Remember in the the beginning of the Wizard of Oz when the tornado, the iconic Midwestern natural disaster, tosses the Kansas farmhouse and lands it on top of the Wicked Witch of the East in Munchkinland? We see in the flowerbed the telltale black witch shoes and socks and they begin to shrivel until they disappear under the house. Then Dorothy starts her trek across Oz to find her way back to Kansas at the behest of the Good Witch of the North, Glinda, and she goes off to see the Wizard only to run into the perils cast into her path by the Wicked Witch of the West. When they meet, Dorothy learns by accident that her salvation is water and that by throwing water on the Wicked Witch, she starts to melt and cries the immortal, “I’m melting!” as she fades away into a pile of black organza. Quite a bit of memorable drama for a childhood movie classic. So here we are today, watching as the rooftop of the world in the Himalayas has been struck by a catastrophic disaster of massive proportions. The glacial shelf in this remote and rural part of the world, a place that is known as a cosmic vortex of enlightenment and meditation, is….melting! And this time it is not the Witch that’s melting, but rather the Wicked Witch of Western Civilization that is the culprit that has thrown the water on Nepal and caused the devastation. The biggest problem is that there may be no yellow brick road available to us at this point to take us to some Emerald City that will get us out of this mess.
A catastrophic flash flood hit Nepal on August 26th. What triggered it was a series of flash floods along a 72 km stretch of the Trishuli River. Those floods struck dozens of settlements in Nepal’s Rasuwa and Nuwakot districts, also affecting the China–Nepal border crossing at Gyirong Port. It was likely triggered by rapid slope failure involving a glacier in Langtang National Park near the China border. The precipitating event is thought to have been a glacier collapse in the Himalayas, which caused a tremor measuring magnitude 5.2 on the Richter Scale. The flood wave was a mix of water, pulverized ice, and rock and descended the first 22 kilometers at an average speed of 193 km/h (120 mph), covering nearly 14 miles in under 7 minutes. At least 389 people are confirmed dead and 910 are currently missing in Nepal, with 3 dead and 558 missing in China. Around 90 Americans are among those missing, including some who had been on a pilgrimage to Mount Kailash in Tibet. Authorities have issued flood warnings for communities along rivers in Rasuwa, Nuwakot, Dhading, Gorkha, and Chitwan districts. The threat of further landslides and flooding is making search-and-rescue efforts even more dangerous.
A glacier slope failure is when a mass of ice, sometimes along with the rock, soil, and debris it’s sitting on or embedded in, suddenly breaks loose from a steep slope and gives way, rather than melting or moving gradually the way glaciers normally do. This happens when a steep, unstable section of a glacier (often at a cliff-like edge called a serac) fractures and comes crashing down, similar to a rockslide but made of ice. In rare cases, an entire lobe of a glacier can detach from its bed all at once, especially if the ice is resting on a slippery, saturated, or thawing base (permafrost degradation from warming is a common culprit). The collapsing ice rips loose surrounding rock and debris, turning into a much larger, more destructive mass than the ice alone. What makes these events so dangerous downstream is what happens next, which is that the falling ice and rock can slam into a valley, instantly melt on impact or churn up trapped water, and turn into a fast-moving flood of water, mud, ice, and debris. That is exactly what’s believed to have driven the Nepal disaster. That combination of a sudden trigger (rather than gradual melt) plus a huge volume of material hitting a valley at once is why these floods can arrive with almost no warning and travel so fast.
Scientists are linking this event to climate change, but with real caveats about certainty for this specific event. There is no doubt that climate change is causing glaciers across Nepal and Tibet to melt at an alarming rate, and scientists say glaciers in the region are increasingly unstable because of human-caused global warming. A 2023 UN report found Nepal had lost a third of its ice volume in the past 30 years, with glaciers there melting 65% faster in the last decade than in the previous one. The warming melts the permafrost, which usually acts as the “glue” holding rock and ice together on steep slopes. As that glue weakens, glacier collapses become more likely. Reuters and the BBC reported that scientists believe climate change likely helped trigger this particular glacier collapse, but some scientists stopped short of directly attributing this disaster to climate change, pointing instead to more proximate causes. The collapse also appears linked to tectonic uplift, not warming alone. Scientists are still investigating the precise mechanics, and there’s even ongoing debate about where exactly the huge volume of water came from (melted ice, entrained sediment water, or river water), and no confirmed evidence yet that this was a classic glacial lake outburst flood. Nevertheless, this fits a broader, well-established pattern where Himalayan glaciers are destabilizing as the region warms, making these collapse-triggered floods more frequent. But scientists are careful to distinguish that trend from claiming climate change directly caused this one collapse on this one day.
It’s felt that things can be done to prevent this though nothing eliminates the risk entirely. It’s really all about reducing the odds of it happening again and the mitigating the potential damage. Better and faster detection is the place to start. Nepal and China already had a flash flood early warning system, but experts say that the speed of this flood likely overwhelmed the system entirely. Remote sensors, cameras, and satellite monitoring have been piloted across Nepal, Bhutan, Pakistan, and parts of China, but coverage remains sparse, since expeditions to install or maintain sensors above 5,000 meters are difficult and expensive. Denser, higher-altitude sensor networks would help, but they’re logistically and financially hard to scale. Because floods take time to travel downstream, there’s a real window to save lives if China and Nepal share data quickly, the existing mechanism just needs to function more effectively. Even a perfect warning system buys minutes, not hours, in the fastest events and this flood moved pretty fast. The bottom line is that this is a global emissions problem that no amount of local infrastructure spending fixes on its own; it only manages the fallout.
WHo is to blame for this emissions problem? Since warming is driven by the total stock of CO2 built up in the atmosphere since industrialization, this is the most relevant number for responsibility. By most analyses (e.g., Carbon Brief, Global Carbon Project) the US alone accounts for roughly 20% of cumulative CO2 emissions since 1850 with the EU (as a bloc) accounting for roughly 12–15%. Trait in the UK and the US/EU/UK and other early-industrializing Western nations (plus historically Japan) account for somewhere around 50%+ of cumulative emissions. China’s cumulative share is around 14%, though it’s been the largest annual emitter since the mid-2000s (China is now the largest annual emitter with ~30% of global CO2). India is also starting to catch up. Non-Western countries now account for the majority of current emissions, largely because China and India industrialized later and have much larger populations, but the West sure showed them all the way.
The house fell on Nepal and its valley’s and glaciers are certainly melting…and it was the Wicked Witch of the West that started the snowball rolling down the hill.