Topic 19: Climate Change Effects — Water & Ocean
Groundwater contamination and depletion, India's water mission architecture (Jal Shakti Abhiyan, Jal Jeevan Mission, National Water Mission, Atal Bhujal Yojana), ocean acidification, and methane hydrates.
Table of Contents
Conceptual Clarity — Why this Topic Matters
UPSC tests water & ocean impacts of climate change in three distinct ways:
- Definitional / static: precise distinctions — water stress vs scarcity vs depletion, the ocean-acidification chemistry chain (CO2 → carbonic acid → lower pH → carbonate depletion), methane-hydrate clathrate structure.
- Statement-elimination: matching each water scheme to its correct feature — Jal Shakti Abhiyan (campaign), Jal Jeevan Mission (Har Ghar Jal/FHTC), National Water Mission (NAPCC mission), Atal Bhujal Yojana (World Bank, 7 states).
- Applied / current: marine heatwaves & coral bleaching, JJM coverage, groundwater-depletion geography, arsenic/fluoride contamination belts (see Current Affairs section).
Focus especially on the water-scheme architecture, ocean-acidification chemistry, and the NWM-as-NAPCC-mission link — the three highest-frequency themes.
1. Groundwater — Status & Contamination
- India: world's largest groundwater extractor, more than USA + China combined, mainly for irrigation.
- Excessive extraction caused sharp water-table decline in Punjab, Haryana, Rajasthan, parts of Tamil Nadu.
- Arsenic contamination: Ganga-Brahmaputra floodplains (West Bengal, Bihar, parts of UP/Assam).
- Fluoride contamination: Rajasthan, Gujarat, parts of south India — causes fluorosis.
- Climate change alters monsoon recharge patterns, deepening groundwater dependence in erratic rainfall years.
2. Conceptual Clarity — Water Stress vs Scarcity vs Depletion
Don't confuse these three
- Water stress: demand approaches/exceeds supply (per capita availability <1,700 m³/yr).
- Water scarcity: acute shortfall — physical shortage + poor governance/access; <1,000 m³/capita/yr = "water scarce."
- Groundwater depletion: extraction > natural recharge over time — physical, measurable water-table decline, distinct from demand-supply concepts.
3. Jal Shakti Abhiyan
- Launched 2019 under new Ministry of Jal Shakti (merged Water Resources + Drinking Water & Sanitation).
- Time-bound, mission-mode campaign — water conservation in 250+ water-stressed districts.
- 5 interventions: rainwater harvesting, renovating traditional water bodies, borewell reuse/recharge, watershed development, intensive afforestation.
4. Jal Jeevan Mission
- Launched 2019 — aims to provide Functional Household Tap Connections (FHTC) to every rural household, "Har Ghar Jal."
- Decentralised, community-participation model: village-level Water and Sanitation Committees (Paani Samitis/VWSCs) oversee local infrastructure.
- Also focuses on source sustainability + greywater management.
5. National Water Mission & Atal Bhujal Yojana
- National Water Mission (NWM): 1 of 8 NAPCC missions (Topic 20) — integrated water resource management, minimise wastage, equitable distribution across/within states.
- Targets 20% improvement in water-use efficiency.
- Atal Bhujal Yojana (ABY): World Bank-supported Central Sector Scheme, launched 2020.
- Covers 7 water-stressed states (Gujarat, Haryana, Karnataka, MP, Maharashtra, Rajasthan, UP).
- Combines community-led demand-side management + supply-side infra, with performance-based state incentive grants.
| Scheme | Year | Type / Ministry | Core aim & distinguishing feature |
|---|---|---|---|
| Jal Shakti Abhiyan | 2019 | Campaign, Min. of Jal Shakti | Time-bound water-conservation drive in 250+ stressed districts; 5 interventions (harvesting, water-body renovation, borewell recharge, watershed, afforestation) |
| Jal Jeevan Mission | 2019 | Centrally-sponsored, DDWS | "Har Ghar Jal" — Functional Household Tap Connection to every rural home; Paani Samiti-led |
| National Water Mission | 2011 | 1 of 8 NAPCC missions | Integrated water management; targets 20% water-use-efficiency improvement |
| Atal Bhujal Yojana | 2020 | Central Sector, World Bank-aided | Community-led groundwater management in 7 stressed states; performance-based incentive grants |
| Namami Gange | 2014 | Flagship, NMCG | Ganga rejuvenation — pollution abatement + river-ecology restoration (distinct from JJM) |
6. Ocean Acidification
- Ocean acidification: ongoing ocean pH decrease from absorbing anthropogenic atmospheric CO2 (oceans absorbed ~1/4-1/3 of all human-emitted CO2 since Industrial Revolution).
- Dissolved CO2 + seawater → carbonic acid → lowers pH, reduces carbonate ion availability.
- Threatens calcifying organisms (corals, molluscs, pteropods, foraminifera) building CaCO3 shells/skeletons.
- Directly threatens coral reefs (already bleaching-stressed) and base of marine food webs.
Coral Reefs & Coral Bleaching — the Mechanism
- Corals live in symbiosis with zooxanthellae — microscopic algae (dinoflagellates) inside coral tissue that photosynthesise, giving corals colour + up to ~90% of their energy.
