BharatNotes Why this chapter matters for UPSC: The four domains — lithosphere, hydrosphere, atmosphere, and biosphere — are the conceptual pillars of physical geography and environmental science. UPSC Prelims tests atmospheric layers, ocean names and sizes, ozone layer location, greenhouse gases, and biodiversity hotspots. UPSC GS III (Environment) draws heavily on atmosphere and biosphere concepts for climate change, ozone recovery, and conservation questions.
Critical correction from standard textbooks: Many NCERT-based notes incorrectly state India has 2 biodiversity hotspots. The correct figure, per Conservation International (the defining authority), is 4 biodiversity hotspots in India — Himalaya, Western Ghats & Sri Lanka, Indo-Burma, and Sundaland (which includes the Nicobar Islands).
PART 1 — Quick Reference Tables
Four Domains of the Earth
| Domain | Definition | Key Components | % of Earth |
|---|---|---|---|
| Lithosphere | The solid rocky outer shell — Earth's crust and uppermost mantle | Continents, islands, ocean floor, mountains, plains, plateaus | ~29% land surface |
| Hydrosphere | All water on Earth in all forms | Oceans, seas, rivers, lakes, glaciers, groundwater, water vapour | ~71% ocean surface |
| Atmosphere | Layer of gases held by gravity surrounding Earth | Nitrogen 78%, Oxygen 21%, Argon 0.93%, CO₂ ~0.0423% (2024 global annual mean 422.8 ppm per NOAA GML; Mauna Loa 424.61 ppm; May 2025 seasonal peak 430.5 ppm), water vapour, trace gases | Extends to ~10,000 km |
| Biosphere | The zone of life — where the other three domains interact | All living organisms; ecosystems; from deep ocean vents to high atmosphere | Thin zone ~20 km total |
Updated CO₂ figure (May 2026): The standard textbook figure of 0.04% (400 ppm) for CO₂ is outdated. The 2024 global annual mean was 422.8 ppm (NOAA GML); Mauna Loa station recorded 424.61 ppm for 2024. The May 2025 seasonal peak reached 430.5 ppm — the first monthly average exceeding 430 ppm. Source: NOAA Global Monitoring Laboratory / Scripps Institution of Oceanography.
Seven Continents (by Area)
| Continent | Area (million km²) | % of Land | Notable Features |
|---|---|---|---|
| Asia | 44.6 | 29.5% | Largest continent; Himalayas (highest peaks), Siberia, Gobi Desert, largest population |
| Africa | 30.3 | 20.4% | Second largest; Sahara (largest hot desert), equatorial rainforests, Great Rift Valley |
| North America | 24.7 | 16.5% | Rocky Mountains, Great Plains, Mississippi-Missouri river system, Great Lakes |
| South America | 17.8 | 12.0% | Amazon Basin (largest tropical rainforest), Andes (longest mountain range), Angel Falls |
| Antarctica | 14.0 | 9.2% | Southernmost; 98% covered by ice sheet averaging ~2 km thick (over 1.8 km per NSIDC; thickest point ~4.9 km); no permanent human population; governed by Antarctic Treaty System |
| Europe | 10.5 | 7.0% | Second smallest; Alps, River Rhine; most industrialised continent historically |
| Australia | 7.7 | 5.2% | Smallest continent; entirely in Southern Hemisphere; also called "island continent" |
Memory aid (decreasing order of area): Asia, Africa, North America, South America, Antarctica, Europe, Australia — "All Animals Need Special Attention Every Afternoon"
Five Oceans (by Area)
| Ocean | Area (million km²) | Key Features |
|---|---|---|
| Pacific | ~165 | Largest (~30% of Earth's total surface); Ring of Fire volcanic arc; deepest point (Mariana Trench, ~10,935 m per NOAA 2020 measurement) |
| Atlantic | ~106 | S-shaped; Mid-Atlantic Ridge (the largest segment of the global mid-ocean ridge system — the full system at ~65,000 km is the longest mountain chain on Earth); separates Americas from Europe/Africa |
| Indian | ~70 | Third largest; warm waters; monsoon-driven circulation; critical for India's trade and security |
| Southern (Antarctic) | ~21 | Recognised by National Geographic (June 8, 2021) as 5th ocean; encircles Antarctica from 60°S to the continent; unique Antarctic Circumpolar Current |
| Arctic | ~15 | Smallest; mostly frozen (sea ice); rapidly shrinking due to climate change; Arctic warming at ~4× global average rate |
Southern Ocean — important nuance for UPSC: National Geographic officially recognised the Southern Ocean as the 5th ocean on World Oceans Day, 8 June 2021. However, the International Hydrographic Organization (IHO) — the global authority for ocean boundaries — has not yet achieved full member consensus on recognising it as a separate ocean (it was recognised in 1937 but delisted in 1953). The IHO is still deliberating. For UPSC: the answer "5 oceans" is now accepted; the Southern Ocean exists; note the IHO nuance for Mains.
