Environment & Ecology is one of the highest-yield sections of UPSC CSE Prelims, often contributing 15-20 questions, and feeds directly into Mains GS Paper III. This module covers ecology fundamentals, biodiversity and conservation, climate change, international environmental conventions, protected areas and wildlife projects, and India's environmental legal framework — with every formula, committee, convention year, species status and numeric fact carried over, plus worked examples and diagrams for each topic.
After studying this chapter you will be able to:
Environment & Ecology has no strict subject prerequisite, but it connects closely with other UPSC GS papers — climate agreements tie into Indian Economy's trade and finance discussions, and protected-area geography overlaps with Geography's physical features. Once you've worked through the chapters below, head to the Environment & Ecology hub page to generate practice tests, or explore Study Material for other UPSC CSE subjects.
Ecology fundamentals — ecosystem types, food chains, nutrient cycles, and ecological succession — form the conceptual backbone of Environment & Ecology for UPSC. These concepts underlie all higher topics.
| Type | Characteristics | Examples |
|---|---|---|
| Tropical Rainforest | Highest biodiversity; warm & wet; multi-layered canopy; rapid nutrient cycling | Amazon, Western Ghats, NE India |
| Grassland / Savanna | Seasonal rainfall; grasses dominant; large herbivores; fire-maintained | African savanna, Indian grasslands |
| Desert | <250 mm annual rain; extreme temps; xerophytes (CAM metabolism); high evaporation | Thar (India), Sahara, Atacama |
| Wetland | Transitional between aquatic and terrestrial; high productivity; "kidneys of the earth"; carbon sink | Chilika, Sundarbans, Keoladeo |
| Marine | Largest biome on Earth; photic zone (0–200m); abyssal zone; coral reefs most diverse marine ecosystem | Indian Ocean, coral reefs |
| Freshwater | Rivers, lakes, ponds; limnology; lentic (still) vs lotic (flowing) | Ganga, Wular lake |
| Estuary / Mangrove | Where freshwater meets saltwater; highly productive; nursery for fish; protects coasts from erosion | Sundarbans (largest mangrove) |
| Pyramid Type | Always Upright? | Exception |
|---|---|---|
| Pyramid of Numbers | Not always | Inverted in tree ecosystem (1 tree supports many insects) |
| Pyramid of Biomass | Usually upright | Inverted in aquatic ecosystems (phytoplankton < zooplankton biomass at any moment) |
| Pyramid of Energy | Always upright | Never inverted; energy always decreases up the chain |
| Cycle | Key Facts |
|---|---|
| Carbon Cycle | Carbon reservoir: atmosphere (CO₂), oceans (dissolved), lithosphere (fossil fuels, limestone); photosynthesis absorbs CO₂; respiration + combustion releases; Oceans = largest carbon sink |
| Nitrogen Cycle | N₂ fixation (Rhizobium in legume roots; Azotobacter free-living; lightning); nitrification; denitrification; Haber process (industrial); atmosphere 78% N₂ |
| Phosphorus Cycle | No gaseous phase (sedimentary cycle); weathering of rocks; phosphate in soil → plants → animals → decomposers → soil; slow cycling |
| Water Cycle | Evaporation → condensation → precipitation → runoff/infiltration; transpiration; 97.5% saltwater; only 2.5% freshwater (70% in glaciers) |
| Sulphur Cycle | Volcanic eruptions + fossil fuel combustion → SO₂ → acid rain (H₂SO₄); weathering releases sulphate |
~10% of energy transfers to the next trophic level; rest lost as heat
\( E_n = E_1 \times (0.1)^{n-1} \)
2.5% of total water; ~70% of that in glaciers
~78% of the atmosphere is N₂
Given: Producers (T1) fix 10,000 kcal of energy. Using the 10% rule at each transfer, find the energy available to Secondary Consumers (T3).
Solution:
T2 (Primary Consumers) = \(10{,}000 \times 0.1 = 1{,}000\) kcal
T3 (Secondary Consumers) = \(1{,}000 \times 0.1 = 100\) kcal
Answer: 100 kcal — energy shrinks by a factor of 10 at each trophic transfer.
