Shrinking Glaciers Have Put Tibetans in the Path of Climate Chaos
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For Tenzin Dorje, the road home keeps getting longer. Each year the Tibetan shepherd must walk farther to find streams where his sheep can drink.
"I am an old man," he says, clutching the neck of his cane. Sometimes he trudges six hours a day, twice his old route. He has contemplated learning to ride a motorbike like his grandson, but fears it might be too discomfiting for an 80-year-old man.
The problem is that streams in the province of western China where he lives are drying up, receding into the mountains.
As recent years have brought higher temperatures and altered how snowmelt trickles down from glaciers on the Tibetan-Qinghai plateau, water is becoming scarce.
Mr. Tenzin lives in a small village nestled amid dramatic mountains peaks. Strings of Tibetan prayer flags flap against a still-brilliant blue sky. Yet this apparent purity and timelessness masks another reality: He is living on the frontier of climate change.
Tenzin's village is on the slopes of the rugged Qilian mountains in western Gansu province. Glaciers on the mountains are the primary source of water for humans, farms, and industry in his village of Baijiaowan and for others north and south of the range.
The streams distinguish the landscape, including a string of oasis towns along the Old Silk Road, from the abutting Gobi Desert. Today, the desert is expanding.
"The climate is changing," says Zhang Mingquan, a professor of earth and environmental sciences at Lanzhou University, in the provincial capital. "Snow is the source of the stream water, and now the stream water is less than before."
Recent years have seen higher temperatures and less precipitation. As a result, mountaintop ice is receding.
The Chinese Academy of Social Sciences estimates that the glacial area on the Tibetan-Qinghai plateau, the world's largest ice sheets outside the poles, is shrinking about 7 percent each year.
It might seem that melting glaciers would bring more water in the short term. But that isn't necessarily the case, says Michael MacCracken of the Climate Institute in Washington.
"Glaciers and snow on mountains serve as a storage mechanism for water, holding it for later," he says. "The area of the glaciers is an indication for how well that system is working." Think of glaciers as a bowl, and snowfall as rice – a shrinking bowl holds less rice. Receding glaciers capture less annual snowfall.
"Without the glaciers, snow and rainfall tend to seep into the soil – usually mountain soil is quite porous – and then it later evaporates," says Dr. MacCracken.
In nearby Minqing county, instead of walking farther for water, farmers dig deeper. Fifty years ago, wells tapped groundwater at 50 feet. Now they must drill 100 feet or more. With less snowmelt, groundwater is not fully replenished.
Glaciers stretching across the towering Tibetan-Qinghai plateau sustain all the great rivers of Asia – the Yangtze and Yellow Rivers in China; the Ganges, Indus, and Brahmaputra in India; the Mekong and Salween in Southeast Asia.
"With climate change, all these rivers will have greatly reduced flows," says Carter Brandon, director of the World Bank's China environment program in Beijing. "There will also be much more seasonal variation – when flow is more dependent on rainfall, as opposed to the steady inflow of snowmelt from glaciers."
The glacier system delivers water to more than 300 million people in China – and 1 billion across south Asia.
The region is among the globe's most rapidly warming. Average annual temperatures on the "rooftop of the world" have climbed 2 degrees F. in two decades.