Chinese scientists have found that the amount of water supplied to the major river — the Yangtze — at its source on the Tibetan plateau, has fallen for 40 years at 15%, which is contrary to the data on the increase on the same 15% level of the melting of glaciers and the increasing number of storm rainfall during the same period.
This is the conclusion of environmental Chinese Academy of Sciences came to complete the five-year project to study glaciers, snow and permafrost to assess their impact on water resources in western China.
Others of the river to the west of the country, by contrast, were supplemented with water. Yangtze phenomenon was associated with large-scale changes in the permafrost. On the Tibetan Plateau permafrost area decreased by 10% over the last decade.
Experts documented that its depth of the active layer — that freezes and thaws each year — has a major impact on the supply of water in the river. For example, in the event that the melting layer lies at a depth of less than 60 centimeters of water increases and decreases if the melting extends to a greater depth. The reasons for this effect yet inexplicable to scientists, but it is expected that with the melting more permafrost reducing the active layer begins to act as a sponge — soak up the water, which would have to go into the river.
Thinning of the active layer of permafrost depends on air temperature and vegetation cover, especially during melting. The scientists found that the soil in this region better thaws and freezes back worse.
Committed changes in western China could destroy the Yangtze River as a water source.
For scientists, it is clear that all of this is a response to global climate change, but that the behavior of the Tibetan plateau, is very different from the situation in the Arctic, they say. In central Alaska, for example, the so-called permafrost degradation has led to the expansion of the wetlands, and in China, as seen in this situation, on the contrary — to reduce: the land becomes drier and more prone to desertification.
Until recently, Chinese scientists write, the role of permafrost as a water source neglected by focusing on the glaciers. But the permafrost is almost a quarter of the Earth's land frost is less important, especially for a region like Tibet, where they feed on the most important river system in China.
The article was published in the journal Nature.