Layers of the Atmosphere
| Layer | Altitude | Temperature Trend | Key Features |
|---|---|---|---|
| Troposphere | 0–~13 km average (8 km at poles, 16–18 km at equator) | Decreases with altitude (~6.5°C per km) | All weather occurs here; contains ~75% of atmospheric mass and ~99% of water vapour; tropopause is the upper boundary |
| Stratosphere | ~13–50 km | Increases with altitude | Ozone layer (~20–35 km) absorbs UV; aircraft (commercial jets) cruise in lower stratosphere; no weather turbulence; very dry |
| Mesosphere | ~50–80 km | Decreases with altitude | Coldest layer (−90°C at top); meteors burn up here (shooting stars); difficult to study (too high for aircraft, too low for satellites) |
| Thermosphere | ~80–600 km | Increases dramatically (up to 2,000°C) | Auroras (Aurora Borealis/Australis) occur here; ISS orbits at ~400 km within this layer; air is extremely thin |
| Exosphere | ~600–10,000 km | Effectively no temperature | Merges with outer space; most satellites orbit here; hydrogen and helium atoms escape to space |
Troposphere height — corrected: The commonly cited "0–12 km" is an approximation. The correct figures are: ~8 km over the poles and ~16–18 km over the equator (due to thermal expansion of warm air at the tropics). The average is approximately 13 km.
PART 2 — Detailed Notes
The Lithosphere — Earth's Rocky Shell
Lithosphere: The rigid outer shell of Earth, comprising the crust and the uppermost solid part of the mantle. It is broken into large fragments called tectonic plates that float on the semi-molten asthenosphere beneath.
Structure of the Earth (inside out):
| Layer | Depth | State | Composition |
|---|---|---|---|
| Crust | 0–30 km (continental), 0–10 km (oceanic) | Solid | Continental crust: granite (SIAL — silica + aluminium); Oceanic crust: basalt (SIMA — silica + magnesium); oceanic crust is denser but thinner |
| Mantle | 30–2,900 km | Solid but flows slowly (plastic) | Silicate rock; convection currents in the mantle drive plate movement |
| Outer Core | 2,900–5,100 km | Liquid | Iron-nickel; convection of liquid iron generates Earth's magnetic field (magnetosphere) |
| Inner Core | 5,100–6,371 km | Solid | Iron-nickel; solid despite extreme heat (~5,000–6,000°C) because of immense pressure |
Continental Drift and Plate Tectonics:
The continents were once joined as a single supercontinent called Pangaea (from Greek: pan = all; gaia = Earth). Pangaea was fully assembled approximately 300 million years ago (Early Permian, ~299–273 Mya) and began breaking up approximately 200–225 million years ago (Early Jurassic) — not 250 million years ago as sometimes cited in older textbooks.
The breakup sequence:
- Pangaea splits into Laurasia (north — today's North America, Europe, Asia) and Gondwana (south — today's South America, Africa, Antarctica, Australia, India)
- Gondwana further fragments — India broke away and drifted northward, colliding with Asia ~40–50 million years ago to form the Himalayas
- Separation is ongoing — the Atlantic Ocean continues to widen by ~2.5 cm per year
Evidence for continental drift (UPSC Mains):
- Coastlines of South America and Africa fit like puzzle pieces
- Same fossil species (Glossopteris fern; Mesosaurus reptile) found on both sides of the Atlantic
- Matching rock types and mountain chains across currently separated continents
- Paleomagnetism — ancient rocks preserve records of past magnetic pole positions
The next supercontinent: Within approximately 250 million years, the continents will reassemble into a new supercontinent (sometimes called "Amasia" or "Pangaea Proxima") as the Atlantic closes and Africa-Americas merge with Eurasia.
The Hydrosphere — Earth's Water System
Distribution of Earth's water:
| Category | % of Total Water | Detail |
|---|---|---|
| Oceans (salt water) | ~96.5% | Average salinity ~35 parts per thousand (USGS figure; older sources say 97.5% but that includes other saline sources) |
| Fresh water | ~2.5% | All remaining water |
| — Glaciers and ice caps | ~1.74% (~69% of fresh water) | Mostly Antarctic ice sheet and Greenland |
| — Groundwater | ~0.76% (~30% of fresh water) | Aquifers; recharged by rainfall |
| — Surface water (rivers, lakes) | ~0.01% (<1% of fresh water) | All rivers, lakes, swamps |
| — Atmosphere (water vapour) | Trace | Drives the water cycle |
Critical point for UPSC: Of all Earth's water, less than 1% is accessible fresh surface water (rivers, lakes) — the water that humans and most ecosystems depend on. This is why water is a critical resource and why glacial melt from the Himalayas threatens river flows across South Asia.
