The death toll from Nepal’s massive floods has surpassed 600. According to Nepalese media including the Kathmandu Post on the 29th local time, 626 people were killed in Nepal alone by the large-scale flooding that hit Bagmati Province in central Nepal on the 26th. Including seven deaths in China’s Tibet Autonomous Region, the total rises to 633.
The number of missing people is nearing 3,000, with 2,426 in Nepal and 554 in Tibet. Nepalese authorities have deployed 15,224 soldiers and police officers for rescue operations. So far, 4,451 people, including 116 foreigners, have been rescued, and 101 injured people are receiving treatment.
The cause of the disaster is now being sought not at the foot of the mountain, but within the mountain itself. According to The New York Times, glaciologists and geologists say it is highly likely the flooding began when the bedrock beneath a glacier collapsed on a large scale.
The collapse occurred on the north slope of Langtang Lirung peak in northern Nepal, at an altitude of about 5,200 meters. The bedrock failure triggered a landslide, and at the same time, large chunks of ice broke off the glacier and poured thousands of meters down into the valley. Millions of tons of rock and ice shattered and, transformed into mud and water, swept down the mountainside.
◆ The “ice glue” holding the mountain together is weakening
The underlying cause scientists are focusing on is the thawing of permafrost. Permafrost is ground that has remained frozen for thousands of years, mixed with soil, rock, and organic matter. As the planet warms due to fossil fuel use, frozen ground at high elevations in the Himalayas is thawing, and the foundation supporting glaciers is becoming unstable.
Alton Byers, a senior researcher at the Institute of Arctic and Alpine Research at the University of Colorado, said, “Permafrost was the glue that held rocks, ice, and glaciers together for thousands of years, but evidence is growing that it is weakening due to warming.” He has dubbed the phenomenon “not-so-permanent permafrost.”
There is also plenty of precedent. Since 1900, glacier collapses, encompassing ice avalanches, glacier separations, and rock-and-ice avalanches, have been recorded dozens of times along the China-Nepal border region alone.
Some caution that it is still too early to conclude this was caused solely by climate change. Stuart Dunning, a professor at Newcastle University in the UK, said, “It cannot simply be called a result of climate change,” adding that long-term factors were likely combined with short-term factors such as heavy snowfall in the past few days. Asim Sattar, an assistant professor at IIT Bhubaneswar in India, said, “When glaciers retreat and permafrost thaws, slopes become easier to collapse,” and assessed that the link between climate change and disasters is clear.
◆ An early warning system focused only on glacial lakes has exposed a blind spot
Until now, disaster preparedness in the Himalayas has focused on glacial lakes. Lakes formed across mountain regions as glaciers melt can unleash floods that engulf villages and power plants if their dams are breached by avalanches or earthquakes. This is known as a glacial lake outburst flood, or GLOF.
At first, this incident was also suspected to be a glacial lake overflow. But satellite analysis showed otherwise. Umesh Haritashya, a professor at the University of Dayton in the United States, said, “Whenever something like this happens, glacial lakes are blamed, but in the future we need to examine other risk factors more closely.”
Gaps in the warning system have also been identified. Nepal’s Department of Hydrology and Meteorology operates a network of sensors that measures water levels in glacial lakes and rivers and sends warnings to downstream villages when abnormal signals are detected. Austin Lord, a senior researcher at the Stimson Center in the U.S., pointed out, “Rapid floods like this move so fast that the existing system has difficulty responding.”
The solution appears to lie in expanding the scope of monitoring. The idea is to use satellites and sensors not only to watch lakes where water accumulates, but also slopes where frozen ground is thawing, and to rebuild alert delivery systems to match the speed of sudden floods. Byers plans to visit Nepal next month to discuss response measures with residents in flood-risk areas.
The Langtang area is also a familiar trekking route for Koreans. Travelers visiting the Himalayas need to factor in the increased risk of slope collapse before and after the rainy season when planning their itineraries. The trend of making climate disaster monitoring a national safety infrastructure is also an opportunity for cooperation and market expansion for countries with satellite and sensor technologies.