Explained: How Climate Change Worsens Avalanches in the Himalayas
Humaira Nabi
In recent months, numerous reports of dangerous avalanches in the Himalayas have made the headlines. These sudden releases of snow, ice and rocks sweep down mountainsides, burying any people, animals and infrastructure in their path.
In the Indian Himalayas alone, at least 120 people have been killed by avalanches over the last two years. In April 2023, three sherpas were buried in a crevasse by an avalanche on Mount Everest.
The Himalayas contain the third-largest accumulation of ice and snow on Earth, after the two poles. The region is also warming faster than the rest of the world, raising questions about what climate change – with snow lines retreating and glaciers melting – might mean for the frequency and destructiveness of avalanches across the 2,500-kilometre Himalayan range.
Are avalanches becoming more frequent in the Himalayas?
Aisha Khan, chief executive of the Pakistan-based Mountain and Glacier Protection Organization and the Civil Society Coalition for Climate Change, says that an increase in avalanche activity is an “expected consequence” of climate change in the Himalayas.
In 2018, scientists from the University of Geneva in Switzerland published research that reconstructed avalanches over the last 150 years in the Indian Himalayan state of Himachal Pradesh, using indications gathered from tree rings. They found that snow avalanches occurred much more frequently in the last 50 years compared with the previous 100, and concluded that the number of avalanches in the western Indian Himalayas has been rising since the 1970s.
Previously, they found, avalanches were rare in the region, with “virtually no activity between the 1940s and 1960s”. In the 1970s and 1990s, by contrast, they noted “very high activity”.
“Our study has shown a recent increase in the number of snow avalanches, which matches with an increase of temperature in late winter / early spring,” says Juan Antonio Ballesteros-Cánovas, a senior lecturer at the University of Geneva’s Institute for Environmental Sciences and lead author of the study.
Wetter snow leads to more avalanches
Scientists have established that temperature and precipitation patterns in the Hindu Kush Himalayas have changed significantly over the past 100 years. With its steep mountain slopes, the Himalayan region is naturally avalanche-prone, Khan points out. But warmer temperatures are changing the structure of the snowpack – the layers of compressed snow that cover much of the rock in the Himalayas’ higher reaches – and destabilising slopes, she says.
Warmer temperatures mean that rain, rather than snow, is falling more often than in the past. “Most precipitation now falls in the form of rain, reducing the snowfall on the relatively lower reaches,” says Sourav Laha, a glacio-hydrologist at India’s National Centre for Polar and Ocean Research. Laha says that precipitation – whether new snow or rain – can increase the risk of an avalanche.
Rain falling on snow is a common trigger of wet-snow avalanches. As the water percolates through the snowpack, it can weaken its structure, causing melting, changing the shape and texture of grains of snow, and reducing the friction that holds the grains together. Rainwater can also accumulate and alter the distribution of weight in certain areas of the snowpack, creating new stresses. These changes can result in less stable snow cover – and therefore make avalanches more likely.
On the steep slopes of the Himalayas, “the transformation of dry snowpacks into wet snowpacks is decisive for releasing snow avalanches,” Laha says.
Are Himalayan avalanches becoming more dangerous?
In a 2021 paper, experts from Italy, Switzerland and the United States wrote that “with a wetter and warmer snow climate, consequences of burial [by an avalanche] may become more severe”. The paper says that avalanches may cause more traumatic injuries in a warmer climate, since thinner snow cover offers less protection from underlying rock, and that people buried in wetter, denser snow are at higher risk of suffocating. “Asphyxia and trauma as causes of avalanche death may therefore increase,” they conclude.
The same paper notes that unlike the European Alps, in the Himalayas there are few protective structures in place like snow fences, barriers and snowsheds to reduce the impact of avalanches on infrastructure, leaving the local population at risk.
This is compounded by the fact that in most Himalayan countries, the population in mountainous areas is on average poorer than in other regions. This economic marginalisation often means mountain communities are overlooked in governance – with little opportunity to input into policy, infrastructure planning, or disaster preparedness.
According to Juan Antonio Ballesteros-Cánovas from the University of Geneva, avalanches are becoming more dangerous in the Himalayas, as warming leads to the degradation of permafrost. Data from the International Centre for Integrated Mountain Development’s Avalanches in High Mountain Asia database shows that deadly avalanches have become more common, particularly in the past 20 years.
Avalanches are also a major trigger of another growing risk in the Himalayas: glacial lake outburst floods (GLOFs). These occur when meltwater that has accumulated at the snout of a glacier breaches the dam holding it back, thanks to a trigger such as an earthquake or avalanche. Analysis of 30 GLOFs that occurred in the Hindu Kush Himalayas since 1930, conducted by scientists at the University of East London in the UK, found that 23% were started by avalanches.