The Indian Ocean — strategic significance:
- Third largest ocean but most strategically important for India
- ~80% of the world's seaborne oil trade passes through the Indian Ocean
- India's trade: ~90% by volume and ~70% by value moves by sea
- India's Exclusive Economic Zone (EEZ): 2.37 million km² — rich in fisheries, minerals, energy
- Indo-Pacific concept: Links the Indian Ocean to the Western Pacific as a single strategic space — India's extended neighbourhood under SAGAR (Security and Growth for All in the Region) doctrine
The Atmosphere — Earth's Protective Blanket
Why the atmosphere is essential for life:
- Oxygen: For respiration by all aerobic organisms
- CO₂: Raw material for photosynthesis; without it, all plant life collapses
- Greenhouse effect: Traps heat → maintains average surface temperature of +15°C (without atmosphere, Earth would average −18°C — too cold for liquid water)
- Ozone layer: Absorbs UV-B radiation → prevents DNA damage, skin cancer, cataracts
- Water cycle: Evaporation, condensation, precipitation — the atmosphere is the medium through which the water cycle operates
- Protection from meteors: Most space debris burns up in the mesosphere
Atmospheric composition (updated to May 2026):
- Nitrogen (N₂): 78.09%
- Oxygen (O₂): 20.95%
- Argon (Ar): 0.93%
- Carbon dioxide (CO₂): ~422.8 ppm (2024 global annual mean, NOAA GML); 424.61 ppm (Mauna Loa 2024 annual mean); 430.5 ppm (May 2025 seasonal peak) — up from pre-industrial 280 ppm; rising at ~2.5–3 ppm/year
- Water vapour (H₂O): 0–4% (variable)
- Methane (CH₄), Nitrous oxide (N₂O), ozone (O₃), and other trace gases: remainder
Greenhouse gases and their sources:
| Gas | Main Human Sources | Global Warming Potential (100-yr) |
|---|---|---|
| CO₂ | Fossil fuels, deforestation | 1 (baseline) |
| CH₄ (Methane) | Livestock, rice paddies, landfills, natural gas leaks | ~28–34 |
| N₂O (Nitrous Oxide) | Fertilisers, combustion | ~265–298 |
| HFCs | Refrigerants (replacement for CFCs) | Up to 14,800 |
| SF₆ | Electrical switchgear | ~23,500 |
UPSC GS III: India is the 3rd largest emitter of CO₂ in absolute terms (after China and the USA), but has per-capita emissions far below the global average. India's NDC (Nationally Determined Contribution) under the Paris Agreement commits to: 45% reduction in emission intensity of GDP by 2030 (vs 2005); 50% of cumulative electric power from non-fossil sources by 2030.
The Ozone Layer — Latest Status (May 2026):
Ozone (O₃): An allotrope of oxygen — three oxygen atoms bonded together. Concentrated mainly in the stratosphere (15–35 km) where it forms the "ozone layer" — Earth's UV shield, with peak concentration at 20–25 km altitude.
Ozone depletion — mechanism:
- Chlorofluorocarbons (CFCs) and other halocarbons drift into the stratosphere
- UV breaks them down, releasing chlorine atoms
- Each chlorine atom can destroy up to 100,000 ozone molecules catalytically
- This thinning is most severe over Antarctica each spring (September–November) — the "ozone hole"
Montreal Protocol (1987):
- International treaty to phase out ozone-depleting substances (ODS)
- Has now achieved the phase-out of over 99% of controlled ODS production globally
- Considered the most successful international environmental treaty ever
Recovery status (2025):
- The 2025 Antarctic ozone hole was the 5th smallest since 1992 (when Montreal Protocol began taking effect)
- 2025 hole closed on 1 December — earliest closure since 2019
- Ozone layer projected to recover to 1980 levels:
- Tropics and mid-latitudes: by ~2040
- Arctic: by ~2045
- Antarctica: by ~2066
- March 2025 MIT study confirmed: ozone recovery is primarily attributable to CFC reductions — direct proof the Montreal Protocol worked
Kigali Amendment (2016) to Montreal Protocol:
- Extended the Protocol to phase down HFCs (Hydrofluorocarbons) — used as CFC replacements in refrigeration/air conditioning
- HFCs don't deplete ozone but are powerful greenhouse gases (up to 14,800× CO₂)
- India ratified the Kigali Amendment in 2021
Tropospheric ozone vs stratospheric ozone — an important distinction:
- Stratospheric ozone: Beneficial — shields life from UV-B; being recovered under Montreal Protocol
- Tropospheric ozone (ground-level): Harmful — a pollutant formed when NOₓ and VOCs react in sunlight; damages lungs and crops; a major air quality problem in Indian cities
The Biosphere — The Zone of Life
Biosphere: The global ecological system encompassing all living organisms and their interactions with the other three domains. It extends from the deepest ocean trenches (~11 km below sea level — home to chemosynthetic bacteria at hydrothermal vents) to the upper atmosphere (~10 km — where spores and microorganisms are found).
