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Subject: Cryosphere,Glacier Melting

  • Building trust is key in warnings on melting glaciers

    Why in the News

    The disaster that unfolded in Nepal and Tibet began with a rock-ice avalanche that transformed into a devastating debris flow. First reports read the event as an earthquake and possibly a glacial lake outburst flood (GLOF), a flood released when a lake held back by glacial ice or debris gives way. The shaking was in fact the force of the rock-ice avalanche hitting the valley floor. There was no glacial lake in the valley at all. The same sequence produced the Chamoli disaster in 2021, from a rock-ice avalanche off Ronti Peak, and the Dharali disaster in 2025. Himalayan warning systems are organised around glacial lakes whose location is known. The hazard that killed at Rasuwa can begin on any of hundreds of thousands of thawing slopes.

    What is a rock-ice avalanche hazard cascade?

    1. Rock-ice avalanche: A mass of rock and ice detaches from a steep, deglaciating slope and falls to the valley floor.
    2. Transformation into a debris flow: The impact converts the avalanche into a debris flow, which then travels down the valley and destroys what stands in its path.
    3. Hazard cascade: One process sets off the next, so the damaging flood has no single identifiable source waiting to be watched.
    4. Disaster rather than natural event: Many rock avalanches and thousands of debris flows occur every year, and they become disasters only where they strike lives and surroundings.

    Why is a hazard cascade harder to plan for than a glacial lake flood?

    1. Known water source in a GLOF: For a glacial lake outburst flood, the origin of the water is the glacial lake itself.
    2. Three interventions available at a lake: A lake can be modelled to forecast flood behaviour, drained where it is judged dangerous, or fitted with real-time monitoring.
    3. No lake at Rasuwa: There was no large lake in that valley, so none of those three options was available and the event was as difficult to plan for as Chamoli.
    4. Number of possible sources: Rock-ice avalanches could originate from many hundreds of thousands of steep, rapidly deglaciating slopes with thawing permafrost in the Himalaya.
    5. Limits of failure prediction: Detecting slopes that are already moving is perhaps possible, and working out which of them will fail catastrophically is not yet reliable.

    Who is exposed to these hazards, and where did the deaths occur?

    1. Global GLOF exposure: 15 million people worldwide live with glacial lake outburst flood danger.
    2. Concentration in High Mountain Asia: Over 9 million of those people are in High Mountain Asia, and nearly 3 million are in India alone.
    3. Hydropower workers among the dead: In both Chamoli and Rasuwa, a significant number of the dead and missing were workers at hydropower infrastructure standing in the path of the flows.
    4. Decisions downstream: The open questions are where people can and cannot live below such slopes, and what the benefits and risks of hydropower development in these environments are.

    What would a denser seismic station network deliver?

    1. Detection of landslide-generated earthquakes: Seismic stations can detect and locate the earthquake that a landslide itself generates.
    2. Seismic signature of the flood: Extreme flood events produce continuous seismic noise as they move down a valley, in the same way glacial lake outburst floods do.
    3. Technically possible, not yet built: The denser network is achievable with existing science and has not been done.
    4. Cost and cross-border requirement: It would need co-operation across the Himalaya’s international borders and tens of millions of dollars.

    Challenges to early warning for Himalayan hazard cascades

    1. Instrumenting every valley is impractical: River gauges or monitoring in every single high mountain valley cannot realistically deliver warning in time. Eg. At Rasuwa the cascade began where there was no lake and no instrumented source to watch.
      The Fix: Concentrate instruments on the valleys that carry settlements or hydropower works below a rapidly deglaciating slope.
    2. No usable lead time near the source: Warning shrinks to nothing for people living close to where the cascade begins. Eg. The system in place during the Rasuwa event gave enough warning for those further downstream and not enough for those upstream.
      The Fix: Pair instrumented warning with pre-agreed evacuation routes for the upstream valley, where no alert will ever arrive early enough.
    3. Warning as a communication problem: Detection has to be followed by the news reaching people, by the speed at which they respond, and by what they actually do. Eg. Workers at hydropower sites in the flow path died in both Chamoli and Rasuwa.
      The Fix: Embed the warning system in the communities expected to act on it, so an alert is trusted and attached to a rehearsed response.
    4. Cost of a wrong call: Naming a slope as dangerous, and failing to name one, both carry high consequences. Eg. Identifying which moving slopes will catastrophically fail is not yet reliable science.
      The Fix: Publish slope hazard assessments with their stated uncertainty, so the confidence attached to a warning travels with the warning.