Given: In an aquatic ecosystem, phytoplankton (producers) have lower standing biomass at any instant than the zooplankton (consumers) that feed on them, even though phytoplankton produce far more biomass over time due to rapid turnover. Which pyramid is inverted here?
Solution: This is a snapshot of biomass at one moment, not a flow of energy — so it is the Pyramid of Biomass that can invert in aquatic systems, while the Pyramid of Energy (always cumulative and always upright) is unaffected.
Answer: Pyramid of Biomass is inverted; Pyramid of Energy remains upright.
Given: A pond gradually fills with sediment and organic matter over decades, progressing through marsh, swamp, and scrubland stages before becoming forest. Name this type of succession and its starting point.
Solution: Succession beginning in a water body and progressing toward a terrestrial climax community is specifically termed a hydrosere — a form of primary succession since it starts on a substrate without pre-existing soil.
Answer: Hydrosere — starting substrate is the water body (pond) itself.
Fig. 1.1 — Energy pyramid: each trophic level retains only about 10% of the energy from the level below, so the pyramid narrows sharply and is always upright.
Biodiversity is one of the most heavily tested topics in UPSC Environment. Hotspots, IUCN Red List categories, in-situ vs ex-situ conservation, and international conventions (CBD, CITES) are asked almost every year.
| Criteria (Norman Myers) | ≥1,500 endemic plant species AND ≥70% original habitat lost |
|---|---|
| Global hotspots | 36 hotspots cover only ~2.5% of Earth's land surface but hold ~70% of all species |
| Western Ghats & Sri Lanka | Extends along India's west coast; Anamudi (2695m) highest peak; UNESCO World Heritage (2012); >7,000 flowering plant species |
| Eastern Himalayas (Indo-Burma) | NE India, Bhutan, Myanmar; extremely diverse; Indo-Burma hotspot includes NE states |
| Himalaya hotspot | Covers entire Himalayan arc; rich endemics |
| Sundaland | Andaman & Nicobar Islands; highly endemic; volcanic origin A&N |
| Category | Abbreviation | Meaning |
|---|---|---|
| Extinct | EX | No known living individuals anywhere |
| Extinct in the Wild | EW | Survives only in captivity/cultivation |
| Critically Endangered | CR | Extremely high risk of extinction in the wild |
| Endangered | EN | Very high risk of extinction |
| Vulnerable | VU | High risk of extinction |
| Near Threatened | NT | Close to qualifying as threatened |
| Least Concern | LC | Widespread and abundant |
| Data Deficient | DD | Insufficient data to assess |
| Species | IUCN Status | Note |
|---|---|---|
| Bengal Tiger | Endangered (EN) | India: ~3,682 tigers (2022 census); Project Tiger 1973 |
| Snow Leopard | Vulnerable (VU) | High altitudes; Himalayas; ~450–500 in India |
| One-horned Rhinoceros | Vulnerable (VU) | Kaziranga NP; ~3,700 globally |
| Asiatic Lion | Endangered (EN) | Only in Gir NP, Gujarat; ~700 lions |
| Gangetic Dolphin | Endangered (EN) | National Aquatic Animal of India |
| Great Indian Bustard | Critically Endangered (CR) | <200 left; Rajasthan; power lines threat |
| Indian Cheetah | Locally extinct; reintroduced (Namibian) 2022 | Cheetahs from Namibia/S.Africa brought to Kuno NP |
| Giant Panda | Vulnerable (VU) | Downlisted from Endangered in 2016 |
| Type | Definition | Examples |
|---|---|---|
| In-situ Conservation | Protection in natural habitat; best method; "on-site" | National Parks, Wildlife Sanctuaries, Biosphere Reserves, Sacred Groves |
| Ex-situ Conservation | Protection outside natural habitat; "off-site" | Zoos, botanical gardens, seed banks (Svalbard Global Seed Vault), cryopreservation, gene banks |
≥1,500 endemic plants AND ≥70% habitat loss
36 hotspots; ~2.5% land; ~70% of species
8th in plants; 7th in mammals; 1 of 17 megadiverse nations
Protect 30% of land & oceans by 2030 (COP 15)
Given: A region has 1,800 endemic plant species and has lost 72% of its original habitat. Does it qualify as a biodiversity hotspot under Myers' criteria?
