[Editorial] New hazards

Nature has found a new way to defeat complacency. On Wednesday, a huge collapse beneath a glacier near Langtang Lirung in the Himalayas sent ice, rock and debris into the Trishuli River basin, producing a devastating flash flood across Nepal and Tibet.

As of Sunday afternoon, at least 750 people were confirmed dead and 3,044 remained missing. Nine South Korean workers were among those unaccounted for.

The disaster is a warning that climate change is altering more than rainfall patterns. It is destabilizing physical structures that once seemed permanent.

The immediate priority for Seoul is to locate and rescue the nine missing Koreans: six Doosan Enerbility employees and working for Korea South-East Power. They were working at the Upper Trishuli-1 hydroelectric project in Nepal's Rasuwa district when the disaster struck.

The government has sent a rapid response team and chartered helicopters to search for them, while negotiating with Nepali authorities over access. Nepal has restricted foreign search operations because of dangerous terrain, unpredictable weather and the threat of further flooding.

Those constraints should be respected. Nepal's military and police are leading rescue operations, and the country's own authorities must determine what assistance is most useful.

Seoul should nevertheless be prepared to provide technical support, relief supplies and other humanitarian assistance. Nepal's finance minister has estimated that reconstruction could cost as much as $5 billion.

The tragedy also exposes the limitations of conventional disaster planning. This was no ordinary monsoon flood. There was little rain when a massive section of rock beneath a glacier collapsed at high altitude.

The resulting avalanche carried millions of tons of ice and rock down the mountainside, gathering up water and river sediment along the way. The debris temporarily blocked the river before the barrier gave way, unleashing a destructive surge downstream.

A magnitude 5.2 seismic signal was recorded as the collapse occurred, illustrating the scale of the event. Nepal's early-warning sensors, designed largely to track gradual changes in glacial lake levels, were ill-suited to a sudden chain of geological failures.

Climate change makes such events harder to regard as remote anomalies. Global warming is weakening alpine permafrost that has helped anchor rock and ice formations for centuries. Himalayan glaciers have been melting more than twice as fast since 2000, and similar glacial disasters have occurred elsewhere.

The lesson is that hazards can emerge from changing interactions among natural forces and infrastructure that historical statistics scarcely capture.

Although Korea has no Himalayan glacier looming over its cities, it does have dams, drainage systems, flood barriers, underground roads and densely developed coastal areas designed partly around historical weather records.

With the pattern of natural disasters rapidly shifting, Korea’s disaster preparedness system could become less reliable. Recent rainfall offers a glimpse of the problem. Torrential rain in Geoje reached 124 millimeters per hour, a level the Korea Meteorological Administration described as a once-in-200-years event.

Supposedly rare extremes are occurring more often around the world. That should prompt a fundamental review of what constitutes a safe design standard.

Recalculating the capacity of existing dams is useful, but applying 100-year criteria to new infrastructure while the climate itself is shifting could mean designing for conditions that no longer exist.

Coastal areas, major cities and transport hubs require forward-looking hazard models that incorporate changing rainfall, sea levels and storm surges.

The Himalayan flood has two implications for Seoul. Abroad, the government must strengthen protections for Koreans working in high-risk environments, where companies cannot anticipate every compound disaster alone. At home, infrastructure standards must be adapted to the hazards they are supposed to contain.

The deadliest floods may begin without a cloudburst. Disaster policy should be prepared for that possibility.