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The swelling barrier lake after a landslide forced evacuations along the Yarlung Zangbo River. YouTube screenshot / CCTV+

Six thousand people have been evacuated after a landslide in Tibet Wednesday blocked a river that flows downstream into India, creating a lake that could cause major flooding in the subcontinent once the debris is cleared, The Associated Press reported.

Chinese emergency officials announced the evacuations Thursday. The landslide impacted a village in Menling County, but no one was killed or injured, Chinese officials said.

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On July 17, 130 million cubic yards of ice and rock suddenly let go from a glacier in Tibet, hurtling down six-tenths of a mile and killing nine herders along with 350 sheep and 110 yaks. Scientists were baffled. Now, by examining satellite images before and after the event, they think it is an example of a rare glacial surge, when a glacier moves at 10 to 100 times its normal speed. Some researchers believe that climate change at high elevations can trigger such surges.

NASA

"It doesn't make sense," said Tian Lide, a glaciologist at the Chinese Academy of Sciences' Institute of Tibetan Plateau Research (ITPR) in Beijing, who runs a research station in Rutog. Most avalanches occur on slopes of 25 to 45 degrees, but the Rutog avalanche, as this event is known, started from a flat area some 17,000 to 20,000 feet above sea level. When it came to rest, it covered an area of nearly 3.8 square miles to a depth of almost 100 feet. The only other event of comparable size was the 2002 collapse of the Kolka Glacier in the Caucasus. That avalanche killed 140 people.

An entire tongue of the Rutog glacier in Northwest Tibet collapsed at once. Lide noted that the glacier came down with such force that it widened the gully it came to rest in. Two different satellites captured before-and-after pictures of the area. NASA's Operational Land Imager acquired an image on June 24, just about a month before the avalanche. The European Space Agency's Sentinel-2 satellite captured an image of the debris field on July 21, days after. The pre-collapse imagery revealed that the glacier was already showing signs of change.

Glacial surges can be caused by meltwater at the base of the glacier, which essentially lubricates the surface it flows over. These types of surges can have a sudden onset and a very high flow rate. Many surge-type glaciers are found in Western Tibet.

Researchers from Moscow State University and the University Center for Engineering Geodynamics and Monitoring in Moscow have investigated the Kolka avalanche on the ground. Glacial surges are not new there; events dating back to at least 1902 are known. They found striations in the moraine rocks, which they'd never seen before.

"Moraine rocks are not scraped by the glacier because they move with it," Dmitry Petrakov, a geologist at Moscow State University, said. "But at Kolka, the collapse happened so fast that the ice mass must have simply flown over the moraine, producing striations several millimeters deep in minutes."

They found that the avalanche moved with tremendous speed, perhaps up to 112 miles per hour. They concluded that it was a surge event.

A year after the Kolka collapse, the researchers still found the area unstable. In the days following the Rutog avalanche, cracks occurred in nearby glaciers. Temperatures in the Tibetan plateau have risen 0.4 degrees Celsius per decade, twice the global average. One-tenth of the permafrost has melted in just the past decade. Rapidly melting glaciers have added to the number of lakes by 14 percent since 1970 and 80 percent of existing lakes have grown, flooding towns and pastures. In addition, precipitation in the area has increased 12 percent since 1960.

EcoWatch reported Aug. 26 on the issues facing this area, known as the "Third Pole." The Himalayas and Tibetan Plateau hold the largest mass of ice on Earth after the polar regions. The loss of these glaciers threatens the water supply for 1 billion people in China, India and Tibet, Nepal, Bhutan and Southeast Asia.

In response to the Rutog avalanche, China Radio International reported, "Experts believed that the icefall is a result of global warming, which has caused melting and cracking of the glaciers."

Those killed in the Rutog avalanche were residents of Dungru village in Rutog county in Southwest China's Tibet autonomous region.

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The Himalayan Mountains and Tibetan Plateau, dubbed the "Third Pole" for having the largest ice mass on Earth after the polar regions, are rapidly losing their glaciers. Eighteen percent of China's glaciers have vanished in the past 50 years according to the Chinese Academy of Sciences. Air pollution and rising air temperatures are combining to increase glacial melt, threatening water supplies for one billion people.

Mount Everest is Earth's highest mountain.

Glacial surfaces are vulnerable to the effects of black carbon. What, exactly, is black carbon? The U.S. Environmental Protection Agency (EPA) defines it as "the most strongly light-absorbing component of particulate matter (PM), and is formed by the incomplete combustion of fossil fuels, biofuels and biomass." Airborne black carbon absorbs sunlight, creating local atmospheric warming. Deposited on glaciers, it darkens the surface, allowing the sun to warm the snow and ice just as wearing dark clothing on a summer day can make you feel the heat.

Source: Nature Communications

It's not just China's famous pollution or fossil fuel burning that's to blame. It's also yak dung.

Traditional Tibetan use of biomass such as animal dung for cooking and heating, along with open burning of garbage and crop waste, was found to be a greater contributor to the creation of black carbon in certain areas of the Himalaya-Hindu-Kush and Tibetan Plateau than burning of fossil fuels. A new study published this week in Nature Communications concludes that "the results of this extensive observation-based source-diagnostic study provide strong isotope-based evidence that biomass-sourced BC [black carbon] plays a quantitatively more important role in TP [Tibetan Plateau] glacier melting than fossil fuel-sourced BC, especially in the inland TP, and presumably arises mainly from domestic sources." The research was conducted by the Institute of Tibetan Plateau Research, Chinese Academy of Sciences.

The mineral-rich lands of Tibet are a source of diamonds, gold, uranium and copper, bringing extractive industries to the region. China is the world's fourth largest lithium producer, most of it coming from the Chang Tang plain in Western Tibet.The Tibet Express stated, "Glacier-water mining has major environmental costs in terms of biodiversity loss, impairment of some ecosystem services due to insufficient runoff water, and potential depletion or degradation of glacial springs."

Degrading glaciers threatens a critical Asian water source.

China, India and other countries surrounding the Tibetan Plateau have looked to it to supply growing water needs as populations increase and fresh-water sources suffer from industrial and human-waste pollution. China is also tapping the glaciers of the Himalaya's to support its bottled-water market, the world largest. At least 30 companies have been granted licenses to tap Tibetan glaciers.

Fossil fuels are by no means blameless in the degradation of the Himalayan glaciers. In the Himalayas, the Chinese study found fossil fuels accounted for 46 percent of black carbon versus 54 percent for biomass burning. Fossil fuel sources ranged as high as 70 percent in the Langtang and Mustang Valleys, largely from sources in Kathmandu and Northern India. The study also saw seasonal variations. Biomass-sourced black carbon decreased during monsoon season, presumably because these particles are more efficiently flushed out by precipitation.

Most of the 5,500 glaciers in the Himalaya-Hindu-Kush region—home of Mount Everest—may vanish by the end of this century. The long history of climbing through the Khumbu Icefall and up the Lhotse Face may become a rock scramble instead.

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