That’s about the height of a three-story building in the time it takes to drink a cup of tea. Homes, bridges, roads, and power plants were all erased. By the time the water went down, at least 469 people had died and more than 1,500 were still missing in Nepal and Tibet.
People thought it was an earthquake at first. Nepal’s foreign minister told the parliament that early reports said an earthquake may have caused a landslide. They did say that there was an earthquake on the border between Nepal and China that was about 4.4 on the Richter scale. But by that evening, the agency had changed its mind about everything. An earthquake caused by plates did not happen. They found out how strong it was when a glacier melted and ice and rock hit the valley floor so hard that it sent out its own seismic signal. After it was reclassified, the event was recorded at 5.2 on the Richter scale.
A geomorphologist at the University of Calgary named Daniel Shugar looked at Planet Labs satellite images and clearly explained what he saw. A 0.2-square-kilometer chunk of ice broke off from the base of a 5,200-meter-high glacier and fell 1,200 meters to the valley floor below. He used the word “crashed.” Along the way, as it went down, it picked up rocks and other things. Then it hit the Lhende River in Tibet and blocked it for a while. Then it sent a huge wave further downstream. The flood started in the Bhote Koshi River, went through Nepal around 9 a.m., and then poured into the Trishuli.
From the order of events, it looks like the disaster happened almost mechanically, with one failure following on quickly after the other. Shugar also saw on the satellite pictures that many of the valley’s glaciers that had snow on them the day before were now just ice. It was clear what it meant: it had been warm. Most likely not to be warm. Overnight, it got warm enough that the snow on top of a few glaciers melted.
Shugar said that building work in the area might have also been a factor, but that was still an open question. Another scary thing that was brought up was the permafrost by Prof. Andrew Mackintosh, a glaciologist at Monash University in Melbourne. He thinks of frozen ground as the “glue” that holds steep mountain sides together. When it gets warmer, that glue doesn’t stick as well. Slopes that haven’t moved in hundreds of years start to do so. It’s not exciting like a flood. You might not notice how slow and quiet it is until it’s over.
About twice as fast as the rest of the world, the Himalayas are getting warmer. It makes sense to think about what that number means for places like Nepal, India, China, Bhutan, and Pakistan, where rivers are cut off by glaciers. The UN said in 2023 that Nepal’s mountains had lost almost a third of their ice in just over thirty years. Another study says that the Hindu Kush Himalayan glaciers will melt 65% faster between 2011 and 2020 than they did the previous ten years. This is not a guess. These are the amounts that show what has happened so far.
It’s hard not to think about Uttarakhand. In 2021, a piece of a Himalayan glacier broke off in an Indian state and killed or went missing about 200 people. Later, scientists talked about how the event created “an incredibly large and mobile debris flow.” Recently, something similar happened in Nepal. However, it’s still not clear if it was just the glacier that broke or if the rock and glacier along with the rest of the mountainside fell apart at the same time.
Mackintosh thought about what he said. It is “very likely” that climate change and the melting of glaciers are connected, he said. It’s not as clear that one collapse event can be directly linked to climate change. It’s hard to draw firm statistical lines because there haven’t been many big glacier melts. The fact that we don’t know what will happen doesn’t make them less scary. It makes them more difficult to prepare for.
This country has over 2,000 glacial lakes. The UN says 21 of them might be dangerous. This year, floods from glacial lakes have already killed more than 12,000 people around the world. There are different kinds of floods here than there were here, but they all fit into the same bigger picture. It melts more when the world gets warmer. The water has to go somewhere. It stays behind a natural wall until it can’t go any further.
The events of Wednesday morning were not a “freak event,” which is what some disasters are called when nature does something strange. Climate change is really making the mountain able to do something it can’t do before. The ice sheet broke. The river grew. The valley below didn’t have any signs that were worth the name either.
