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Environment: the ideas UPSC returns to.

75 ideas came three times or more. Under each is the one line to remember from every question. Tap a year to open the solved question.

9 timesForest types and trees

Forests and trees of India · 2023, 2016, 2015, 2014, 2010, 2008, 2002

Deciduous: teak, sal, mahua, sandalwood, tendu. Evergreen: jackfruit, rosewood, mahogany, ebony. 2023 ›
Red Sanders: Seshachalam (AP), dry deciduous; IUCN Endangered; smuggled for its red wood (CITES Appendix II). 2016 ›
A&N Islands = mangroves + tropical evergreen + moist deciduous. 2015 ›
Tropical wet evergreen: Western Ghats, NE, A&N Islands. None in the western Himalaya. 2015 ›
Teak and sal = moist deciduous (India’s largest forest type). 2015 ›
Himalaya: oak, rhododendron, deodar, pine, birch. Sandalwood: Karnataka / Tamil Nadu. 2014 ›
Among these four, tropical moist deciduous covers the largest area. In the Forest Survey’s mapping, tropical dry deciduous (not an option here) covers even more. 2010 ›
Himalayan conifers: deodar, chir pine, blue pine, fir, spruce, juniper. 2008 ›
Thorn forests: Rajasthan, Gujarat, Rayalaseema, rain-shadow Deccan (<70 cm). 2002 ›

8 timesPrimates

Primates, bats and small mammals · 2026, 2024, 2023, 2013, 2008, 2004, 1994

Hoolock gibbon = India's only ape · Endangered · Hollongapar (Assam) · light body + brachiation. 2026 ›
Lemurs (indri) = Madagascar only · Bonobo = DR Congo only · Elk = cold northern forests. 2024 ›
Lion-tailed macaque = diurnal, Western Ghats. Malabar civet and sambar = nocturnal. 2024 ›
Stick tool for insects = orangutan (and chimp). Sloth bear = lips and suction, no tool. 2023 ›
Lion-tailed macaque: endemic to the Western Ghats (TN, Kerala, Karnataka), Endangered. 2013 ›
Apes (no tail): gibbon, orangutan, gorilla, chimpanzee, bonobo. India’s only ape: hoolock gibbon. 2008 ›
India: 2 pangolins (Schedule I) · 1 ape (hoolock gibbon). 2004 ›
Hoolock gibbon = India’s only ape (Hollongapar Gibbon Sanctuary, Assam). 1994 ›

8 timesWhere air pollutants come from

Air pollutants, smog and gases · 2024, 2021, 2020, 2019, 1995, 1979

SO₂: power plants (coal) > industry (smelters) > ships and vehicles. 2024 ›
Magnetite (Fe₃O₄) nanoparticles in brains linked to Alzheimer’s (2016 study) — from traffic and combustion. 2021 ›
Furnace oil & pet coke: high-sulphur fuels; banned in Delhi NCR (2017). 2021 ›
Benzene (carcinogen, leukaemia): petrol vehicles, tobacco smoke, burning wood/biomass. 2020 ›
Stubble burning: CO, CO₂, CH₄, NOₓ, SO₂, PM2.5 → ozone. Fixes: Happy Seeder, bio-decomposer. 2019 ›
H-CNG: ~18% H₂ in CNG; ↓CO, ↓CO₂, ↓HC; Delhi pilot 2019. 2019 ›
Hydrogen: cleanest combustion. Green hydrogen = made with renewable electricity. 1995 ›
Smoke = particulate matter (PM) — the most widespread air pollutant. 1979 ›

7 timesForest cover and policy

Forests and trees of India · 2022, 2019, 2010, 2005, 2004, 1999, 1979

Miyawaki = dense native mini-forests in cities (Japan; used by many Indian municipal bodies). 2022 ›
By area: MP > Arunachal > Chhattisgarh. By %: Mizoram, Lakshadweep, Andaman, Arunachal lead. 2019 ›
India: net sown ≈ 46%, forest ≈ 23% (recorded), target 33% (National Forest Policy 1988). 2010 ›
Target = one-third of India under forest/tree cover (1988 policy; 2/3 in the hills). 2005 ›
Lowest forest share: Haryana, Punjab (~3–4%). 2004 ›
33% forest target (66% in hills) — National Forest Policy 1988. 1999 ›
Deforestation → erosion → silt in rivers → floods; also less local rain. 1979 ›

7 timesPark and State matching

Where the parks are · 2008, 2007, 2006, 2005, 1990, 1985

Madhya Pradesh has the most national parks; Andaman & Nicobar has 9. 2008 ›
Top Slip = Anamalai (Indira Gandhi) Tiger Reserve, Coimbatore (TN). 2007 ›
Indravati NP/TR (Bastar, Chhattisgarh): wild buffalo (state animal of Chhattisgarh). 2007 ›
Karera (MP, near Jhansi) was once a Great Indian Bustard sanctuary. 2006 ›
Bondla (Goa) · Kanger Ghati (Chhattisgarh, caves) · Orang (Assam, rhinos) · Ushakothi (Odisha). 2005 ›
Navegaon NP = Maharashtra · Palamau TR = Jharkhand · Gir = Gujarat. 1990 ›
Keoladeo Ghana = Rajasthan · Gir = Gujarat · Corbett = Uttarakhand. 1985 ›

7 timesClimate initiatives and alliances

International organisations and initiatives · 2022, 2021, 2018, 2017, 2016

Climate Action Tracker = independent research consortium. UNEP = Emissions Gap Report. 2022 ›
Common Carbon Metric (UNEP-SBCI) = carbon footprint of building operations. 2021 ›
GACSA (2014, New York; FAO hosts it) = voluntary; India not a member. 2018 ›
Climate Neutral Now (2015) = UNFCCC secretariat. 2018 ›
CCAC (UNEP-hosted) = short-lived climate pollutants; India joined in 2019. 2017 ›
GCCA (2007) = EU. GHG Protocol = WRI + WBCSD. 2017 ›
GHG Protocol = accounting tool; Scope 1 (direct), 2 (bought energy), 3 (value chain). 2016 ›

