Desertification of Tibetan mountain grasslands (Google / The Guardian)

Read at : Google Alert – desertification

http://www.guardian.co.uk/environment/2010/sep/02/tibetan-plateau-climate-change

Tibetan nomads struggle as grasslands disappear from the roof of the world

Scientists say desertification of the mountain grasslands of the Tibetan plateau is accelerating climate change

Jonathan Watts in Madou

Like generations of Tibetan nomads before him, Phuntsok Dorje makes a living raising yaks and other livestock on the vast alpine grasslands that provide a thatch on the roof of the world.

But in recent years the vegetation around his home, the Tibetan plateau, has been destroyed by rising temperatures, excess livestock and plagues of insects and rodents.

The high-altitude meadows are rarely mentioned in discussions of global warming, but the changes to this ground have a profound impact on Tibetan politics and the world’s ecological security.

For Phuntsok Dorje, the issue is more down to earth. He is used to dramatically shifting cloudscapes above his head, but it is the changes below his feet that make him uneasy.

“The grass used to be up to here,” Phuntsok says, indicating a point on his leg a little below the knee. “Twenty years ago, we had to scythe it down. But now, well, you can see for yourself. It’s so short it looks like moss.”

The green prairie that used to surround his tent has become a brown desert. All that is left of the grasslands here are yellowing blotches on a stony surface riddled with rodent holes.

It is the same across much of this plateau, which encompasses an area a third of the size of the US.

Desertification

Scientists say the desertification of the mountain grasslands is accelerating climate change. Without its thatch the roof of the world is less able to absorb moisture and more likely to radiate heat.

Partly because of this the Tibetan mountains have warmed two to three times faster than the global average; the permafrost and glaciers of the “Third Pole” are melting.

To make matters worse, the towering Kunlun, Himalayan and Karakorum ranges that surround the plateau act as a chimney for water vapour – which has a stronger greenhouse gas effect than carbon dioxide – to be convected high into the stratosphere. Mixed with pollution, dust and black carbon (soot) from India and elsewhere, this spreads a brown cloud across swaths of the Eurasian landmass. When permafrost melts it can also release methane, another powerful greenhouse gas. Xiao Ziniu, the director general of the Beijing climate centre, says Tibet‘s climate is the most sensitive in Asia and influences the globe.

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Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.