At least 89% of 2,431 glacial lakes in the Himalayas have notably expanded since 1984, the Indian Space Research Organisation (ISRO) said in a report on Tuesday.
The expansion of glacial lakes due to the impact of global warming can lead to cascading consequences in lower regions, experts have warned.
Over the last three to four decades, satellite data archives have laid bare the changes occurring in glaciated environments, ISRO stated.
According to the ISRO report, 601 glacial lakes, or 89%, have expanded more than twice, while 10 lakes have grown 1.5-2 times their original size. 65 lakes have expanded 1.5 times.
Of the 2,431 glacial lakes larger than 10 hectares, 676 have significantly expanded, with approximately 130 of these lakes located in India – 65 in the Indus river basin, 7 in the Ganga river basin, and 58 in the Brahmaputra river basin.
The ISRO report, titled ‘Satellite Insights: Expanding Glacial Lakes in the Indian Himalayas,’ explains that 314 lakes are situated between 4,000 and 5,000 meters, while 296 lakes are over 5,000 meters above sea level.
The report highlights the significant expansion of the Ghepang Ghat glacial lake in Himachal Pradesh between 1989 and 2022. The lake, which is situated at an elevation of 4,068 meters in the Indus river basin, has grown by 178% from 36.49 hectares to 101.30 hectares. This indicates an annual increase of approximately 1.96 hectares.
The long-term satellite-derived change analyses provide valuable insights for comprehending glacial lake dynamics. This information is crucial for evaluating environmental impacts and designing strategies for managing the risks of glacial lake outburst floods (GLOFs) and climate change adaptation in glacial environments.
ISRO noted that the study faced challenges due to the rugged and inaccessible terrain. However, the space agency emphasized that satellite remote sensing technology is an excellent tool for inventory and monitoring tasks due to its wide coverage and revisit capability.
The Himalayan mountains are often referred to as the ‘Third Pole’ due to their extensive glaciers and snow cover. These mountains are highly sensitive to global climate changes, both in their physical characteristics and their societal impacts.
Globally, research has consistently shown that glaciers have experienced unprecedented rates of retreat and thinning since the Industrial Revolution’s beginning in the 18th century, ISRO stated in the report.
Glaciers that recede give rise to new lakes and expand existing ones in the Himalayan region. These water bodies, resulting from melting glaciers, are known as glacial lakes and play a critical role as freshwater sources for Himalayan rivers. However, they also present significant risks, such as GLOFs, which can have devastating effects on communities living downstream.
GLOFs occur when glacial lakes release large volumes of meltwater due to breaches in natural dams, such as those formed by moraine or ice, causing sudden and severe flooding downstream. Avalanche of ice or rock, extreme weather events, and other environmental factors can all trigger these dam failures.
