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Tibetben: A lassan mozgó fölcsuszamlást bemutató drámai videó kérdéseket vet fel a klímaváltozással kapcsolatban

2017. szeptember 13./ICT/TibetPress

Jelenleg csak angolul olvasható. Magyarul később.

eredeti cikk



graphic video depicting a slow-moving landslide, looking like a lava flow, in a nomadic area of eastern Tibet has circulated online leading to questions about climate change and grasslands degradation on the world’s highest and largest plateau. The video shows the top layer of the grasslands sliding downhill in a steady stream, near livestock and nomadic dwellings, as Tibetans look on in distress.

National Geographic described it as “an earthflow, a type of landslide that generally oozes […] unlike some landslides that can be quick and sudden.”.[1] As the video began to circulate on social media, there was speculation that the earthflow was caused by melting permafrost. Permafrost plays an important role in cold environments by keeping the overlying layer of soil in place and serving as the foundation on top of which trees and plants grow.[2] While Siberian permafrost is deep and permanent, in Tibet the alternate freezing and thawing of the earth at the surface or just below it comes and goes seasonally, or sometimes even daily because of the wide temperature swings between day and night.

The location of the earth-flow in Tibet has been identified as Dimye village in the Tibetan area of Kham in Dzatoe township, Trindu (Chinese: Chènduō) county, Yulshul (Ch: Yùshù) Tibetan Autonomous Prefecture in Qinghai. A second video shows a white van that appears to be stuck in the earth-flow. According to a Chinese language website, the family affected is being relocated.

In a microblog thread about the video, geophysicist Mika McKinnon posted on September 9: “Earthflows are slow-moving fine-grained material saturated with water. This looks like rich soil; melty permafrost fits the criteria.”

While it is not known whether this video depicts melting permafrost, a new scientific survey carried out in Tibet shows that melting permafrost may be a more dangerous threat to the fragile high-altitude ecosystem than glacial melt, according to the website GlacierHub.[3] The study, by five Chinese scientists, found that permafrost melt was becoming a central driver of alpine lake expansion and related environmental hazards. The Tibetan plateau, source of most of Asia’s major rivers and a global biodiversity hotspot, is warming more than twice as fast as the rest of the world.[4]

In the case of the Yushu earthflow, Mika McKinnon and other scientists agreed that it is impossible to decisively determine what caused the landslide from the video alone. On his blog about landslides, Dave Petley, Pro-Vice-Chancellor at the University of Sheffield in the UK, pointed out that it may not depict melting permafrost, because the video does not show any obvious frozen soil or ice blocks. He writes: “To me this is quite reminiscent of the landslides that we see in peat in the uplands of Europe. […] The soils involved in the Dimye village landslide are extremely dark in color, which suggests that they are rich in organic matter. It is not possible to say whether this is indeed a peat landslide, or something similar in an organic soil, or a permafrost slide.”

Dave Petley cites a recent academic paper in which Chinese scientists describe peat areas in Tibetan area, noting that there is significant environmental degradation occurring in these places, causing rapid peat loss. The paper states: “Often referred to as the ‘Third Pole’, China’s Qinghai–Tibetan Plateau developed large amounts of peatland owing to its unique alpine environment. As a renewable resource, peat helps to regulate the climate as well as performing other important functions. However, in recent years, intensifying climate change and anthropogenic disturbances have resulted in peatland degradation and consequently made sustainable development of peatland more difficult.”[5]

An elderly Tibetan nomad in eastern Tibet who watched the video said that he had never seen anything like the earth-flow, nor heard about anything similar from other nomads of his generation. A relative in exile who showed him the video said: “He found it a frightening phenomena, and said that he had heard of sandstorms and ‘snow floods’ (avalanches), also landslides from the top of mountains to the bottom, but never about the grasslands that flowed across the land like a river. He said there is no language for that in Tibetan.”

Tibet environment specialist Gabriel Lafitte states that the process occurring in the video appears to be gelifluction, which is the seasonal freeze-thaw action upon waterlogging topsoils that induces downslope movement. Gelifluction is prominent in periglacial regions where snow falls during six to eight months of the year, and results in bare rock scree that will not support plants for some time afterwards. Gabriel Lafitte, whose blog about environmental and other issues in Tibet is at: www.rukor.org, says that gelifluction usually occurs at the upper limit of where sedges can grow, along a belt at a fixed altitude. “China calls this degradation, but in fact it is perfectly natural, and happens intermittently whether the sedges are grazed or not,” he says.

According to the National Geographic, University of Sussex geography professor Thomas Opel noted that he saw a slide similar to the one in Tibet in the Siberian Arctic. “In many regions, the depths of the seasonal thawing have increased due to climate warming,” he said. As greenhouse gases increase global temperatures, warming permafrost can in turn release a slew of carbon and further raise temperatures.

