Glaciers and the Cryosphere of India

Introduction to Glaciers

A glacier is a large, persistent body of dense ice formed from compacted snow that moves under its own weight due to gravity.

Formation Process

1. Snow accumulates year after year in a zone of accumulation (high altitude/polar regions).
2. Lower layers are compressed by the weight above → snow crystals recrystallise into firn (granular ice, ~1 year old) and then into glacial ice (~decades).
3. When ice becomes thick enough (~30–40 m), it deforms plastically and begins to flow downhill.
4. Glaciers terminate (melt/calve) in a zone of ablation where mass loss equals or exceeds gain.
5. Equilibrium Line Altitude (ELA): The altitude separating accumulation zone from ablation zone — rising ELA indicates glacier retreat.

Types of Glaciers

Glacier Terminology (UPSC-relevant)

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The Cryosphere

The cryosphere is the collective term for all frozen water components of the Earth system:

• Glaciers and ice sheets
• Sea ice
• Lake/river ice
• Snow cover
• Permafrost and seasonally frozen ground

India's cryosphere is primarily the Himalayan–Karakoram–Hindu Kush–Tibetan Plateau complex — part of what scientists call the "Third Pole".

The Third Pole

• The Tibetan Plateau and surrounding mountain ranges contain the largest reservoir of freshwater outside the Arctic and Antarctic.
• Area: ~4 million km² of high-altitude frozen terrain.
• Freshwater stored: ~46,000 BCM (billion cubic metres) — dwarfing India's total utilizable water.
• 10 major Asian river systems originate here: Ganga, Indus, Brahmaputra, Mekong, Yangtze, Yellow River, Irrawaddy, Salween, Amu Darya, Tarim.
• Population served: ~1.65 billion people depend on Third Pole meltwater (including ~700 million Indians).

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Himalayan Glaciers of India

Inventory

Major Glaciers

Key fact: Siachen Glacier is the source of Nubra River, which joins the Shyok, which joins the Indus. It is NOT a source of the Ganga.

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Glacier Retreat — Current Status

India-Specific Data

• ~70% of Himalayan glaciers are retreating (IPCC AR6 + GSI data).
• Rate of retreat: Accelerating — average ~22 m/year for Gangotri; faster for smaller glaciers.
• Area loss: Himalayan glaciers lost ~40% of their area in the 20th century; ongoing.
• Volume loss: Indian Himalayan glaciers losing ~0.5–0.6 m water equivalent per year (mass balance deficit).

Glacier-by-Glacier Data

The Karakoram Anomaly

Unlike most Himalayan glaciers, many Karakoram glaciers are stable or even advancing — an anomaly called the Karakoram Anomaly:

• Reason: Increased winter snowfall (from strengthened Western Disturbances) in high Karakoram compensates summer melt.
• Affected glaciers: Siachen, Baltoro, Batura, Hispar.
• Not universal: Some Karakoram glaciers are still retreating; surging glaciers also present.
• UPSC angle: "Not all Himalayan glaciers are retreating" — Karakoram Anomaly is a direct UPSC Prelims trap.

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Causes of Glacier Retreat

1. Rising temperatures: Hindu Kush Himalaya (HKH) region is warming at ~0.3°C per decade — nearly double the global average.
2. Black carbon (soot): Aerosols from South Asian biomass burning and diesel engines deposit on glacier surfaces → reduce albedo → accelerate melt.
3. Reduced winter snowfall in most Himalayan ranges (except Karakoram): Weakening Western Disturbances → less snow accumulation.
4. Feedback loops: Less snow cover → lower albedo → more solar absorption → faster melt (positive feedback).
5. Permafrost thaw: Destabilises slopes around glaciers → more debris input → alters dynamics.

IPCC AR6 Projections

Under the 4°C scenario, many small glaciers in the western Himalayas and Eastern Himalayan ranges will virtually disappear.

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Glacial Lakes and GLOF Risk

Formation of Glacial Lakes

As glaciers retreat, they leave behind:

1. Moraine-dammed lakes: Meltwater impounded behind terminal or lateral moraines.
2. Ice-dammed lakes: Water pooled against a glacier or ice barrier.
3. Bedrock-scooured lakes (tarns): In cirque depressions.

