From Kedarnath to Nepal Sherpa village tragedy: The story of unstable Himalayan glacial lakes and icy floods

The flood devastation in the Nepal village of Thame (courtesy: X)

June 2013: A catastrophic glacial lake outburst flood hit Uttarakhand's Kedarnath Valley, leading to the tragic deaths of over 6,000 people.

February 2021: A chunk of a Himalayan glacier broke off in Uttarakhand, triggering a flash flood that devastated the region. More than a dozen people were confirmed dead, and at least 170 went missing as the floodwaters ravaged bridges, roads, and two hydroelectric power plants.

October 2023: In Sikkim, the southern bank of South Lhonak Lake breached, unleashing a torrent of icy water and debris. The flood wiped out the Chungthang Dam, NHPC hydropower projects, and critical infrastructure.

August 2024: A Sherpa village in Nepal's Everest region was engulfed by an icy flood, further highlighting the growing dangers in the Himalayas.

Hundreds of glacial lakes have emerged across the Himalayas in recent decades, born from the melting of glaciers. But how do these lakes form? As glaciers move, they erode the landscape, carving out depressions in the terrain. When the glaciers retreat, meltwater fills these depressions, creating the glacial lakes we see today.

Scientists have long warned that climate change is accelerating the melting of Himalayan glaciers, leading to the formation of unstable glacial lakes. These lakes are often dammed by loose rocks and ice, making them prone to sudden and unpredictable outbursts.

In a report titled "Satellite Insights: Expanding Glacial Lakes in the Indian Himalayas" published on April 22, 2024, the Indian Space Research Organisation (ISRO), explains how Glacial Lake Outburst Floods (GLOFs) pose threat.

The long-term changes in the Ghepang Ghat Glacial Lake area (ISRO iimage)

"Long-term changes in the Ghepang Ghat glacial lake (Indus River Basin) at an elevation of 4,068 m in Himachal Pradesh, India, show a 178% increase in size from 36.49 to 101.30 hectares between 1989 and 2022. The rate of increase is about 1.96 hectares per year," the study mentioned.

Out of nearly 7,500 glacial lakes in the Indian Himalayas, the NDMA has identified these 189 as particularly hazardous. Accelerated by global warming, the rapid melting of ice in these lakes raises the chances of flooding events similar to the devastating Kedarnath disaster in 2013 and the Chamoli floods in 2021.

To address the looming threat, the NDMA, alongside central and state agencies, has already conducted expeditions to 15 of these high-risk lakes—six in Sikkim, six in Ladakh, one in Himachal Pradesh, and two in Jammu and Kashmir. An additional seven expeditions are currently underway.

Scientists have long warned that climate change is accelerating the melting of Himalayan glaciers (ISRO image)

Uttarakhand, home to 13 of the most vulnerable glacial lakes in India, is also closely assessing the risk of GLOFs in the region.