During the International Symposium on Climate Change, which ended in Beijing on Wednesday, Prof. Ding Yihui, special advisor on climatic change with the China Meteorological Administration, said the alpine ecology was very sensitive to climatic changes, as illustrated by the shrinkage of glaciers due to rising temperatures.

According to scientific calculations, the total glacial area in China's northwestern mountains has been reduced by approximately 7,000 square kilometers, or 24.7 percent, since the Minor Ice Age.

In 1964, the glacial coverage along the Urumqi River valley in westernmost Xinjiang Uygur Autonomous Region stood at 48.2 square kilometers. By 1992, however, the figure had fallen to 40.9 sq km.

Taking into account what factors guided into glacier reduction since the Minor Ice Age and the predictions of temperature and precipitation changes for the coming summers, scientists have estimated that the melting of west China's glaciers will proceed at an even faster pace in the next 50 years.

Scientists predict that, by the year 2050, glacier coverage in the country's western region will have been reduced by 16,184 cubic km, or an additional 27.2 percent.

They also predict that glaciers in the Qaidam Basin of China's northwestern Qinghai Province and the Qinghai-Tibet Plateau will undergo intensive melting during a 20-year period from 2030 to 2050. The melt water from glaciers around the Tarim Basin is predicted to increase the runoff volume from local rivers by about 25 percent before 2050.

Prof. Ding Yihui acknowledged that, although the massive thawing of glaciers may increase river runoff, it is also likely to cause floods.

Experts also warned that global warming will alter the spatial distribution of frozen soil on the Qinghai-Tibet Plateau over the next 50 years.

The rise in temperature will generate a more profound seasonal thawing of frozen earth, giving rise to "thawing interlayers". In addition, frozen topsoil will be reduced by 10 to 15 percent, and the bottom limit of permafrost soil will be raised by 150 to 250 meters.

"Marshes will form on the thawed frozen ground. Meanwhile, large amounts of carbon dioxide, methane and other greenhouse gases, formerly sealed in the frozen soil, will also be released into the air, which, in turn, will aggravate global warming," Ding Yihui said.

Moreover, experts note that the designers of the Qinghai-Tibet Railway, on the advice of meteorologists, have given full consideration to the problem of the thawing of frozen earth because of climatic warming on the plateau. The future security of the railway will thus not be affected.

Designed to be built partially on the plateau's frozen ground, the Qinghai-Tibet Railway, currently under construction, is expected to play a significant role in China's western development strategy.

Experts have also predicted that seasonal snows in China will be of shorter duration due to warmer winters. By the year 2100, snow will largely disappear even before March, which will reduce the water level of rivers and intensify spring dry spells.

(Xinhua News Agency April 3, 2003)