A study led by the Centre for Earth Sciences and Himalayan Studies in Arunachal Pradesh to investigate the accelerating glacier retreat and associated flood risks in the Mago Chu sub-basin has revealed some alarming data.
In association with the National Centre for Polar and Ocean Research, IIT Roorkee, and IIT Guwahati, along with other partner institutions, the study has reported that the glaciers in the Mago Chu sub-basin lost nearly 28.5% of their area (over 15 sq km) between 1988 and 2019.
Larger glaciers have broken into smaller, unstable fragments, especially on south-west-facing slopes, where ice loss reached almost 50%, with the ELA, an indicator of glacier health, rising by about 137 meters – indicating that glaciers are not replenishing and have a negative mass balance. These glaciers rely on the summer monsoon for recharge, but monsoon rainfall has drastically declined from 2,100 mm in the 1980s to barely 900 mm in 2024. The number of glacial lakes doubled from 15 in 1988 to 29 in 2017, with the total lake area expanding from 0.71 to 2.11 sq km – increasing flood risks. Four lakes in the basin are designated as ‘high-risk’ by the National Disaster Management Authority due to potential flood hazards.
Field data showed rapid ice loss (around 1 metre in one winter on Khangri glacier) with minimal snow accumulation, confirming accelerated melting. A breach in one of the high-risk lakes could cause floods exceeding 12,000 cubic metres per second, threatening villages and hydropower projects downstream, the study says.
The monitoring needs to be stepped up for early warning systems, and efforts must be put in place not to stress the fragile ecology. Policy must be rooted in ground reality.