7 timesIndia’s climate action and clean energy

2026, 2025, 2017, 2010

LT-LEDS (COP27, 2022) → net zero 2070. BUR-4 (Dec 2024): 2020 emissions −7.93% vs 2019. 2026 ›
India’s first Plan Vivo REDD+: Khasi Hills (Meghalaya), community forests, sells carbon credits. 2026 ›
NMSA (NAPCC mission): RAD, Soil Health Card, Paramparagat Krishi Vikas Yojana. 2026 ›
Green hydrogen = made with renewable energy (electrolysis, or biomass within the emission limit) 2026 ›
India: 3rd largest emitter overall, ~2 t CO₂/capita, power sector #1. 2025 ›
Algal biofuel = 3rd generation; open ponds or photobioreactors. 2017 ›
India’s mitigation limits (2010): technology access, finance, R&D. 2010 ›

6 timesNitrogen

Carbon, nitrogen, phosphorus and oxygen cycles · 2022, 1992, 1991, 1988, 1987, 1979

Pea family = nitrogen-fixer: alfalfa, chickpea, clover. Leafy greens (amaranth, purslane, spinach) are not. 2022 ›
Legumes (pea, gram, beans, clover, alfalfa) + Rhizobium root nodules = nitrogen fixation. 1992 ›
Maize = wind cross-pollinated (male tassel on top, female silk below). 1991 ›
Legume + Rhizobium = biological nitrogen fixation; that is why pulses are rotated with cereals. 1988 ›
Plants absorb nitrogen mainly as nitrate (NO₃⁻), some as ammonium. 1987 ›
Legumes fix nitrogen. Cereals (rice, wheat, maize) do not. 1979 ›

6 timesEquatorial climate and rainforest

World climates and biomes · 2023, 2021, 2015, 2013, 2011, 2003

Rainforest: nutrients in the biomass, soil poor (leached laterite). Cleared rainforest farms fail within a few years. 2023 ›
Rainforest: fastest decomposition, thin litter, lianas + epiphytes, multi-layered canopy. 2021 ›
Equatorial = daily convectional rain (the “4 o’clock rain”), no seasons. 2015 ›
Equatorial forest: closed canopy + highest species richness + epiphytes and lianas. 2013 ›
Rainforest nutrients are in the biomass. Remove it → poor, leached soil → slow regrowth. 2011 ›
Rainforest: highest productivity, poorest soils — cleared land fails fast. 2003 ›

6 timesFound in India · endangered lists

Large mammals of India · 2019, 2013, 2012, 2002

India-only: Asiatic lion (Gir). Shared: one-horned rhino (Nepal), Bactrian camel (Mongolia, China). 2019 ›
Pygmy hog: Manas (Assam), Endangered (earlier Critically Endangered). Spider monkey: Americas only. 2013 ›
Gharial = CR · Barasingha: Kanha (hard-ground), Dudhwa, Kaziranga. 2013 ›
Cheetah: extinct in India 1952; African cheetahs reintroduced at Kuno (MP) 2022. 2012 ›
GIB (CR, Rajasthan), red panda (Sikkim state animal), wild ass (Little Rann of Kutch). 2012 ›
Equus hemionus (khur) · Rucervus duvaucelii (barasingha) · Gazella bennettii (chinkara) · Boselaphus (nilgai). 2002 ›

6 timesBirds of India

Birds · 2026, 2020, 2016, 2014, 1980, 1979

Amur falcon: Mongolia/China → Nagaland (Doyang, Pangti) → southern Africa; ~22,000 km round trip. 2026 ›
Coppersmith barbet (“tuk-tuk” call) and Ceylon frogmouth (Western Ghats, nocturnal) are birds. 2020 ›
Great hornbill: Western Ghats + NE forests; state bird of Kerala and Arunachal. 2016 ›
Birds following cattle: cattle egret, myna, drongo. 2014 ›
Great Indian Bustard: Rajasthan (state bird), Critically Endangered; power lines are a big threat. 1980 ›
GIB: Rajasthan (Desert NP), small numbers in Gujarat; fewer than 150 left. 1979 ›

6 timesConservation bodies

International organisations and initiatives · 2023, 2017, 2015, 2014, 2011

ISSG → IUCN Species Survival Commission → Global Invasive Species Database. 2023 ›
TRAFFIC (1976, WWF + IUCN) = wildlife trade monitoring NGO. 2017 ›
BirdLife → IBAs (India partner: BNHS). Hotspots → Myers / Conservation International. 2015 ›
IUCN (1948, Gland): govts + NGOs, Red List. CITES (1973/75): binding, Appendices I–III. 2015 ›
Wetlands International = NGO (Netherlands), Ramsar partner; Asian Waterbird Census. 2014 ›
Red Data Book / Red List (IUCN) = threatened species. Historical pink pages = endangered species. 2011 ›

6 timesCarbon credits and the CDM

Carbon markets and climate finance · 2023, 2020, 2011, 2009, 2008

UPSC 2023 official key: (a). Auctioned allowances and carbon taxes move money to the State; free allowances and offsets need not. 2023 ›
Kyoto mechanisms: CDM (→ CERs), Joint Implementation, Emissions Trading. Cartagena = GMOs · Nagoya = ABS. 2020 ›
Carbon credit = 1 tonne CO₂e; price set by supply and demand. 2011 ›
CDM (Kyoto) → Certified Emission Reductions (CERs). Paris successor: Article 6.4 mechanism. 2009 ›
Kyoto (1997, in force 2005): binding targets for Annex I → carbon credits. 2009 ›
CDM: project in non-Annex I (India, China), buyer from Annex I. JI: project in another Annex I country. 2008 ›

