UPSC CSE Prelims
Environment & Ecology Previous Year Questions (PYQs)

Detailed Explanation:

Answer: Option 3 — Statement-I is correct but Statement-II is incorrect

This question tests understanding of India's groundwater usage patterns and the primary purposes of extraction. Statement-I correctly cites the UN World Water Development Report 2022 data, while Statement-II incorrectly attributes the high extraction primarily to drinking water and sanitation needs.

✅ Statement-I – Correct: According to the UN World Water Development Report 2022, India extracts approximately 251 km³ of groundwater annually from an estimated 20 million wells and tube wells, which indeed represents more than a quarter (about 25-26%) of the world's total groundwater withdrawal.

❌ Statement-II – Incorrect: While India does need to cater to approximately 18% of the world's population, the major reason for high groundwater extraction is not drinking water and sanitation. Approximately 89% of India's groundwater extraction is used for irrigation purposes, not for drinking water and sanitation. Agriculture is the primary driver of groundwater depletion in India.

📝 Short Notes: India's Groundwater Usage

• Total Annual Extraction: Approximately 251 km³, the highest in the world (>25% of global extraction)
• Sectoral Distribution: ~89% for irrigation, ~9% for domestic use, ~2% for industrial use
• Infrastructure: Over 20 million wells and tube wells across the country
• Critical Concern: Unsustainable extraction rates leading to groundwater depletion, particularly in northwestern and southern India
• Key States Affected: Punjab, Haryana, Rajasthan, Gujarat, Tamil Nadu, and Karnataka face severe groundwater stress
• Recharge Gap: Extraction rates significantly exceed natural recharge rates in many regions, especially in agricultural belts

Detailed Explanation:

Answer: Option 3 — All three

All three activities mentioned are recognized methods for carbon capture and sequestration (CCS) that are actively discussed in climate mitigation strategies.

✅ Activity 1 – Correct: Spreading finely ground basalt rock on farmlands (enhanced weathering) captures atmospheric CO₂ through chemical weathering reactions that form stable carbonates, effectively sequestering carbon in the soil.

✅ Activity 2 – Correct: Increasing ocean alkalinity by adding lime enhances the ocean's natural capacity to absorb and store atmospheric CO₂ by shifting the carbonate equilibrium, making oceans a more effective carbon sink.

✅ Activity 3 – Correct: Capturing industrial CO₂ emissions and storing them as carbonated water in abandoned subterranean mines is a direct carbon capture and storage (CCS) technique that prevents greenhouse gases from entering the atmosphere.

📝 Short Notes: Carbon Capture and Sequestration Methods

• Enhanced Weathering: Accelerates natural rock weathering by spreading silicate minerals (like basalt) on land; reacts with CO₂ to form stable carbonates that lock carbon for thousands of years.
• Ocean Alkalinization: Adding alkaline substances (lime, olivine) to oceans increases pH and carbonate concentration, enhancing CO₂ absorption capacity and counteracting ocean acidification.
• Geological Sequestration: Industrial CO₂ is captured at source, compressed, and injected into deep geological formations (depleted oil/gas fields, saline aquifers, mines) where it mineralizes or remains trapped.
• Other CCS Methods: Afforestation, soil carbon sequestration, biochar application, direct air capture (DAC), and bioenergy with carbon capture and storage (BECCS).
• Global Significance: CCS technologies are essential for achieving net-zero emissions targets and limiting global warming to 1.5-2°C as outlined in the Paris Agreement.

Detailed Explanation:

Answer: Option 2 — Both Statement-I and Statement-II are correct and Statement-II is not the correct explanation for Statement-I

Carbon markets are indeed widely recognized as crucial market-based mechanisms under the Paris Agreement (Article 6) for achieving emission reduction targets cost-effectively. Carbon markets do facilitate resource transfers from private sector to the State, particularly through auction-based cap-and-trade systems where governments sell emission permits. However, the widespread adoption of carbon markets stems from their economic efficiency and flexibility in reducing emissions, not primarily from their revenue generation function for governments.

✅ Statement-I – Correct: Carbon markets (cap-and-trade systems, voluntary carbon credits) are recognized globally as key tools for climate mitigation, allowing cost-effective emission reductions through price signals.
✅ Statement-II – Correct: In many carbon market schemes, particularly cap-and-trade systems with auctioned permits, private entities pay the government for emission allowances, transferring resources to the State.
However, Statement-II does not explain Statement-I: The prominence of carbon markets arises from their economic efficiency in achieving climate goals, not from their revenue-transfer function.

