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Himalayan lakes are exacerbating glacial melt

Himalayan lakes are exacerbating glacial melt
Figure 1: A typical situation in the Himalaya: glaciers have largely retreated, and lakes now cover the area where the glacier tongue was in earlier times – Garlung Co lake in Central Himalaya. Photo taken by J Pronk in October this year during a joint expedition with Chinese colleagues from the Institute of Tibetan Plateau Research. Credit: University of St Andrews

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The rate glaciers are melting in the Himalaya is being significantly accelerated by lakes already formed by glacial retreat, new research led by the University of St Andrews has found.

The study, published in Scientific Reports, concluded that the  which have flowed into the lakes in recent decades are retreating and thinning at a much greater rate than any other glaciers in the Himalaya.

These glaciers are responsible for as much as 30 percent of the ice loss in different parts of the mountain range, despite comprising just 10 to 15 percent of the total glacier population.

The behavior of glaciers provides the clearest indication of climatic change in high mountain regions. Long-term atmospheric warming has caused the recession of glaciers across the Himalaya.

Meltwater from glaciers in this region sustains the flow of river systems on which hundreds of millions of people depend for their basic needs.

Not all the meltwater instantly drains to downstream catchments and thousands of  have developed and continue to expand high in the Himalaya. Until this study, the influence of glacial lakes on glacier behavior has not been thoroughly investigated in the Himalaya, despite the rapid increase in  area and number.

  • Himalayan lakes are exacerbating glacial melt
    Figure 3: Where lakes formed, glaciers retreated significantly: Lake Garlung Co, Central Himalaya. Credit: J Pronk
  • Himalayan lakes are exacerbating glacial melt
    Figure 2: A large lake formed where once a glacier was: Lake Garlung Co. Credit: T Bolch, University of St Andrews
  • Himalayan lakes are exacerbating glacial melt
    Figure 3: Where lakes formed, glaciers retreated significantly: Lake Garlung Co, Central Himalaya. Credit: J Pronk
  • Himalayan lakes are exacerbating glacial melt
    Figure 2: A large lake formed where once a glacier was: Lake Garlung Co. Credit: T Bolch, University of St Andrews

Now, scientists have used declassified US Hexagon spy satellite imagery, data from the Shuttle Radar Topographic Mission in 2000 and data from modern satellites to examine the relationship between glaciers and glacial lakes since the 1970s.

The results show that glacier mass loss has occurred since at least the 1970s and has accelerated since the millennium. Glaciers in contact with glacial lakes, showed significantly higher mass loss and terminus retreat rates and are therefore likely to be driving the accelerating mass loss from the region.

Dr. Owen King, of the School of Geography and Sustainable Development at the University of St Andrews, said: “Further enhanced mass loss is very likely should the increases in the total number and area of glacial lakes continue.”

  • Himalayan lakes are exacerbating glacial melt
    Figure 5: Significant retreat of a glacier and growth of its proglacial lake in Sikkim Himalaya: comparison of the situation years 1974 based on Hexagon KH-9 US spy satellite data and 2017 Pleiades satellite data. Credit: University of St Andrews
  • Himalayan lakes are exacerbating glacial melt
    Figure 4: Lake Jialong Co in Central Hiamalya. Credit: T Bolch, University of St Andrews
  • Himalayan lakes are exacerbating glacial melt
    Figure 5: Significant retreat of a glacier and growth of its proglacial lake in Sikkim Himalaya: comparison of the situation years 1974 based on Hexagon KH-9 US spy satellite data and 2017 Pleiades satellite data. Credit: University of St Andrews
  • Himalayan lakes are exacerbating glacial melt
    Figure 4: Lake Jialong Co in Central Hiamalya. Credit: T Bolch, University of St Andrews

Dr. Tobias Bolch, also of the School of Geography and Sustainable Development, added: “Our results have important implications for future projections of ice loss from the region, as the interaction of glaciers and glacial lakes has not previously been considered in future glacier  estimates.”

The paper, “Glacial lakes exacerbate Himalayan glacier ,” by Owen King, Atanu Bhattacharya and Tobias Bolch, is published in Scientific Reports.


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More information: Owen King et al. Glacial lakes exacerbate Himalayan glacier mass loss, Scientific Reports (2019). DOI: 10.1038/s41598-019-53733-x

Journal information: Scientific Reports
Indigenous no-state people

Profile: Into the heart of the glacier

by Xinhua writers Cheng Lu and Wang Qin’ou

BEIJING, March 9 (Xinhua) — For most of his career, Yao Tandong has led researchers to drill into the heart of glaciers on the Qinghai-Tibet Plateau to collect ice cores, a key to understanding climate change.