6 timesAcid rain

2022, 2013, 1994, 1993, 1988, 1984

Acid rain = SO₂ (→ H₂SO₄) + NOₓ (→ HNO₃); pH below 5.6. 2022 ›
Acid rain: SO₂ + NOₓ. Normal rain pH ≈ 5.6 due to CO₂. 2013 ›
Taj damage = acid rain (SO₂/NOₓ) + tropospheric ozone → marble cancer. Supreme Court: Taj Trapezium Zone (1996). 1994 ›
Acid rain = SO₂ + NOₓ from fossil fuels; damages lakes, forests, monuments. 1993 ›
Acid rain: NOₓ + SO₂. 1988 ›
Taj: acid rain + particulates; Taj Trapezium Zone (SC, 1996). 1984 ›

5 timesPhotosynthesis and chlorophyll

Photosynthesis and plant adaptations · 1992, 1987, 1986, 1982, 1979

Chlorophyll → Mg · Haemoglobin → Fe · Haemocyanin → Cu · Vitamin B12 → Co. 1992 ›
Photosynthesis = in chloroplasts, wherever they are (leaves, green stems, cactus stems). 1987 ›
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Final product = carbohydrate; O₂ = by-product. 1986 ›
Chlorophyll = green pigment, Mg at the centre, absorbs red + blue, reflects green. 1982 ›
Phytoplankton produce about half of Earth’s oxygen. 1979 ›

5 timesWhere diversity is highest

Biodiversity: patterns, hotspots and threats · 2011, 1994, 1993, 1981

Diversity decreases with latitude and with altitude (every ~1,000 m up ≈ several hundred km towards the pole). 2011 ›
Himalayan richness = meeting of biogeographic realms + altitude gradient. 2011 ›
Tropical moist forests = highest species diversity on land; coral reefs in the sea. 1994 ›
Named species ≈ 1.5 million (1990s), ~2.1 million today; the total is estimated at ~8.7 million (2011) or more. 1993 ›
Species diversity increases from the poles to the equator. 1981 ›

5 timesSpecial places

Forests and trees of India · 2019, 2015, 2012, 1984

Valley of Flowers = alpine meadow, part of the Nanda Devi WHS. Namdapha = tropical to alpine. 2019 ›
Living root bridges = Meghalaya (Khasi–Jaintia hills) · Ficus elastica · stronger with age. 2015 ›
Namdapha: tropical to arctic; the only park with four big cats (tiger, leopard, clouded leopard, snow leopard). 2015 ›
Arunachal: largest forest area in the NE, ~80% forest cover. 2012 ›
Silent Valley (Palakkad, Kerala): project dropped, NP 1984; core of the Nilgiri Biosphere Reserve. 1984 ›

5 timesAntelopes, wild ass and camels

Large mammals of India · 2016, 2012, 2011, 1994, 1993

Kharai camel: Kutch (Gujarat), swims, grazes mangroves, domesticated. 2016 ›
Chiru (Tibetan antelope): Ladakh / Tibet, poached for shahtoosh wool. 2012 ›
Indian wild ass: Little Rann of Kutch (Wild Ass Sanctuary), Gujarat. 2011 ›
Camel: hump = fat; very water-efficient body (little sweat, dry dung, concentrated urine). 1994 ›
Camel hump = fat. Dromedary (1 hump, Rajasthan) · Bactrian (2 humps, Ladakh). 1993 ›

5 timesPandas and other mammals

Large mammals of India · 2009, 2007, 1987, 1984, 1980

Giant panda = bear family. Red panda = its own family, found in India (Sikkim, Arunachal). 2009 ›
Red panda: eastern Himalaya (State animal of Sikkim). Slow loris: North-East India. Slender loris: South India. Both lorises are active at night. 2007 ›
Desi pigs: small litters (~4–6), hardy. 1987 ›
Elephant ~65 · horse ~28 · tiger ~15–20 · wolf ~12. 1984 ›
Tallest: giraffe · heaviest land: elephant · largest bird: ostrich. 1980 ›

5 timesDugong and dolphins

Life in seas and rivers · 2019, 2015, 2014, 2009

Irrawaddy dolphin → Chilika · Gangetic dolphin → Ganga, Chambal, Brahmaputra. 2019 ›
Dugong: seagrass, 4 sites (Mannar, Palk Bay, Kutch, A&N); India’s first dugong reserve in Palk Bay (TN). 2015 ›
National aquatic animal = Gangetic dolphin (2009); “Dolphin Day” 5 October. 2015 ›
River dolphin threats: dams/barrages, fishing nets, pollution, sand mining, oil poaching. Project Dolphin 2020. 2014 ›
Dugong = marine mammal (Sirenia), herbivore, seagrass. 2009 ›

5 timesPlankton and the ocean food chain

Life in seas and rivers · 2021, 2012, 1998, 1982

Ocean producers: diatoms, cyanobacteria, dinoflagellates, coccolithophores. 2021 ›
Filter feeders: oysters, mussels, sponges, baleen whales, flamingos, whale sharks. 2021 ›
Phytoplankton: base of ocean food chains + biological carbon pump + ~50% of Earth’s oxygen. 2012 ›
Red tide = dinoflagellate bloom (harmful algal bloom); can cause shellfish poisoning. 1998 ›
Plankton = drifters · nekton = active swimmers · benthos = bottom-dwellers. 1982 ›

5 timesBird facts

Birds · 2022, 1998, 1994, 1990, 1980

Golden mahseer = fish (Himalayan rivers), Endangered. 2022 ›
Dodo (Mauritius, extinct ~1681) ↔ tambalacoque tree — the classic co-extinction story. 1998 ›
First bird: Archaeopteryx, ~150 million years ago; birds evolved from dinosaurs. 1994 ›
Urea (mammals) needs water. Uric acid (birds, reptiles, insects) saves water. 1990 ›
Woodpecker: chisel bill, zygodactyl feet, stiff tail for support. 1980 ›