📝 Short Notes: Carbon Markets

• Carbon Markets: Market-based mechanisms that put a price on carbon emissions to incentivize emission reductions through economic instruments.
• Cap-and-Trade Systems: Government sets an emission cap; permits are allocated/auctioned; entities can trade permits, creating market price for emissions.
• Carbon Offset Markets: Voluntary or compliance-based systems where emission reductions from one activity offset emissions elsewhere through tradable credits.
• Paris Agreement Article 6: Establishes frameworks for international cooperation through market and non-market mechanisms to achieve Nationally Determined Contributions (NDCs).
• Resource Transfer Mechanism: When governments auction emission permits, private emitters pay for allowances, generating public revenue while creating emission reduction incentives.
• Key Advantage: Achieves emission targets at lowest economic cost by allowing flexibility—entities that can reduce emissions cheaply do so and sell permits to those facing higher reduction costs.

Detailed Explanation:

Answer: Option 2 — Only two

Two out of three statements regarding mercury pollution are correct. Gold mining activities and coal-based thermal power plants are both significant sources of mercury pollution globally. However, the claim that there is "no known safe level" is scientifically inaccurate, as regulatory bodies like WHO have established reference doses and tolerable intake levels for mercury exposure.

✅ Statement 1 – Correct: Gold mining, especially artisanal and small-scale mining, uses liquid mercury to amalgamate with gold particles, releasing significant mercury into water bodies and forests, notably in regions like the Amazon.

✅ Statement 2 – Correct: Coal-based thermal power plants (TPPs) are the largest anthropogenic source of mercury emissions, releasing mercury through fly ash and flue gases; studies show TPPs contribute over 80% of mercury emissions in countries like India.

❌ Statement 3 – Incorrect: While mercury is highly toxic, regulatory and scientific bodies establish safe exposure thresholds; WHO's Provisional Tolerable Weekly Intake for methylmercury is 1.6 µg/kg body weight/week, and drinking water limit is 1 µg/litre, demonstrating that safe levels do exist below which health risks are minimal.

📝 Short Notes: Mercury Pollution

• Sources of Mercury Pollution: Coal-fired power plants (largest source), artisanal gold mining, chlor-alkali industry, waste incinerators, cement production, and volcanic eruptions.
• Mercury in Environment: Converts to toxic methylmercury in aquatic systems through bacterial action; bioaccumulates in fish and biomagnifies up the food chain.
• Health Effects: Damages nervous system, kidneys, and developing fetuses; causes Minamata disease (severe neurological syndrome); particularly harmful to children and pregnant women.
• Minamata Convention: Global treaty (2013) to protect human health and environment from anthropogenic mercury emissions and releases; India ratified in 2018.
• Safe Exposure Levels: WHO guidelines: 1.6 µg/kg body weight/week for methylmercury; 1 µg/litre for drinking water; concept of "dose makes the poison" applies.
• Mercury from Coal Plants: Indian coal contains 0.05-0.5 ppm mercury; released during combustion; fly ash disposal in ponds creates aquatic ecosystems contaminated with mercury.

Detailed Explanation:

Answer: Option 3 — Honeybees

The waggle dance is a unique form of communication performed by worker honeybees to inform other members of the colony about the direction and distance to food sources. This remarkable behavior was decoded by Austrian scientist Karl von Frisch, who won the Nobel Prize for this discovery. The direction of the dance relative to the vertical indicates the angle to the food source in relation to the sun, while the duration of the waggle portion indicates the distance.

📝 Short Notes: Honeybee Waggle Dance

• Discovered by: Karl von Frisch (Austrian ethologist, Nobel Prize 1973)
• Purpose: Communication among worker bees about food source location (nectar, pollen, water)
• Direction indication: Angle of the waggle run relative to vertical = angle to food source relative to the sun's position
• Distance indication: Duration and number of waggles indicate distance to the source (longer dance = farther distance)
• Round dance: Performed for food sources very close to the hive (within 50-100 meters)
• Significance: Demonstrates complex social communication in insects and symbolic language in non-human species

Detailed Explanation:

Answer: Option 3 — Both 1 and 2

Both statements correctly describe the role and powers of Biodiversity Management Committees (BMCs) in India under the Biological Diversity Act, 2002, which implements the Nagoya Protocol objectives at the local level.