    Conclusion

    Himalayan risk planning is built around a hazard whose source can be located, and the events now killing people begin on slopes nobody is watching. The science to close that gap exists and the network to carry it does not, because it requires money and agreement between countries that share the range. A warning that communities do not trust, or do not know how to act on, saves nobody, which makes trust part of the engineering rather than an afterthought. Lives can be saved on those terms, and the places cannot, which turns the harder question into where building should be permitted at all.

    Matching Previous Year Question

    “[2020, GS1, 10 marks] How will the melting of Himalayan glaciers have a far-reaching impact on the water resources of India? (हिमालय के हिमनदों के पिघलने का भारत के जल-संसाधनों पर किस प्रकार दूरगामी प्रभाव होगा ?)”

  • How melting glaciers could ‘put 20% of GDP at risk’

    Why in the News

    A new assessment of the Himalayas has put a monetary value on India’s dependence on the mountain range, estimating that Rs 64.8 lakh crore, or 21.5% of India’s FY24 GDP, rests on Himalayan water and Himalayan economies. The report, ‘A resilient Himalaya: protecting a region at risk and securing future prosperity’, follows the Nepal floods that placed the warming Himalayas under public attention. It converts glacier retreat from an environmental concern into a measurable macroeconomic exposure. The tension it exposes is one of timing. Meltwater flows are rising now and are expected to peak around the middle of this century before declining, while the one driver India can act on quickly, black carbon, is being tackled unevenly across States.

    What is the ‘A resilient Himalaya’ report?

    1. Compiling body: The report was compiled by the consultancy Systemiq, in partnership with the Integrated Mountain Initiative.
    2. Supporting institutions: It was supported by the International Centre for Integrated Mountain Development (ICIMOD), Nepal, and the GB Pant National Institute of Himalayan Environment, Uttarakhand.
    3. Core estimate: It places Rs 64.8 lakh crore, equal to 21.5% of India’s FY24 GDP, as dependent on the Himalayas.

    How was the 20% of GDP figure arrived at?

    1. Direct layer: The Gross State Domestic Product of the Himalayan States is counted in full as Himalaya dependent output.
    2. Indirect layer: Downstream agriculture, manufacturing, hydropower and services reliant on Himalayan fed rivers and on groundwater recharge are added. Rain fed production is expressly excluded from this layer.
    3. Induced layer: Supply chain and wage spending effects are counted, such as tractors sold from southern States into the Indo Gangetic Plains, and wages spent on food and services.

    Why does glacier retreat translate into economic risk?

    1. Three river systems: The Himalayas feed the Indus, Ganga and Brahmaputra systems, which support agriculture, cities and industry downstream.
    2. Named dependent economies: The report ties these flows to wheat and rice across the Indo Gangetic plain, tea in Assam and Bengal, hydropower in the Northeast, and pilgrimage economies in downstream towns.
    3. Disaster concentration: The Himalayas account for 18% of India’s land but roughly 35% of its disasters, making them a standing disaster hotspot rather than an occasional one.
    4. The reconstruction trap: Disasters create food and water insecurity, disrupt supply chains, displace people and raise macroeconomic and sovereign debt pressure. Reconstruction spending then leaves less money available for building future resilience.

    Why do meltwater flows rise before they fall?

    1. Glaciers as storage: Glaciers hold water as ice and release meltwater into rivers, particularly during the dry season when rainfall contributes least.
    2. Peak Water: Himalayan river basins are expected to reach ‘Peak Water’ around the middle of this century, the point at which glacier meltwater reaches its maximum.
    3. The decline after the peak: Flows begin to fall after that point as the ice reserve shrinks, so today’s higher flows are not a durable supply.

    Why is black carbon the driver India can act on fastest?

    1. What black carbon is: Black carbon is soot produced by incomplete combustion, and unlike global warming as a whole it is a pollutant India can act on quickly on its own.
    2. The snow darkening effect: When black carbon lands on snow it darkens the surface, so the snow absorbs more sunlight instead of reflecting it. Modelling shows this adds about 40 watts per square metre of surface heating in the spring season across the Himalaya.
    3. Zigzag kiln technology: Converting brick kilns to zigzag firing, a method that burns fuel more efficiently, cuts black carbon and particulate emissions by roughly 70% and fuel use by 20% to 30%.
    4. Uneven adoption: Punjab and Haryana have completed the switch to zigzag kilns. Uttar Pradesh, India’s largest brick producer, is at only 56%, and the rest of India runs on traditional technology.
    5. Kilns are not the whole story: Real progress requires kilns, cookstoves, transport and crop residue burning to be tackled together rather than one source at a time.