Solution: Myers' criteria require BOTH conditions: ≥1,500 endemic plant species AND ≥70% habitat loss. Here, 1,800 ≥ 1,500 ✓ and 72% ≥ 70% ✓.
Answer: Yes — both conditions are satisfied, so it qualifies as a hotspot.
Given: Rank the following in increasing order of extinction risk: Vulnerable (VU), Near Threatened (NT), Critically Endangered (CR).
Solution: The IUCN Red List orders categories by increasing risk as: Least Concern → Near Threatened → Vulnerable → Endangered → Critically Endangered → Extinct in the Wild → Extinct.
Answer: NT < VU < CR, in increasing order of extinction risk.
Given: (a) A seed sample of an endangered plant is stored at the Svalbard Global Seed Vault. (b) A tiger population is protected within Kaziranga National Park. Classify each method.
Solution: (a) removes the organism from its natural habitat for off-site storage — ex-situ. (b) protects the species within its natural habitat — in-situ.
Answer: (a) Ex-situ conservation; (b) In-situ conservation.
Fig. 2.1 — IUCN Red List spectrum: extinction risk increases from Least Concern (LC) through to Extinct (EX); Data Deficient (DD) sits outside this risk scale.
Climate change is among the most current-affairs-linked topics in UPSC Environment. Paris Agreement, NDCs, carbon credits, and IPCC reports are asked regularly — and the answers shift with each COP.
| GHG | GWP (100-yr) | Major Source |
|---|---|---|
| Carbon Dioxide (CO₂) | 1 (baseline) | Fossil fuel combustion, deforestation; 76% of GHG emissions |
| Methane (CH₄) | 25 | Livestock, rice paddies, landfills, natural gas leaks; 16% of emissions |
| Nitrous Oxide (N₂O) | 298 | Agriculture (fertilisers), combustion; 6% of emissions |
| HFCs / PFCs / SF₆ | Very high (thousands) | Industrial processes; Kigali Amendment (2016) adds HFCs to Montreal Protocol |
| Water Vapour | — | Most abundant GHG but not directly controlled by human activity; amplifies warming |
| Agreement | Year | Key Provision |
|---|---|---|
| UNFCCC (UN Framework Convention on Climate Change) | 1992 (Rio); in force 1994 | Framework convention; "common but differentiated responsibilities" (CBDR); 198 parties |
| Kyoto Protocol | 1997 (in force 2005) | Legally binding emission cuts for developed countries (Annex I); India/China exempt; US never ratified; 1st commitment 2008–12 |
| Copenhagen Accord | 2009 | Non-binding; pledged to limit warming to 2°C; developed countries: $100 bn/yr to developing by 2020 |
| Paris Agreement | 2015 (COP 21); in force Nov 2016 | Limit warming to well below 2°C, preferably 1.5°C above pre-industrial; NDCs; 5-year review cycles; loss and damage |
| Glasgow Climate Pact | COP 26, 2021 | "Phase down" (not phase out) coal; $100 bn climate finance; 1.5°C goal reaffirmed |
\( \text{CO}_2\text{e} = \text{Mass}\times\text{GWP} \)
CO₂=1; CH₄=25; N₂O=298
Well below 2°C, preferably 1.5°C above pre-industrial
45% emissions intensity cut by 2030 (vs 2005); Net Zero by 2070
Given: A source emits 4 tonnes of methane (CH₄), which has a 100-year GWP of 25. Find its CO₂-equivalent emission.
Solution:
\( \text{CO}_2\text{e} = 4 \times 25 = 100 \) tonnes
Answer: 100 tonnes of CO₂-equivalent — methane's warming effect is 25 times more potent than the same mass of CO₂ over 100 years.
Given: A facility emits 2 tonnes of N₂O and separately 2 tonnes of CH₄. Which contributes more CO₂-equivalent warming, and by how much?
