Nepal’s flash floods expose something more fundamental: the problem is not the absence of a warning system – it is a climate crisis that is producing hazards that behave differently from those the systems were designed to detect.
An enormous chunk of glacier around 2,000 feet wide sheared off Langtang Lirung mountain in northern Nepal, accompanied by landslide, according to satellite analysis. It sent a deadly mix of ice, water, rock, sediment and boulders the size of cars crashing 7,000 feet downward, causing such a powerful tremor, it was initially mistaken for an earthquake.
The warning system in the high-mountain Bhotekoshi valley illustrates the problem. The sudden, debris-laden flood destroyed upstream hydrological stations before they could register a rising water level and trigger an alert.
The system was designed to detect a more gradual rise in water levels.
This flood arrived as a massive surge of rock, mud and water, destroying the very instruments meant to detect it.
"Preliminary assessments indicate that a large glacial collapse triggered an ice-rock avalanche and debris flow, temporarily blocking the river before a massive surge travelled downstream," says an article in 'The Guardian'.
The precise sequence is still being investigated. Whatever the final scientific explanation, the event shows how quickly hazards can cascade in a warming mountain environment.
Nestled in the rapidly warming Himalayas, the country has long been a hotspot for flooding and landslides. But what happened on Wednesday “was of significantly larger scale than what we have seen in the recent past,’ said Prashant Baral, a cryosphere analyst at ICIMOD, a Nepali climate organization.
The torrent of pulverized ice, water, rock, silt and sand — described by some as “liquid concrete” — surged through narrow gorges, wiping out homes, buildings, power plants, bridges and roads.
Hundreds have died; many hundreds more are missing.
Water forms under Nepal's Khumbu glacier as the ice melts (Reuters/CNN)
On 26 August, a wall of ice, water, rock and mud tore through communities, destroying homes, markets, bridges, roads and hydropower infrastructure in Nepal and Tibet.
Hundreds of people were killed and many more remain missing.
The devastation came with terrifying speed. For people living along the rivers and the tourists trekking in the hills, there was little time between the hazard emerging high in the mountains and destruction reaching the valleys below.
A warning is useful only if there is time to act.
It cannot stop a mountain of ice and rock from collapsing. It cannot protect infrastructure in an increasingly hazardous corridor. And it cannot bring back a home, a hydropower station or a livelihood once it has disappeared.
Adaptation has limits, too. For years, Nepal and other vulnerable countries have been ramping up efforts to adapt: by strengthening infrastructure, improving preparedness, and protecting livelihoods – but often without financial support from the countries that historically contributed most to the climate crisis through historical emissions.
Nepal needs much greater international support for adaptation: early warning, mountain monitoring, climate science, anticipatory action, resilient infrastructure and disaster preparedness.
Because Himalayan hazards originate beyond national borders, this must also include stronger cross-border cooperation and timely sharing of information.
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