    Challenges to securing the Himalayan economy

    1. Transboundary river dependence: The three river systems the estimate rests on originate outside India in whole or in part, so flow security is not a purely domestic policy variable. Eg. The Indus system is governed by a treaty arrangement with Pakistan, and the Brahmaputra rises in Tibet where upstream storage decisions are not disclosed to India.
      The Fix: Build hydrological data sharing into existing basin level dialogues so flow changes are detected upstream rather than inferred from downstream damage.
    2. Gaps in glacier monitoring: India monitors only a small fraction of its glaciers on the ground, so mass balance estimates rest heavily on modelling. Eg. Glacier and lake monitoring shortfalls were flagged after the February 2021 Chamoli disaster in Uttarakhand.
      The Fix: Expand automated weather station and mass balance networks across benchmark glaciers in each Himalayan basin.
    3. Glacial lake outburst risk: Warming creates and expands moraine dammed lakes whose failure sends a flood wave downstream with little warning time. Eg. The October 2023 South Lhonak lake outburst in Sikkim destroyed the Teesta III hydropower project at Chungthang.
      The Fix: Attach early warning instrumentation and drawdown works to every high risk lake identified in the national expansion inventory.
    4. Construction in a fragile zone: Hydropower, highway and tunnel projects add load and cut slopes in terrain that is already seismically active and steep. Eg. Land subsidence in Joshimath, Uttarakhand, in January 2023 forced the evacuation of hundreds of households.
      The Fix: Make cumulative basin level impact assessment, rather than project by project clearance, the condition for approving new infrastructure in the Himalayan States.
    5. Fiscal asymmetry between hill and plain States: Himalayan States carry the cost of protecting catchments while the economic benefit accrues largely downstream. Eg. Forest cover in the Himalayan States supports irrigation and power generation in the plains without a matching transfer for that service.
      The Fix: Widen ecological and forest cover weightage in Finance Commission devolution so catchment protection is financed rather than assumed.

    Conclusion

    The estimate changes the category of the problem rather than the facts of it. A mountain range treated as an environmental subject now carries a fifth of national output as a stated exposure, which places it inside fiscal and investment planning rather than only inside climate policy. Two things cannot both hold: flows rising toward a mid century peak are being planned against as though they were permanent, while the ice reserve that produces them is shrinking. The near term marker is whether brick kiln conversion moves beyond the two States that have completed it.

    Back2Basics: International Centre for Integrated Mountain Development (ICIMOD)

    1. Nature: An intergovernmental knowledge and learning centre for the Hindu Kush Himalaya region.
    2. Establishment and headquarters: Founded in 1983, with its headquarters at Kathmandu, Nepal.
    3. Membership: Its eight regional member countries are Afghanistan, Bangladesh, Bhutan, China, India, Myanmar, Nepal and Pakistan.
    4. Mandate: It supports mountain research, cryosphere monitoring and transboundary cooperation across the Hindu Kush Himalaya.

    Matching Previous Year Question

    “[2020, GS1, 10] How will the melting of Himalayan glaciers have a far-reaching impact on the water resources of India? (हिमालय के हिमनदों के पिघलने का भारत के जल-संसाधनों पर किस प्रकार दूरगामी प्रभाव होगा ?)”

  • Why risk-monitoring in the Himalayas is like looking for ‘needles in haystacks’

    Why risk-monitoring in the Himalayas is like looking for ‘needles in haystacks’

    Why in the News

    A Senior Fellow of the Energy, Water and Sustainability Program at the Stimson Center, a US based non-profit think tank, has set out the sequence of the recent Nepal flood and the lessons it holds for hazard monitoring across the Himalayas.

    What triggered the Nepal flood, and why is the trigger still uncertain?

    1. A glacial detachment carrying bedrock: The present consensus is that the initial trigger was a glacial detachment that included bedrock on the northern slopes of Langtang Lirung, a 7,000-plus-metre peak in the Langtang range.
    2. The triggering process is not understood: The failure could be related to climate-related risks or to gradual shifts at the site itself.
    3. A slow creep, then a tipping point: Preliminary analysis indicates minor movement of the glacial mass in the weeks or months before the event, followed by a tipping point.

