Himalayan glacier changed track 20,000 years ago: study

Context:

Nearly 20,000 years ago, a 5-km-long Himalayan glacier “abruptly” changed course and over time fused into an adjacent glacier in present day Pittoragarh, Uttarakhand.

Relevance:

GS-I: Geography (Physical Geography, Distribution of Key Natural Resources, Water Resources, Important Geophysical Phenomena), GS-III: Environment and Ecology (Climate change and its impact)

Dimensions of the Article:

1. What is a Glacier?
2. About the Himalayan glacier that changed track
3. Important Glaciers in India

What is a Glacier?

• A glacier is a persistent body of dense ice that is constantly moving under its own weight. It is form by the accumulation of snow exceeds its ablation (melting and sublimation) over many years. It is the largest reservoir of fresh water on the Earth (75 percent of the world’s fresh water).
• Glaciers are unique because they are reservoir of fresh water, have sheer mass and their ability to move (Glaciers flow like very slow rivers). It may move in two ways- Internal flow is when the pressure and gravity on the ice in a glacier cause it to move downhill; Basal sliding is when an entire glacier moves because its base is slightly melted. Rivers, valleys and lakes are formed after melting of glaciers.
• As per National Snow & Ice Date Centre, it occupies about 10 percent of the world’s total area.

About the Himalayan glacier that changed track

• A Himalayan glacier changed course and over time fused into an adjacent glacier, and this is the first time that such a turn in glacier’s course has been recorded in the Himalayas.
• Change in climate along with tectonic movement probably caused this to happen.
• The study adds to evidence of the inherent instability of the Himalayan region, among the youngest mountain ranges in the world due to which the underlying tectonic plates that support it are not stable but are jittery and frequently trigger earthquakes and landslides.
• The event had “similarities” to the February disaster in Rishiganga valley, Uttarakhand, in which a large mass of rock and debris detached from a glacier and hurtled down the Rishiganga river.

Important Glaciers in India

-Source: The Hindu