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Why are glaciers of Ladakh retreating? Know geographical reasons behind it?

Why are glaciers of Ladakh retreating? Know geographical reasons behind it?

Relevance:

  • GS 1 || Geography || Geomorphology || Glacial Landforms

Why in news?

Ladakh Glacier retreat due to warming low winter precipitation

Background:

  • Since 2015, a team of scientists from the Wadia Institute of Himalayan Geology (WIHG), Dehradun, has ventured to study the less explored region of the Himalayas, focusing on Zanskar, Ladakh.
  • Scientists evaluated the impact of climate change through the perspective of past and present responses of the PensilungpaGlacier.

Location of Pensilungpa Glacier:

  • The Pensilungpa Glacier is located in Zanskar Range, Ladakh.
  • The Zanskar Range is a mountain range in the union territory of Ladakhthat separates Zanskar from Ladakh.
  • Geologically, the Zanskar Range is part of the Tethys Himalaya.
  • The average height of the Zanskar Range is about 6,000 m.
  • The highest peaks of Himachal are in Zanskar range. 13000 feet high Zojila Pass is in the extreme northwest of Zanskar range.
  • This range, is a branch of the Great Himalayan range of mountains.

Base of the research:

  • The evaluation was done based on field observations for glacier mass balance collected via stake networking over the glacier surface from 2016 to 2019.
  • In this technique, a bamboo stake is installed on the glacier surface using a steam drill for mass balance measurement.

Findings of the study:

  • The study said that field observations for four years (2015–2019) showed that the glacier is now retreating at an average rate of 6.7 plus/minus 3 metre per annum.
  • In the study published in the journal Regional Environmental Change, the team attributes the observed recessional trends of the Pensilungpa Glacier to an increase in the temperature and decrease in precipitation during winters.

Impact:

  • Impact on Human Life:
    • It will have an impact on water, food, energy security, and agriculture, including soil erosion, landslides, and floods.
    • Glacial lakes can also arise as a result of melted ice, causing Glacial Lake Outburst Floods (GLOF) and even modifying global climate by spilling freshwater into the oceans and disrupting circulation.
  • Leaves Debris:
    • Glacial retreat leaves glacial moraines, which are boulders and masses of scraped-together rocky debris and soil.

About Glacier:

What is glacier?

  • A glacier is a long-term accumulation of dense ice that moves under its own weight. Over several years, it is formed when the accumulation of snow surpasses its ablation (melting and sublimation).
  • It has the world’s largest fresh water reservoir (75 percent of all fresh water).
  • Glaciers are remarkable in that they are a freshwater reservoir with sheer mass and the ability to move (Glaciers flow like very slow rivers).
  • It can go in two directions: Internal flow occurs when the pressure and gravity on the ice in a glacier compel it to move downhill; basal slide occurs when the glacier’s base is partially melted and the entire glacier flows.
  • The melting of glaciers creates rivers, valleys, and lakes.

What causes the formation of glaciers and glacial lakes?

  • Glaciers can be found on every continent except Australia, and some of them are hundreds of thousands of years old; the Himalayas have a significant cluster of glaciers.
  • Glaciers are built up of layers of compressed snow that move or “flow” as a result of gravity and the relative softness of ice versus rock.
  • The “tongue” of a glacier can extend hundreds of kilometers from its high-altitude origins, and the end, or “snout,” can advance or recede depending on the amount of snow that accumulates or melts.
  • After glaciers retreat, proglacial lakes are generally bounded by sediment and boulder
  • Both natural and manufactured dams can burst due to increased water or pressure, or structural weakness, producing a deluge of floodwater rushing down the rivers and streams fed by the glacier.

Glacier Retreating:

  • When a glacier’s terminus does not extend as far down valley as it once did, it retreats.
  • When glacial ice melts or ablates faster than snowfall can accumulate and generate new glacial ice, glaciers may recede. Many glaciers throughout the world have recently receded due to rising temperatures and decreased snowfall.
  • Glacial moraines are boulders and clumps of scraped-together stony debris and dirt left behind by glacial retreat. Large temporary lakes of glacier melt water could burst, creating catastrophic floods and potentially modifying global climate by spilling freshwater into the oceans and disrupting their circulation.

About the Study on Zanskar Valley’s Retreating:

  • Glacier observations during a four-year period (2015–2019) found that the Pensilungpa Glacier is retreating at about 6 meters per year.
  • This is due to a decrease in precipitation and a rise in temperature throughout the winter months. The study also found that debris cover has a significant impact on the glacier’s mass balance and retreat, especially in the summer.
  • According to the study, as air temperatures continue to rise in line with global trends, melting will accelerate, and summer precipitation at higher altitudes may change from snow to rain, thereby influencing summer and winter weather patterns.

Initiative Himalayan Ecosystem:

  • NAPCC: One of the eight national missions under the National Action Plan on Climate Change is the National Mission for Sustaining the Himalayan Ecosystem (NAPCC).