"Not a Single Drop of Rain, Yet a Catastrophic Flood in Nepal": The Scary Reality of Himalayan Climate Change

As a massive and sudden flood in the mountainous Himalayan region near the Chinese border caused heavy casualties, attention has focused on the cause of the disaster.

Although the Nepalese government initially presumed it to be the impact of an earthquake, the possibility has been raised that a massive disaster occurred due to the collapse of enormous glaciers and rocks driven by climate change in the Himalayas caused by global warming.

According to AFP and Reuters on the 27th (local time), the large-scale flood that occurred the previous morning in the Bagmati Province area of north-central Nepal has left 157 people dead and 484 missing, including 391 foreigners, so far in Nepal.

Nine South Koreans belonging to Korea Southern Power and Doosan Enerbility, who were constructing a hydroelectric power plant in the region, have also lost contact.

In Gyirong County, Xigaze (Rikaze), in China's Tibet Autonomous Region near the border with Nepal, a landslide believed to be linked to the cause of this flood also occurred the previous day, resulting in 3 fatalities and 265 people missing.

The previous day, the Nepalese government stated based on preliminary findings that the flood was triggered when a glacier collapsed due to an earthquake that occurred in Tibet.

Nepalese Foreign Minister Arzu Rana Deuba explained in parliament that an earthquake occurred at 8:37 AM and a flash flood was reported three minutes later, adding that a massive landslide blocked the flow of the local Bhotekoshi River.

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

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

The USGS explained, "After further analysis of long-period seismic waves and satellite imagery, the seismic energy (which was not a magnitude 4.4, but rather around magnitude 5.2) was actually generated by the landslide," adding, "No earthquake occurred."

The analysis indicates that an earthquake-like shock occurred during the process in which massive glaciers and rocks collapsed, after which glacier collapse and debris flows swept downstream, causing a major flood.

Weather experts analyzed that the likelihood of major disasters like this one in the Himalayas has been steadily increasing due to climate change.

In the Himalayas, a major water source for about 2 billion people in Asia, the rate at which glaciers are melting and disappearing due to warming has accelerated by more than twice in the 21st century.

It was found that the thickness of glaciers in this region decreased by an annual average of 34 centimeters before 2000, but has been shrinking more than twice as fast at 73 centimeters per year since 2000.

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 ICIMOD expert explained, "The cause was a situation where ice and rock originating from the glacier on the Nepalese side blocked the river, releasing a sudden surge 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 in which a massive amount of water is suddenly released from a lake formed by melted glaciers.

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

Water from melted glaciers can form glacial lakes, and the number and scale of glacial lakes have been increasing since the 1990s.

Floods occur when these so-called 'natural dams' made of ice and rock holding back 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 around Gyirong Port in Gyirong County, Xigaze, Tibet, where the landslide occurred this time, resulting in a total of 1 person dead and 28 missing across both Nepal and Tibet.

Analyzing satellite images after last year's disaster, Chinese authorities found 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 lakes on the glacier surface.

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

He pointed out, "This is a case that essentially exposes the limitations of virtually all flood warning systems around the world."

Because 'flood warnings' based on rainfall do not sound, residents in downstream areas have no time to evacuate, he explained.

He emphasized that the massive muddy water rushing rapidly through mountainous terrain forms a lethal combination akin to liquid concrete, making it useless to spot and try to run away, with the only solution being to climb up onto a hill 6 meters high.

The 'V'-shaped valleys of the Himalayan mountainous terrain, where sediment and muddy water poured down at extreme speeds, were also cited as a secondary factor that amplified casualties.

Dorothy Heinrich, a researcher at the University of Reading in the UK, explained, "In mountainous terrain, rivers can narrow significantly in some sections, and (when the river is blocked by an avalanche or landslide) a large amount of water builds up, causing an unbelievably fast flood (when it finally bursts all at once)."

Amidst ongoing difficulties in searching for missing persons and conducting rescues due to massive debris and rugged terrain, concerns have also been raised that a 'secondary flood' could occur.

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