Centre working on plan to assess vulnerability of all glacial lakes: Sources

New Delhi: As cloud bursts in Himalayan states get more frequent, the Centre will study the vulnerability of all glacial lakes through ground surveys and establish a monitoring system to disseminate information about potential glacial lake outburst floods (GLOFs).

“A comprehensive assessment of the vulnerability of glacial lakes in the country is necessary. Our current understanding of these lakes is primarily based on remote sensing. We are now planning to conduct ground validations of all glacial lakes. Their vulnerability cannot be determined without this exercise,” said an official at the National Disaster Management Authority (NDMA).

Glacial lakes are formed by the melting of glaciers and the accumulation of meltwater in depressions on or near the glacier's surface. GLOFs occur when these lakes suddenly burst open due to various factors, such as excessive water accumulation or triggers like earthquakes.

When a glacial lake bursts, it releases a massive volume of water, resulting in flash floods downstream. These floods can be extremely destructive and dangerous for both people and the environment in the affected area.

According to environment expert Anjal Prakash, vulnerable areas include Himachal Pradesh, Jammu and Kashmir, Uttarakhand, Sikkim, and Arunachal Pradesh, where numerous glacial lakes are rapidly expanding due to climate change.

Recently, the devastating floods caused by the Lhonak lake outburst in Sikkim due to heavy rains earlier this month resulted in at least 60 fatalities and extensive damage in Mangan, Gangtok, Pakyong, and Namchi districts. It also led to the destruction of the Chungthang dam, also known as Teesta III dam, a vital component of a major hydropower project in the state.

Climate scientist Roxy Mathew Koll warned that the likelihood of cloudbursts, heavy rainfall, landslides, and glacial outbursts has markedly increased, especially over mountainous regions, in a swiftly warming world.

If we have data over these regions, we can identify the hotspots and also improve our weather forecasts, Koll, from Pune's Indian Institute of Tropical Meteorology (IITM) said.

However, as glacial lakes are located in remote, high-altitude areas, conducting ground surveys is a challenging task, the official said.

“The majority of these lakes are situated at altitudes of 5,000 metres or higher. Experts with knowledge of hydrology, topography, and other characteristics of glacial lakes, who can endure harsh weather and difficult terrain, will be part of the teams selected for ground validation exercises,” the source added.

“The conditions of glaciers in one state may differ from another, so we will need to develop a comprehensive monitoring system. This will be transformed into an early warning system, and the entire process is expected to take at least five years and a significant effort,” another source explained.

Experts also attribute GLOFs to melting glaciers, a consequence of escalating temperatures driven by human-induced pollution and unchecked construction in the region. Factors such as earthquakes and black carbon emissions also play a role.

According to environmental engineer Mohammed Farooq Azam, climate change is working in two ways.

First, global warming is resulting in glacier wastage that is more pronounced post-2000 in the Himalayan region. The receding glaciers are leaving depressions where they terminate. These depressions are filled with meltwater and produce pro-glacial lakes, which are often held by the fragile natural dams. These lakes in turn enhance glacier wastage and are growing in size as well as numbers with ongoing global warming, he explained.

Further, climate change is also resulting in extreme weather conditions, Azam, associate professor at the Indian Institute of Technology-Indore, added.

The frequency of extreme precipitation and heat waves is increasing, making pro-glacial lakes more vulnerable to breaches. This was the case in the 2013 Kedarnath disaster where the Chorabari pro-glacial lake was completely breached and that is probably what happened in Sikkim too, Azam said.

Emphasising that climate change plays a pivotal role in driving GLOFs, the research director and adjunct associate professor at the Indian School of Business (ISB), Hyderabad, said the detrimental influence of infrastructure, deforestation, and human settlements in these vulnerable Himalayan regions are exacerbating the threat.

Earthquakes, a common occurrence in tectonically active regions like the Himalayas, can also trigger GLOFs by destabilising the glacier or the dam. Landslides, often caused by a mix of thawing permafrost and increased water pressure, can also rupture glacial lakes. Human activities like road construction and deforestation in fragile mountain ecosystems further contribute to GLOF risks, Prakash said.

Climate change is a risk multiplier in this case where the mountains are already at ecological and environmental risk because of biophysical and topographic characteristics, Shah, co-founder at Reading Himalaya, a research and policy consultancy, told PTI.

Half the Earth's 215,000 glaciers are expected to melt by the end of the century, even if global warming is limited to 1.5 degrees Celsius, revealed a study published in the journal Nature, underscoring the criticality of the situation.

This alarming revelation comes alongside another concerning statistic: the volume of glacial lakes has surged by 50 per cent in just 30 years, according to a 2020 study based on satellite data.

While glacier lakes can emerge in any area left behind after a glacier retreats, the experts said GLOF hotspots are primarily concentrated in the eastern and central Himalayan regions.

All the Himalayan countries are prone to have GLOF events in the future due to enhanced glacier wastage, increase in number and size of pro-glacier lakes, increase in erratic precipitations and heatwaves, Azam explained.