5 timesCrocodiles, lizards and dinosaurs

Reptiles, amphibians and poisons · 2008, 2003, 1989, 1985, 1980

Saltwater crocodile: Andaman, Sundarbans, Bhitarkanika. No tapirs in India. 2008 ›
Spirogyra, Ulothrix = mostly freshwater. Chameleon = independent eye movement. 2003 ›
Dinosaurs = reptiles (Mesozoic); birds descend from them. 1989 ›
Dinosaurs: ~230–66 million years ago (asteroid, Chicxulub). Humans (Homo): ~2.5 million years ago. 1985 ›
Chameleon: colour change (iridophores), independent eyes, sticky tongue. 1980 ›

5 timesInsect groups, spiders and parasitoids

Insects, spiders and worms · 2025, 2024, 1984

Peacock (Gooty) tarantula: arachnid · arboreal · Eastern Ghats (AP) only · Critically Endangered. 2025 ›
Cicada (loud song), froghopper (spittlebug), pond skater (walks on water) = insects. 2024 ›
Parasitoid = lays eggs in/on a host, larva kills it. Wasps, tachinid flies, some beetles. Trichogramma = biocontrol. 2024 ›
Chewing: cockroach, ant, grasshopper · Sucking: butterfly · Piercing-sucking: mosquito · Sponging: housefly. 1984 ›
Housefly = vector (carries germs), not a parasite. 1984 ›

5 timesFungi, lichens and mosses

Plants, trees and fungi · 2024, 2022, 2021, 1990, 1984

Mushrooms: medicinal, psychoactive, insecticidal and bioluminescent species all exist. 2024 ›
Gucchi = morel mushroom, wild in Himalayan forests, not commercially cultivated. 2022 ›
Primary succession on rock: lichens → mosses → grasses → shrubs → trees. 2021 ›
Mycorrhiza = fungus + root (phosphorus uptake). Rhizobium = bacteria + legume root (nitrogen). 1990 ›
Lichen = fungus + alga; pioneer on rocks; indicator of clean air (sensitive to SO₂). 1984 ›

5 timesTrees

Plants, trees and fungi · 2024, 2016, 2011, 1999

From the Americas via the Portuguese: cashew, papaya, chilli, potato, tomato, pineapple, guava. 2024 ›
Fig ↔ fig wasp = obligate co-evolved mutualism. Figs are keystone species (fruit all year). 2024 ›
Musa indandamanensis = new wild banana from the Andaman Islands. 2016 ›
Taxol (paclitaxel) from yew bark → cancer (breast, ovarian). Himalayan yew is threatened. 2011 ›
Neem: azadirachtin (biopesticide), neem cake (manure), neem-coated urea (slows nitrogen loss). 1999 ›

5 timesUseful plants

Plants, trees and fungi · 2021, 2019, 2012, 1994, 1989

Lemongrass / citronella oil = natural mosquito repellent. Parthenium = invasive weed. 2021 ›
Himalayan nettle (Girardinia diversifolia, “allo”) = textile fibre. 2019 ›
Seabuckthorn: Ladakh / Spiti, erosion control, vitamin-rich berries (“Leh berry”). 2012 ›
Biofertilisers: Rhizobium, Azotobacter, Azospirillum, BGA, Azolla, mycorrhiza. 1994 ›
Neem = natural insect repellent and biopesticide. 1989 ›

5 timesTiger reserves

Tiger reserves and big-cat sites · 2026, 2020, 2012, 1991, 1989

Madhav = Shivpuri (MP) · 58th Tiger Reserve (March 2025) · Sakhya Sagar Ramsar lake inside. 2026 ›
Largest tiger reserve = Nagarjunsagar-Srisailam (Nallamala). Oldest = Corbett. Core = CTH, notified under the Wildlife Act. 2020 ›
First 9 tiger reserves (1973) include Bandipur, Manas, Sundarbans, Corbett, Kanha, Simlipal, Palamau, Melghat, Ranthambore. 2012 ›
Project Tiger 1973 → NTCA 2006; tigers ~3,682 (2022). 1991 ›
Bandipur (Karnataka): part of the Nilgiri Biosphere Reserve; one of the first tiger reserves. 1989 ›

5 timesBiosphere reserves

2019, 2014, 2008, 2005, 2001

Agasthyamala BR: Neyyar, Peppara, Shendurney + KMTR; UNESCO list 2016. 2019 ›
Biosphere reserve = core + buffer + transition (UNESCO Man and Biosphere, 1971). 2014 ›
In 2008: Nilgiri, Gulf of Mannar, Sundarbans, Nanda Devi. Today 13 of India’s 18 biosphere reserves are in the UNESCO network. 2008 ›
First BR: Nilgiri (1986). Pachmarhi, Agasthyamala = BRs. Nallamala = NSTR. 2005 ›
ENVIS (1982, MoEFCC) → EIACP (2022) · GAP (1985) → NRCP (1995–96); Namami Gange (2014) is Ganga-specific. 2001 ›

5 timesWild Life (Protection) Act

Wildlife and forest laws of India · 2023, 2022, 2020, 2017

Conservation / community reserves (2002 amendment, WPA Sec 36A–36D). First conservation reserve: Tiruppadaimarathur (Tamil Nadu, 2005). First community reserve: Keshopur Chhamb (Punjab, 2007). 2023 ›
WPA: Sec 39 = government property · Sec 11 = CWW may permit hunting of dangerous animals. 2022 ›
WPA 1972 (pre-2022): Schedule VI = specified plants (licence to cultivate). After the 2022 amendment: Schedule III. 2020 ›
Schedule I = highest protection (tiger, elephant, star tortoise…). 2017 ›
Hunting of any scheduled wild animal is banned (Sec 9) except under Sec 11/12. 2017 ›

5 timesMissions and policies

Indian bodies, missions and reports · 2020, 2018, 2016, 2012, 2008

National Policy on Biofuels 2018: sugarcane juice, sugar beet, sweet sorghum, cassava, damaged grains, rotten potatoes, surplus grains. 2020 ›
SECI = auctions / PPAs. Tariffs = bidding + CERC/SERC. PLI scheme now pushes domestic wafers. 2018 ›
Green India Mission (NAPCC): increase forest/tree cover on 5 million ha + improve quality on another 5 million ha. 2016 ›
NWM (NAPCC): +20% water-use efficiency; recycling, desalination, groundwater regulation. 2012 ›
National Biodiesel Mission (2003, Planning Commission) — nodal: Rural Development; jatropha. 2008 ›