    How did a single glacial failure cascade more than 100 kilometres downstream?

    1. The descent: The failed mass swept down a gully toward the Lhende River, which reaches the Chinese border. The source area was around 5,200 metres, so the flow descended a couple of thousand metres.
    2. A temporary natural dam: The flow deposited a mixture of ice, rock and sediment that blocked the river.
    3. Three contested water sources: Debate continues on how much water came from the glacier itself, from melting of entrained ice, and from water that accumulated behind the landslide dam.
    4. Nine minutes to the border: The dam failed and sent a major pulse of water downstream, which reached the China border in roughly nine minutes. Footage from the Gyirong border facility shows a massive dark wave carrying a large volume of material, not just water.
    5. Back into Nepal within seconds: The border facility sat at a confluence with the Gyirong River tributary, and within seconds of hitting it the flow was already moving back into Nepal. There was no realistic opportunity to warn communities downstream, and many of those who could have generated an alert were themselves swept away.
    6. Dams, hydropower and villages: The flow destroyed dams and hydropower projects downstream, recruited additional sediment, and swept through villages along the river corridor.
    7. Beyond every mapped floodplain: The event continued into Nuwakot district and affected larger market towns in the floodplain, in areas well beyond the 100-year or 500-year floodplain (the extent a flood of that average recurrence interval is expected to reach). This was a thousand-year-plus flood event.
    8. Registered at the India-Nepal border: Significant impacts extended more than 100 kilometres downstream, and the flood pulse also registered at the India-Nepal border.

    Why are cascading hazard chains the larger Himalayan problem?

    1. A pattern across three countries: The same chain has appeared in Chamoli, in Sikkim with the South Lhonak GLOF (glacial lake outburst flood), and in Nepal with the Melamchi disaster.
    2. Climate risk as an amplifier: Climate risks are interacting with and amplifying other disaster risks, and these events are becoming more frequent and more intense.

    Why does hazard monitoring keep missing the sites that fail?

    1. Known high-risk sites exist, and this was not one: Several places around Nepal have been identified as high-risk areas for glacial detachment and surges, and glaciers immediately on the other side of Langtang Lirung are high-priority research sites. This particular location had no red flags.
    2. Hindsight still needs a target: Analysts are examining whether changes could have been detected in the days before the event, but that would still require knowing where to look.
    3. No signal to separate from noise: Monitoring every glacier and every mountainside that could collapse is not feasible without some signal that narrows the search.
    4. Satellites answer only the question they were pointed at: Remote sensing and satellite-based analysis are important, but different satellite tools answer different questions, and each needs a target. Engaging local communities is how the target is found.
    5. Almost every event came from an unknown place: Of over a dozen extreme events in the Himalayas over 10 years, almost all came from unknown places, the South Lhonak GLOF being the one known risk.
    6. No borrowed training data: Patterns are beginning to emerge, but no training dataset from the Alps or Norway can simply be transferred to the Himalayas, which have their own context and significant data scarcity and data sparsity.

    What monitoring triangle does the interview propose for India, Nepal and the Himalayas?

    1. Mapping is the baseline: The mapping exercise undertaken by India’s Home Ministry and space agencies to monitor glacial lakes and hazards is an absolute necessity. Nepal does not have the same level of resources. Some mapping has been done there, and it is not as comprehensive.
    2. Maps enable zoning; monitoring is the key: Once maps exist, hazard zoning and modelling can begin, but detection depends on continuous monitoring.
    3. Corner one, remote sensing: Remote sensing and satellite imagery form one part of the triangle.
    4. Corner two, fixed station networks: Hydromet (hydrological and meteorological) and seismic stations form the second.
    5. Corner three, localised monitoring through local government: Local governments, disaster managers and Community Disaster Management Committees can collect local data, report landslides and monitor impacts after storms.
    6. Localised monitoring through people immersed in the terrain: Yak herders and fishermen notice changes in rivers, glaciers and glacial lakes. Oral histories with elders reveal smaller avalanches, glacial-lake floods and other events that science has not recorded, helping identify potential hotspots.
    7. The combination is the detector: Combining the station network, remote sensing and localised monitoring gives a better chance of detecting changes and distinguishing the signal from the noise that tells you where to look.