India's Biodiversity — corrected facts for UPSC:
India's 4 Biodiversity Hotspots (Conservation International definition — a hotspot must have ≥1,500 endemic vascular plant species AND have lost ≥70% of its original habitat):
| Hotspot | India's Portion | Key Species |
|---|---|---|
| Himalaya | Entire Indian Himalayan region (north of Indo-Gangetic Plain) | Snow leopard, red panda, Himalayan brown bear; 10,000+ plant species, ~3,160 endemic |
| Western Ghats & Sri Lanka | Western Ghats mountain chain (~160,000 km²) | Lion-tailed macaque, Nilgiri tahr, purple frog; 508 bird species, 131 amphibian species (87% endemic) |
| Indo-Burma | Northeast India south of Brahmaputra (Meghalaya, Manipur, Mizoram, etc.) | Hoolock gibbon (India's only ape), Sangai deer (brow-antlered deer); large freshwater fish diversity |
| Sundaland | Nicobar Islands (the Andaman Islands are NOT part of this hotspot) | Nicobar megapode, Nicobar flying fox; shared with SE Asia |
Critical correction: Many textbooks and coaching notes still cite only 2 hotspots for India (Western Ghats and Eastern Himalayas). The correct, current answer per Conservation International is 4 hotspots. This distinction has appeared in UPSC mains.
India's overall biodiversity status:
- One of 17 megadiverse countries — together these 17 countries hold ~70% of the world's biodiversity
- India has 2.4% of Earth's land area but accounts for ~7–8% of all known species
- ~1,04,561 species of animals documented (per MoEF's 2023 fauna checklist — the world's first complete national fauna inventory) and ~45,500 species of plants
- High endemism: 55.8% of amphibians, 45.8% of reptiles, 33% of plants found nowhere else on Earth
- India ranks 3rd globally for reptile diversity (889 species)
PART 3 — UPSC Enrichment
Analytical Dimensions — Mains Answer Writing
Q: "The atmosphere acts as both a shield and a blanket for life on Earth. Critically examine how human activities are altering both these functions."
Structure:
Shield function (ozone layer):
- Stratospheric ozone absorbs UV-B → protects DNA, prevents skin cancer, cataracts, immune suppression
- CFCs (refrigerants, aerosols) depleted the ozone layer → ozone hole over Antarctica
- Montreal Protocol (1987) + Kigali Amendment (2016) → ODS phase-out → ozone layer is recovering
- India's role: ratified Kigali Amendment 2021; HFC phase-down under implementation
Blanket function (greenhouse effect):
- Natural greenhouse gases (CO₂, CH₄, H₂O vapour) maintain Earth's temperature at +15°C
- Human fossil fuel burning → CO₂ rose from 280 ppm (pre-industrial) to 427 ppm (2025) — a 52% increase
- Enhanced greenhouse effect → global warming → 1.1°C above pre-industrial average (as of 2023–24)
- Consequences for India: monsoon disruption, Himalayan glacial melt, sea level rise (threatens Mumbai, Kolkata, Chennai), extreme weather events
Conclusion: The Montreal Protocol shows international cooperation can fix an atmospheric problem. The Paris Agreement attempts the same for climate change — but is less binding, less comprehensive, and the CO₂ trend shows it is insufficient so far.
Q: "India's vast biodiversity is both a strength and a responsibility. Discuss with reference to India's international commitments."
