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18:15 Sep 28 2011

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Glaciers in Tibet Plateau never really large: Swedish researcher
10:52, June 04, 2010  

The glaciers in Tibet Plateau have remained relatively small and have not been much larger than today for tens of thousands to hundreds of thousands of years back in time, according to a thesis in Physical Geography of Stockholm University issued on Thursday.

At the same time as huge ice sheets covered northern Europe and North America during the last Ice Age twenty thousand years ago, the glaciers in Tibet were not much larger than today, said Jakob Heyman, author of the dissertation.

The study deals with the growth and decay of glaciers in Tibet far back in time, with the aim of attaining better knowledge of glaciations and their link to climate variations, a statement from the university said.

The results show that the glaciers in Tibet have varied in size but they have been fairly small far back in time. In several places the glaciers seems to have been similar in size to today's glaciers or just slightly larger during the entire last Ice Age.

Considering that Tibet, often called the roof of the world or the third pole, is where the largest number of glaciers outside the polar regions are located, this is remarkable, Heyman said.

The field data can be used, together with a mathematical model for the growth of a glacier, to find out how large the climatic variations have been during the last Ice Age. Preliminary results show that the climate was probably somewhat colder than today but was nevertheless relatively stable.

If today's temperature in Tibet were to decrease by five degrees or more, which is not much for an Ice Age cycle, a large ice sheet would probably start growing. No ice sheet seems to have existed in Tibet, and the cooling can therefore not have been that strong, Heyman said.

Analysis of the large-scale geomorphology also indicates that glacial erosion has been dominant in the elevated mountain areas on the low-relief plateau, whereas fluvial erosion outpaces glacial erosion along the plateau margin.

Source: Xinhua

(Editor:王千原雪)

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