Regional changes of permafrost in Central Asia
|Location||International Geological Congress,oslo 2008|
|Holding Date||11 October 2008|
The recent progress of permafrost research about the characteristic of permafrost changes under the scenarios of climatic warming in Central Asia has been summarized in this paper. Most of the permafrost in Central Asia is located on the Qinghai-Tibet Plateau in China, the Tien shan Mountain regions in China and Kazakhstan, and the mountain regions in Mongolia. Monitoring of the permafrost thermal regime has been carried out in all these regions in the past several decades. Accompanied with the climate warming, the thermal regime of permafrost changed greatly in all the permafrost regions in central Asia. Permafrost in the Tibetan Plateau is most widespread, occupies about 1.5 million square kilometers. In the continuous permafrost regions on the plateau, the annual mean temperature has risen by 0.1~0.2°C, while in the discontinuous permafrost regions the annual mean temperature has risen by 0.2~0.5°C from 1995 to 2002. The thickness of the active layer has increased by 0.15 to 0.50 m between 1996 and 2001 and detachment layer formed fast in recent years. The Hovsgol mountain region of northern Mongolia contains widespread mountain permafrost and comprises the southern fringe of the Siberian continuous permafrost zone, and it is the most typical permafrost regions in Mongolia. The average rate of increase in mean annual permafrost temperatures is from 0.2 °C to 0.4 °C per decade. Permafrost has been degrading more intensively during the last 15 years (since 1990s) than during the previous 15–20 years (1970s and 1980s). The permafrost occupies about 0.16 million square kilometers in area in Tien Shan Mountain Regions, and it extends from its eastern part in China to western part in Kazakhstan. Geothermal observations during the last 30 yr indicate an increase in permafrost temperatures from 0.3 °C up to 0.6 °C. At the same time, the average active-layer thickness increased by 23% in comparison to the early 1970s.