Context:

 A recent study has revealed a significant loss of glaciers in the eastern Himalayas of Arunachal Pradesh, where 110 glaciers disappeared between 1988 and 2020. Conducted by researchers from Nagaland University and Cotton University, the study highlights the rapid retreat of glaciers, raising concerns about climate change, ecosystem disruption, and increasing risks of Glacial Lake Outburst Floods (GLOFs).

Key Findings of the Study

Published in the Journal of Earth System Science, the study used remote sensing and Geographic Information Systems (GIS) to analyze glacier retreat over 32 years. The research identified the following trends:

• Glacial Area Loss: The glaciers in Arunachal Pradesh shrank by 309.85 square kilometers, retreating at a rate of 16.94 square kilometers per decade.
• Reduction in Glacier Count: The number of glaciers decreased from 756 to 646, marking a 47% loss in glacial cover.
• Geographical Characteristics: Most of the studied glaciers were located at elevations of 4,500 to 4,800 meters above sea level, with north-facing slopes (15° to 35° inclination).
• Environmental Consequences: The retreat of these glaciers has exposed bedrock and created glacial lakes, significantly increasing the risk of GLOFs, which can cause severe flooding and destruction in downstream regions.

Climate Change in the Eastern Himalayas

• Temperature Increase: The Himalayas have warmed by 1.6°C in the past century, with the eastern Himalayas warming at 0.1° to 0.8°C per decade—a rate surpassing the global average.
• Future Projections: By the end of the century, the region is expected to experience a temperature rise of 5-6°C and an increase in precipitation by 20-30%.
• Impact on Small Glaciers: Glaciers smaller than 5 square kilometers are retreating at the fastest rate, making them particularly vulnerable to climate variations.

What are Glacial Lakes?

Glacial lakes are water bodies formed by melting ice, typically accumulating in depressions created by glacier movement. These lakes are categorized into four types based on their formation:

1.   Moraine-dammed lakes

2.   Ice-dammed lakes

3.   Erosion lakes

4.   Other types

What are Glacial Lake Outburst Floods (GLOFs)?

GLOFs occur when a glacial lake suddenly releases water due to dam failure, leading to catastrophic flooding downstream. These events have three key characteristics:

• Sudden and sometimes cyclic release of water
• Short-lived but highly destructive floods (lasting hours to days)
• Large downstream river discharges causing severe damage

Notable GLOFs in Recent History

• 2023 South Lhonak GLOF (Sikkim): Destroyed the Teesta III Dam at Chungthang.
• 2013 Chorabari Glacial Lake GLOF (Uttarakhand): Triggered severe flooding in the Mandakini River, contributing to the Kedarnath disaster.

Conclusion

The loss of 110 glaciers in Arunachal Pradesh over three decades underscores the severe impact of climate change on the fragile Himalayan ecosystem. The rapid retreat of glaciers threatens freshwater availability, biodiversity, and local communities, while increasing the risk of catastrophic GLOFs. Given that the Himalayas serve as a crucial water source for over 1.3 billion people, urgent climate action and sustainable environmental policies are essential to mitigate further damage and preserve the region’s delicate balance.