Disaster in Nepal draws attention to risks of glacier melting
In Nepal, thousands of people are considered missing after a devastating mudflow, while the death toll is rising. Dozens of bridges were washed away, and major sections of roads were destroyed, complicating rescue operations in the mountainous Himalayan region, ABC News Australia reports.
Unstable slopes and glacial lakes
Scientists warn that warming is destabilizing the Himalayas. The Himalayan, Karakoram and Hindu Kush mountain systems contain more than 55,000 glaciers, which is why the region is called the “third pole.” It is warming faster than the global average, and glaciers are retreating.
Glaciologist Umesh Haritashya of the University of Dayton, who is taking part in an international investigation into the disaster, said that researchers have data on areas with unstable slopes and on the locations of glacial lakes. According to his research, more than 1,466 glacial lakes have been recorded in the region; most of them formed as a result of rising temperatures since the second half of the 20th century.
Such lakes may be contained by unstable natural barriers made of loose sediment and rocks. The collapse of a barrier, an avalanche, or a rockfall entering a body of water can create a wave that overtops the natural dam and causes a sudden flood.
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Permafrost thawing
An additional threat is the thawing of permafrost. Ice in mountain rocks binds rock fragments and sediments together, but as temperatures rise it melts, and slopes lose stability. This increases the risk of landslides, mudflows, and rock-ice avalanches.
A study by the Indian Institute of Technology Bhubaneswar, published this year, showed that the 0°C boundary at which permafrost remains solid is shifting higher into the mountains. At the same time, scientists stress that it is still too early to determine what exactly caused the glacier’s collapse during the current disaster. The glacier was located at an altitude of more than 5,000 meters, where temperatures are usually low enough for ice to remain frozen throughout the year.
Risks to infrastructure
Thawing frozen soils weakens their ability to bear loads. The ground can settle unevenly, subside, or collapse, creating problems for buildings, roads, bridges, pipelines, and power grids. Glaciologist and polar engineer Adrian McCallum of the University of the Sunshine Coast said that countries with cold climates, from North America to Asia, are increasingly facing this problem.
Climate historian Ruth Gamble, who is in Kathmandu, also drew attention to changing precipitation patterns. According to her, monsoons are becoming more uneven, while warmer air brings more rain instead of snow. She noted that flash floods and landslides have occurred in the region before, but such events are now happening increasingly often.