- Bleaching = under thermal/acidification/pollution stress, corals expel the zooxanthellae, turn white, and lose their food source. Prolonged bleaching → coral death.
- Main trigger: sea-surface temperature ~1–2°C above normal summer maximum for sustained weeks (marine heatwaves); worsened by acidification, UV, sedimentation, low salinity.
- Reefs need warm (23–29°C), shallow, clear, sunlit, saline water — hence mostly tropical.
| Reef type | Form | Example |
|---|---|---|
| Fringing reef | Grows directly along the coast, no lagoon (most common) | Gulf of Mannar, Andaman coasts |
| Barrier reef | Parallel to coast, separated by a wide deep lagoon | Great Barrier Reef (Australia) |
| Atoll | Ring-shaped reef around a central lagoon (often on subsided volcanic island) | Lakshadweep, Maldives |
Sea-Level Rise (SLR) — Two Drivers
- Thermal expansion of warming ocean water (seawater expands as it heats) — historically the largest single contributor.
- Land-ice melt — melting glaciers + ice sheets (Greenland, Antarctica) adding new water to oceans.
- Impacts: coastal inundation, saltwater intrusion into aquifers/farmland, loss of mangroves & deltas, displacement (e.g. Sundarbans islands, Lakshadweep).
7. Methane Hydrates
- Methane hydrates (clathrates): ice-like crystals — methane trapped in water-molecule lattice under high pressure/low temp.
- Found in deep ocean sediments + Arctic/sub-Arctic permafrost.
- Potential future energy resource — India's eastern continental margin surveyed under National Gas Hydrate Program.
- Climate risk: warming oceans/thawing permafrost could destabilise deposits, releasing methane (potent GHG, Topic 17) — "clathrate gun hypothesis" feedback loop.
8. Current Affairs (2024–2026)
In April 2024, NOAA + ICRI declared the 4th global mass coral-bleaching event (the 2nd in a decade); >60% of reef areas affected. India's Gulf of Mannar, Lakshadweep & Andaman reefs recorded bleaching stress amid record 2023–24 ocean surface temperatures — compounding thermal + acidification pressure.
FHTC coverage crossed ~75%+ of rural households; the mission timeline was extended (2028) in Union Budget 2025 to close remaining gap areas, with focus on source sustainability & quality (arsenic/fluoride-affected habitations).
Central Ground Water Board's latest Dynamic Groundwater Resource assessment shows marginal improvement in extraction stage; Atal Bhujal Yojana mid-term review reports water-level gains in participating stressed blocks across the 7 states.
9. Prelims PYQs
Q. With reference to "Atal Bhujal Yojana," consider the following statements:
1. It is a Central Sector Scheme with World Bank support.
2. It focuses exclusively on surface water conservation.
3. It covers identified water-stressed areas in seven states.
Which of the statements given above is/are correct?
Ans: (b). ABY is a World Bank-aided Central Sector Scheme across 7 states, but targets groundwater (not surface water), so statement 2 is wrong.
Q. Ocean acidification is primarily caused by:
Ans: (b). Oceans absorb ~1/4–1/3 of anthropogenic CO2; dissolved CO2 forms carbonic acid, lowering pH.
Q. "Jal Jeevan Mission" aims at:
Ans: (a). JJM = "Har Ghar Jal," FHTC to every rural household. Ganga cleaning is Namami Gange.
Q. Consider the following statements regarding "methane hydrates":
1. They are crystalline structures of methane trapped within water-ice lattices.
2. They are found in deep ocean sediments and permafrost regions.
3. India's National Gas Hydrate Program has surveyed potential deposits along the eastern continental margin.
Which of the statements given above is/are correct?
Ans: (d). All three correct — clathrate structure, deep-ocean/permafrost occurrence, and NGHP surveys of the eastern margin (Krishna-Godavari basin).
Q. Which of the following states in India commonly report groundwater contamination by arsenic?
1. West Bengal 2. Bihar 3. Rajasthan
Select the correct answer using the code given below:
Ans: (a). Arsenic affects the Ganga-Brahmaputra floodplains (WB, Bihar). Rajasthan's signature contaminant is fluoride, not arsenic.
Q. The "National Water Mission" is one of the missions under which of the following?
Ans: (a). NWM is 1 of the 8 missions under NAPCC (2008), targeting 20% water-use-efficiency improvement.
10. Mains PYQs
Q. Describe the various causes and effects of ocean acidification on marine biodiversity and coral reef ecosystems, along with international efforts to address it.
Model Answer Framework
- Introduction: Define ocean acidification — fall in ocean pH from absorbing ~1/4–1/3 of anthropogenic CO2; often called "the other CO2 problem."
- Body — causes:
- Rising atmospheric CO2 → dissolves in seawater → carbonic acid → lower pH, reduced carbonate ions
- Local aggravators — coastal pollution, nutrient runoff (eutrophication)
- Body — effects:
- Calcifiers (corals, molluscs, pteropods, foraminifera) can't build CaCO3 shells
- Coral reef degradation (compounded by warming-driven bleaching), disrupted marine food webs, fisheries decline
- Threat to livelihoods (Gulf of Mannar, Lakshadweep reefs)
- Body — international efforts: UNFCCC/Paris CO2 cuts, SDG-14 (Life Below Water), ICRI, Global Ocean Acidification Observing Network (GOA-ON), MPAs.