Solution:
N₂O: \(2\times298=596\) tonnes CO₂e; CH₄: \(2\times25=50\) tonnes CO₂e
Answer: N₂O contributes far more (596 vs 50 tonnes CO₂e) — a difference of 546 tonnes CO₂e — because N₂O's GWP is much higher than methane's.
Given: Which international climate agreement first introduced Nationally Determined Contributions (NDCs) as its core mechanism, and in what year did it enter into force?
Solution: Unlike Kyoto's top-down binding targets for developed countries only, the Paris Agreement introduced a bottom-up system where every country submits its own NDC.
Answer: The Paris Agreement (adopted COP21, 2015); entered into force November 2016.
Fig. 3.1 — Global Warming Potential (100-year) comparison: N₂O (298) > CH₄ (25) > CO₂ (1, baseline); bar heights are compressed for display, not linearly to scale.
International conventions are asked almost every year in UPSC. Ramsar, CITES, Montreal Protocol, Basel/Rotterdam/Stockholm, and MARPOL are high-frequency topics. Memorise year, purpose, and India's specific role.
| Convention | Year | Focus | India's Note |
|---|---|---|---|
| Ramsar Convention | 1971 (Ramsar, Iran) | Conservation and sustainable use of wetlands of international importance | India: 75+ Ramsar sites (most in world after UK); first two = Chilika (Odisha) + Keoladeo (Rajasthan) in 1981 |
| CITES | 1973 (Washington); in force 1975 | Convention on International Trade in Endangered Species; regulates wildlife trade via 3 Appendices | Appendix I = banned trade; II = regulated; III = protected in at least one country |
| Montreal Protocol | 1987 | Phase-out of ozone-depleting substances (ODSs): CFCs, HCFCs, halons, methyl bromide | Most successful international environmental agreement; 198 parties; ozone layer recovering; Kigali Amendment (2016) adds HFCs |
| Basel Convention | 1989 | Control transboundary movement of hazardous wastes and their disposal | India ratified; bans export of hazardous waste to developing countries |
| Rotterdam Convention | 1998 | Prior Informed Consent (PIC) for trade in hazardous chemicals and pesticides | Notification required before exporting listed chemicals |
| Stockholm Convention | 2001 | Eliminate/restrict Persistent Organic Pollutants (POPs) — "Dirty Dozen" initially: DDT, PCBs, dioxins, etc. | India ratified; DDT still used for malaria control (exemption) |
| Minamata Convention | 2013 | Protects human health and environment from mercury; named after Minamata disease (Japan, 1956) | India ratified 2018 |
| MARPOL | 1973/78 | International Convention for Prevention of Pollution from Ships; 6 annexes covering oil, chemicals, sewage, garbage | Marine pollution prevention |
| Body/Event | Details |
|---|---|
| UNEP | UN Environment Programme; HQ Nairobi, Kenya; established 1972 (after Stockholm Conference); only major UN body headquartered in developing country |
| World Environment Day | 5 June; since 1972; theme announced annually by UNEP |
| Earth Day | 22 April; since 1970 |
| Wetlands Day | 2 February (Ramsar Day) |
| World Wildlife Day | 3 March (CITES signing date) |
| International Day for Biodiversity | 22 May (CBD entry into force) |
| IUCN | International Union for Conservation of Nature; HQ Gland, Switzerland; publishes Red List; founded 1948 |
| WWF | World Wide Fund for Nature; panda logo; founded 1961; Gland, Switzerland |
CFC-11 = 1.0; HCFC-22 = 0.055; HFCs ≈ 0
75+ sites; most in world after UK
I = banned; II = regulated; III = protected in ≥1 country
Stratosphere, 15–35 km
Given: A convention requires "Prior Informed Consent" before exporting listed hazardous chemicals and pesticides. Identify the convention and its year.
Solution: The specific mechanism of Prior Informed Consent (PIC) for hazardous chemical trade is the defining feature of the Rotterdam Convention.
Answer: Rotterdam Convention (1998).
Given: A species is threatened with extinction and international trade is completely prohibited except in exceptional circumstances. Which CITES Appendix applies?
Solution: Appendix I is reserved for species facing the most severe threat, where commercial international trade is essentially banned.
Answer: Appendix I.
