The Himalayas contain the third-largest accumulation of ice and snow on Earth, after the two poles. The region is also warming faster<\/a> than the rest of the world, raising questions about what climate change \u2013 with snow lines retreating and glaciers melting \u2013 might mean for the frequency and destructiveness of avalanches across the 2,500-kilometre Himalayan range.<\/p>\n\n\n\n Aisha Khan<\/a>, 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 \u201cexpected consequence\u201d of climate change in the Himalayas.<\/p>\n\n\n\n In 2018, scientists from the University of Geneva in Switzerland published research<\/a> 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.<\/p>\n\n\n\n Previously, they found, avalanches were rare in the region, with \u201cvirtually no activity between the 1940s and 1960s\u201d. In the 1970s and 1990s, by contrast, they noted \u201cvery high activity\u201d.<\/p>\n\n\n\n \u201cOur study has shown a recent increase in the number of snow avalanches, which matches with an increase of temperature in late winter \/ early spring,\u201d says Juan Antonio Ballesteros-C\u00e1novas<\/a>, a senior lecturer at the University of Geneva\u2019s Institute for Environmental Sciences<\/a> and lead author of the study.<\/p>\n\n\n\n Scientists have established that temperature and precipitation patterns in the Hindu Kush Himalayas have changed significantly<\/a> 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 \u2013 the layers of compressed snow that cover much of the rock in the Himalayas\u2019 higher reaches \u00ad\u2013 and destabilising slopes, she says.<\/p>\n\n\n\n Warmer temperatures mean that rain, rather than snow, is falling more often<\/a> than in the past. \u201cMost precipitation now falls in the form of rain, reducing the snowfall on the relatively lower reaches,\u201d says Sourav Laha<\/a>, a glacio-hydrologist at India\u2019s National Centre for Polar and Ocean Research. Laha says that precipitation \u2013 whether new snow or rain \u2013 can increase the risk of an avalanche.<\/p>\n\n\n\n There are a number of types<\/a> of avalanches, but they mainly fall into two groups: sluffs and slabs. A sluff avalanche<\/strong> is when a weak top layer of snowpack slides downhill as a powdery, formless mass.<\/p>\n\n\n\n A slab avalanche<\/strong> occurs when there is a weak layer lower down in the snowpack, covered by other layers of compressed snow. When triggered, the weak layer breaks off and takes with it all the layers on top of it, which fall down the slope as a block or slab. This is much more dangerous than a sluff avalanche.<\/p>\n\n\n\n Wet snow avalanches<\/strong> may occur as a slab or as loose snow. They are caused by liquid water in the snowpack, coming from rainfall or melting caused by the sun or warm temperatures. The presence of water weakens the bonds between the layer boundaries. This type of avalanche occurs particularly during springtime, especially after rain or daytime warming.<\/p>\n\n\n\n Sources: <\/em>National Geographic<\/em><\/a>, <\/em>Avalanche.org<\/em><\/a>, <\/em>WSL Institute for Snow and Avalanche Research SLF<\/em><\/a><\/p>\n<\/div><\/div><\/div>\n\n\n\n Rain falling on snow is a common trigger<\/a> of wet-snow avalanches. As the water percolates through the snowpack, it can weaken its structure<\/a>, 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 \u2013 and therefore make avalanches more likely.<\/p>\n\n\n\n On the steep slopes of the Himalayas, \u201cthe transformation of dry snowpacks into wet snowpacks is decisive for releasing snow avalanches,\u201d Laha says.<\/p>\n\n\n\n In a 2021 paper<\/a>, experts from Italy, Switzerland and the United States wrote that \u201cwith a wetter and warmer snow climate, consequences of burial [by an avalanche] may become more severe\u201d. 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. \u201cAsphyxia and trauma as causes of avalanche death may therefore increase,\u201d they conclude.<\/p>\n\n\n\n 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.<\/p>\n\n\n\n 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 \u2013 with little opportunity to input into policy,\u00a0infrastructure planning<\/a>, or disaster preparedness. <\/p>\n\n\n\n According to Juan Antonio Ballesteros-C\u00e1novas 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\u2019s Avalanches in High Mountain Asia database<\/a> shows that deadly avalanches have become more common, particularly in the past 20 years.<\/p>\n\n\n\nAre avalanches becoming more frequent in the Himalayas?<\/h2>\n\n\n\n
![\"Annapurna](\"https:\/\/dialogue.earth\/content\/uploads\/2023\/05\/F20RJR_Avalanches-Annapurna-himalayas-climate-change.jpg\")
<\/div>Wetter snow leads to more avalanches<\/h2>\n\n\n\n
Are Himalayan avalanches becoming more dangerous?<\/h2>\n\n\n\n