- Conclusion: Only deep global CO2 mitigation truly addresses acidification — a shared ocean-climate imperative.
Q. Discuss the causes of depletion of groundwater and mention the ways to replenish it through the schemes launched by the Government of India in this regard.
Model Answer Framework
- Introduction: India is the world's largest groundwater extractor (more than USA + China combined) — over-reliance is now a resource crisis.
- Body — causes of depletion:
- Over-extraction for irrigation (~60% of irrigation), free/subsidised power
- Green-Revolution water-intensive cropping (paddy in Punjab/Haryana)
- Urbanisation reducing recharge, erratic monsoon lowering natural recharge
- Body — replenishment schemes:
- Atal Bhujal Yojana (community-led groundwater management, 7 states)
- Jal Shakti Abhiyan (recharge + water-body renovation)
- National Water Mission (20% WUE), MGNREGA water structures, Per Drop More Crop (PMKSY)
- Conclusion: Demand-side management (crop shift, pricing) + supply-side recharge together break the depletion spiral.
Q. Bring out the causes for urban flooding in major Indian cities. Discuss the mechanisms for preparedness to reduce the risks, with reference to groundwater recharge and water conservation.
Model Answer Framework
- Introduction: Urban floods (Chennai 2015, Mumbai 2005, Bengaluru 2022) increasingly frequent as climate change intensifies rainfall bursts.
- Body — causes:
- Encroachment on natural drains/wetlands, unplanned concretisation reducing infiltration
- Inadequate/clogged stormwater drains, loss of urban water bodies
- Intense short-duration cloudbursts (climate variability)
- Body — preparedness & recharge:
- Sponge-city design, rooftop rainwater harvesting, permeable pavements, recharge pits/wells
- Restore urban lakes/wetlands, desilt drains, real-time flood early-warning
- AMRUT/Smart Cities stormwater components
- Conclusion: Flood water is a recharge opportunity — integrate drainage with harvesting to convert a hazard into a resource.
Q. What is water-use efficiency? Describe the role of micro-irrigation in increasing water-use efficiency in India.
Model Answer Framework
- Introduction: Water-use efficiency (WUE) = crop output per unit water; India's flood irrigation wastes vast water.
- Body — micro-irrigation's role:
- Drip/sprinkler deliver water to root zone — cuts evaporation/runoff, raises WUE 40–60%
- Fertigation, "Per Drop More Crop" (PMKSY), reduced groundwater draw
- Prevents waterlogging/salinisation, supports water-stressed regions
- Body — constraints: high upfront cost, small landholdings, clogging/maintenance, awareness gaps.
- Conclusion: Subsidy support + FPO-led adoption can mainstream micro-irrigation as a water-security cornerstone.
Q. "In the villages of India, the growing water crisis is largely a governance crisis." Critically examine in the context of Jal Shakti Abhiyan and related interventions.
Model Answer Framework
- Introduction: India's water crisis is not merely physical scarcity but poor management — supporting the "governance crisis" view.
- Body — governance failures:
- Fragmented authority (water = state subject), free-power-driven over-extraction
- Weak enforcement, poor demand management, neglect of traditional water bodies
- Body — governance responses:
- Jal Shakti Abhiyan (mission-mode, district-level campaign), Ministry of Jal Shakti consolidation
- Atal Bhujal Yojana (community participation), Jal Jeevan Mission (Paani Samitis)
- Body — counterpoint: physical drivers (climate, geography, aquifer type) also matter — not purely governance.
- Conclusion: Crisis is largely but not solely governance — decentralised, community-led management is the durable fix.
15-Minute Revision Box
Must-Remember Facts — Climate Change Effects on Water & Ocean
- India = world's largest groundwater extractor (> USA + China combined); arsenic in Ganga-Brahmaputra plains, fluoride in Rajasthan/Gujarat/south India
- Water stress = <1,700 m³/capita/yr | scarcity = <1,000 m³/capita/yr | depletion = extraction > recharge
- Jal Shakti Abhiyan (2019): 5-pronged campaign in 250+ stressed districts
- Jal Jeevan Mission (2019): FHTC to every rural household, "Har Ghar Jal," Paani Samiti-led
- National Water Mission = 1 of 8 NAPCC missions, 20% water-use efficiency target
- Atal Bhujal Yojana (2020): World Bank-supported, 7 states, community-led groundwater management
- Ocean acidification: CO₂ + seawater → carbonic acid → lower pH + less carbonate ion → calcifiers (coral, molluscs, plankton) struggle to build shells
- Coral bleaching: heat/acidity stress → corals expel zooxanthellae → whiten, starve
- Sea-level rise: thermal expansion + land-ice melt (sea-ice melt does NOT raise level)
- Methane hydrates: ice-lattice methane in deep ocean/permafrost; "clathrate gun" feedback; India's National Gas Hydrate Program surveys eastern margin