Glaical retreat in Asia, especially on the Tibetan Plateau, has aroused interest and concern of a journalist fron Newsweek Internatioanl, Craig Simons, who reports of his interviews with glaciologists about the potential environmental problems caused by falling ice. The following is the full article for your reference.
Beware of Falling Ice; Asia's glaciers are melting at an alarming rate, creating a host of environmental problems from flooding to disease.
By Craig Simons 1,392 words 6 June 2005 Newsweek International Atlantic Edition The Chinese ask river gods for protection against floods. Each year tens of millions of Indian Hindus make pilgrimages to the Ganges to seek spiritual cleansing. In impoverished villages from Nepal to Bangladesh, waterways are the lifeblood of society, relied on for everything from drinking water to industry to burial. The veneration that Asians hold for rivers was on Chu Duo's mind as he fiddled with his instruments--a bevy of thermometers, barometers, solar-radiation meters, rainfall gauges--in a small, flat field near Lhasa's Jokhang Temple, Tibet's holiest Buddhist monastery. For the past five years, Chu, a 36-year-old meteorologist at the Tibet Institute of Plateau Atmospheric and Environmental Sciences in Lhasa, has been trying to measure changes in the local climate. He found that temperatures have risen more than 1 degree Celsius since the 1960s, while rainfall has increased.
The results aren't out of line with what climate scientists have been finding for other parts of the world. But for the three fifths of the world's people who live in Asia, the prognosis is especially dire.
The 2.5 million-square-kilometer Tibetan Plateau, which stretches from Kazakhstan in the northwest to India in the south, is the main source of Asia's big rivers--the Yangtze, Yellow, Mekong, Indus and Ganges. For hundreds of thousands of years, more than 46,000 glaciers on the plateau have provided a steady flow of water to the lowlands. Each winter the glaciers have grown as snow has piled onto them. In May and June they begin to retreat as some of the ice and snow melt. Until recently, they've stayed pretty much the same size. But during the last several decades, glaciologists have recorded more melting in the summer than gets replaced in the winter. According to Yao Tandong, the director of China's Institute of Tibetan Plateau Research, glaciers on the plateau have retreated an average 7 percent during the past 40 years, and the rate at which they are melting is increasing. For glaciologists, the change has been abrupt: "By nature, glaciers are slow movers," says Yao. "The glacial retreat has happened very suddenly."
Because the glaciers are melting faster than usual, more water is pouring out of the mountains and into the rivers. According to Yao, annual glacial runoff on the Tibetan Plateau and surrounding areas is now equal to the total yearly discharge of the Yellow River, roughly 20 percent more than 40 years ago. Some of that water is making its way into Asia's rivers, increasing floods and spreading waterborne diseases. More of it is pouring into valleys, enlarging old lakes and creating new ones. This glacial melting is expected to continue at least at the present rate for many decades. In the process, it will transform Asia, creating a host of new environmental problems.
The increased melting has already begun to change the region's geography. One lake in northern Tibet, Fuqilin Lake, has risen 20 centimeters a year since 1997, spreading over local pastures and towns, and forcing residents to move to higher ground. Occasionally the lakes break their embankments, emptying tons of water into rivers and even dry valleys and causing devastating flash floods. In Nepal, a series of landslides and flash floods killed more than 350 people and left some 10,000 families homeless in 2003.
The struggle to contain rapid increases in water flow will occupy Asia for decades to come. Glacial runoff has already contributed to massive floods in India, China and Bangladesh. Flooding along the Yangtze River in 2002 caused billions of dollars of damage and killed at least 1,000. Last year, floods in India killed more than 1,000 and left millions homeless, while Bangladesh suffered its worst floods in 15 years, with high water spreading deadly diseases including diarrhea and cholera. Because glacial runoff peaks during monsoon season in India and Southeast Asia, "it is very complex to separate the two," says Joseph Gergan, a glaciologist at the Wadia Institute of Himalayan Geology in northern India. But some experts say that glaciers, as opposed to rainfall, are responsible for as much as 70 percent of the flow of some of Asia's largest rivers during the late summer, up from some 60 percent in the 1960s.
Another problem is that as glaciers and permafrost melt, rivers wash away more loose topsoil. In China the problem of river silting is particularly acute. China has the largest number of large dams in the world--148 on the Yangtze River basin alone--and as mud and debris backs up behind them, the dams require expensive dredging that doesn't always work. Opponents of the Yangtze's Three Gorges Dam, the world's largest, point to a recent U.S. study that found silt buildup in U.S. dams amounts to 2 cubic kilometers each year. Because the Yangtze carries the fifth-largest sediment discharge of any river in the world, silt trapped behind the dam could render the river impassable for large ships.
In the longer term, the problem will reverse. Yao predicts that 60 percent of the glaciers on the Tibetan Plateau will be gone by the end of the century and that the average volume of most Asian rivers will begin to fall in 2050. The flow of several Ganges tributaries fed by shrinking glaciers in southeastern Tibet has already declined by 40 percent, says Shen Yongping, the author of a recent WWF report on glacial melting. The problem will be more acute in inland rivers, which do not feed into larger rivers or reach the sea but eventually dry up as water is siphoned out. In China's northwestern Xinjiang province, Shen says, 60 percent of the Kumarik River originates in glacial runoff, and many other rivers in the province are also primarily glacial. "People are moving to parts of Xinjiang where there is increased flow that they can use for agriculture and industry," he says. "But in 10 or 20 years the flow will begin to abate. Once the rivers decrease and finally disappear, the oases will dry up and there will be no more cities."
Reduced flows will also have a severe impact on China's heavily populated northeast. China's per capita water resources are about one quarter of the world average, and in northern China that ratio drops to one twentieth. Most of the rivers in eastern and northern China are so polluted that making them fit for drinking is prohibitively expensive. Water tables around major urban areas, including Beijing, are dropping, forcing the cities to transport water from elsewhere.
So far Asian governments have been slow to react. In Nepal and the tiny Buddhist nation of Bhutan, a recent United Nations Environmental Program project located 44 new or growing glacial lakes threatening nearby villages. In China scientists are using satellites to track rising lake volumes and will evacuate villagers if a glacial flash flood seems imminent. Beijing has invested $24 billion to build a reservoir in Xinjiang province to prevent flooding and to control rampant water use. But with glaciers melting over an area as large as one fourth of the United States, Yao says, those efforts will yield limited benefits and, regardless, won't slow climate change. "Officials," he says, "don't really take a long-term view."
Environmental groups appear ready to push the issue. The U.N.'s annual environmental report, issued in February, highlighted glacial melting, and the Intergovernmental Panel on Climate Change--a group established by the World Meteorological Organization and the United Nations--has made glacial retreat a top issue. Former U.S. vice president Al Gore is expected to visit a glacial monitoring station near Lhasa this summer to raise awareness. Yao believes that while there "is probably no way to stop the glacial melting, there are ways to slow it down." That would require a global effort to reduce carbon emissions dramatically, which isn't likely to happen anytime soon. For Asia, Yao thinks, it's probably better to prepare for the consequences.
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