Guwahati: In the remote, rugged terrains of Arunachal Pradesh, where the mighty Himalayas stand as guardians of a timeless landscape, glaciers—once vast reservoirs of frozen freshwater—are quietly disappearing. Over decades, they have been shrinking at an alarming pace, offering stark evidence of the accelerating impacts of climate change. Despite their environmental importance, these glaciers in the Eastern Himalayas have long remained under-researched due to challenging terrain and limited technological access.
Now, thanks to advancements in satellite imagery, scientists are finally able to capture the troubling dynamics unfolding in this fragile cryosphere.
A new study led by scientists from Nagaland University and Cotton University presents a sobering assessment of glacial retreat in Arunachal Pradesh. Published in the Journal of Earth System Science, the research spans three decades from 1988 to 2020, uncovering startling trends in glacial shrinkage.
Using satellite imagery from Landsat and Sentinel-2A, researchers mapped changes and found that the number of glaciers decreased from 756 to 646, with a glacial cover reduction from 585.23 sq km to 275.38 sq km—a loss of over 50%. Glaciers retreated at a distressing rate of 16.94 sq km per year, exposing bedrock and forming new glacial lakes that pose risks of catastrophic outburst floods (GLOFs).
Arunachal Glaciers are crucial freshwater sources, sustaining rivers during dry seasons. As they melt, an initial surge in river flows may seem beneficial.
However, long-term glacial decline will reduce flows to dangerously low levels, threatening agriculture, drinking water supplies, and hydropower. The study underscores the urgent need to address this retreat, which jeopardizes biodiversity, ecosystems, and the livelihoods of downstream communities. Rising temperatures and erratic precipitation are identified as primary drivers of glacial retreat.
The Eastern Himalayas have warmed faster than the global average, with monsoon months seeing the highest temperature spikes. Smaller glaciers below 5 sq km have shrunk the fastest. Interestingly, while rainfall patterns have been erratic, the study found no statistically significant trend in precipitation, emphasizing the unpredictable nature of climate changes in the region.
One of the study’s breakthroughs lies in its sophisticated use of Remote Sensing (RS) and Geographic Information Systems (GIS).
These technologies allowed scientists to accurately map glacier boundaries, even in debris-covered areas, despite the challenging topography of Arunachal Pradesh. The researchers employed a combination of semi-automatic mapping and manual digitization, setting a valuable precedent for future studies in similarly remote glaciated regions. The study highlighted several worrying trends.
The glacial area of Arunachal glaciers declined from 348.10 sq km in 1988 to 202.59 sq km by 2020, with smaller glaciers suffering the greatest losses. Larger glaciers split into smaller ones, momentarily increasing the glacier count in certain years. Glaciers are concentrated between 4,500 and 4,800 meters, with fewer found at higher or lower elevations due to extreme temperatures. North-facing glaciers confined to slopes between 15° and 30° experienced the most pronounced melting.
“The cryosphere plays a crucial role in regulating regional climate systems. Changes in this fragile ecosystem will accelerate climate change,” said Dr. Nabajit Hazarika, Assistant Professor of Environmental Biology and Wildlife Sciences at Cotton University.
Hazarika is the corresponding author of the study. He emphasized that the cryosphere provides vital ecosystem services, sustaining livelihoods for indigenous populations. “The glaciers are freshwater sources for millions downstream. Their retreat will drastically impact freshwater availability, distribution, and ecosystem health. It also heightens the risk of hazards such as glacial lake outburst floods (GLOFs),” he warned.
The authors stress the need for continued monitoring and adaptive management strategies of Arunachal glaciers to mitigate the impacts of glacial loss. They call for enhanced international cooperation, more efficient water resource management, and the adoption of advanced satellite technologies for glacier surveillance.
As the glaciers of the Eastern Himalayas recede, this groundbreaking research serves as a wake-up call for policymakers, scientists, and communities alike. Protecting this fragile ecosystem is not just about preserving landscapes but ensuring the survival of ecosystems and people in a rapidly warming world.
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