In a stark reminder of the ongoing environmental challenges posed by climate change, the South Lhonak Lake in Sikkim burst on the night of October 3-4, 2023, fulfilling the warnings made by scientists back in 2021.
The catastrophe was predicted in a detailed study titled 'Future Glacial Lake Outburst Flood (GLOF) Hazard of the South Lhonak Lake, Sikkim Himalaya', which underscored the lake's increased growth due to glacial retreat, escalating the risks of glacial lake outburst floods (GLOF).
Located at an altitude of 5,200 meters above sea level, the South Lhonak Lake had rapidly expanded over the decades due to glacial retreat, becoming the largest and fastest-growing glacial lake in the state.
Between 1962 and 2008, the glacier receded almost two kilometres, with an additional 400-meter retreat recorded between 2008 and 2019, intensifying the hazard potential.
The glacier's length reduced from 6.4 km to 5.1 km in 29 years, indicating a significant reduction of approximately 0.96 sq km. The Central Water Commission of the central government had issued advisories to assess the lake system's condition, foreseeing the impending danger.
This natural disaster has dire implications for the downstream Chungthang village, home to over 10,000 residents, who find themselves cut off from the rest of the world due to the disaster.
The study also highlighted the unstable nature of the terminal moraine, the natural dam holding the lake, which is thinning towards the ends. Scientists have pointed out that climate change is accelerating glacial retreat in the Himalayas, contributing to the growing number of glacial lakes, many of which are susceptible to GLOFs.
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Studies published over the years have consistently emphasised the impact of climate change on Himalayan glaciers and lakes. One such study, published in 2012, indicated a rise in the number of glacial lakes in the Sikkim Himalayas, many of which are prone to GLOFs.
Additionally, research conducted by the International Centre for Integrated Mountain Development (ICIMOD) in 2003 identified several hazardous lakes in the Sikkim Himalayas, underscoring the urgent need for climate action and disaster preparedness.
Another study, titled 'Glacial Lake Evolution (1962–2018) and Outburst Susceptibility of Gurudongmar Lake Complex in the Teesta Basin, Sikkim Himalaya (India),' highlighted the risks associated with the Gurudongmar lake complex. The research predicted that if global temperatures continue to rise, the crevasses near the icefall area will shrink, increasing the risks of outbursts or overflow.
These studies collectively emphasise the pressing need for comprehensive strategies to mitigate the impacts of climate change in the fragile Himalayan region.
The bursting of South Lhonak Lake serves as a sombre reminder of the urgent action required to safeguard vulnerable communities and ecosystems in the face of a changing climate.