Geography of Tibet

[1][2][3] Tibet is often called "the roof of the world," comprising tablelands averaging over 4,950 metres above the sea with peaks at 6,000 to 7,500 m, including Mount Everest, on the border with Nepal.

It is bounded on the north and east by the Central China Plain and on the west and south by the Indian subcontinent (Ladakh, Spiti and Sikkim in India as well as Nepal and Bhutan).

Most of Tibet sits atop a geological structure known as the Tibetan Plateau, which includes the Himalaya and many of the highest mountain peaks in the world.

The valleys of Lhasa, Shigatse, Gyantse and the Brahmaputra are free from permafrost, covered with good soil and groves of trees, well irrigated, and richly cultivated.

Due to the extremely high mountain barriers it has a very arid alpine climate with annual precipitation around 100 millimetres (4 in) and possesses no river outlet.

Due to the presence of discontinuous permafrost over the Chang Tang, the soil is boggy and covered with tussocks of grass, thus resembling the Siberian tundra.

The lake region is noted for a vast number of hot springs, which are widely distributed between the Himalaya and 34° N., but are most numerous to the west of Tengri Nor (north-west of Lhasa).

So intense is the cold in this part of Tibet that these springs are sometimes represented by columns of ice, the nearly boiling water having frozen in the act of ejection.

[4] The climate of Tibet is severely dry nine months of the year, and average annual snowfall is only 46 cm (18 inches), due to the rain shadow effect.

Qin Dahe, the former head of the China Meteorological Administration, said that the recent fast pace of melting and warmer temperatures will be good for agriculture and tourism in the short term; but issued a strong warning: "Temperatures are rising four times faster than elsewhere in China, and the Tibetan glaciers are retreating at a higher speed than in any other part of the world."

Owing to this drop in temperature a supposed drier climate has partly been compensated with regard to the glacier feeding by a minor evaporation and an increased relative humidity.

Accordingly, the Tibetan glaciation was the actual cause of the enormous loess production and the transport of the material into the Chinese middle- and lowlands continuing to the east.

Actually they can be understood the better by a superimposed glacioisostatic compensation movement of Tibet about 650 m.[19] An alternative view held by some scientists[20] is that the glaciers on the Tibetan Plateau have remained restricted over the entire data published since 1974 in the literature referred to in Kuhle (2004),[21] which are relevant as to the maximum ice extent.