Given: Arrange the following in chronological order: Stockholm Convention (POPs), Ramsar Convention, Minamata Convention, Montreal Protocol.
Solution: Ramsar (1971) → Montreal Protocol (1987) → Stockholm Convention (2001) → Minamata Convention (2013).
Answer: Ramsar (1971), Montreal Protocol (1987), Stockholm Convention (2001), Minamata Convention (2013).
Fig. 4.1 — Timeline of major international environmental conventions: from Ramsar (wetlands, 1971) through to the Minamata Convention (mercury, 2013).
The distinction between National Parks, Sanctuaries, Biosphere Reserves, and Tiger Reserves is tested every year. Project Tiger, Project Elephant, and key NPs with their states/features are UPSC essentials.
| Category | Protection Level | Human Activity | Boundary Change |
|---|---|---|---|
| National Park | Highest; under WPA 1972 | None permitted (including grazing, forestry) | Only by Act of State Legislature (Parliament for some) |
| Wildlife Sanctuary | High; under WPA 1972 | Some activities (grazing, forestry) with permission; private ownership allowed | State government can alter |
| Conservation Reserve | Moderate; newer category (WPA amendment 2002) | Local communities may continue traditional uses | State govt. in consultation with communities |
| Community Reserve | Moderate; community-led | Community manages; no private land acquisition | State govt. |
| Biosphere Reserve | UNESCO designation; three-zone model | Core = strictly protected; Buffer = research; Transition = sustainable use | UNESCO + national decision |
| National Park | State | Known For |
|---|---|---|
| Jim Corbett NP | Uttarakhand | First NP in India (1936); tigers; Project Tiger's first reserve (1973) |
| Kaziranga NP | Assam | One-horned rhinoceros (70% of world's population); UNESCO WHS; also tigers, elephants |
| Sundarbans NP | West Bengal | World's largest mangrove; Royal Bengal Tiger; UNESCO WHS |
| Gir NP | Gujarat | Only wild habitat of Asiatic Lions; ~700 lions |
| Keoladeo (Bharatpur) NP | Rajasthan | Avifauna; Siberian Crane wintering; UNESCO WHS; Ramsar site |
| Valley of Flowers NP | Uttarakhand | Alpine flowers; UNESCO WHS (along with Nanda Devi) |
| Manas NP | Assam | UNESCO WHS; Project Tiger + Project Elephant; buffers Bhutan's Royal Manas NP |
| Periyar NP | Kerala | Tigers, elephants; Periyar Lake reservoir; biosphere reserve |
| Namdapha NP | Arunachal Pradesh | Only park with all 4 big cats: Tiger, Leopard, Snow Leopard, Clouded Leopard |
| Hemis NP | Ladakh | Largest NP by area in India; snow leopards |
| Project | Launch Year | Key Facts |
|---|---|---|
| Project Tiger | 1973 (Indira Gandhi) | 54 tiger reserves; 2022 tiger census: ~3,682 tigers; India = 75% of world's wild tigers; MP has most tigers; NTCA (National Tiger Conservation Authority) |
| Project Elephant | 1992 | 33 elephant reserves; corridor protection; man-animal conflict; ~30,000 elephants in India |
| Crocodile Conservation Project | 1975 | Three species: Mugger (freshwater), Saltwater Crocodile (largest reptile), Gharial (Critically Endangered); Chambal & Ken rivers |
| Project Cheetah | 2022 | World's first inter-continental reintroduction; Namibian cheetahs to Kuno NP (MP) |
| Sea Turtle Project | 1975 | Olive Ridley turtles; Gahirmatha & Odisha coast; mass nesting (Arribada) |
18 total; 12 in UNESCO's World Network
1973; 54 reserves; ~3,682 tigers (2022); ~75% of world's wild tigers
1992; 33 reserves; ~30,000 elephants
Jim Corbett (1936); Nilgiri BR (1986)
Given: India's 2022 tiger census recorded ~3,682 tigers, representing approximately 75% of the world's wild tiger population. Estimate the total world population.
Solution:
\( \text{World total} = \dfrac{3682}{0.75} \approx 4909 \)
Answer: Approximately 4,900 wild tigers worldwide.
