Devastating flash floods and mudslides have swept away buildings and bridges along the Nepal-Tibet border. hundreds of tourists are still missing.
In Nepal, houses and roads were swept away by rushing water and mudslides.
Meanwhile, officials in Chinese-controlled Tibet said they feared “major casualties.”
Why are these floods so catastrophic?
According to Professor Liz Stephens, professor of climate risk and resilience at the University of Reading, the cause is likely to be a ‘complex chain of hazards’.
“Most people think flash floods are caused by heavy rainfall,” she explained.
‘But in Nepal and Tibet, as in many other high mountain areas, they can also result from complex chains of hazards, including landslides, avalanches and glacial lake flooding.
‘This complexity makes early warning particularly difficult.’
Devastating flash floods and mudslides have swept away buildings and bridges along the Nepal-Tibet border – and hundreds of tourists are still missing
A boy looks at the devastation caused by flash floods along the Trishuli River in Nepal’s Nuwakot district
Although details remain scarce at this time, early reports suggest that a magnitude 4.4 earthquake caused an ice avalanche, which in turn blocked the Lhende River.
Water then collected behind the blockage before bursting downstream – with devastating consequences.
Professor Stephens explained: ‘Early reports from Nepal suggest that an earthquake occurred around the same time as a landslide or avalanche, which subsequently led to the catastrophic flooding.
‘One way this can happen in steep mountain valleys is when a landslide blocks a river, allowing water to build up behind it.
“If that landslide dam then fails, there could be a sudden, devastating release of water and sediment downstream.”
As it stands, it remains unclear whether climate change played a role in these floods.
However, a study published last month in Climate limits warned that glacier melting and Glacial Lake Outburst Floods (GLOFs) will increase in the region as temperatures rise.
“Across the Himalayan region, warming is exceeding the global average, increasing climate-related hazards and associated losses, contributing to glacier melting and increasing the risk of GLOF, as some of the most visible indicators leading to climate change-induced losses and damage,” the researchers explained.
Although details are scarce at this time, early reports suggest that a magnitude 4.4 earthquake caused an ice avalanche, which in turn blocked the Lhende River.
Water collected behind the blockage before bursting downstream – with devastating consequences
‘Rising temperatures have accelerated glacier melt, changed snow cover dynamics and contributed to the rapid formation and expansion of glacial lakes, many of which are dammed by unstable moraine structures, and are prone to unexpected eruptions that can cause destructive flooding downstream.’
Meanwhile, following floods caused by heavy rains in Nepal in 2024, World Weather Attribution scientists said climate change had worsened the floods.
“If the atmosphere had not been overloaded with fossil fuel emissions, these floods would have been less intense, less destructive and less deadly,” said researcher Mariam Zachariah of Imperial College London.
Unfortunately, as temperatures continue to rise, scientists say these types of floods will become even more common in the region.
“Climate change is no longer a distant threat,” said Roshan Jha, a researcher at the Indian Institute of Technology in Mumbai.
‘With every fraction of a degree of warming, the atmosphere could potentially retain more moisture, leading to much heavier rainfall and catastrophic flooding like this.’
Authorities have so far found the bodies of 55 people after the natural disaster, amid fears that many more will be found as search and rescue operations begin.
Terrifying footage shows a tsunami wave of floodwaters sweeping through a town, sweeping away everything in its path in Nepal’s mountainous Rasuwa region.
In Tibet, one clip showed the land crossing of Gyirong harbor being destroyed by the flood.
Dozens of people were seen running away in terrifying seconds before water and mud rushed into the structure and swept it away.
There are fears that a second flood will plunge Nepal, Tibet and neighboring India into even more chaos.
Flood warnings were issued in the densely populated northern Indian states of Uttar Pradesh and Bihar, which border Nepal and have several rivers flowing through the mountains into their plains.
Nepalese officials said hundreds of tourists and trekkers were missing, including 341 foreigners and at least 93 Nepalese citizens.
The missing include 12 from Britain – including a 13-year-old girl – 105 Indian nationals, four from South Africa, 17 from Malaysia and three from the United States.
One from Australia and the Netherlands is also missing.