GLOF (Glacial Lake Outburst Flood)

When a glacial lake dam breaches:

• Sudden massive flood releases millions of cubic metres of water within hours.
• Travels downstream as a debris flow — far more destructive than water alone.
• Typically triggered by: ice avalanche into lake (seiche wave), moraine dam seepage/piping, earthquake.

India's Glacial Lake Inventory

• ~4,000+ glacial lakes identified in the Indian Himalayas (SAC/ISRO, 2021).
• ~200 high-risk lakes identified for monitoring by NDMA.
• Lake area is expanding as glaciers retreat — creating new GLOF hazards.

Major GLOF Events in India

South Lhonak Lake GLOF (2023) — UPSC Relevance

• South Lhonak Lake (North Sikkim, ~17,000 ft elevation): A moraine-dammed proglacial lake that had been growing for decades.
• October 4, 2023: Lake breached — 10+ million cubic metres of water + debris released in minutes.
• Impact: Teesta River flooded, Chungthang dam (2,000 MW capacity) destroyed, multiple bridges gone, 77+ deaths.
• Significance: Demonstrated how a single GLOF can destroy critical infrastructure and downstream communities hours away.

GLOF Early Warning — India's Approach

• NDMA GLOF guidelines (2020): Identifies high-risk lakes; response protocols.
• SAC/ISRO satellite monitoring: Real-time lake expansion tracking; 200+ high-risk lakes monitored.
• Community-based early warning: Sirens, SMS systems in Uttarakhand and Sikkim valleys.
• Building codes: NDMA recommends avoiding construction within 50 m of river banks in GLOF-prone valleys.

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Permafrost and Frozen Ground

What is Permafrost?

• Permafrost: Ground that remains at or below 0°C for at least two consecutive years.
• Found in: Ladakh (extensively), high Himalayan zones, Sikkim high altitude areas, parts of Arunachal Pradesh.
• India has an estimated ~90,000 km² of permafrost-affected terrain.

Permafrost Thaw — Consequences

1. Slope instability: Frozen ground holds hillsides together; thaw → landslides.
   • Chamoli 2021 disaster linked in part to permafrost thaw destabilising slopes.
2. Infrastructure damage: Roads, buildings on permafrost crack as ground shifts.
   • Leh–Manali Highway, Leh–Srinagar Highway maintenance increasingly difficult.
3. Carbon release: Permafrost stores carbon; thaw releases CO₂ and methane → feedback loop.
4. Water source disruption: Rock glaciers and permafrost are important dry-season water sources for Ladakh streams.

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Snow Cover

Himalayan Snow Cover Trends

• Snow cover provides critical dry-season river flow (snowmelt from April–June).
• ISRO/SAC monitoring shows declining snow cover in northwestern Himalayas over 2001–2023.
• Consequences: Rivers like Indus, Chenab, Jhelum have lower pre-monsoon discharge → water stress in Punjab, Sindh.
• Exception: Some years with strong WDs bring above-normal snow → Jhelum flood risk in spring.

Snow Water Equivalent (SWE)

A critical metric for water management:

• SWE = volume of water stored as snow.
• India is developing SWE monitoring through ISRO satellites and field stations (part of National Mission for Sustaining the Himalayan Ecosystem — NMSHE).

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National Missions and Policy

National Mission for Sustaining the Himalayan Ecosystem (NMSHE)

• Part of India's National Action Plan on Climate Change (NAPCC) — 8 missions.
• Goals:
  1. Understanding glacial retreat patterns.
  2. Monitoring ecosystem changes in the Himalayas.
  3. Developing traditional knowledge systems.
  4. Capacity building in Himalayan states.
• Implemented by: Ministry of Science and Technology + Ministry of Earth Sciences.

ICIMOD (International Centre for Integrated Mountain Development)

• Headquartered in Kathmandu, Nepal.
• Members: Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal, Pakistan.
• India's primary multilateral body for Hindu Kush Himalaya research.
• HKH Assessment 2019: Found the Third Pole is warming at twice the global rate and projected catastrophic glacier loss.

Glacier Authority of India (Proposed)

• Multiple expert committees have recommended a dedicated Glacier Protection Authority — not yet enacted (as of 2026).
• The Uttarakhand Spatial Data Infrastructure and state glacier monitoring exist but no central statutory body.

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Siachen Glacier — Special Context

Military and Strategic Significance

• Siachen Glacier (~76 km, Karakoram): India has controlled it since Operation Meghdoot (April 13, 1984).
• World's highest battlefield: Indian and Pakistani troops stationed at altitudes >6,000 m.
• Siachen is the source of the Nubra River (joins Shyok → Indus).
• Strategic importance: Controls the Saltoro Ridge and denies Pakistan access to key passes.

