Overview

Environment, Ecology and Biodiversity is a high-scoring section in both UPSC Prelims and GS3 Mains. This section covers the entire syllabus across 32 detailed chapters — from ecology fundamentals and biodiversity to climate change, renewable energy, environmental laws, and environmental ethics. Every year, 8--12 Prelims questions and at least one Mains question are drawn from these topics.

Chapters

#ChapterKey Topics
1Ecology FundamentalsEcosystems, food chains, food webs, ecological pyramids, 10% law, ecological succession, biogeochemical cycles, biomes, productivity
2Biodiversity and ConservationBiodiversity hotspots, IUCN Red List, National Parks, Tiger Reserves, Biosphere Reserves, Ramsar Sites, environmental legislation, international conventions (CBD, CITES, CMS, Ramsar)
3Wildlife ConservationProtected areas network, Wildlife Protection Act 1972, Project Tiger, Project Elephant, Biosphere Reserves, Ramsar wetlands, IUCN categories, human-wildlife conflict
4Biodiversity Hotspots & Species RecoveryNorman Myers' criteria, India's 4 hotspots (Western Ghats, Eastern Himalayas, Indo-Burma, Sundaland), Project Tiger (58 reserves, 3,682 tigers), Project Elephant, Snow Leopard, GIB breeding centre, vulture recovery
5Biosphere Reserves in IndiaUNESCO MAB programme, India's 18 biosphere reserves, 12 World Network sites, core/buffer/transition zones, key biodiversity values
6National Biodiversity Authority & ABSBiological Diversity Act 2002, NBA, State Biodiversity Boards, Biodiversity Management Committees, Access and Benefit Sharing, Nagoya Protocol, People's Biodiversity Registers
7Ecosystem Services & Natural CapitalMEA 2005, four service types, TEEB framework, PES mechanisms, REDD+, CAMPA, Kunming-Montreal GBF resource mobilisation
8Forest & Wetland ConservationForest types (Champion & Seth), ISFR 2023, FCA 2023, FRA 2006, mangroves, coral reefs, 99 Ramsar sites, CAMPA, Green India Mission
9Forest Governance, JFM & CAMPAISFR 2023, Forest Conservation Act 2023, JFM, FRA 2006, CAMPA Act 2016, Green India Mission, Van Dhan, forest carbon credits
10Wetlands, Ramsar Sites & Freshwater EcosystemsRamsar Convention 1971, India's Ramsar sites, Montreux Record, Wetland Rules 2017, Chilika, Keoladeo, Loktak, freshwater biodiversity
11Coastal & Marine Ecosystems — Blue EconomyIndia's 7,516.6 km coastline, coral bleaching (4th global event 2024), mangroves 4,992 sq km (ISFR 2023), CRZ Notification 2019, Blue Economy ($186B), Deep Ocean Mission (Matsya 6000), BBNJ Treaty 2023, microplastics, MPAs
12Marine Pollution, Ozone Depletion & Global ConventionsMarine pollution sources, ozone layer, Montreal Protocol, MARPOL, global environmental MEAs
13Cryosphere, Himalayan Glaciers & Polar Regions~9,575 Himalayan glaciers (Third Pole), Chamoli 2021 (rock-ice avalanche), Sikkim GLOF Oct 2023 (Teesta-III dam destroyed), Arctic warming 4x faster, India's polar stations: Maitri (1989), Bharati (2012), Himadri (2008 Svalbard); Arctic Council observer 2013; NMSHE
14Invasive Alien SpeciesIAS definition, introduction pathways, Lantana, Parthenium, Water hyacinth, African catfish, CBD Article 8(h), GBF Target 6, management methods
15Soil Degradation & DesertificationUNCCD, Land Degradation Neutrality, soil health, desertification mapping, soil conservation
16Groundwater Depletion in IndiaAquifer types, groundwater extraction trends, over-exploited blocks, CGWB, Atal Bhujal Yojana, Model Groundwater (Sustainable Management) Bill
17Agriculture's Environmental FootprintIndia agriculture GHG share 13.72% (BUR-4 2024), global AFOLU ~22% (IPCC AR6), CH4 from enteric fermentation & paddy (AWD technique), N2O from fertilizers (273x GWP), stubble burning (Punjab ~19.5 MT), water pollution (nitrate leaching, Punjab cancer belt), monoculture costs, ZBNF/APCNF, SRI, PKVY 2015, PM-PRANAM 2023, PM-KUSUM 2019, India's NDC
18Air & Water PollutionAir pollutants, AQI, NCAP, vehicular emissions, industrial pollution, water pollution sources, BOD/COD, effluent standards, river cleaning programmes
19River Conservation & Water GovernanceNamami Gange, river interlinking, National Water Policy, water disputes, groundwater regulation
20Light, Noise & Thermal PollutionLight pollution impacts, Bortle scale, noise decibel standards, Noise Rules 2000, thermal pollution from power plants, mitigation measures
21Waste Management & Ecosystem ServicesSolid waste, plastic waste, e-waste, biomedical waste, hazardous waste rules, ecosystem services valuation, SBM
22Circular Economy & Waste to WealthCircular economy principles, EPR, plastic waste management rules, e-waste rules, industrial symbiosis, zero-waste cities, India's circular economy roadmap
23Environmental Impact of MiningMining environmental impacts, illegal mining, coal vs. critical minerals, forest diversion for mining, EIA in mining, mine closure plans, restoration
24Climate Change and PollutionGreenhouse gases, IPCC reports, Paris Agreement, Panchamrit, NDCs, NAPCC 8 missions, AQI, NCAP, waste management rules, EIA, NGT
25Climate Change PolicyUNFCCC, Kyoto Protocol, Paris Agreement, COP outcomes, India's NDCs, Net Zero 2070, renewable energy, carbon markets, climate finance
26Carbon Markets & Climate FinanceArticle 6 Paris Agreement, voluntary & compliance carbon markets, carbon credits, CDM, REDD+, CCUS, Green Climate Fund, climate bonds
27Climate Change Adaptation, India's NDC & Loss and DamageUpdated NDC Aug 2022 (45% intensity cut, 50% non-fossil by 2030, 2.5-3 Bt carbon sink), Panchamrit 5 targets, 8 NAPCC missions, COP27 L&D fund, COP28 $700M pledged, Ahmedabad HAP 2013, LiFE Mission, IPCC AR6 India findings
28Renewable Energy & Sustainable DevelopmentSolar (136 GW), wind (55 GW), hydrogen mission, EVs, nuclear, SDGs, circular economy, green finance, carbon markets
29Biofuels & Ethanol BlendingNational Biofuel Policy 2018, E20 target by 2025, blending progress, GOBAR-Dhan, compressed biogas, aviation biofuels, food vs. fuel debate
30EIA, Environmental Clearance & Coastal Regulation — EIA 2006, CRZ 2019, NGT, Forest Clearance & Green TribunalEIA 2006 (4 stages, Category A/B), CRZ 2019 (all zones, NDZ), FCA 1980/2023 (100 km exemption), CAMPA (₹95,000 crore), NBWL wildlife clearances, NGT (5 benches, 1st developing country), Draft EIA 2020 controversy, SEA, Parivesh portal, green building ratings, MoEFCC/CPCB governance structure
31Environmental Laws and GovernanceEPA 1986, Air Act, Water Act, Forest Conservation Act, Wildlife Protection Act, Biological Diversity Act, CRZ, EIA, NGT, CAMPA, international MEAs
32Environmental Movements & EthicsChipko, Appiko, Silent Valley, Narmada Bachao, Bishnoi, deep ecology, environmental justice, intergenerational equity