    Challenges to Himalayan hazard monitoring

    1. Hydropower sited in hazard corridors without upstream sensing: Projects sit in narrow gorges below unstable ice and rock with no instrument between the source and the intake. Eg. The February 2021 Chamoli rock and ice avalanche from Ronti peak destroyed the Rishiganga and Tapovan-Vishnugad projects with no upstream warning.
      The Fix: Make a hazard chain assessment and ridge line sensors with satellite telemetry a condition of clearance for every Himalayan hydropower project.
    2. Instruments die with the event they are meant to detect: A sensor placed at the lake or in the channel is destroyed by the first surge and reports nothing. Eg. Monitoring equipment installed at South Lhonak lake in September 2023 was washed away in the October 2023 outburst that also breached the Teesta III dam at Chungthang.
      The Fix: Place redundant stations on high ground and at staggered distances downstream so at least one survives to trigger sirens.
    3. Cross-border flows carry no shared alert: The upstream country holds the first minutes of warning and no protocol obliges it to pass them on. Eg. India’s hydrological data sharing arrangement with China on the Brahmaputra lapsed in 2023.
      The Fix: Adopt a Hindu Kush Himalaya alert protocol through the International Centre for Integrated Mountain Development (ICIMOD) that pushes automatic upstream alerts to downstream disaster authorities within minutes.
    4. Warnings that never reach the last mile: A satellite detection is useless to a village asleep in a gorge with no siren and no signal. Eg. The Sikkim outburst struck after 10 pm on 3 October 2023 and reached the Teesta valley settlements in the dark.
      The Fix: Pair the National Disaster Management Authority’s Common Alerting Protocol based cell broadcast with battery-backed community sirens in every mapped downstream settlement.

    Conclusion

    India has the baseline map; Nepal has part of one. Neither has the monitoring triangle that turns a map into a warning. The unresolved gap is that detection still depends on knowing where to look, and the herders, fishermen and village committees who hold that knowledge are not yet wired into any station network. The test of the next monsoon is whether a single high mountain site with no red flag gets watched because a community reported it first.

    Back2Basics

    1. What it is: A sudden release of water from a lake formed by melting glaciers, held back by a natural dam of loose moraine debris or ice rather than bedrock.
    2. How it starts: An avalanche, rockfall or ice calving into the lake sends a displacement wave over the dam, or seepage erodes the moraine from within until it collapses.
    3. Why it is deadlier than a rain flood: The surge carries rock and sediment, arrives with minutes of warning, and can breach infrastructure far below the lake.
    4. India’s framework: The National Disaster Management Authority issued dedicated guidelines on GLOF and Landslide Lake Outburst Flood management in 2020.

    [2021, GS1, 15 marks] How does the melting of the Arctic ice and glaciers of the Antarctic differently affect the weather patterns and human activities on the Earth? Explain. (250 words)

  • Ladakh’s glaciers are slowing as the mountains warm

    Why in the News?

    A new study in the journal The Cryosphere reports that glaciers in the Zanskar region of Ladakh are moving more slowly than they did 30 years ago, as sustained warming thins them and reduces their driving force. The slowdown carries long term implications for the Indus basin, where glacier melt sustains river flows during dry summer months.

    Why are the Zanskar glaciers slowing down?

    1. Thinning mechanism: When a glacier loses more ice than it gains over many years it becomes thinner, and thinner ice exerts less driving force, causing it to flow more slowly.
    2. Warming link: The study connects mass loss, thinning and reduced flow, showing that thinning is not only a consequence of warming but also weakens the glacier’s ability to move.
    3. Downstream effect: Slower flow means the lower parts of a glacier receive less replenishment from higher elevations, making continued shrinkage more likely.
    4. Local variation: Glacier geometry, debris cover and conditions at the snout influence how quickly each glacier responds.

    What is peak water?

    1. Definition: Peak water is the point at which increased melting from a shrinking glacier temporarily raises river runoff before the water supply begins to decline.
    2. Why it matters: More melting may boost flows in the near term, but once glaciers lose a substantial fraction of their stored ice, their meltwater contribution to rivers is expected to drop.

    What did the study find?

    1. Study design: The researchers examined how glacier flow changed from 1992 to 2023 across 12 glaciers in the Zanskar Himalaya using satellite derived surface velocities.
    2. Velocity decline: Glaciers slowed by 2.4 metres per year per decade on average.
    3. Faster thinning: The pace of surface thinning increased from around 0.22 metres per year between 2000 and 2005 to around 0.57 metres per year between 2015 and 2020.
    4. Sample caveat: The 12 glaciers studied are representative, but the Zanskar basin hosts around 1,755 glaciers, so caution is needed before extending the findings to all of Ladakh.

