Hundreds of people have been killed and more than 1,500 are still missing after devastating flash floods swept the Nepal-Tibet border.
Scientists think the disaster was caused by the collapse of a glacier on Langtang-Lirung Mountain, which had a magnitude of 5.2 earthquake.
While it may take months of investigation to uncover the exact story, experts are already warning that this is ‘not a one-off event’.
Dr. Jonathan Carrivick, a glacier flooding expert from the University of Leeds, told the Daily Mail: ‘Climate change warms the mountains, causing permafrost and glaciers to melt.”
According to the expert, this ‘makes the chance of these types of events – possibly greater – more frequent.’
Overall, researchers estimate that as many as 15 million people worldwide live in danger zones.
While the Himalayas, Karakoram, Hindu Kush and adjacent areas in Asia are most at risk, people in the US and Canada are also at risk.
“North America could experience something similar to what we are seeing in Nepal today,” Dr. Carrivick warned.
As rescue efforts continue in flood-affected areas of Nepal and Tibet, scientists have mapped out which glaciers around the world are at risk of a similar disaster. Here the red areas show areas of high flood risk from Glacial Lake Overflow in North America
Asia’s High Mountains are the most threatened region because they are rapidly warming and home to rapidly melting glaciers, growing meltwater lakes and some of the steepest mountains in the world.
Hundreds of people have been killed and more than 1,500 are still missing after devastating floods swept the Nepal-Tibet border.
Although scientists are still struggling to understand the disaster, current evidence points to deadly flooding in Nepal are the result of the collapse of the glaciers.
Dr. Carrivick says: ‘This event in Nepal appears to have been a massive rock break that took away a large part of the glacier.’
According to the Antarctic Glaciers research group, which combines the efforts of about fifty leading experts, an initial analysis shows that a landslide and glacier collapse occurred shortly before the flood.
This caused ice and rock to flow down the mountain, mixing with sediment left by previous floods and temporarily blocking the Lhende Khola River.
That temporarily created a large lake before breaking through in a devastating flood.
Deadly events like these have occurred in the past and will likely continue to occur with increasing regularity as climate change continues.
In 2021, for example, huge rocks and ice caused a deadly flow of debris, killing more than 200 people and damaging two hydroelectric power stations.
Meanwhile, in Canada, a landslide in 2020 dumped 18 million cubic meters of rock into a glacial lake, sending 100-metre-high waves scouring a 10-kilometre-long channel.
Outside Asia, glaciers in the Alps also put many areas at high risk of glacial lake flooding
The researchers note that the Andes is a risk area that may have been greatly undervalued in previous research
Scientists say Nepal’s floods were not caused by glacial lake flooding, but warn this associated risk is increasing around the world. In the photo: Distribution of people at risk of flooding from glaciers
Scientists have also raised the alarm that mountainous areas are increasingly at risk of a similar threat, known as a Glacial Lake Outburst Flood (GLOF).
This happens when meltwater from a glacier forms a large lake at its base that is held back by a thin, unstable natural dam.
If the glacier collapses or the meltwater gets too high, that barrier could break, releasing a devastating cascade downhill.
Scientists currently do not believe the deadly floods in Nepal and Tibet were caused by a GLOF because satellite images do not show any large lakes that formed in the area before the landslide.
However, glaciers around the world now are putting more people at risk from this form of floodingwhich could prove just as, if not more, deadly than what has been seen in Nepal.
In their article, published in Nature communicationresearchers used the latest models to map where this risk was highest.
They found that more than half of the 15 million people threatened by GLOFs live in just four countries: India, Pakistan, Peru and China.
Populations in the High Mountains of Asia (HMA), including the Himalayas, Karakoram, Hindu Kush and adjacent areas, are most at risk.
Scientists currently believe that the floods were caused by a rockslide that led to the collapse of the glaciers on Langtang-Lirung Mountain
Geological factors in the Himalayas lead to ‘hazard cascades’, chain reactions that release enormous amounts of ice and water in populated areas – much like the recent disaster in Nepal
Here, on average, people are most exposed and live closest to glacial lakes, while more than a million people live within ten kilometers of one glacial lake.
This region is home to 62 percent of all people exposed to GLOFs, including three million in India and two million in Pakistan.
Co-author Dr Matt Westoby, associate professor of physical geography at the University of Plymouth, told the Daily Mail: ‘High mountain Asia is one of the fastest warming regions in the world.
‘It is home to rapidly melting glaciers, growing meltwater lakes and some of the steepest mountains in the world.
‘As the climate warms, shrinking glaciers and thawing frozen ground could destabilize mountain slopes, increasing the risk of rockfalls, landslides and avalanches.’
Dr. Westoby adds that these could cause ‘hazard cascades’, chain reactions that release huge amounts of ice and water in populated areas – much like the recent disaster in Nepal.
However, the researchers note that the Andes is a risk area that may have been greatly undervalued in previous research.
The number of glacial lakes in this region has increased by 93 percent since 1990, compared to only 37 percent in HMA.
Peru is the third most dangerous country in the world, and two of the three most dangerous river basins in the world are in the Andes: the Santa Basin in Peru and the Beni Basin in Bolivia.”
Co-author Professor Rachel Carr, a glaciologist from Newcastle University, told the Daily Mail: ‘It is important to note that it is not just rural populations that are at risk: major cities get their water from the Andean glaciers,’ says Professor Carr.
But it’s not just these highly vulnerable regions that are at risk, as the researchers show that North America, particularly the Pacific Northwest and Canada, and the Alps are threatened by GLOFs.
While there is debate about whether GLOFs are becoming more common, what is certain is that they are becoming more dangerous.
This is because the downstream population is growing, putting more people and critical infrastructure at risk.
Part of what makes this so dangerous is that experts can’t say exactly where or when the next devastating flood will hit.
Professor Carr says: ‘Usually larger events are rarer and smaller events are more common, but they are random in nature, especially when caused by events such as landslides.
‘So it’s probably a project of similar size [to Nepal] will happen in the future, but when and where is much harder to say.’