Environmental Impact of Military Presence

• Decades of military activity: waste, fuel spills, artillery shells.
• ~1,000 metric tonnes of waste estimated on Siachen and surroundings.
• India has proposed demilitarisation, contingent on Pakistan first authenticating and accepting the current positions on the Actual Ground Position Line (AGPL); Pakistan has declined this condition, stalling any agreement.
• Environmental NGOs and GSI have documented pollution from military camps.

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UPSC Corner

High-Frequency Prelims Topics

• Siachen = longest glacier in India (~76 km); Karakoram, Ladakh; source of Nubra River.
• Gangotri = source of Bhagirathi (tributary → Ganga); Uttarakhand; retreating ~22 m/year.
• Zemu = largest glacier in Eastern Himalayas (Sikkim); source of Teesta.
• Bara Shigri = largest glacier in Himachal Pradesh; source of Chandra River.
• Karakoram Anomaly: Many Karakoram glaciers stable/advancing — due to increased WD snowfall.
• Third Pole = Tibetan Plateau + Hindu Kush Himalaya; 10 major Asian rivers originate here.
• GLOF = Glacial Lake Outburst Flood; South Lhonak 2023, Kedarnath 2013, Chamoli 2021.
• ICIMOD HQ: Kathmandu, Nepal; India is a member.
• NMSHE = National Mission for Sustaining the Himalayan Ecosystem — one of 8 NAPCC missions.
• Cirque → Arête → Horn: Three stages of glacial landform development on a peak.

UPSC Mains GS1 Angles

1. "Himalayan glaciers are retreating at an unprecedented rate. What are the causes and what are the long-term implications for India's water security?"
2. "Critically examine the Karakoram Anomaly — why are some glaciers advancing while most are retreating?"
3. "Glacial Lake Outburst Floods (GLOFs) are an emerging disaster risk in the Indian Himalayas. Discuss with recent examples." [Use Sikkim 2023, Chamoli 2021]
4. "Distinguish between glacial erosion and glacial deposition landforms and explain their significance for Indian geography."

GS3 Angles

1. "How is permafrost thaw in Ladakh and the Himalayas threatening infrastructure development in India's border regions?"
2. "Evaluate India's policy response to the glacial retreat crisis through the NMSHE and related initiatives."

MCQ Trap Awareness

• Trap: "Gangotri is the source of the Ganga" → Gangotri is the source of the Bhagirathi, a headstream; the Ganga is traditionally said to originate at Gangotri but formed at Devprayag (confluence of Bhagirathi and Alaknanda).
• Trap: "Siachen is the source of the Ganges" → Incorrect; Siachen → Nubra → Shyok → Indus.
• Trap: "All Himalayan glaciers are retreating" → Incorrect; the Karakoram Anomaly means many K2-region glaciers are stable or advancing.
• Trap: "Zemu glacier is in Uttarakhand" → Incorrect; Zemu is in North Sikkim.
• Trap: "Third Pole = South Pole" → Completely wrong; Third Pole = Tibetan Plateau + HKH complex.
• Trap: "ICIMOD is headquartered in New Delhi" → Kathmandu, Nepal.

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Key Facts at a Glance

• Glaciers in India: ~9,575 (GSI)
• Glaciated area: ~37,000 km²
• Freshwater stored: ~3,735 BCM
• Longest glacier (India): Siachen (~76 km) — Nubra River source
• Ganga's glacial source: Gangotri → Bhagirathi; retreat: ~22 m/year
• Largest glacier, Eastern Himalayas: Zemu (North Sikkim)
• Largest glacier, Himachal Pradesh: Bara Shigri — Chandra River
• Karakoram Anomaly: Stable/advancing due to Western Disturbance snowfall
• Third Pole warming rate: ~0.3°C/decade (2× global average)
• GLOF: South Lhonak 2023 (Sikkim), Chorabari 2013 (Kedarnath), Chamoli 2021
• 200+ high-risk glacial lakes monitored by SAC/ISRO
• NMSHE: 1 of 8 NAPCC missions; Ministry of Science & Technology
• ICIMOD HQ: Kathmandu, Nepal
• Operation Meghdoot (1984): India secured Siachen Glacier