    What are the implications for the Indus basin?

    1. Summer flows: Glacier melt contributes significantly to Indus river flows during the dry summer months, so long term storage decline threatens that supply.
    2. Multiple dependencies: River flows also depend on snowfall, rainfall, groundwater and water management, so slowing glaciers alone will not immediately cause shortages.
    3. Sectors at risk: Continued thinning and slowdown signal declining long term water storage, with implications for water security, agriculture, hydropower and downstream ecosystems in coming decades.

    Why do the study’s own limitations qualify its conclusions?

    1. Sub surface blind spot: Satellite surface velocity observations cannot directly reveal processes beneath the glacier, such as subglacial hydrology or basal sliding, which strongly influence motion.
    2. Data gaps: Long term field measurements of ice thickness, mass balance and bed conditions remain limited in the region, making full attribution of observed changes difficult.
    3. Exceptions to the trend: Some glaciers can temporarily accelerate due to increased meltwater at the bed, glacier surges, or interactions with proglacial lakes.

    What does the global comparison show?

    1. European Alps and Alaska: Similar glacier slowdowns have been reported, driven by the same thinning and reduced driving stress mechanism.
    2. Canadian Arctic and Andes: These regions show comparable slowdowns linked to warming.
    3. Tibetan plateau: Parts of the plateau display the same dominant mechanism of thinning leading to slower flow.
    4. Shared lesson: Glacier slowdown is becoming widespread globally, though local glacier characteristics still shape individual behaviour.

    Conclusion

    The study establishes that Zanskar glaciers are not only losing mass but slowing down, with thinning reducing their capacity to move and replenish lower reaches. This points to a long term decline in stored water that will eventually reduce Indus basin flows after a phase of peak water. The findings underscore the need for sustained ground based monitoring to validate satellite data and to prepare downstream communities for shifting water availability.

    Back2Basics:

    Foundational Context: The Cryosphere and Himalayan Glaciers

    1. About: The cryosphere comprises the frozen parts of the Earth, including glaciers, snow cover, permafrost and ice, that store and release freshwater.
    2. Third Pole: The Hindu Kush Himalaya holds the largest ice mass outside the polar regions and is often called the Third Pole.
    3. Function: Himalayan glaciers act as natural reservoirs, releasing meltwater in warmer months to sustain rivers, agriculture and ecosystems in otherwise arid areas.
    4. Climate indicator: High altitude glaciers respond distinctly to warming, making them valuable natural indicators of environmental change.

    The Zanskar Region and Indus Basin

    1. Location: The Zanskar region lies in Ladakh and hosts some of the largest and most extensive glaciers in the Himalaya.
    2. Climatic setting: Its glaciers receive most of their snowfall from mid latitude westerly disturbances during winter and sit at high altitude.
    3. Indus basin: The Indus rises in the Tibetan plateau and flows through Ladakh, with glacier melt feeding its dry season flows.
    4. Significance: The basin supports water security, agriculture and hydropower across northern India and beyond.

    Key Facts about Himalayan Glacier Monitoring

    1. Study journal: The findings appear in the journal The Cryosphere.
    2. Zanskar glacier count: The basin hosts around 1,755 glaciers, of which 12 were studied.
    3. Observation record: The study covers more than 30 years, from 1992 to 2023.
    4. Peak water: A key concept describing the temporary runoff increase before long term decline.

    Challenges in Glacier Conservation and Monitoring

    1. Data scarcity: Long term field measurements of ice thickness and mass balance are limited in high altitude terrain.
    2. Warming pace: Rising temperatures accelerate thinning and mass loss.
    3. Black carbon: Soot deposition on ice lowers reflectivity and speeds melting.
    4. Glacial lake hazards: Meltwater expansion raises the risk of glacial lake outburst floods.
    5. Downstream dependence: Millions rely on glacier fed rivers, amplifying the impact of any decline.

    Way Forward

    1. Expand ground monitoring: Add measurements of ice thickness, mass balance and meltwater discharge to validate satellite data.
    2. High altitude weather stations: Install continuous observation stations to capture varied mountain climate conditions.
    3. Basin water planning: Prepare Indus basin water management for the eventual decline after peak water.
    4. Reduce black carbon: Cut regional emissions that hasten glacier melt.
    5. Regional cooperation: Share transboundary glacier and river data across the basin.