Structure:
- India's biodiversity strength: 4 hotspots, megadiverse country, 7–8% of global species in 2.4% of land
- Threats: habitat destruction, invasive species, climate change, human-wildlife conflict
- Protected area network: 107 National Parks (April 2025), 573 Wildlife Sanctuaries, 18 Biosphere Reserves (13 in UNESCO MAB)
- International commitments: CBD (Convention on Biological Diversity), Nagoya Protocol on access and benefit-sharing, Kunming-Montreal Global Biodiversity Framework (2022) — "30×30" target (protect 30% of land and ocean by 2030)
- India's targets under Kunming-Montreal: restore 30% of degraded ecosystems; reduce invasive species by 50%; align biodiversity into sectoral policies
Key Treaties, Bodies & Policies
| Item | Relevance |
|---|---|
| Montreal Protocol (1987) | Phase-out of ODS; most successful environmental treaty; ozone layer recovering |
| Kigali Amendment (2016) | Phase-down of HFCs under Montreal Protocol; India ratified 2021 |
| Paris Agreement (2015) | Limit global warming to 1.5–2°C; India's NDC: 45% emission intensity reduction by 2030, 50% non-fossil power by 2030 |
| CBD (Convention on Biological Diversity) | International treaty on biodiversity conservation; India is a party |
| Kunming-Montreal Framework (2022) | "30×30" — protect 30% of land and ocean by 2030; successor to Aichi Targets |
| Antarctic Treaty System (1959) | Governs Antarctica; bans military activity and mineral extraction; India is a consultative party (since 1983); India has two research stations: Maitri and Bharati |
| SAGAR doctrine | India's maritime security framework for the Indian Ocean — Security and Growth for All in the Region; PM Modi, 2015 |
High-Yield Prelims Facts Checklist
| Fact | Answer |
|---|---|
| Largest continent | Asia (44.6 million km²) |
| Smallest continent | Australia (7.7 million km²) |
| Largest ocean | Pacific |
| Smallest ocean | Arctic |
| Ocean most important for India | Indian Ocean |
| Deepest point on Earth | Mariana Trench, Pacific (~10,935 m per NOAA 2020; older figure of 11,034 m is superseded) |
| Southern Ocean recognised by National Geographic | June 8, 2021 (World Oceans Day) |
| Southern Ocean IHO status | Not yet officially recognised by IHO |
| Fresh water % of total | ~2.5% |
| Fresh water in glaciers/ice | ~69% of all fresh water |
| Accessible surface fresh water | <1% of all water |
| All weather occurs in | Troposphere |
| Ozone layer located in | Stratosphere (15–35 km; peak concentration at 20–25 km) |
| Meteors burn up in | Mesosphere |
| Auroras occur in | Thermosphere |
| ISS altitude | ~400 km (Thermosphere) |
| Troposphere height at equator | 16–18 km |
| Troposphere height at poles | ~8 km |
| Troposphere height average | ~13 km |
| CO₂ concentration (2024 annual mean) | 422.8 ppm (NOAA global); 424.61 ppm (Mauna Loa); May 2025 seasonal peak: 430.5 ppm (first monthly avg >430 ppm) |
| Pre-industrial CO₂ | ~280 ppm |
| N₂ in atmosphere | 78.09% |
| O₂ in atmosphere | 20.95% |
| Pangaea fully assembled | ~300 million years ago (Early Permian) |
| Pangaea began breaking up | ~200–225 million years ago (Early Jurassic) |
| India's biodiversity hotspots | 4 — Himalaya, Western Ghats & Sri Lanka, Indo-Burma, Sundaland |
| Global biodiversity hotspots total | 36 |
| India as megadiverse country | One of 17 megadiverse countries |
| India's % of global species | ~7–8% (in 2.4% of land) |
| Ozone hole location | Over Antarctica (South Pole) |
| Montreal Protocol year | 1987 |
| Ozone full recovery projected | 2040 (tropics/mid-lat), 2045 (Arctic), 2066 (Antarctica) |
| India's research stations in Antarctica | Maitri and Bharati |
| India joined Antarctic Treaty as consultative party | 1983 |
[Additional] 5a. Deep Ocean Mission — India's Seabed Exploration Program
The chapter covers the hydrosphere and oceans but has no coverage of India's Deep Ocean Mission (DOM) — approved in June 2021 with a Rs. 4,077 crore outlay — which includes the Matsya 6000 manned submersible (India's answer to China's Jiaolong) and the exploitation of polymetallic nodules in the Central Indian Ocean Basin. The DOM is a direct UPSC GS3 Science & Technology and GS3 Environment target.
Key Terms — Deep Ocean Mission:
| Term | Meaning |
|---|---|
| Deep Ocean Mission (DOM) | India's flagship ocean science programme; Cabinet Committee on Economic Affairs (CCEA) approved on 16 June 2021; total outlay Rs. 4,077 crore over 5 years (Phase 1: Rs. 2,823.4 crore for 2021–24); implementing ministry = Ministry of Earth Sciences (MoES) |
| NIOT | National Institute of Ocean Technology — autonomous institution under MoES; headquartered at Pallikaranai, Chennai (established November 1993); nodal institution for DOM; developer of Matsya 6000 and earlier ROSUB 6000 (tested at 5,289 m depth) |
| Samudrayaan | India's first manned deep sea mission under DOM; aims to place 3 aquanauts in the deep ocean aboard the Matsya 6000 submersible |
| Matsya 6000 | India's manned deep sea research submersible under Samudrayaan; designed depth = 6,000 metres; crew = 3 aquanauts; normal dive duration = 12 hours; emergency endurance = 96 hours; hull material = Ti-6Al-4V titanium alloy, 80 mm thick; developer = NIOT Chennai |
