Rapid Expansion of Himalayan Glacial Lakes

Introduction to Glacial Lake Expansion

The National Green Tribunal (NGT) recently took suo motu cognizance of a news report. This action highlighted the alarming increase in the size of Himalayan glacial lakes.

The NGT has issued a notice to the central government, emphasizing the significant environmental concern. This rapid expansion is primarily attributed to rising temperatures across the Himalayan region.

What are Glacial Lakes?

A glacial lake is a body of water that forms in connection with a glacier. These lakes are typically found at the base of a glacier, but can also develop on, within, or beneath the ice mass.

Their formation is a natural geological process, intricately linked to the dynamics of glacial movement and retreat.

Formation of Glacial Lakes

Glacial lakes primarily form in depressions carved out by advancing glaciers. As these glaciers retreat, the meltwater accumulates in these newly exposed basins.

Natural dams, often composed of ice or moraines (accumulations of glacial debris), can also impound water, leading to the formation of these lakes. However, these natural dams are often unstable.

The instability of these dams makes them prone to bursting, which can lead to catastrophic events known as Glacial Lake Outburst Floods (GLOFs).

Alarming Expansion in India

The NGT's notice underscored a critical finding regarding glacial lake expansion specifically within India. The surface area of these lakes has shown a substantial increase in recent years.

This expansion poses a severe threat to both human settlements and critical infrastructure located downstream in vulnerable regions.

Drivers of Expansion

The rapid expansion of Himalayan glacial lakes is driven by a combination of climate-related factors. These factors accelerate both the formation of new lakes and the growth of existing ones.

• Global Warming: Rising global temperatures lead to accelerated glacier melting in the Himalayas, directly contributing more water to glacial lakes.
• Glacier Retreat: As glaciers retreat, they expose new land surfaces. This creates new depressions and allows existing lakes to expand into the newly uncovered terrain.
• Thawing Permafrost: The thawing of permafrost (permanently frozen ground) creates depressions where water can collect. As permafrost thaws, it loses its natural drainage barrier, further expanding glacial lakes.