The Golmud-Lhasa railway, which has had a dramatic impact on Tibet’s demography and development, could not have been built without massive investment by the Chinese authorities into how to construct infrastructure on the shifting, fragile ground of the Tibetan plateau. China’s top permafrost research facility, the Cold and Arid Regions Environmental and Engineering Research Institute, is based in Lanzhou. However just a month after the line had gone into operation in 2006, the state media made a rare admission that fractures had started to appear in some railroad bridges because of permafrost movements under the rail bed.[6] The official press acknowledged that rising temperatures on the Qinghai-Tibet plateau could threaten the long-term viability of the railway.[7]

Scientists have also documented how a combination of urbanization, intensified militarization linked to China’s strategic aims, infrastructure construction and warming temperatures are creating an ‘ecosystem shift’ in Tibet.[8] This involves irreversible environmental damage, including the predicted disappearance of large areas of grasslands, alpine meadows, wetlands and permafrost on the Tibetan plateau by 2050, with serious implications for environmental security in China and South Asia.

China is currently conducting its second major scientific study of the Tibetan plateau, using drones and satellites, 40 years after the first such survey. The Chinese state media said that the findings will be used to provide scientific support for “economic and social development in Tibet” (Xinhua, March 27, 2017).[9] The scientific survey is aligned with the Chinese Communist Party’s strategic and economic priorities in Tibet – the plateau’s natural and mineral reserves are vital to the future of China and its economic expansion. Tibet’s water is needed to address the progressive scarcity of water resources in the North and North-East of China,[10] and to ensure the productivity of the core industrial cities of Xi’an, Chongqing and Chengdu at the foot of the plateau, involving the expansion of mining the rich resources of Tibet, including lithium, uranium and gold.[11] Because Tibet’s environment is seen as a strategic asset by the CCP leadership, Beijing’s policies on Tibet remain exempt from genuine debate and enquiry.


Footnotes:
[1] National Geographic posting by Sarah Gibbons, September 12, 2017, http://news.nationalgeographic.com/2017/09/permafrost-thaw-landslide-tibet-video-spd/

[2] Permafrost is defined as “perennially frozen ground remaining at or below 0°C for at least two consecutive years,” according to a document on the policy implications of warming permafrost, released by the United Nations Environment Programme. The thickness of permafrost is determined by the distance between the top of the permafrost layer, known as the permafrost table, and the bottom, also called the permafrost base. There may be an active layer above this, which thaws and freezes seasonally. The most robust type of permafrost is continuous coverage, where the permafrost table is very thick and extends for many meters into the soil. Areas with larger gaps in the permafrost can be called discontinuous permafrost zones, or sporadic permafrost.

[3] ‘On Tibetan Plateau, Permafrost Melt Worse Than Glacial Melt’, Posted by Brittany Watts on Jan 14, 2015, referring to a study published in the journal in the journal Public Library of Science, http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0111890#s2

[4] See ICT report, ‘Blue Gold from the Highest Plateau: Tibet’s Water and Global Climate Change’, https://www.savetibet.org/new-report-reveals-global-significance-of-tibet/

[5] ‘Qinghai–Tibetan Plateau peatland sustainable utilization under anthropogenic disturbances and climate change’ published on March 21, 2017, at: http://onlinelibrary.wiley.com/doi/10.1002/ehs2.1263/full. Authors: Gang Yang, Changhui Peng, Huai Chen, Faqin Dong, Ning Wu, Yanzheng Yang, Yao Zhang, Dan Zhu, Yixin He, Shengwei Shi, Xiaoyang Zeng, Tingting Xi, Qingxiang Meng, Qiuan Zhu

[6] Xinhua, June 26, 2007, cited in ICT report ‘Tracking the Steel Dragon: How China’s Economic Policies and the Railway are Transforming Tibet’, https://www.savetibet.org/tracking-the-steel-dragon/

[7] See ICT report ‘Tracking the Steel Dragon: How China’s Economic Policies and the Railway are Transforming Tibet’, https://www.savetibet.org/tracking-the-steel-dragon/

[8] Scientists from the Kunming Institute of Botany warned that warming temperatures, combined with a dramatic infrastructure boom, a growing population and over grazing will combine to push fragile ecosystems on the world’s largest and highest plateau from one state to another. ‘Building ecosystem resilience for climate change adaptation in the Asian highlands’ by JIANCHU XU, R. EDWARD GRUMBINE, Published Online: Aug 28, 2014, at http://wires.wiley.com/WileyCDA/WiresArticle/wisId-WCC302.html . Also see https://www.chinadialogue.net/blog/7422-Tibetan-plateau-faces-massive-ecosystem-shift-/en and ICT report: ‘Blue Gold from the Highest Plateau: Tibet’s Water and Global Climate Change’, https://www.savetibet.org/new-report-reveals-global-significance-of-tibet/

[9] Also Xinhua, March 26, 2017: “China to conduct 2nd scientific survey on Qinghai-Tibet Plateau”, published in Global Times in English at http://www.globaltimes.cn/content/1039661.shtml;

[10] See for instance the report by China Water Risk, March 2010: “China’s Water Crisis”, at http://chinawaterrisk.org/wp-content/uploads/2011/06/Chinas-Water-Crisis-Part-1.pdf;

[11] See Gabriel Lafitte’s book “Spoiling Tibet: China and Resource Nationalism on the Roof of the World”, 2013, Zed Books;

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