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Physical Geography of Northern Eurasia


<<< Engineering Aspects and Protection of Permafrost | Physical Geography Index | Biodiversity and Productivity of Ecosystems >>>


Permafrost occupies about 65 per cent of the total area of Russia, extending from the Arctic islands to Transbaikalia. Its character and distribution are controlled by both the Pleistocene history and by many contemporary factors, such as climate, relief, bedrock, hydrology, and vegetation. Permafrost, which occurs in limited areas in the European part of Russia, attains its greatest spatial extent in Central and Eastern Siberia. The greatest thickness of permafrost is observed in the north-eastern sector of the Central Siberian plateau where perennial freezing has the longest history and where the contemporary climatic conditions are most severe. It is not unusual for the ice content of frozen ground to be as high as 60-80 per cent of soil volume; ice wedges, massive and pingo ice, the largest of the ice bodies, with dimensions which reach 20-60 m, are typical features of the permafrost environments. A striking variety of landforms, such as pingos, thermokarst lakes, and alases, occur in Northern Siberia and central Sakha-Yakutia. At present, one of the most intriguing issues is the response of permafrost environments to climatic change. Modelling shows that under a 4°C temperature increase, the southern boundary of permafrost will move up to 500 km north and the area of continuous permafrost will shrink by 20 per cent. This will be accompanied by thermokarst development, thermal erosion, subsidence of soils, and slope instability. In a more general perspective, thawing of permafrost will increase the natural emission of methane causing a positive feedback which will further enhance global warming. For many years man has been living in the permafrost environments adjusting economic activities to their severe and unique conditions. The 20th century has brought about vast engineering and construction projects, and the intensive development of natural resources in northern regions, a vital source of revenue for Russia, is continuing into the 21st century. It is important to ensure, therefore, that the fragile periglacial environments are managed with care in the future.

<<< Engineering Aspects and Protection of Permafrost | Physical Geography Index | Biodiversity and Productivity of Ecosystems >>>




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