In the process the plateau has also grabbed his heart, even when the eminent glaciologist steps into the Great Hall of the People in Beijing for the annual “two sessions.”

Known as Asia’s water tower, the Qinghai-Tibet Plateau is the source of major rivers of Asia, including the Yangtze, Yellow and Yarlung Zangbo, and a key eco-safety barrier.

Yao, 64, was among more than 2,000 members attending the ongoing session of the 13th National Committee of the Chinese People’s Political Consultative Conference (CPPCC), the top political advisory body.

From all walks of life — economists, scientists, teachers, doctors, artists and religious leaders — they are expected to offer proposals and insight on running state affairs.

In Fengda International Hotel in south Beijing, top scientists from various fields such as space exploration, quantum, climate change and medicine are gathering together to pool their wisdom for the country’s development.

This year, Yao’s proposal is related to the prevention and treatment of the more frequent disasters on the plateau including glacier collapses, floods and glacier lake outbursts.

Glaciers collapsed last October at the Yarlung Zangbo River in southwest China’s Tibet Autonomous Region, blocking the river and forming a barrier lake.

“The climate on the plateau, with a fragile ecosystem, is becoming warmer and more humid. Temperature rise here is twice the global average,” said Yao, honorary director of the Institute of Tibetan Plateau Research with the Chinese Academy of Sciences.

The reasons are yet to be totally clear, and Yao’s team have been working with other scientists at home and abroad to figure them out.

“Changes on the Qinghai-Tibet Plateau is not only Tibet’s business. It matters to other parts of China, its neighbors, and even the world,” he added.

Nearly all of the proposals submitted by Yao since he became a CPPCC member more than a decade ago were regarding the plateau. They have attracted the attention of Chinese authorities who regards the plateau’s ecological protection as a vital task.

In June 2017, China launched its second comprehensive scientific expedition to the plateau after more than 40 years. The expedition, which will last five to 10 years, aims to study changes in climate, biodiversity and environment over the past decades.

As the chief scientist of the expedition, Yao revealed the initial findings in September. One of the discoveries was that glaciers on the Qinghai-Tibet Plateau and neighboring regions have shrunk by 15 percent in the past half century.

“The Qinghai-Tibet Plateau is always at my heart. As a scientist member of the CPPCC National Committee, my job is to tell what I know, see and think, and offer my own suggestion based on the research,” Yao said.

Scientists believe that the information embedded in the ice core will help them solve the climate change mystery.

Despite his age, Yao still ascends the mountains at an altitude of around 6,000 or 7,000 meters, and often stays there with other glaciologists for several months. They drill into the heart of the glaciers to collect ice samples for further analysis.

The process is dangerous. One of his students described the scene: “You can see a board installed on different sections of the road, inscribed with the names of victims and the dates they left this world.”

The cracks on the glaciers, gales and blizzards pose dangers to researchers, who have to carry heavy equipment up the mountains on their shoulders.

When being asked what drives him, Yao said: “When you’re really interested in doing something, challenges will not hold you back.”

Growing up in Tongwei County in northwest China’s Gansu Province, Yao’s childhood was far removed from the glaciers. It was not until he visited Tanggula Mountains during an expedition in 1978 that he fell in love with Tibet and glaciers.

“In our traditional impression, Tibet was supposed to be cold and dry. It was August, and I saw rainy days and rivers,” he recalled. “It’s very beautiful.”

A climbing pack is always ready in his office, containing everything necessary for a scientific expedition.

Over the past decades, Yao and his colleagues have left their footprints on many mountains such as Qomolangma, Muztagh Ata, and Shishapangma. He received the 2017 Vega Medal in Stockholm, recognizing his contributions to the study of glaciers and the environment on the plateau and its surrounding areas.

China is one of the first countries to sign the Paris Agreement on climate change. As the topic has gradually attracted global attention, Yao said the once “cold” discipline of glaciology has gained popularity.

The Qinghai-Tibet Plateau is still one of the cleanest regions on earth, according to the white paper “Ecological Progress on the Qinghai-Tibet Plateau,” published by the Chinese government in 2018.

China is investing big and promoting international cooperation in the scientific research of Qinghai-Tibet Plateau, which is key to the world’s ecological environmental protection.

In 1984, Yao started cooperating with foreign counterparts: “Over the past years, we have never encountered hurdles in cooperation. Climate change has no boundaries.”

Source: Xinhua|Editor: Liangyu