✅ Statement 1 – Correct: BMCs are indeed key institutional mechanisms for realizing Nagoya Protocol objectives in India by ensuring local-level implementation of Access and Benefit Sharing (ABS) provisions and involving local communities in biodiversity governance.

✅ Statement 2 – Correct: BMCs have statutory powers to determine access to biological resources within their jurisdiction and levy collection fees on such access, as mandated under the Biological Diversity Act, 2002 and Biological Diversity Rules, 2004.

📝 Short Notes: Biodiversity Management Committees (BMCs) and Nagoya Protocol

Detailed Explanation:

Answer: Option 2 — Only two

Community Reserves are protected areas in India that act as buffer zones or migration corridors between established national parks and wildlife sanctuaries. Among the four statements given, only two are correct regarding the governance and permitted activities in Community Reserves.

❌ Statement 1 – Incorrect: The Chief Wildlife Warden does not become the governing authority. As per Section 36D of the Wildlife Protection Act, the State Government constitutes a Community Reserve Management Committee which is the responsible authority for managing the community reserve. The committee elects a Chairman who acts as the Honorary Wildlife Warden.

✅ Statement 2 – Correct: Hunting is strictly prohibited in Community Reserves once an area is notified as such under the Wildlife Protection Act.

✅ Statement 3 – Correct: People living in and around Community Reserves are permitted to collect non-timber forest produce (NTFP) as part of their traditional rights and livelihood activities.

❌ Statement 4 – Incorrect: Traditional agricultural practices, including shifting cultivation (jhum), are not allowed in Community Reserves to protect the ecological integrity of these areas.

📝 Short Notes: Community Reserves under Wildlife Protection Act

Detailed Explanation:

Answer: Option 3 — All three

Green hydrogen, produced from renewable energy sources through electrolysis, is a versatile clean fuel that can be utilized in multiple ways. All three statements regarding its applications are correct.

✅ Statement 1 – Correct: Green hydrogen can be used directly as a fuel in modified internal combustion engines, replacing conventional fossil fuels.
✅ Statement 2 – Correct: Green hydrogen can be blended with natural gas (up to 20% in existing pipelines) and used for heating, power generation, and industrial applications.
✅ Statement 3 – Correct: Green hydrogen is used in hydrogen fuel cells to generate electricity for running electric vehicles, offering zero-emission transportation.

📝 Short Notes: Green Hydrogen

• Definition: Hydrogen produced through electrolysis of water using renewable energy sources (solar, wind, hydro), resulting in zero carbon emissions.
• Production Method: Water (H₂O) is split into hydrogen (H₂) and oxygen (O₂) using electricity from renewable sources in an electrolyzer.
• Color Coding: Green (renewable energy), Grey (fossil fuels without carbon capture), Blue (fossil fuels with carbon capture), Brown/Black (coal).
• Applications: Transportation (fuel cell vehicles), industrial processes (steel, ammonia production), energy storage, power generation, and heating.
• India's Initiatives: National Green Hydrogen Mission (2023) targeting 5 MMT annual production by 2030; focus on making India a global hub for green hydrogen production and export.
• Advantages: Zero emissions at point of use, high energy density, long-term storage capability, and versatile applications across sectors.
• Challenges: High production costs, energy-intensive electrolysis process, storage and transportation infrastructure requirements, and need for renewable energy scale-up.

Detailed Explanation:

Answer: Option 2 — 2 only

This question tests factual knowledge about solar power installations in India. Only Statement 2 about Kerala's airport is correct, while the claims about Gujarat and Goa are factually incorrect.

❌ Statement 1 – Incorrect: Bhadla Solar Park in Rajasthan (not Gujarat) is the largest solar park in India with a capacity of 2,245 MW, making it one of the largest in the world.

✅ Statement 2 – Correct: Cochin International Airport in Kerala became the world's first fully solar-powered airport in 2015, generating power through its 46 MW solar plant spread across 45 acres.

❌ Statement 3 – Incorrect: The Omkareshwar Floating Solar Project in Madhya Pradesh (not Goa) is the largest floating solar photovoltaic project in India with a capacity of 600 MW.

📝 Short Notes: Major Solar Power Installations in India

Detailed Explanation:

Answer: Option 2 — 2 only

The Wildlife (Protection) Act, 1972 provides species-specific protection based on scheduling, which applies uniformly regardless of location. Only Statement 2 is legally accurate, while Statements 1 and 3 contain critical inaccuracies regarding ownership and conditions for capture/killing.