5 timesBodies

Indian bodies, missions and reports · 2017, 2016, 2015, 2014

M-STrIPES = NTCA software for patrolling and monitoring tiger reserves. 2017 ›
BEE (Energy Conservation Act 2001) star labels: ACs, fridges, TFLs, fans, geysers, TVs… 2016 ›
IREDA (1987, MNRE) = public limited govt company + NBFC; financing renewables. 2015 ›
BNHS (1883, Mumbai) = NGO; Salim Ali; BirdLife partner in India. 2014 ›
AWBI → PCA Act 1960 · NTCA → WPA amendment 2006 · NGRBA (2009, EPA) → now National Ganga Council. 2014 ›

5 timesClimate: UNFCCC to Paris

Global conventions and treaties · 2025, 2016, 2010

Article 6: 6.2 bilateral trading (ITMOs) · 6.4 UN crediting mechanism · 6.8 non-market. Rulebook completed at COP29, Baku. 2025 ›
COP28 (Dubai): first Health Day; Declaration on Climate and Health — voluntary; India did not sign. 2025 ›
INDC → NDC (after ratifying Paris). India’s updated NDC (2022): 45% less emissions intensity by 2030 (vs 2005), 50% non-fossil power capacity. 2016 ›
Paris 2015: well below 2 °C, aim 1.5 °C; in force 4 Nov 2016; $100 bn/yr (NCQG 2024: $300 bn by 2035). 2016 ›
Rio 1992 → UNFCCC (in force 1994; COP1 Berlin 1995). 2010 ›

5 timesEconomics and finance initiatives

International organisations and initiatives · 2025, 2022, 2021, 2018, 2016

ADB (Manila, 1966) → Nature Solutions Finance Hub for Asia and the Pacific (COP28, 2023). 2025 ›
Greenwashing = a false eco-friendly image. India: CCPA greenwashing guidelines, 2024. 2022 ›
WaterCredit = Water.org (co-founded by Matt Damon), microfinance for water and sanitation. 2021 ›
Rio+20 (2012): “The Future We Want”, green economy → PAGE (UNEP, ILO, UNDP, UNIDO, UNITAR). 2018 ›
TEEB (2007, Potsdam G8+5) = UNEP-hosted; value of nature for policy. 2016 ›

5 timesClimate funds

Carbon markets and climate finance · 2016, 2015, 2014

REDD+ = Reducing Emissions from Deforestation and forest Degradation (+ conservation, sustainable management, stock enhancement). 2016 ›
GCF: COP16 Cancún 2010, HQ Songdo (South Korea); financial mechanism of UNFCCC. 2015 ›
FCPF (World Bank, 2008) = REDD+ readiness + carbon fund. 2015 ›
World Bank carbon funds: FCPF, BioCarbon Fund (ISFL), Prototype Carbon Fund. 2015 ›
GEF (1991, Rio): funds for CBD, UNFCCC, UNCCD, POPs, mercury; World Bank = trustee. 2014 ›

5 timesOzone layer

1993, 1992, 1987, 1986, 1982

UV-C 100–280 nm, UV-B 280–315, UV-A 315–400. Ozone blocks UV-C and most UV-B. 1993 ›
Ozone killers: CFCs, halons, CCl₄, methyl bromide, N₂O. Montreal Protocol. 1992 ›
Ozone layer: 15–35 km, absorbs UV-B and UV-C. 1987 ›
Ozone is measured in Dobson Units (~300 DU normal; hole = below 220 DU). 1986 ›
Ozone layer → blocks UV → protects DNA of plants and animals. 1982 ›

5 timesWater pollution

2017, 2013, 2011, 1998, 1994

High BOD = high organic pollution = low DO. Bathing water: BOD ≤ 3, DO ≥ 5 mg/L. 2017 ›
Groundwater: arsenic (Bengal delta), fluoride (Rajasthan), uranium (Punjab), nitrate (farms). 2013 ›
Algal blooms: nutrients (N, P) from rivers, run-off, upwelling; e.g. Noctiluca in the Arabian Sea. 2011 ›
Clean river: DO high, BOD low. Polluted: DO low, BOD high. 1998 ›
Organic pollution → high BOD → low DO → fish kills. 1994 ›

5 timesMetals and industry

Industrial and toxic pollutants · 2023, 2021, 2020, 2014

Mercury: artisanal gold mining (#1), coal burning; Minamata Convention (2013; India ratified 2018). 2023 ›
Copper smelting: SO₂, heavy-metal slag, CO. Sterlite (Thoothukudi) closed 2018. 2021 ›
Steel slag: road aggregate (Surat, 2022), cement, soil conditioner. 2020 ›
Indian coal: high ash, low sulphur. Fly ash → bricks, cement. 2020 ›
Steel ≈ 7–9% of global CO₂. Green steel = low-emission steel, including hydrogen DRI and scrap-based routes. 2014 ›

5 timesGreenhouse effect and gases

Greenhouse effect, warming and ozone · 2019, 2018, 2012, 2010

Methane hydrate = methane in an ice cage · permafrost + seafloor (KG basin) · warming releases it · CH₄ → CO₂ in ~12 years. 2019 ›
CO₂ fertilisation → more growth in C₃ plants (wheat, rice), less in C₄ (maize). 2018 ›
Sunlight in (shortwave) → Earth emits infrared → CO₂, CH₄, H₂O trap it. 2012 ›
Rice: CH₄ (flooding) + N₂O (fertiliser). Fix: alternate wetting and drying, DSR. 2010 ›
Kyoto gases: CO₂, CH₄, N₂O, HFCs, PFCs, SF₆ (+ NF₃). Black carbon = short-lived warmer. 2010 ›