| Polymetallic Nodules (PMN) | Potato-sized mineral concretions found on the deep seabed at depths of 4,000–6,000 m; contain commercially valuable metals — manganese, nickel, copper, cobalt — formed over millions of years by slow precipitation; India's resource = 380 million tonnes in the Central Indian Ocean Basin (CIOB) |
| ISA (International Seabed Authority) | UN body established under UNCLOS; headquartered in Kingston, Jamaica; regulates exploration and exploitation of minerals in the international seabed ("Area") beyond national jurisdiction |
| Pioneer Investor | Status granted by ISA to entities that funded the preparatory work for the deep sea mining regime; India was the first country to receive Pioneer Investor status, granted in 1987, for polymetallic nodules |
[Additional] Deep Ocean Mission — Components, Polymetallic Nodules, and Samudrayaan (GS3 — Science & Technology / Environment):
DOM — Six major components:
| Component | Details |
|---|---|
| Samudrayaan (Matsya 6000) | Manned deep sea submersible to 6,000 m; 3 aquanauts; 12-hour normal / 96-hour emergency; in shallow-water trials as of 2026 |
| Deep sea mining | Exploration/exploitation of polymetallic nodules (CIOB); cobalt-rich crusts; polymetallic sulphides |
| Deep ocean survey and exploration | Biodiversity discovery; hydrothermal vents; chemical, biological and geological studies |
| Deep sea biology and climate change | Long-term ocean observation; deep sea genomics and bioactive compounds |
| Advanced marine station for ocean biology | Marine biology research infrastructure; bio-prospecting |
| Ocean climate change advisory services | Model-based services for ocean state, fisheries, cyclone, tsunamis |
India's Polymetallic Nodule (PMN) program — timeline and resources:
| Milestone | Year | Detail |
|---|---|---|
| First nodule recovery | January 1981 | RV Gaveshani recovered first PMN samples from the Indian Ocean |
| Pioneer Investor status | 1987 | India = first country globally to receive this status from ISA |
| Original allocation | 1987 | 1.5 lakh km² (150,000 km²) in CIOB |
| Mandatory 50% surrender | Required under ISA rules | India retained 75,000 km² |
| ISA exploration contract signed | 25 March 2002 | 15-year contract; extended 2017 (5 years) and 2022 (5 years) |
| Current allocated area | — | 75,000 km² in CIOB |
| First Generation Mine Site | — | ~7,860 km² identified within CIOB |
Resource estimates (MoES/Government of India figures):
| Metal | Estimated Quantity |
|---|---|
| Total PMN resource | 380 million tonnes |
| Manganese (Mn) | 92.59 million tonnes |
| Nickel (Ni) | 4.7 million tonnes |
| Copper (Cu) | 4.29 million tonnes |
| Cobalt (Co) | 0.55 million tonnes |
Why these minerals matter:
- Cobalt: Critical for lithium-ion batteries (electric vehicles, mobile phones); India has no significant land cobalt reserves; deep sea nodules = strategic source
- Nickel + Manganese: Steel alloys, specialty chemicals, battery cathodes
- Strategic significance: DOM = Atmanirbhar Bharat for critical minerals; as EV transition accelerates, demand for Co, Ni, Mn will surge
Matsya 6000 — current status (as of early 2026):
- Completed wet trials at Kattupalli Port (January–February 2025): 8 dives (5 unmanned + 3 manned) to 10 m depth
- Shallow water trials at 500 m planned for 2025–26
- Full unmanned deep-sea tests (6,000 m) targeted 2026
- First manned 6,000 m dive targeted 2027
- Comparison: China's Jiaolong reached 7,062 m in 2012; US Alvin (refit 2022) rated to 6,500 m; Japan's Shinkai 6500 rated to 6,500 m
UPSC synthesis: DOM = GS3 Science & Technology + critical minerals + ocean economy. Key exam facts: CCEA approval = 16 June 2021; outlay = Rs. 4,077 crore over 5 years; implementing ministry = MoES; nodal institution = NIOT, Chennai; Samudrayaan mission = Matsya 6000 = 6,000 m depth = 3 aquanauts = 12-hour dive; India = first country with ISA Pioneer Investor status = 1987; allocated area = 75,000 km² in CIOB (Central Indian Ocean Basin); PMN resource = 380 million tonnes (Mn 92.59 Mt, Ni 4.7 Mt, Cu 4.29 Mt, Co 0.55 Mt); ISA headquarters = Kingston, Jamaica; exploration contract signed 25 March 2002 (extended 2017, 2022). Prelims trap: India's Pioneer Investor status = 1987 (NOT 2002 — the 2002 date is the exploration contract signing, not the Pioneer Investor designation); NIOT = Chennai (NOT Mumbai or Goa); ISA = Jamaica (NOT Switzerland or New York); Matsya 6000 has NOT yet dived to 6,000 m as of 2026 (still in shallow trials).
[Additional] 5b. Cryosphere — The Third Pole, Himalayan Glaciers, and NMSHE
The chapter covers four domains but misses the cryosphere — now formally recognised as a distinct component of the Earth system. The Hindu Kush–Himalaya (HKH) region, called the "Third Pole," holds the world's largest freshwater reserve outside the polar regions. ICIMOD's 2019 assessment projected one-third to two-thirds of HKH glaciers could be lost by 2100. India's National Mission for Sustaining the Himalayan Ecosystem (NMSHE) is the policy response.
