Climate change thawing Tibet plateau's frozen earth

The perennial frozen earth on China's Qinghai-Tibet Plateau has shrunk by 16 percent over the past three decades as a result of global warming, according to new research results.

The volume of frozen earth on the plateau has decreased from 1.5 million to 1.26 million square km, researchers with the Chinese Academy of Sciences (CAS) found after decades of study using remote sensing and satellite monitoring.

The thawing of the frozen earth is an immediate result of global warming, as the Qinghai-Tibet Plateau, at an average altitude of 4,500 meters, is extremely vulnerable to climate change, said a research paper published by the CAS Institute of Tibetan Plateau Research and seen by Xinhua on Monday.

Meteorological data indicates the average temperature on the plateau has risen by 1.8 degrees Celsius over the past three decades, higher than the national average temperature rise.

The climate change has also caused glacial shrinking on the plateau. Its glaciers have decreased by 8,000 square km, or 15 percent, since 1980.

Satellite data indicated glacial shrinking and thawing of frozen earth had accelerated since the 1990s.

"These are detrimental to the plateau vegetation and will worsen the plateau ecology in the long term," said Jin Huijun, a researcher with CAS Cold and Arid Regions Environmental and Engineering Research Institute.

The melting glaciers have swollen lakes and rivers in the plateau region. Two years ago, Ngawang Zhoima, a herder in Namco Village of Damxung County, was forced to move to a higher altitude after a nearby river swelled and threatened to flood his home.

Though the big thaw may supplement ground water and speed up water circulation in the plateau region, Jin and his colleagues are carrying out further research to evaluate whether water resources are still properly allocated on the plateau.

Meanwhile, scientists and railway workers are striving to keep the thaw from damaging the Qinghai-Tibet Railway, the world's highest plateau rail link, which opened in 2006.

The railway, about 550 km of which runs on frozen earth, needs particular protection, as when the icy core of the earth melts, the roadbed may subside.

Thanks to effective maintenance, the railway company said recently that 99.5 percent of the frozen earth under the tracks was "solid and perfectly safe," which meant the subsidence was way below a tolerable 50 mm proposed by the designers.