5 timesEmissions and materials

Emissions, materials and the green economy · 2025, 2024, 2022, 2021, 2020

Cement ≈ 7–8% of global CO₂; CaCO₃ → CaO + CO₂ (calcination) ≈ 60% of it. 2025 ›
PFAS: non-stick pans, waterproof clothing, foams; C–F bond; “forever chemicals”. 2024 ›
PET: polyester fibre, recyclable (#1), burning → CO₂. 2022 ›
R2 = Responsible Recycling standard for e-waste recyclers (SERI). 2021 ›
PMGSY green tech: cold mix, waste plastic, fly ash, slag, geotextiles. 2020 ›

4 timesAtmosphere and climate basics

2025, 2019, 2014, 2002

Natural greenhouse effect: −18 °C → +15 °C (≈ +33 °C). 2025 ›
Cirrus thinning + stratospheric sulphate injection = geoengineering to reduce global warming. 2019 ›
Monsoon (Arabic mausim = season) = seasonal reversal of winds. 2014 ›
Albedo: fresh snow ~0.8–0.9 · tundra high · forests low · dense tropical evergreen lowest (~0.12). 2002 ›

4 timesBats

Primates, bats and small mammals · 2024, 2009, 1992, 1989

Indian flying fox: fruit bat, pollinator; was Schedule V (vermin). Vampire bats are only in the Americas. 2024 ›
Flying fox = fruit bat. Sea horse = fish, starfish = not a fish. 2009 ›
Echolocation: bats, dolphins — ultrasonic sound + echo. 1992 ›
Bats: the only flying mammals; wings = modified forelimbs; echolocation. 1989 ›

4 timesMarsupials and egg-laying mammals

Primates, bats and small mammals · 2023, 2008, 2001, 1979

Marsupials: Australia–New Guinea + American opossums. Absent from mainland Asia because of plate history. 2023 ›
Monotremes (lay eggs): platypus, echidna. Marsupials (pouch): kangaroo, koala. 2008 ›
Marsupials = Australia. Lemurs = Madagascar. Kiwi = New Zealand. 2001 ›
Australia: platypus, echidna (egg-laying), koala, kangaroo (marsupials), emu. 1979 ›

4 timesTurtles, corals and reefs

Life in seas and rivers · 2007, 2002, 1999, 1988

Largest reef = Great Barrier Reef (Australia). Richest coral area = Coral Triangle. 2007 ›
Olive Ridley arribada: Gahirmatha (Bhitarkanika), Rushikulya — Odisha. Vulnerable; Schedule I. 2002 ›
First marine NP: Gulf of Kutch (Jamnagar, Gujarat). Also: Gulf of Mannar, Mahatma Gandhi Marine NP (Andaman). 1999 ›
Coral = colony of polyps (cnidarians) + calcium carbonate skeleton; zooxanthellae give colour and food. 1988 ›

4 timesFish, molluscs and aquaculture

Life in seas and rivers · 2023, 2003, 1994, 1982

RAS biofilter = nitrifying bacteria: ammonia → nitrite → nitrate. 2023 ›
Cephalopods (octopus, squid, cuttlefish) = molluscs. 2003 ›
Cold-water fish: trout, mahseer, tinca. Warm-water: catla, rohu, mrigal. 1994 ›
Pearl = nacre (calcium carbonate) around an irritant in pearl oysters (and some mussels). 1982 ›

4 timesSnakes

Reptiles, amphibians and poisons · 2011, 2008, 1995, 1991

King cobra: oviparous, builds a nest, guards eggs; eats snakes (Ophiophagus). 2011 ›
King cobra (Ophiophagus hannah) = snake-eater, world’s longest venomous snake. 2008 ›
King cobra = only nest-building snake. 1995 ›
India’s Big Four: spectacled cobra, common krait, Russell’s viper, saw-scaled viper. 1991 ›

4 timesSocial insects and behaviour

Insects, spiders and worms · 2024, 2022, 2008, 1982

Waggle dance = honeybee. Angle to vertical = angle to the sun; duration = distance. Von Frisch, Nobel 1973. 2024 ›
Fungus farmers: leaf-cutter ants, some termites (Macrotermes), ambrosia beetles. 2022 ›
Sexual cannibalism: spiders (black widow), praying mantis. 2008 ›
Social insects: honeybees, ants, termites, wasps — colony, queen, division of labour. 1982 ›

4 timesInsectivorous and desert plants

Plants, trees and fungi · 2011, 2008, 2007, 1995

Insectivorous plants (pitcher plant, Drosera, Utricularia) = nitrogen-poor soils. 2011 ›
Insectivorous plants: pitcher plant (Nepenthes khasiana, Meghalaya), sundew (Drosera), bladderwort (Utricularia). 2008 ›
Pitcher = modified leaf (lamina). Cactus spine = leaf. Potato = stem. 2007 ›
Desert flowers bloom at night → moths and bats pollinate. 1995 ›

4 timesRelationships between species

How living things relate and evolve · 2021, 2013, 2000, 1981

Symbiosis: coral–zooxanthellae, fungus–alga (lichen), termite–protozoa, legume–Rhizobium. 2021 ›
Decomposers = fungi + bacteria. Viruses need living hosts. 2013 ›
Keystone = holds the community together. Flagship = public face (tiger). Umbrella = protecting it protects many. 2000 ›
A new predator at two levels cuts both prey levels. 1981 ›

4 timesMixed facts and matching

How living things relate and evolve · 2002, 1993, 1986, 1984

Echinoderms: external fertilisation, larvae. Sharks: internal fertilisation, no swim bladder. 2002 ›
Silverfish: wingless insect · kiwi: flightless (NZ) · snake: limbless reptile. 1993 ›
Alligator: broad U-shaped snout (USA, China). Crocodile: usually V-shaped snout (mugger: broad, rounded). India: mugger, saltwater croc, gharial. 1986 ›
Ringworm = fungal infection. Sea horse = fish. Starfish, cuttlefish = not fish. 1984 ›