Less snow, more wind and retreating glaciers could mean more avalanches
Javier Martin-Torres, professor of planetary sciences at the University of Aberdeen in the UK, explains that when snow accumulates to form snowpack in the Himalayas, this creates a natural ‘glue’ that prevents fresh snow from sliding off the mountain slopes in an avalanche. A decrease in snow in the region has reduced this ‘glue’, he says, “leading to an overall increase in the frequency of avalanches”.
Martin-Torres adds that the melting and retreating of glaciers in the Himalayas, brought on by the region’s warmer temperatures, can lead to avalanches. As a glacier melts, water accumulates as its base and this can cause ice to slide, raising the likelihood of an avalanche being triggered, says Martin-Torres.
Climate change is also altering wind in the Himalayas, another factor in avalanche risk, he says. “The rising temperatures have caused increased wind speeds in the region, allowing the snow to become even more mobile and susceptible to gaining mass and moving quickly in an avalanche,” Martin-Torres explains.
Why are the Western Himalayas particularly at risk from avalanches?
According to Aisha Khan, while snow cover in the high reaches of the Himalayas means there is a risk of avalanches across the mountain range, “the regions in the Western Himalayan belt, including Himachal Pradesh and Uttarakhand [states of India] are more prone.”
More than 1,100 square kilometres of snow cover in the Western Himalayas (north-western India and northern Pakistan) has been classified as ‘avalanche sites’ by Indian government research centre the Snow and Avalanche Study Establishment, and an average of 49 people are killed by snow avalanches in the region every year.
The University of Geneva study which used tree rings to reconstruct avalanches over the past 150 years in Himachal Pradesh concluded that rising air temperatures in winter and early spring have increased snow-wetting in the western Indian Himalayas, leading to more wet snow avalanches. Over the previous 25 years, maximum and mean temperatures have risen across the north-western Himalayas.
What can be done to reduce risk of avalanches in the Himalayas?
Sourav Laha from India’s National Centre for Polar and Ocean Research says it is important to identify potential avalanche hotspots across the Himalayas, and carry out risk assessments before developing infrastructure. He adds that environmental impact assessments for projects near glaciers should thoroughly scrutinise the projects’ disaster-mitigation measures.
More generally, measures to slow and control avalanches that could be deployed more broadly in the Himalayas include:
- Catch dams, which slow down avalanches
- Diversion dams, which deflect avalanches away from where they could pose a risk to life and property
- Earthen mounds, which create friction to slow down avalanches on relatively flat slopes
- Planting trees, which can slow avalanches, cushioning their impact
(Humaira Nabi is an independent journalist based in Kashmir. Courtesy: The Third Pole, a multilingual platform dedicated to promoting information and discussion about the Himalayan watershed and the rivers that originate there.)
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Taking Stock of India’s Himalayan Crisis
Rashme Sehgal
The vast green cover of the Himalayan range has been an eco-service provider for India and all countries around its mountain chains. Combined with the Karakoram region, it has the largest volumes of snow and ice outside the polar regions. The Himalayan region is the source of major Asian rivers and a regional and global climate regulator. Yet it is also a fragile ecosystem where a great deal of anthropogenic activity takes place. The biggest source of disruption to this delicate region over the last decade has been the race to build infrastructure, especially hydropower projects, roads, airstrips, railways and tunnels, even in the higher mountain reaches.
What we can look back to over the last decade in this region is incessant activity, often sanctioned despite warnings about melting glaciers and disappearing permafrost. This development pattern is self-destructive, considering Earth’s rising temperatures. There are already over 1,500 dams, functioning or under construction, in India, China, Bhutan, Nepal and Pakistan. Scientists warned over a decade ago in a study published in the journal Conservation Biology that the Himalayan region will soon have the highest dam density—one dam per 32 kilometres of river channel—most of them in areas known for high species diversity, such as Sikkim. Some parts of India had already overtaken the global dam intensity metric when the widely-reported study was published. Conducted by the Centre for Inter-disciplinary Studies of Mountain and Hill Environment at Delhi University and R Edward Grumbine of the Kunming Institute of Botany, China, this report analysed the impact of 132 of the 292 dams in the Indian Himalayas at the time.
