"Not a Single Drop of Rain, Yet a Massive Flood in Nepal"... The Grim Reality of Himalayan Climate Change

As a sudden and devastating flood in the Himalayan mountainous region near the Chinese border causes massive casualties, attention is focusing on the cause of the disaster.

Although the Nepalese government initially presumed an earthquake was to blame, the possibility has been raised that a massive collapse of glaciers and rocks, driven by climate change in the Himalayas caused by global warming, triggered the catastrophic disaster.

According to AFP and Reuters on the 27th local time, the massive flood that struck areas in the north-central Bagmati Province of Nepal the previous morning has left 157 people dead and 484 missing, including 391 foreign nationals, in Nepal so far.

Nine South Koreans affiliated with Korea South-East Power Co. and Doosan Enerbility who were constructing a hydroelectric power plant in the region have also lost contact.

In Gyirong County, Xigaze, Tibet Autonomous Region of China, near the Nepalese border, a landslide believed to be linked to the cause of this flood occurred the previous day, leaving 3 people dead and 265 missing.

The previous day, the Nepalese government stated based on preliminary findings that an earthquake in Tibet had collapsed glaciers, triggering the flood.

Nepalese Foreign Minister Sisir Kumar Khanal explained in parliament that an earthquake occurred at around 8:37 AM, and a flash flood was reported 3 minutes later, adding that a massive landslide had blocked the flow of the local Bhote Koshi River.

This raised the possibility that debris and rocks from the landslide blocked the Bhote Koshi River before suddenly giving way, causing muddy water to violently rush downstream.

The U.S. Geological Survey (USGS) also initially stated that a magnitude 4.4 earthquake had occurred in Tibet, 47 kilometers north of Rasuwa District in Bagmati Province, but later issued a revised report correcting this.

The USGS explained, "Additional analysis of long-period seismic waves and satellite imagery showed that the seismic energy (which was closer to magnitude 5.2) was actually generated by the landslide," adding, "No earthquake occurred."

The analysis indicates that the collapse of massive glaciers and rocks generated a shockwave similar to an earthquake, after which the glacial collapse and debris flow swept downstream, causing a major flood.

Meteorological experts analyzed that the likelihood of large-scale disasters like this has been continuously growing due to climate change in the Himalayas.

In the Himalayas, a primary water source for approximately 2 billion people in Asia, the rate of glaciers melting away due to warming has accelerated by more than twofold in the 21st century.

Surveys show that the thickness of glaciers in this region decreased by an annual average of 34 cm before 2000, but has decreased at a rate of 73 cm per year since 2000, more than doubling.

Climate experts from the International Centre for Integrated Mountain Development (ICIMOD), headquartered in Kathmandu, Nepal, diagnosed that an avalanche originating from a glacier was likely the cause of this flash flood as well.

An expert from ICIMOD explained, "The situation was caused by ice and rocks originating from glaciers on the Nepalese side blocking the river and unleashing a sudden torrent of water downstream."

This is also linked to the possibility of floods caused by glacial lake outbursts.

A glacial lake outburst flood is a phenomenon where a vast amount of water is suddenly released from a lake formed by melted glaciers.

Indeed, mountain glaciers are shrinking globally due to rising temperatures.

Melting glacier water can form glacial lakes, and the number and size of glacial lakes have been increasing since the 1990s.

Floods occur when these so-called "natural dams," made of ice and rock trapping the lakes, suddenly collapse.

Experts expect such floods to increase due to climate change.

In July of last year, a large-scale landslide and flood also occurred in the Gyirong Kouan area of Gyirong County, Xigaze, Tibet, where a landslide occurred alongside this event, resulting in a total of 1 death and 28 missing across both Nepal and Tibet.

Following last year's disaster, an analysis of satellite imagery by Chinese authorities revealed that 55 glacial lakes were distributed upstream of the accident site.

The total area of these glacial lakes reached 3.39 square kilometers.

Experts analyzed that last year's flood was also caused by water suddenly draining from a lake on the glacier's surface.

Hatim Sharif, a hydrologist at the University of Texas at San Antonio, pointed out that it is also striking that there was almost no rainfall before this flood occurred.

He noted, "This is a case that effectively exposes the limitations of virtually all flood warning systems worldwide."

Because rainfall-based "flood warnings" are not triggered, residents downstream have no time to evacuate, he explained.

He emphasized that massive muddy water rushing down at high speeds in mountainous regions forms a fatal combination akin to liquid concrete, meaning that trying to spot it and run away is useless, and the only solution is to climb onto a hill 6 meters high.

The "V"-shaped canyons of the Himalayan mountainous region, down which sediment and muddy water poured at extremely high speeds, were also pointed out as a contributing factor that amplified the casualties.

Dorothy Heinrich, a researcher at the University of Reading in the UK, explained, "In mountainous terrain, rivers can narrow considerably in certain sections. When the river is blocked by an avalanche or landslide, a large amount of water accumulates, and when it bursts all at once, a flood of unbelievable speed occurs."

With search and rescue operations for the missing hindered by massive debris and rugged terrain, concerns have also been raised that a "secondary flood" could occur.

An ICIMOD official stated, "Blockages still remain in the upper reaches of the rivers along the Nepal-China border," adding, "Authorities are warning that a second flood could occur."
※ Please note: This article was translated by AI and may contain errors.