    PYQ Relevance

    [UPSC 2020] How will the melting of Himalayan glaciers have a far-reaching impact on the water resources of India?

    Linkage: The PYQ directly relates to the impact of Himalayan glacier melt on India’s water resources. Zanskar glacier slowdown and thinning highlight the emerging risks to Indus basin flows, water security and long-term freshwater availability.

  • Bring out the relationship between the shrinking Himalayan glaciers and the symptoms of climate change in the Indian sub-continent.

  • How does the cryosphere affect global climate?

  • How will the melting of Himalayan glaciers have a far-reaching impact on the water resources of India? (हिमालय के हिमनदों के पिघलने का भारत के जल-संसाधनों पर किस प्रकार दूरगामी प्रभाव होगा ?)

    The Himalayan glaciers are termed as the “Water Towers of Asia.” However, as per UN report, these glaciers have lost approximately 30% of their mass since 1970.

    Short-Term Impacts of Himalayan Glacier Melting

    Accelerated glacier melting temporarily increases river flow. Eg- Enhanced summer discharge observed in Indus basin rivers dependent on glacial melt.

    Glacier lake areas expanded by over 22% between 2011 and 2025, raising severe GLOF risks.

    Chamoli disaster in Uttarakhand

    South Lhonak Lake outburst in Sikkim (2023)

    Melting glaciers release sediments affecting river morphology. Eg- Increased sediment deposition in upper Ganga and Brahmaputra tributaries.

    Over 33% of India’s hydropower is currently at risk from cascading “cryospheric” disasters. Eg- Tapovan-Vishnugad hydropower project in Uttarakhand damaged during the Chamoli disaster.

    Micro-climate Shifts-The loss of white ice (albedo) leads to more heat absorption, creating “heat islands” even at high altitudes.

    Long-Term Impacts

    Most Himalayan basins are expected to pass “Peak Water” by 2030-2050, after which river flows will permanently decline. Eg- Ganga and Yamuna may eventually become “seasonal”.

    Groundwater Depletion-As surface water vanishes, farmers will over-extract aquifers, accelerating the “Water Bankruptcy” of the Indo-Gangetic plain.

    Water Quality Crisis-Lower river volumes reduce the “self-purification” capacity, concentrating pollutants like Arsenic and Fluoride.

    Groundwater Recharge Reduction – Lower river flows reduce recharge in alluvial aquifers.

    Urban Water Supply Stress – Eg- Cities like Delhi depend heavily on Yamuna and Ganga river systems.

    Ecosystem Degradation – Altered flow regimes threaten aquatic biodiversity. Eg- Habitat of the Ganges river dolphin depends on stable river flow.

    Scarcity may intensify interstate and transboundary disputes. Eg- Indus water treaty dispute with Pakistan

    Reduced freshwater inflow affects sediment transport and delta stability. Eg- accelerating erosion in the Ganga-Brahmaputra delta.

    Glaciers act as natural reservoirs stabilizing river flows. Loss of glaciers makes river systems more dependent on erratic monsoon rainfall.

    Way Forward

    Deploying Glacial Lake Early Warning Systems using automated radar and satellite sensors at high-risk sites.

    Springshed Management-Rejuvenating “Dharas” (mountain springs) to provide alternative water sources as glaciers retreat.

    Artificial Glaciers-Scaling the “Ice Stupa” model to store winter meltwater for spring irrigation in arid high-altitude regions.

    Climate-Resilient Infrastructure-Mandating “Cryosphere Impact Assessments” for all new dams and highways in the Himalayas.

    Ecosystem-Based Adaptation – Protect Himalayan forests and wetlands that regulate water flows.

    A strategy combining climate mitigation, scientific monitoring and sustainable water management is essential to safeguard the vital water resources originating in the Himalayas.

  • How does the melting of the Arctic ice and glaciers of the Antarctic differently affect the weather patterns and human activities on the Earth? Explain. (250 words) आर्कटिक की बर्फ़ और अंटार्टिक के ग्लेशियरों का पिघलना किस तरह अलग-अलग ढंग से पृथ्वी पर मौसम के स्वरूप और मनुष्य की गतिविधियों पर प्रभाव डालते हैं? स्पष्ट कीजिए। (250 शब्दों में उत्तर दीजिए)