Key Terms — Cryosphere:
| Term | Meaning |
|---|---|
| Cryosphere | All parts of the Earth system where water exists in solid (frozen) form; includes glaciers, ice sheets, ice shelves, sea ice, permafrost, snow cover, river and lake ice; now recognised as a distinct Earth system component alongside lithosphere, hydrosphere, atmosphere, and biosphere |
| Glacier | A persistent mass of ice formed from accumulated snow over many years; moves slowly downslope under gravity; acts as a natural reservoir — accumulating precipitation in winter and releasing meltwater in dry seasons |
| Permafrost | Ground (soil or rock) that remains at or below 0°C for two or more consecutive years; found in Arctic, Antarctic, and high-altitude regions; contains vast quantities of organic carbon |
| Third Pole | The Hindu Kush–Karakoram–Himalayan (HKKH) system including the Tibetan Plateau; contains the largest concentration of glacial freshwater outside the polar regions; ~54,000 glaciers; ~60,000 km² glacier area; ~6,000 km³ ice volume |
| GLOF | Glacial Lake Outburst Flood — sudden catastrophic release of water from a glacial lake when the ice/moraine dam fails; a major hazard in the Himalayas — 200+ glacial lakes form as glaciers retreat |
| ICIMOD | International Centre for Integrated Mountain Development — Kathmandu, Nepal; research organisation for the Hindu Kush–Himalayan region; published the landmark HKH Assessment 2019 |
| Karakoram Anomaly | The paradox that Karakoram glaciers (Pakistan/India) are stable or advancing while most other HKH glaciers retreat; attributed to specific regional wind and temperature patterns; not a sign that climate change is not happening |
[Additional] Cryosphere, Third Pole, and Himalayan Glacier Threat (GS1 — Physical Geography / GS3 — Environment / Disaster Management):
The Third Pole — key figures:
| Parameter | Figure |
|---|---|
| Number of glaciers (HKH region) | ~54,000 glaciers |
| Total glacier area | ~60,000 km² |
| Estimated ice volume | ~6,000 km³ |
| Population in HKH mountain areas | ~250 million |
| Population dependent on HKH rivers below | ~1.65 billion |
| Major rivers fed by HKH glaciers | Indus, Ganga, Brahmaputra, Amu Darya, Mekong, Yangtze, Yellow River |
| Largest glacier in India/Karakoram | Siachen glacier (~926 km²; Indus basin) |
Gangotri glacier — India's most monitored glacier:
| Parameter | Figure |
|---|---|
| Source of | Bhagirathi river (headstream of the Ganga) |
| Retreat documented since | 1780 |
| Average retreat rate 1936–1996 | ~19 metres per year (1,147 m total over 61 years — Geological Survey of India) |
| Retreat 1996–1999 alone | 76 metres in 3 years (accelerated) |
| Total retreat 1935–2022 | ~1,700 m |
| Total retreat since 1780 | More than 2 km (>2,000 m) |
| Current length | ~30.2 km (declining) |
ICIMOD HKH Assessment 2019 — key findings:
Published February 2019; 350+ researchers from 22 countries; first comprehensive HKH assessment.
| Warming Scenario | Glacier Loss by 2100 |
|---|---|
| 1.5°C global warming | One-third (~36%) of HKH glaciers lost |
| 2°C global warming | Half (~50%) of HKH glaciers lost |
| High emissions (current trajectory) | Two-thirds or more of glacier volume lost |
Critical consequence: All major rivers of South and Southeast Asia (Indus, Ganga, Brahmaputra, Mekong) are glacially fed. After mid-century "peak water" (when meltwater contribution is maximum), river flows will decline — threatening water security for 1.65 billion people downstream.
