January 20, 2014
Melting Glaciers Can Flood Farmlands And Lakes In Tibet
[ Watch the Video: Melting Tibetan Glaciers Flooding Farmland ]
Ranjini Raghunath for redOrbit.com - Your Universe Online
As glaciers melt and sea levels rise due to global warming, coastal regions and islands are beginning to panic. But even places as high up in the mountains as Tibet can face the negative consequences of melting glaciers.
The Tibetan Plateau, also known as the Qinghai-Tibet Plateau, is the largest plateau in the world – about four times the size of France. Its thousands of glaciers cover an area of more than 15,000 square miles, making it the third largest reserve of ice in the world. The melt waters from the glaciers are a vital lifeline for most of the major Asian rivers.
Recent years of global warming have caused the glaciers to retreat, faster than in any other part of the world. Much of the glacier melt doesn’t end up in the ocean; a large proportion of it stays on land, flooding farmlands and lakes, a new study shows.
A team of international researchers measured the rate of loss of glaciers in Tibet using satellite data. They found that 80 percent of the glaciers lost around 16 gigatons of mass per year – which is equivalent to around six percent of total global glacier loss.
But most of the glacier melt does not run down to the ocean and cause the ocean level to rise. About two gigatons of melted ice-water a year stays on land, and, without an “outlet on the plateau,” flow into lakes, making them overflow and “burst their banks,” Tobias Bolch, University of Zurich glaciologist said, in a statement. “In many regions, this means that valuable pasture areas become submerged.”
Although some glaciers in the central and north-west regions of Tibet have actually increased in their mass slightly, “on the whole, the entire region is clearly characterized by a loss in mass,” Bolch stated.
“The bigger picture shows an overall negative trend in glacier mass budgets with the highest speciﬁc mass loss in the monsoon-inﬂuenced north-eastern and south-eastern margins,” the authors wrote.
The study authors used precise satellite-based laser measurements to measure changes in the glaciers’ mass and heights over time.
Previous findings by a satellite mission had indicated that Tibet’s glaciers were actually becoming thicker during the same time period. The current study contradicts those findings, the authors wrote. In those findings, the results were noted by calculating glacier gain based on water/mass gain in lakes, they wrote.
“Similar to the fact that the rising sea-level threatens coastal areas on the globe, the rising lake levels pose problems to the local population as pastures are often situated close to the lakes and will be ﬂooded,” they wrote.
The study was published in the journal Environmental Research Letters.