Shrinking Himalayan glaciers: Glacier inventory, glacial cover mapping and changes in Eastern Himalayas, India

Abstract

Abstract: Glaciers are considered to be important indicators of climate change. However, they are still poorly inventoried in the Himalayas, especially in the eastern region, owing to the difficult terrain and lack of technological advancement. The present study fills a knowledge gap in glacier dynamics by monitoring changes over multiple decades using Landsat and Sentinel-2A imagery in Arunachal Pradesh, India. The glaciers were delineated using a semi-automatic approach and Randolph Glacier Inventory of Global Land Ice Measurements from Space (GLIMS) was used as a reference. The results indicate that in 1988, there were 756 glaciers covering an area of 585.23 (±3.4) km2. By 2020, this number had decreased to 646 glaciers, with a corresponding reduction in the area to 275.381 (±2.9) km2. The overall rate of change is observed to be 16.94 km2/year. The study also showed that the majority of the glaciers lie at an elevation of 4500–4800 m above mean sea level (AMSL), and the maximum area of the glaciers is oriented towards the north, confined between a slope of 15° and 35°. This study highlights a significant glacial recession throughout the study period. Monitoring and assessing these natural frozen freshwater reserves are crucial for water resource management and understanding climate change impacts. Research highlights: The present work highlights the glacier and its changes in Arunachal Pradesh, Eastern Himalayas, over a span of 32 years. Continuous decline in glaciers was observed. Changes in glaciers are more common at smaller glaciers (<5 km2). The research highlights the importance of understanding the impacts of climate change on frozen freshwater reserves.