December 12, 2015, by Alex Kirby
The overgrazing of yaks and other mismanagement is contributing to the desert’s spread.
Image: Dennis Jarvis via Wikimedia Commons
COP21: China’s leading scientists warn that large areas of the Tibetan plateau – the life-giving source of Asia’s major rivers – are suffering from desertification.
PARIS, 12 December, 2015 – Hours before the UN climate talks end, a warning from China’s top scientific body – the twin influences of human activities and climate change are turning much of the Tibetan plateau into a desert.
The damage is not only transforming grasslands and wetlands into sand and rock where nothing can grow. The plateau is also the source of Asia’s major rivers, on whose water about 1.4 billion people depend.
More than 100 scientists have contributed to a report – published by the Chinese Academy of Sciences – that discloses the rate of the desertification process and its spread.
The report, which appears on the website of thethirdpole newsletter, says the plateau is already warming twice as fast as the global average.
The scientists expect temperatures there to rise by up to 4.6°C by the end of this century, and say that glaciers are shrinking, lakes expanding and river flows increasing, all signs of an intensifying water cycle.
While more water is flowing on the plateau, desertification is spreading and will continue to expand. Together with melting permafrost, the growing desert is thought to be the major driver of environmental degradation on the plateau.
The Tibetan Plateau is known as the world’s “third pole” because it holds the largest store of fresh water outside the Antarctic and Arctic. It is the source of 10 of Asia’s major rivers, including the Yangtze, the Yellow River and the Mekong, which support about 1.4 billion people downstream.
The report says that the loss of grasslands, alpine meadows, wetlands and permafrost threatens environmental security across China and South Asia.
The headwaters of the rivers are said to be suffering the worst desertification and land degradation.
The most severe damage is at the headwaters of the Brahmaputra and the Yangtze, where soil erosion and sand have spread along rivers and risen up hillsides and mountains. The Yangtze flows east across China, powering the country’s largest economic zone. The plight of the upper Yellow river region is no less serious.
The scientists say there are many factors working to turn the plateau into a desert, both natural physical processes and human mismanagement. Geology, climate change and rodent damage as well as human activities all play a role in worsening the situation.
Permafrost is a particular concern at the source of the Yangtze, where the scientists found that the active layer of frozen soil beneath the surface, which thaws each summer, is getting warmer every year and is thickening by 3.6mm-7.5mm per year.
Permafrost areas will continue to shrink throughout the century, the report predicts. Wetlands rely on permafrost: summer melt supplies them with water, while the year-round sub-surface frozen layer prevents water from seeping deeper into the soil, and so benefits surface vegetation.
On the Yellow River, the combination of overgrazing of yaks and sheep, cultivation without proper protection, and climate change are blamed for the desert’s spread
Infrastructure construction is another problem. The report says the building of the Qinghai-Tibet road and railway, without adequate knowledge of the ecosystem and permafrost conservation, has resulted in “serious impacts on the eco-system” and threatened further soil erosion and degradation.
Careless mining practices and the dumping of waste have polluted water, further increasing the risk of soil erosion, landslides and other natural disasters. – Climate News Network
Alex Kirby is a former BBC journalist and environment correspondent. He now works with universities, charities and international agencies to improve their media skills, and with journalists in the developing world keen to specialise in environmental reporting.