It hardly needs mention that the best practices are still being ignored in the construction and development of these regions, and the tiny state of Uttarakhand has been bearing the brunt of this. According to the Forest Survey of India 2019, between January 2015 and February 2019, over 2,800 hectares of forest land were diverted for non-forestry purposes under the Forest Conservation Act of 1980. In 2014-15, nearly 64% of the land in Uttarakhand was forest. In the 2019 report, this had slipped to just below 565 of the land area. Today, metal roads in Uttarakhand alone cover 40,000 kilometres of route. The problem is that many roads, like those under the 900-kilometre Char Dham project, have had experts warn of violation of environmental norms and well-laid conservation strategies and plans of successive governments. The Char Dham project envisages four-laning from the plains to the religious sites at Gangotri, Yamunotri, Badrinath and Kedarnath, a process involving cutting slopes vertically, resulting in destabilised slopes.
The Union Ministry of Science and Technology had in June 2010 released a document emphasising the need to build roads fully compliant with the Himalayas’ fragile environment. This report was prepared as part of a “national mission” to sustain the Himalayan ecosystem, but the government itself flouts warnings in such documents in favour of unscientific road widening, leaving people to cope with the catastrophic consequences.
The result is eight landslides per day and tremendous hardship for pilgrims and tourists alike. One of the worst was in June, near Pithoragarh on the border with China, which left 300 tourists stranded for five days and nights. The Char Dham project has seen several tourists die in landslides. In 2020, the National Crime Records Bureau recorded 264 deaths from cyclones and landslides the previous year; landslides were the dominant cause of death in Mizoram, Arunachal Pradesh, Kerala and Uttarakhand.
Dam construction is also causing irreversible damage to India’s hilly and mountainous terrain. No town symbolises this better than Joshimath, also in Uttarakhand, whose residents blame the National Thermal Power Corporation’s Vishnugad-Tapovan hydropower project for damaging their homes and livelihoods. Blasting work on the Tapovan tunnel had been on for over two decades when there was a sudden significant subsidence in the dwellings and roads of the area in 2022.
The local and state authorities ignored the residents’ complaints about subsidence for years and ultimately resorted to demonstrations. The National Remote Sensing Centre confirmed that Joshimath had sunk 9 cm between April and November 2022 and 5.4 cm over just 12 days in January 2023.
But Joshimath is not the only city facing this problem. Geologist Prof SP Sati points out that cities are sinking across Uttarakhand from Nainital, Uttarkashi, Bhatwari, Gopeshwar, Guptkashi, and Karnpragyag to Mussorie, where homes and hotels have developed cracks. The problem is spreading to different parts of the country, as reports show, including Jammu and Kashmir, and it is unfair and incorrect to call these incidents “natural” disasters or “acts of god”, since it is caused by poor planning and unscientific development.
Like many geologists, Sati blames tunnelling for the Rishikesh-Karnprayag rail project and the use of dynamite on the Char Dham project.
Dr C P Rajendran, adjunct professor at the National Institute of Advanced Studies, Bengaluru and an expert on earthquakes, has frequently warned against the large-scale infrastructure projects (66 tunnels and over 200 dams under construction in Uttarakhand) that risk the fragile ecosystem of the small hilly state. He believes the 125 km rail track (105 km will be tunnelled) adversely impacts Himalayan tectonics.
“There is a belief that building tunnels may decrease the impact of infrastructure on the environment. But these subsurface structures could result in gross damage to the environment,” says Rajendran.
“Rail traffic may rely on electric locomotion, but constantly generated vibrations during train movement in tunnels would also weaken rock formations, leading to landslides besides generating a huge waste,” he explains.
Rajendran and other scientists warn that the Himalayan environment—including in China, Nepal and Bhutan—is on the brink of collapse and may not withstand another anthropogenic push. Massive construction in semi-permafrost leads to landslides and avalanches in all these countries. In Pakistan, the Shispir glacier in Gilgit Baltistan has been melting due to global temperature rise, creating unstable lakes. There was a massive spillover in May 2022, in which a historic bridge on the Karakoram Highway was damaged, apart from houses, agricultural land and two hydropower projects destroyed.
In February 2021, part of the Nanda Devi glacier broke off, triggering a massive flash flood in the Rishiganga River, destroying two hydropower projects and causing the death of 200 workers, most trapped in an under-construction.
In winter 2021, which was unusually warm, avalanches, usually expected in March-April, occurred in February. Extreme weather is frequent, while hazardous construction amplifies problems in eco-sensitive regions.
Against this backdrop, scientists worldwide are urging the Himalayas to be declared an international biosphere reserve where no hazardous or anti-ecological activity is permitted. The people in these countries are highly vulnerable to climate change effects, and it seems India is jeopardising their future for short-term gains. All efforts should be made to reverse this trend and strengthen our vulnerable ecosystems.
(The author is a freelance journalist. Courtesy: Newsclick.)