❌ Statement 1 – Incorrect: Section 39 of the Wildlife (Protection) Act specifies that only animals in Schedules I to IV are government property; vermin species (Schedule V) are excluded, making the claim of 'sole property' legally incorrect.

✅ Statement 2 – Correct: Protected status under the Wildlife (Protection) Act is determined by the animal's listing in the Schedules and applies uniformly whether the animal is found inside Protected Areas or outside in human-dominated landscapes.

❌ Statement 3 – Incorrect: Section 11 requires the Chief Wildlife Warden to be satisfied that the animal 'has become dangerous' to human life (actual danger), not merely apprehended danger; mere fear or anticipation is insufficient legal ground for capture or killing.

📝 Short Notes: Wildlife (Protection) Act, 1972 - Key Provisions

• Section 11: Chief Wildlife Warden may permit capture/killing only when animal has become dangerous to human life or is disabled/diseased beyond recovery
• Section 39: Wild animals listed in Schedules I-IV are property of State/Central Government
• Protection applies uniformly: Inside and outside Protected Areas for all scheduled species
• Protected Areas: Include National Parks, Wildlife Sanctuaries, Conservation Reserves, and Community Reserves
• Recent Amendment (2022): Introduced Schedule VI for prohibited plants and enhanced penalties

Detailed Explanation:

Answer: Option 2 — Only two pairs

This question tests the geographical location of important Ramsar wetlands in India. Out of the four pairs given, only two pairs are correctly matched: Renuka Wetland with Himachal Pradesh and Rudrasagar Lake with Tripura.

✅ Pair 1 – Incorrect: Hokera Wetland is located in Jammu & Kashmir (near Srinagar), not Punjab. It is a natural perennial wetland contiguous to the Jhelum basin.

✅ Pair 2 – Correct: Renuka Wetland is indeed located in Himachal Pradesh (Sirmaur district). It is a natural wetland with freshwater springs and inland subterranean karst formations.

✅ Pair 3 – Correct: Rudrasagar Lake is correctly matched with Tripura. It is a lowland sedimentation reservoir in the northeast hills, fed by three perennial streams discharging into the River Gomti.

✅ Pair 4 – Incorrect: Sasthamkotta Lake is located in Kerala (Kollam district), not Tamil Nadu. It is the largest freshwater lake in Kerala.

📝 Short Notes: Important Ramsar Wetlands of India

Detailed Explanation:

Answer: Option 1 — Database created by coalition of research organisations

The Climate Action Tracker (CAT) is an independent scientific analysis created and maintained by a coalition of research organisations, specifically Climate Analytics and NewClimate Institute. It is not a UN body, IPCC wing, or UNFCCC committee, but rather an independent initiative that tracks government climate action and measures it against the Paris Agreement goals of limiting global warming to well below 2°C and pursuing efforts to limit it to 1.5°C. The CAT has been providing independent analysis to policymakers since 2009, quantifying and evaluating climate change mitigation targets, policies, and actions across countries.

📝 Short Notes: Climate Action Tracker

• Nature: Independent scientific analysis platform tracking government climate commitments and actions
• Established: 2009, providing analysis for over a decade
• Managed by: Coalition of two research organisations - Climate Analytics and NewClimate Institute
• Primary Function: Tracks national emission reduction pledges and measures them against Paris Agreement targets (well below 2°C, pursuing 1.5°C)
• Methodology: Uses MAGICC climate model to quantify likely temperature increases based on country actions
• Scope: Evaluates mitigation targets, policies, and actions; aggregates country-level data to global projections; develops sectoral analysis for climate pathways
• Independence: Not affiliated with UN, IPCC, UNFCCC, UNEP, or World Bank - operates as autonomous research initiative

Detailed Explanation:

Answer: Option 4 — 1, 2 and 3

System of Rice Intensification (SRI) is a climate-smart agricultural practice that optimizes resource use through alternate wetting and drying (AWD) of rice fields. This method significantly reduces seed, water, and energy requirements while minimizing methane emissions from paddy fields.

✅ Statement 1 – Correct: SRI requires only 5-8 kg/ha of seeds compared to 60-80 kg/ha in traditional methods, as single younger seedlings are planted with wider spacing.

✅ Statement 2 – Correct: Alternate Wetting and Drying (AWD) prevents continuous flooding, reducing anaerobic conditions that produce methane through methanogenic bacteria, cutting emissions by 30-40%.

