An international research team has concluded that the devastating flood disaster in Sikkim, India, in October 2023 was caused by the collapse of 14.7 million cubic meters of frozen moraine material into South Lhonak Lake, triggering a tsunami-like flood wave that reached up to 20 meters in height. This tragic event, which claimed at least 55 lives and caused widespread damage along the Teesta River, serves as a stark reminder of the escalating dangers posed by climate change in high mountain regions.
A Massive Tsunami-like Wave
On October 3, 2023, the collapse of frozen moraine material into the lake unleashed a catastrophic glacial lake outburst flood (GLOF), releasing about 50 million cubic meters of water—equivalent to the volume of 20,000 Olympic-sized swimming pools. The flood caused severe destruction over a 385-kilometer stretch, washing away vast amounts of sediment, inundating infrastructure like hydroelectric power plants, and leaving massive economic losses. Additionally, 70 people remain missing, while the flood displaced thousands and led to significant erosion and sedimentation that affected farming and local businesses.
Climate Change Amplifies Risks
The research, led by experts from nine countries, including the University of Zurich, highlights the urgent need for climate action to address the vulnerability of high mountain regions. “This event is a stark reminder of the vulnerability of high mountain regions to the effects of climate change,” said Christian Huggel, a co-author of the study. The thawing of permafrost and the instability of rock, ice, and moraine structures are increasingly threatening these areas, where temperature changes are particularly pronounced.
Technological Innovation for Understanding Disasters
To reconstruct the event in detail, the research team employed cutting-edge techniques such as high-resolution satellite imagery, digital elevation models, and seismic data. These technologies helped the researchers pinpoint the exact timing of the moraine collapse and quantify the water and sediment released. “The use of high-resolution remote sensing data was crucial to understanding the complex processes and cascading effects of the flood,” said Ashim Sattar, the study’s first author.
Need for Early Warning Systems
The study underscores the pressing need for early warning systems in the region. It found that the moraine’s instability had been noticeable for years before the disaster, with shifts of up to 15 meters annually. This suggests that better monitoring and preventive measures could have mitigated the damage. “Our findings highlight the urgent need for early warning systems and international cooperation,” Sattar emphasized.
Risk Assessment and Future Preparedness
The research team warns that such disasters are likely to become more frequent as global temperatures rise. The study calls for enhanced risk modeling, better adaptation strategies, and stronger regulations around hydropower development in high-risk areas. With similar glacial lakes around the world at risk, the team advocates for coordinated global efforts to monitor and manage these vulnerabilities more effectively.
As the world faces the growing impacts of climate change, the Sikkim disaster serves as a crucial reminder of the need to prioritize risk assessment and early intervention to safeguard communities in high mountain regions.