Given: An area permits regulated grazing by local communities with government permission and allows some private land ownership within its boundary. Which protected area category is this?
Solution: National Parks prohibit any human activity including grazing; only Wildlife Sanctuaries permit limited activities with permission and allow private ownership.
Answer: Wildlife Sanctuary.
Given: Which national park is the only one in India home to all four big cat species — Tiger, Leopard, Snow Leopard, and Clouded Leopard?
Solution: This unique combination of high-altitude and lowland habitats supporting all four species is found only in one northeastern park.
Answer: Namdapha National Park, Arunachal Pradesh.
Fig. 5.1 — Biosphere Reserve three-zone model: a strictly protected Core, surrounded by a research-permitted Buffer, surrounded by a sustainable-use Transition zone.
India's environmental legal framework — EPA 1986, NGT 2010, Forest Rights Act — and institutional structures (CPCB, SPCB) are regularly examined. EIA notification, e-waste rules, and plastic waste rules are current affairs links.
| Act / Law | Year | Key Provisions |
|---|---|---|
| Wildlife Protection Act | 1972 | Prohibits hunting/poaching; establishes PAs; schedules I–VI (Schedule I = highest protection, absolute ban); CITES implementation |
| Water (Prevention and Control of Pollution) Act | 1974 | Establishes Central and State Pollution Control Boards; standards for industrial effluent discharge |
| Forest Conservation Act | 1980 | Requires Central government approval for diverting forest land for non-forest purposes |
| Air (Prevention and Control of Pollution) Act | 1981 | Air quality standards; CPCB sets standards; SPCB enforces |
| Environment (Protection) Act | 1986 (post Bhopal disaster) | Umbrella legislation; empowers Central govt. to issue directions; EIA under this Act; most comprehensive |
| Forest Rights Act (FRA) | 2006 | Recognises forest dwellers' (Scheduled Tribes + Other Forest Dwellers) rights over forest land and resources; community forest resource rights |
| National Green Tribunal (NGT) Act | 2010 | Specialised court for environmental cases; quasi-judicial; principal bench Delhi; 5 zonal benches; judges + expert members; cannot override SC/HC |
| Biological Diversity Act | 2002 | Implements CBD; three-tier: NBA (National Biodiversity Authority, Chennai) → SBB → BMC (Biodiversity Management Committee at local level) |
| Type | Key Facts / Standards |
|---|---|
| Air Pollution | CPCB publishes AQI (Air Quality Index): 6 categories 0–50=Good to 401–500=Severe; 8 pollutants: PM2.5, PM10, NO₂, SO₂, CO, O₃, NH₃, Pb; Bharat Stage (BS) VI emission norms from 2020 |
| Water Pollution | BOD (Biochemical Oxygen Demand): <3 mg/L = clean; >10 mg/L = heavily polluted; Ganga Action Plan 1986; Namami Gange Programme 2015 (₹20,000 cr) |
| Soil / Land Pollution | Solid Waste Management Rules 2016; plastic waste Rules; e-waste Rules 2022 (Extended Producer Responsibility — EPR) |
| Noise Pollution | Day: 55 dB (residential), 65 dB (commercial); Night: 45 dB, 55 dB |
| Thermal Pollution | Hot water discharge from power plants into water bodies; reduces dissolved oxygen; kills aquatic life |
<3 mg/L = clean; >10 mg/L = heavily polluted
55 dB residential; 65 dB commercial
6 bands: 0–50 Good to 401–500 Severe
A = Central + SEAC appraisal; B = SEAC only
Given: A river sample shows a BOD of 12 mg/L. Classify the water quality.
Solution: A BOD above 10 mg/L falls into the "heavily polluted" category, since clean water typically has BOD below 3 mg/L.
Answer: Heavily polluted — well above the 10 mg/L threshold.
Given: A company wants to divert 50 hectares of forest land for a mining project. Which Act's approval is required?
Solution: Diversion of forest land for non-forest purposes specifically requires Central government approval under the Forest Conservation Act.
Answer: Forest Conservation Act, 1980.
Given: A large thermal power project requires appraisal at the central level, involving the Ministry and an Expert Appraisal Committee. Which EIA category does it fall under?