4 timesBustard, gharial and others

Which park protects which species · 2020, 2017, 2015, 2010

Desert NP: Jaisalmer + Barmer; GIB stronghold; wood fossils (Akal). 2020 ›
Gharial = Chambal (Critically Endangered); also Girwa (Katarniaghat), Son. Saltwater croc = Bhitarkanika. 2017 ›
Keibul Lamjao: phumdis on Loktak Lake, sangai (brow-antlered deer). 2015 ›
Eravikulam = Nilgiri tahr (+ Neelakurinji). Hoolock gibbon = Hollongapar (Assam). 2010 ›

4 timesTypes of protected areas and their rules

2014, 2012, 2011, 2010

Park or sanctuary = Wildlife Act 1972. The buffer around it (ESZ) = Environment Protection Act 1986. ESZ regulates, it does not freeze. 2014 ›
National parks strictly limit use; Ramsar sites and biosphere reserves may include them, so there is no universal strictness ladder. 2012 ›
In-situ: NP, sanctuary, BR, sacred groves. Ex-situ: zoos, botanical gardens, seed and gene banks. 2011 ›
NP: no human use, boundaries fixed by law · Sanctuary: limited use · BR: whole ecosystem + people. 2010 ›

4 timesEnvironment (Protection) Act and its bodies

Environment Act, waste, water and biodiversity rules · 2022, 2020, 2019, 2015

CGWA (1997) = under EPA 1986, Sec 3(3); issues NOCs for groundwater use. 2022 ›
India: largest groundwater user; ~60% of irrigation from groundwater. 2020 ›
EPA 1986 (after Bhopal): umbrella law; Sec 3 standards; EIA notification (1994, 2006) under it. 2019 ›
GEAC (MoEFCC) — under the EPA 1986 “Rules 1989”; approves GM crops (Bt cotton 2002). 2015 ›

4 timesBiodiversity and biosafety

Global conventions and treaties · 2014, 2012, 2009, 2005

Biodiversity-related conventions: CBD, CITES, CMS, Ramsar, WHC, ITPGRFA, IWC. 2014 ›
MEA 2005: provisioning (food) · regulating (climate) · supporting (soil, nutrient cycling) · cultural (recreation). 2012 ›
Cartagena Protocol (2000, in force 2003) = biosafety of living modified organisms; India’s nodal = MoEFCC. 2009 ›
Biosafety Protocol = GMOs/LMOs; MOP1 Kuala Lumpur 2004; USA not a party; India a party. 2005 ›

4 timesLaws abroad and campaigns

International organisations and initiatives · 2026, 2025, 2024, 2014

FAO four betters: production, nutrition, environment, life. UNOC3: Nice, France, June 2025. 2026 ›
EU Nature Restoration Law (2024): restore 20% of land & sea by 2030, all degraded ecosystems by 2050. 2025 ›
EU: climate-neutral 2050 (European Climate Law); NZIA: 40% of net-zero tech made in the EU by 2030. 2024 ›
Earth Hour = WWF, a Saturday in late March (usually the last one), 8:30–9:30 pm. 2014 ›

4 timesClean-up and waste treatment

Plastics, waste and clean-up · 2025, 2019, 2017

Activated carbon = adsorption on a huge surface area; made cheaply from carbon-rich waste. 2025 ›
Circular economy: reduce, reuse, recycle → less extraction + less waste → lower GHG. 2025 ›
Waste-to-energy: incineration, pyrolysis, gasification, plasma arc, biomethanation. 2019 ›
Bioremediation works on organics (oil, pesticides); metals are only immobilised or taken up. 2017 ›

4 timesGoals, days and finance

Emissions, materials and the green economy · 2026, 2021, 2016, 2001

Green (env) · Social · Sustainability (both) · Sustainability-linked (tied to KPIs). India issued sovereign green bonds in 2023. 2026 ›
Tree Cities of the World = FAO + Arbor Day Foundation; Hyderabad 2020, 2021 (and Mumbai 2021). 2021 ›
SDGs: 17 goals, 169 targets, UNGA 2015, Agenda 2030. MDGs: 2000–2015. 2016 ›
Environment Day 5 June · Forests 21 March · Ozone 16 Sept · Wetlands 2 Feb · Biodiversity 22 May. 2001 ›

3 timesBiomagnification and DDT

Poisons in the food chain · 2010, 1997, 1987

Fat-soluble + slow to degrade + slowly excreted = biomagnification. Top predator = highest concentration. 2010 ›
Biomagnification: highest in the top predator (the snake here; fish-eating birds in real life — thin eggshells). 1997 ›
DDT = persistent organic pollutant (Stockholm Convention). Rachel Carson, Silent Spring (1962). India still allows it for malaria control. 1987 ›

3 timesPesticides and herbicides

Poisons in the food chain · 1995, 1985, 1984

Agent Orange = defoliant used in the Vietnam War; its dioxin (TCDD) is the lasting toxin. 1995 ›
Herbicide → weeds · insecticide → insects · fungicide → fungi · rodenticide → rats. 1985 ›
DDT = organochlorine insecticide, a persistent organic pollutant. 1984 ›

3 timesHotspots

Biodiversity: patterns, hotspots and threats · 2011, 2010

Hotspot = ≥1,500 endemic plants + ≥70% habitat lost (Myers 1988; 36 hotspots today). 2011 ›
India’s 4 hotspots: Himalaya · Indo-Burma (NE) · Western Ghats–Sri Lanka · Sundaland (Nicobar). 2010 ›
Australia: South-West Australia + Forests of East Australia are hotspots — not the north-west. 2010 ›

3 timesSavannah and steppe

World climates and biomes · 2021, 2013, 2012

Savannah is kept open by: seasonal rain + fire + grazing. 2021 ›
Temperate grasslands: steppe (Eurasia), prairie (N America), pampas (S America), veld (S Africa), downs (Australia). 2013 ›
Savannah (Aw) = distinct wet summer + dry winter. 2012 ›