✅ Statement 3 – Correct: SRI reduces water requirement by 30-50% through controlled irrigation, directly lowering electricity/fuel consumption for pumping groundwater.

📝 Short Notes: System of Rice Intensification (SRI)

• Origin: Developed in Madagascar in the 1980s by Fr. Henri de Laulanié; promoted globally for sustainable rice cultivation.
• Key Principles: Early, quick, and healthy plant establishment; reduced plant density; improved soil conditions with organic matter; reduced and controlled water application.
• Planting Method: Single seedlings (8-12 days old) transplanted with wide spacing (25×25 cm), unlike traditional clumps of 3-4 seedlings.
• Water Management: Alternate Wetting and Drying (AWD) instead of continuous flooding; fields kept moist but not submerged, saving 25-50% water.
• Environmental Benefits: 30-40% reduction in methane emissions; lower water pollution; reduced energy consumption; enhanced soil health and biodiversity.
• Yield & Economics: 20-50% higher yields with 80-90% less seed requirement; reduces input costs while improving grain quality and farmer income.
• Challenges: Labor-intensive initially; requires knowledge and training; not suitable for all soil types; needs good water control infrastructure.

Detailed Explanation:

Answer: Option 1 — Conveying a false impression that a company's products are eco-friendly and environmentally sound

Greenwashing is a deceptive marketing practice where companies mislead consumers by falsely portraying their products, services, or organizational practices as environmentally friendly when they are not. This involves using misleading labels, imagery, vague claims, or selective disclosure of environmental benefits while hiding negative impacts. The term has become increasingly relevant as consumer demand for sustainable products grows, prompting some companies to exaggerate or fabricate their environmental credentials rather than making genuine improvements.

📝 Short Notes: Greenwashing

• Definition: Misleading marketing that creates a false impression of environmental responsibility or sustainability
• Common Tactics: Vague claims ("eco-friendly", "natural"), misleading labels, irrelevant claims, hidden trade-offs, false certifications, and use of green imagery
• Examples: Companies claiming "carbon neutral" without credible offsets, "biodegradable" plastics that require specific conditions, or highlighting one green feature while ignoring overall environmental harm
• Impact: Undermines genuine sustainability efforts, erodes consumer trust, and diverts attention from companies making real environmental progress
• Regulations: Many countries are developing stricter advertising standards and disclosure requirements to combat greenwashing
• Consumer Protection: Look for third-party certifications (Energy Star, Fair Trade, FSC), detailed data, and transparent reporting to identify genuine environmental claims

Detailed Explanation:

Answer: Option 2 — 1 and 4 only

The WHO Air Quality Guidelines (2021) set stringent limits for particulate matter and other pollutants to protect public health. Statement 1 correctly states WHO's recommended limits for PM2.5, and Statement 4 correctly identifies ozone's role in triggering asthma. However, statements 2 and 3 contain factual errors regarding ozone formation conditions and the penetration capabilities of different particulate matter sizes.

✅ Statement 1 – Correct: WHO guidelines (2021) recommend 24-hour mean of PM2.5 should not exceed 15 µg/m³ and annual mean should not exceed 5 µg/m³.
❌ Statement 2 – Incorrect: Ozone pollution peaks during sunny, hot, and stagnant weather conditions, not during inclement weather; sunlight drives the photochemical reactions that produce ground-level ozone.
❌ Statement 3 – Incorrect: PM2.5 (not PM10) can penetrate the lung barrier and enter the bloodstream; PM10 particles are too large and typically deposit in the upper airways and bronchi.
✅ Statement 4 – Correct: Excessive ozone in the air irritates the respiratory system, triggers asthma attacks, and exacerbates other respiratory conditions.

📝 Short Notes: Air Pollutants and Health Effects

• WHO Air Quality Guidelines (2021): PM2.5 annual mean: 5 µg/m³; 24-hour mean: 15 µg/m³
• WHO Air Quality Guidelines (2021): PM10 annual mean: 15 µg/m³; 24-hour mean: 45 µg/m³
• Ozone peaks: During summer months with high temperature, strong sunlight, and stagnant air masses
• Ultrafine particles (PM0.1): Even smaller than PM2.5, can directly enter blood and organs
• India's National Ambient Air Quality Standards (NAAQS): Less stringent than WHO guidelines; PM2.5 annual: 40 µg/m³, 24-hour: 60 µg/m³