T.V. Padma
The Third Pole
December 12, 2014
New study will map risks associated with thawing ‘permafrost’ – or frozen soil – due to global warming, which may cause extensive damage to environment and infrastructure
Melting permafrost will lead to landslides, flooding and loss of wildlife habitat (© Wu Haitao / Greenpeace)
For the first time, the Indian government is planning a pilot study of permafrost in Himachal Pradesh. It is expected to provide crucial data in a little-studied area of climate change impact in the Himalayas.
Part of an Indo-Swiss science and technology initiative, the study will look at whether global warming is thawing the permafrost that is typically found at elevations of 2,400-2,800 metres in the Himalayas, depending on the direction and exposure of the slopes.
Unlike the Andes and the Alps where scientists have collected data on permafrost – soil at or below the freezing point of water – there is no data from the Himalayas, says Markus Stoffel, professor at the Institute of Environmental Sciences, University of Geneva, and lead scientist from Switzerland for the project. Rising temperatures are believed to have led to permafrost melting in these ranges, and in Alaska.
The only indication of possible extensive presence of permafrost in the Himalayas comes from a global study by Stephan Gruber, department of geography, University of Zurich, which analyses mean annual temperatures at various heights along slopes. “But it is no direct proof,” points out Stoffel.
When permafrost melts, the land above it sinks or changes shape, and the shifting ground could potentially damage buildings and infrastructure such as roads, airports, and water and sewer pipes. It also causes landslides, slope collapse, and glacial lake outburst floods (GLOFs) and topples trees.
Permafrost received considerable attention in the latest fifth assessment report of the Intergovernmental Panel on Climate Change, but much of the focus is on studies from the European Alps, says Stoffel. In the Hindu-Kush Himalayas, where many people live in areas with permafrost or those that will be impacted by permafrost melt, data is absent.
The study in India will attempt to gain a first impression of permafrost in the region, including insights into areas where it is present, and areas where it is close to melting point which is a critical situation as it increases the risk of increased loose rock fragmentation and debris flow.
It will use a combination of methods: satellite imagery, identifying areas with potential permafrost features such as tongue-shaped rock glaciers, and mapping areas with active and fossil permafrost features. Rock glaciers or frozen rock debris cemented by ice are considered important indicators of permafrost.
Scientists will also combine permafrost analysis with an assessment of hazards, to help develop a framework for assessment of risks and vulnerability to natural hazards in the Himalayas.
Downstream areas are also vulnerable to the impacts of permafrost thawing. “Melting of Himalayan permafrost would contribute to river floods downstream in neighbouring Bangladesh too,” N.B. Kishore Tripura, secretary, Ministry of Chittagong Hill Tracts Affairs, Bangladesh, told an international conference on mountain people adapting to climate change, held in Kathmandu in November.
While the Indo-Swiss study will glean insights on a limited scale at a local level, another project initiated by the Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD) is attempting for an overarching view of permafrost in the entire Hindu-Kush-Himalayan region. It was initiated in 2013 and is scheduled to end in mid-2015.
Arun Bhakta Shreshtha, regional programme manager, river basin development, in ICIMOD, says permafrost is the least studied part of the three components of the Himalayan cryosphere – the frozen part of earth. Most of the attention is on the other two components: glaciers and snow, as they are visible and one can observe their changes. “Glaciers also have a dramatic aura about them, while snow cover is huge, and so any changes in them can be not only observed long-term but also updated regularly,” says Shreshtha.
In contrast, permafrost that lies obscured under rocks or boulders does not catch anybody’s attention.
“Himalayan permafrost has absolutely not been studied,” and there are only “bits and pieces” of studies on infrastructure, housing, railways in scattered locations, says Shreshtha.
“When we started, we did not know what to map and where to map. So the ICIMOD team began by mapping rock glaciers – as a proxy to permafrost locations. It is very likely that permafrost lies in areas with rock glaciers.”
Rock glaciers have a substantial amount of ice, and move at the rate of 1-2 decimetres to 1-2 metres every year. “But in the last three or four years, they have been observed to be moving at a rate of 100-150 metres every year,” which is being attributed to rising temperatures, he adds.
The Himalayan data could add to global efforts to understand the impacts of permafrost melting due to global warming. A 2012 United Nations Environment Programme (UNEP) report says Arctic and alpine air temperatures are expected to increase at roughly twice the global rate, and climate projections indicate substantial loss of permafrost by 2100. A global temperature increase of three degrees Celsius means a six-degree Celsius increase in the Arctic, resulting in anywhere between 30% to 85% loss of near-surface permafrost, the report says.
Landslides, floods and loss of wildlife habitat
The UNEP report cautions that widespread permafrost degradation “will permanently change local hydrology, increasing the frequency of fire and erosion disturbances.” Disappearing permafrost will also impact critical habitat, particularly for migratory birds.
“Risks associated with rock fall and erosion will increase, particularly in cold mountain areas,” while damage to critical infrastructure, such as buildings and roads, “will incur significant social and economic costs,” it warns.
Stoffel explains that the frozen permafrost acts as an underground binder, with soil, humus, and disintegrated rock particles. “When it melts, the bound particles are loosened and the permafrost water melt produces a debris flow.”
According to ICIMOD experts, glacial lakes or hydropower dams in the vicinity of mountains with permafrost will witness an increase in rockfall hazards, which may lead to outburst floods with grave downstream consequences.
When permafrost in moraines and debris slopes thaws, the sediments are deposited in lower reaches of rivers, the experts say.
This could happen either as a slow and steady process, or as a catastrophic event in combination with extreme precipitation, destroying downstream infrastructure such as houses, bridges and roads.