3 timesOther climate types

World climates and biomes · 2024, 2010, 2002

Marine West Coast (Cfb) = westerlies + ocean → mild, rain all year (NW Europe). 2024 ›
Mediterranean = dry summer, wet winter (westerlies). “World’s orchards”: olive, citrus, grapes, cork oak. 2010 ›
Mediterranean = winter rain · equator = no seasons · altitude = latitude in miniature. 2002 ›

3 timesReading climate data

World climates and biomes · 2010, 2001, 1999

Warm all year + no dry month + low altitude = tropical rainforest. 2010 ›
Mediterranean: ~40–75 cm rain, mostly in winter; mild average temperature. 2001 ›
West European: mild range, rain all year · Mediterranean: dry hot summer, wet winter. 1999 ›

3 timesSquirrels, pangolins and other small mammals

Primates, bats and small mammals · 2024, 2021, 1989

Indian squirrels: tree nests (dreys), cache seeds in soil, omnivorous. 2024 ›
Roll up: pangolin (scales), hedgehog (spines), three-banded armadillo. Pangolin = most trafficked mammal. 2021 ›
Guinea pig = South American rodent (cavy), used in research. 1989 ›

3 timesWorms and soil life

Insects, spiders and worms · 2021, 2001, 1988

Detritivores: earthworms, millipedes, woodlice, dung beetles, sea cucumbers. 2021 ›
Guinea-worm = nematode (India declared free in 2000). Annelids = earthworm, leech. 2001 ›
Earthworms: aerate soil, make humus and casts rich in nitrogen; vermicompost. 1988 ›

3 timesExtreme life and evolution

How living things relate and evolve · 2023, 2011, 2005

Extremophiles: thermophiles (heat), psychrophiles (cold), acidophiles (acid), halophiles (salt). 2023 ›
Vertebrate order: fish → amphibians → reptiles → birds / mammals. 2011 ›
Amoeba: binary fission. Paramecium: fission + conjugation. Yeast: budding + spores. 2005 ›

3 timesWetlands and Ramsar sites

2014, 2012, 2011

Harike = Beas + Sutlej · Kolleru = between Godavari and Krishna · Keoladeo = Gambhir, Banganga. 2014 ›
Wetlands (Atlas 2011): ~4.6% of India; Gujarat largest; inland ≈ 70%, coastal ≈ 27%. 2012 ›
Ramsar (1971, Iran) = conservation + wise use. India joined 1982. 2011 ›

3 timesForest Rights Act

Wildlife and forest laws of India · 2021, 2018, 2013

FRA 2006: nodal = Ministry of Tribal Affairs; gram sabha starts the claim process. 2021 ›
FRA 2006: critical wildlife habitat; habitat rights for PVTGs — Baigas first (MP). 2018 ›
FRA: Gram Sabha → Sub-Divisional Level Committee → District Level Committee (final). 2013 ›

3 timesWetland and biodiversity rules

Environment Act, waste, water and biodiversity rules · 2023, 2019, 2012

Biological Diversity Act 2002: NBA (Chennai) → SBBs → BMCs (People’s Biodiversity Registers). 2023 ›
Wetland Rules 2010 → replaced by 2017 Rules (State Wetland Authorities). Ramsar = wise use. 2019 ›
NBA (Chennai, 2003): access + benefit sharing, IPR approval. GEAC: GM approvals. 2012 ›

3 timesWetlands, land and ozone

Global conventions and treaties · 2016, 2015, 2014

UNCCD (1994, Paris; in force 1996) — Rio convention; land degradation neutrality; India hosted COP14 (2019). 2016 ›
Vienna Convention (1985) → Montreal Protocol (1987) → Kigali Amendment (2016, HFCs). 2015 ›
Montreux Record = Ramsar sites under threat. India today: Keoladeo + Loktak. Chilika was removed in 2002. 2014 ›

3 timesSummits, declarations and alliances

Global conventions and treaties · 2021, 2016

NYDF 2014: halve forest loss by 2020, end by 2030; voluntary; India not an original signatory. 2021 ›
Rio 1992: Agenda 21, UNFCCC, CBD, UNCCD talks, Rio Declaration, Forest Principles. 2016 ›
ISA: launched COP21 (2015), HQ Gurugram; first treaty-based body headquartered in India. 2016 ›

3 timesSmog and carbon monoxide

Air pollutants, smog and gases · 2013, 2010, 2003

Photochemical (LA) smog: NO₂, O₃, PAN, sunlight. Classical (London) smog: SO₂ + smoke + fog. 2013 ›
CO + Hb → carboxyhaemoglobin (≈ 200× O₂ affinity) → hypoxia. 2010 ›
Smog inputs: NOₓ + VOCs. Products: O₃ + PAN. 2003 ›

3 timesImpacts of warming

Greenhouse effect, warming and ozone · 2025, 2018, 2014

Wet-bulb 35 °C = the theoretical upper limit for the human body; danger starts well below it. It is heat + humidity together. 2025 ›
5 past mass extinctions (last: 66 Mya, asteroid). The 6th = the Anthropocene extinction. 2018 ›
IPCC: >1.5 °C → 70–90% of reefs lost; 2 °C → >99%. Land sinks weaken with warming. 2014 ›

3 timesNatural sinks

Carbon sinks and carbon capture · 2022, 2021, 2012

Biorock = mineral accretion by a low-voltage current → coral restoration. India: Gulf of Kachchh (ZSI). 2022 ›
Blue carbon = ocean and coastal carbon: mangroves, salt marshes, seagrass. It is stored in the sediment. 2021 ›
Soil carbon: zero tillage, cover/relay crops, bunds, agroforestry, residue retention. 2012 ›

3 timesCapture and storage

Carbon sinks and carbon capture · 2025, 2023, 2017

DAC → DACCS (store) or CCU (fuels, plastics, drinks). 2025 ›
Carbon removal: enhanced weathering, ocean alkalinity, DAC, BECCS, mineralisation (CarbFix). 2023 ›
CCS storage: saline aquifers, depleted oil/gas fields (enhanced oil recovery), coal seams. 2017 ›

Asked and not asked: Environment Gap Sheets ›