National Mission for Sustaining the Himalayan Ecosystem (NMSHE):
| Parameter | Detail |
|---|---|
| Parent framework | National Action Plan on Climate Change (NAPCC) — 8 national missions under NAPCC |
| Nodal ministry | Department of Science and Technology (DST) |
| Launched | June 2010 (formally approved 2014) |
| Geographic scope | All 12 Himalayan States of India |
| Key objectives | 1. Continuous monitoring of Himalayan ecosystem health; 2. Observational + forecasting network; 3. Regional cooperation with neighbouring countries for Himalayan glaciology; 4. Annual Status Reports on Himalayan ecosystem sub-components; 5. Bi-annual advisories to the Himalayan Sustainable Development Forum |
8 missions of NAPCC (for context):
- National Solar Mission
- National Mission for Enhanced Energy Efficiency
- National Mission on Sustainable Habitat
- National Water Mission
- National Mission for Sustaining the Himalayan Ecosystem (NMSHE)
- National Mission for a Green India
- National Mission for Sustainable Agriculture
- National Mission on Strategic Knowledge for Climate Change
Cryosphere crisis implications for India:
| Impact | Details |
|---|---|
| River flows | Ganga, Indus, Brahmaputra = glacially fed; "peak water" mid-century → declining flows after |
| GLOFs | 200+ glacial lakes formed as Himalayan glaciers retreat; GLOF risk = high for Uttarakhand, Himachal Pradesh, Sikkim, Arunachal Pradesh |
| Agriculture | 60% of India's agricultural water = Himalayan rivers; glacier decline threatens dry-season flows when irrigation demand is highest |
| Hydropower | India's major Himalayan hydropower projects depend on snowmelt + glacial melt flows |
| Sea level | HKH glacial melt contributing to global sea level rise (in addition to polar ice sheet melt) |
| Permafrost thaw | High-altitude permafrost in Ladakh, Himachal Pradesh, Sikkim = infrastructure risk (road slippage, building subsidence) |
UPSC synthesis: Cryosphere = GS1 Physical Geography + GS3 Environment + Disaster Management. Key exam facts: Cryosphere = 5th Earth system component (after lithosphere, hydrosphere, atmosphere, biosphere); Third Pole = Hindu Kush–Himalaya = ~54,000 glaciers, ~60,000 km² area, ~6,000 km³ ice volume; 1.65 billion people dependent on HKH rivers; ICIMOD HKH Assessment 2019: 1.5°C → 1/3 lost; 2°C → 1/2 lost; high emissions → 2/3+ lost; Gangotri glacier = retreating since 1780, avg 19 m/year (1936–96), total >2 km; NMSHE = under NAPCC = nodal ministry DST = covers 12 Himalayan States; 8 missions under NAPCC total. Prelims trap: NMSHE nodal ministry = DST (NOT MoEF or MoES); ICIMOD = Kathmandu, Nepal (NOT India); Karakoram Anomaly = some Karakoram glaciers are stable/growing (NOT proof that Himalayas are not warming — they are, and Eastern Himalayas retreat faster); Gangotri = source of Bhagirathi (NOT Alaknanda — these are both Ganga headstreams).
Exam Strategy
Prelims traps:
- India has 4 biodiversity hotspots, NOT 2 — Western Ghats, Himalaya, Indo-Burma, Sundaland
- Ozone layer is in the stratosphere — NOT the troposphere; ground-level ozone is a pollutant in the troposphere (two different things)
- Meteors burn in the mesosphere — NOT thermosphere or stratosphere
- ISS is in the thermosphere — NOT the exosphere
- Southern Ocean — National Geographic recognises it as 5th; IHO has not given full official status
- Pangaea broke up ~200–225 million years ago — not 250 million years ago
- CO₂ 2024 annual mean: 422.8 ppm (NOAA global) / 424.61 ppm (Mauna Loa); May 2025 peak 430.5 ppm — the textbook figure of "0.04%" (400 ppm) is outdated
- Troposphere average height is ~13 km — not 12 km; varies 8 km (poles) to 18 km (equator)
- Smallest continent is Australia — Europe is the second smallest; a common confusion
- Mariana Trench (Pacific) is the deepest — NOT in the Indian Ocean
Mains topics from this chapter:
- Ozone layer depletion and recovery — Montreal Protocol and Kigali Amendment
- Greenhouse effect and climate change — India's NDC and Paris Agreement
- India's biodiversity — hotspots, megadiversity, Kunming-Montreal Framework
- Indian Ocean — strategic importance, Indo-Pacific, SAGAR doctrine
- Continental drift and plate tectonics — formation of the Himalayas
Practice Questions
Prelims:
The ozone layer that protects Earth from UV radiation is located in which layer of the atmosphere? (a) Troposphere (b) Stratosphere (c) Mesosphere (d) Thermosphere
Which ocean is the largest in the world? (a) Pacific Ocean (b) Atlantic Ocean (c) Indian Ocean (d) Arctic Ocean
Approximately what percentage of Earth's total water is fresh water? (a) 30% (b) 10% (c) ~2.5% (d) 50%
All weather phenomena like rain, storms, and cyclones occur in which layer of the atmosphere? (a) Troposphere (b) Stratosphere (c) Mesosphere (d) Thermosphere
How many biodiversity hotspots does India have, according to Conservation International? (a) 2 (b) 3 (c) 4 (d) 6
The International Space Station (ISS) orbits in which layer of the atmosphere? (a) Stratosphere (b) Mesosphere (c) Thermosphere (d) Exosphere
The Kigali Amendment (2016) to the Montreal Protocol addresses which substance? (a) CFCs (Chlorofluorocarbons) (b) HFCs (Hydrofluorocarbons) (c) Carbon dioxide (d) Nitrous oxide
Which of the following is NOT one of India's four biodiversity hotspots? (a) Western Ghats (b) Indo-Burma (c) Thar Desert (d) Himalaya