Solution: Category A projects, unlike Category B (state-level SEAC only), require central-level appraisal due to their larger scale and impact.
Answer: Category A.
Fig. 6.1 — EIA process flow: screening and scoping, baseline study and impact prediction, environmental management plan and public hearing, then expert appraisal and approval.
A disaster is a serious disruption of a community's functioning causing losses that exceed its capacity to cope. Disaster management (Mains GS-III) is the organised effort to reduce those losses before, during and after an event.
| Category | Examples |
|---|---|
| Natural — geophysical | Earthquakes, landslides, tsunamis, volcanic activity |
| Natural — hydro-meteorological | Floods, cyclones, droughts, cloudbursts, heat waves |
| Biological | Epidemics, pandemics, pest attacks |
| Man-made | Industrial/chemical accidents, nuclear, fires, stampedes |
Management is a continuous cycle with a pre-disaster and a post-disaster half:
The Disaster Management Act, 2005 created a three-tier structure: the National Disaster Management Authority (NDMA) chaired by the Prime Minister, State Authorities (SDMA) under Chief Ministers, and District Authorities. The NDRF is the specialised response force. Internationally, India follows the Sendai Framework for Disaster Risk Reduction (2015–2030), which shifts the focus from managing disasters to managing risk.
Only 10% energy transfers between trophic levels (Lindeman's Law)
Always upright; never inverted
Sedimentary; no atmospheric phase
Lichens (primary succession)
17 megadiverse countries; 4 biodiversity hotspots
Biodiversity hotspot + UNESCO WHS (2012)
Gland, Switzerland; founded 1948
Critically Endangered (CR); Rajasthan
Gangetic Dolphin (Endangered)
~3,682; India = 75% of world's wild tigers
Only in Gir NP, Gujarat (~700 lions)
Only NP with all 4 big cats
Hemis NP, Ladakh
Jim Corbett NP (1936, Uttarakhand)
1973; 54 reserves; NTCA
Nilgiri (1986)
75+; first: Chilika + Keoladeo (1981)
1971; wetlands of international importance
1973; Appendix I = trade banned
1987; phase-out of ODSs; Kigali Amendment 2016 adds HFCs
16 September
1992 Rio Earth Summit; in force 1994
1.5°C above pre-industrial; in force 2016
2070
25 (100-year); N₂O = 298
Nairobi, Kenya; est. 1972
5 June
Chennai (National Biodiversity Authority)
1986; umbrella environmental law
2010; principal bench New Delhi
2006; rights of Scheduled Tribes + OFDs over forest land
World's largest mangrove; UNESCO WHS; India + Bangladesh
| Topic | Prelims Focus | Mains GS-III Focus |
|---|---|---|
| Ecology Basics | Pyramid types; cycle facts; energy rule numericals | Rarely directly asked; underpins ecosystem service discussions |
| Biodiversity | Hotspot criteria; IUCN status of species; CBD facts | Conservation strategy debates; human-wildlife conflict |
| Climate Change | GWP values; agreement years and provisions; NDC facts | Climate justice, CBDR principle, India's energy transition |
| International Conventions | Convention year, purpose, India's role | Global environmental governance debates |
| Protected Areas | PA category distinctions; NP facts; project launch years | Human-wildlife conflict; conservation vs development trade-offs |
| Environmental Laws | Act years and provisions; institution facts; EIA process | Ease of doing business vs environmental clearance debates |
Q1. If a producer fixes 10,000 kcal of energy, how much energy is available to Secondary Consumers (T3), assuming the 10% rule applies at each transfer?
Q2. Methane has a 100-year GWP of 25. If a source emits 4 tonnes of CH₄, what is its CO₂-equivalent emission?
Q3. A region has 1,800 endemic plant species and has lost 72% of its original habitat. Does it qualify as a biodiversity hotspot?
Q4. A pond gradually fills with sediment, progressing through marsh, swamp and scrubland before becoming forest. Name this succession type.
Q5. India's 2022 tiger census recorded ~3,682 tigers, representing ~75% of the world's wild tiger population. Estimate the world total.