CHENNAI: Images of melting glaciers are perhaps the most common representation of climate change. Glaciers around the world are melting at an alarming rate due to global warming. A recent study by researchers from Nagaland University and Cotton University estimates that glaciers in the Eastern Himalayas, particularly in Arunachal Pradesh, have retreated by an average of 16.94 sq km per year between 1988 and 2020. The Himalayas, often referred to as the ‘third pole’, contain the highest concentration of glaciers outside the polar regions. The study’s authors, Vimha Ritse, Nabajit Hazarika, Amenuo Susan Kulnu, and Latonglila Jamir, noted that “changes in glaciers are considered to be more rapid in the Himalayas than in other parts of the world”.
Arunachal Pradesh represents the easternmost sector of the Himalayan mountain range. The researchers used imagery from Landsat and Sentinel-2A satellites to track changes over several decades. In 1988, 756 glaciers were observed; by 2020, the number had decreased to 646. “A net area decrease of 309.8 sq km, along with the loss of 110 glaciers, was observed during the study period,” the researchers reported. In northern Arunachal Pradesh, the retreat of glaciers exposed the underlying bedrock. These findings were published in the peer-reviewed Journal of Earth System Science.
Although the number of glaciers decreased overall between 1988 and 2020, there were periods where the numbers actually increased. “The present study shows that the number of glaciers has exhibited both increasing and decreasing trends,” the researchers noted. For example, in 2005, 25 more glaciers were observed than in 2000. However, between 2015 and 2020, the count declined by 68. During this period, around 34 sq km of ice was lost each year, compared to the overall average loss of 19.6 sq km per year. The increase in glaciers observed in earlier years could be due to larger glaciers fragmenting into smaller ones, the researchers suggested, citing previous studies.
The research highlights the need for enhanced monitoring of glaciers in the Eastern Himalayas. While studies have focused on glacial retreat in the western Himalayas, there is a lack of detailed research on the Eastern side. “Mapping and monitoring these naturally frozen freshwater reserves is essential for managing water resources, understanding the impacts of climate change, and anticipating the long-term effects on future water availability and rising sea levels,” the researchers concluded.
Himalayan glaciers are a vital source of freshwater for northern India. Several major rivers, including the Ganga and Yamuna, which supply water to large parts of northern India, originate from these glaciers. As glaciers continue to shrink, water availability in the long term could decrease significantly.