Font size:
Print
Himalayan Glacier Loss in Arunachal Pradesh
Context:
A new study revealed that 110 glaciers in the eastern Himalayas of Arunachal Pradesh disappeared over 32 years (1988 to 2020).
More on News
- These glaciers covered an area of 309.85 sq. km, retreating at a rate of 16.94 sq. km per year.
- The retreat exposed bedrock and led to the creation of glacial lakes, increasing the risk of Glacial Lake Outburst Floods (GLOFs), which can be catastrophic for downstream areas.
The Himalayan glaciers, situated in a region with high-altitude and subtropical climates, hold the largest concentration of frozen freshwater reserves outside the polar regions. These glaciers, vital to the human population, serve as important sources of water for the Indus, Ganga, and Brahmaputra river systems. Glaciers and snow contribute significantly to global climate regulation, impacting the radiation balance and affecting monsoon patterns. However, they are sensitive to climate change, making them crucial indicators of environmental shifts.
Key Findings
- The research was authored by Vimha Ritse, Amenuo Susan Kulnu, Latonglila Jamir from Nagaland University, and Nabajit Hazarika from Cotton University.
- Published in the Journal of Earth System Science, the study used remote sensing and Geographic Information Systems (GIS) to map glaciers in areas including Tawang, Lohit, West Kameng, Kurung Kumey, Upper Siang, and Upper Dibang Valley districts.
- The Randolph Glacier Inventory was used for reference, revealing a decrease in the number of glaciers from 756 to 646 over the 32-year period.
- The total glacial cover shrank by 309.85 sq. km or about 47% of its previous size.
- Glacier Characteristics: Most glaciers studied were at 4,500-4,800 meters above sea level. These glaciers are typically north-facing and lie on slopes between 15° and 35°.
Role of Himalayan Glaciers
-
- The Himalayas, also known as the “Third Pole”, are critical to the freshwater supply for over 1.3 billion people in downstream regions.
- The glaciers play a key role in maintaining the region’s hydrological balance and influence global sea levels.
- Importance for Water Security:
-
- The glaciers in the Himalayas, covering about 33,000 square kilometres, are a critical water source for the Indus, Ganga, and Brahmaputra rivers.
- These rivers support over a billion people, and meltwater from these glaciers accounts for 30-50% of the river’s annual flow, especially during dry summer months.
- The meltwater sustains agriculture, industries, and domestic water supply, as well as hydropower generation and biodiversity in the region.
Climate Change Impact
- The study reports an increase in temperature by 1.6°C over the past century, with a higher rate in the northwestern Himalayas compared to the global average.
- The eastern Himalayan region is warming at a rate exceeding the global average:
- Temperature increase: Between 0.1°C and 0.8°C per decade.
- Expected rise by end of the century: 5-6°C.
- Expected precipitation increase: 20-30%.
- Glacier retreat in the Himalayas is occurring at a faster rate than the global average, with a yearly area loss of 0.4%.
- Smaller glaciers (below 5 sq. km) are shrinking the fastest.
- Rainfall patterns have been erratic, with no statistically significant trend in precipitation, highlighting climate unpredictability.
Risks and Consequences
- Glacier retreat reduces freshwater availability and disrupts ecosystem balance.
- Increased risk of GLOFs and other hazards, such as the 2023 Sikkim disaster, which killed at least 55 people, and destroyed a 1,200-megawatt hydropower project on the Teesta River.
Research and Government Initiatives
- The Space Applications Centre (SAC) and National Remote Sensing Centre (NRSC) of ISRO have developed techniques for snow and glacier monitoring, such as automated snow cover estimation algorithms, helping to track and map glacier changes.
- The government has launched national projects, such as the Monitoring Snow and Glaciers of the Himalayan region under the National Natural Resources Management Program (NNRMS), to assess future water availability and the impact of climate change.
Future Challenges and Needs
- As glaciers continue to retreat, predicting future changes and their impacts on water supply is critical for long-term planning. Tools like the Divecha Model developed by Anil Kulkarni are important for assessing where new glacial lakes will form and predicting their potential risk of GLOFs.
- Remote sensing technology can help authorities take precautionary measures, such as issuing early warnings to vulnerable populations.
