Environment: previous-year questions
273 real UPSC Prelims questions (2011–2026) with the official answer and a clear explanation. 80 of them came in the last five papers.
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Which of the following statements with regard to the arrival of Amur Falcons at Doyang Lake in Nagaland each year from Mongolia is/are correct ?
- 1. It showcases how sustained local conservation efforts can contribute to the arrival and protection of international migratory birds.
- 2. It reflects the global success of advanced tracking technologies that guide migratory birds back to their stopover sites.
- 3. It confirms that Amur Falcons have adapted to permanent residency in India due to favourable habitat changes.
Select the answer using the code given below :
Answer (a) & explanation
Only statement 1 is correct (a). Statement 1 is right: around 2012, villages near Doyang in Nagaland, once known for mass hunting of the birds, turned into protectors, so the falcons now roost safely. Statement 2 is wrong: satellite tags only track the birds; they do not guide them. Statement 3 is wrong: Amur falcons stay only a few weeks, so they are not permanent residents. So options (b), (c) and (d) fail.
Notice their journey: they breed in Mongolia, Siberia and northern China, rest in Nagaland, then cross the Arabian Sea to winter in southern Africa, one of the longest raptor migrations. Pangti village is called the "Falcon Capital of the World". Tagged birds have been named after these villages.
Answer as per the official UPSC answer key.
With reference to Madhav National Park, which of the following statements is/are correct ?
- 1. It was declared a Tiger Reserve in India in 2025.
- 2. Sakhya Sagar, which is designated as a Ramsar Site, is situated within this National Park.
- 3. Its area is shared between Madhya Pradesh and Rajasthan.
Select the answer using the code given below :
Answer (b) & explanation
Statements 1 and 2 are correct (b). Statement 1 is right: Madhav National Park in Shivpuri district became India's 58th tiger reserve in March 2025. Statement 2 is right: Sakhya Sagar lake inside it was named a Ramsar site in 2022. Statement 3 is wrong: the park lies wholly in Madhya Pradesh, not shared with Rajasthan. So options (a), (c) and (d) fail.
Notice MP's place as the "Tiger State", with the most tigers and nine reserves, including Kanha, Bandhavgarh, Pench and Panna. The NTCA approves tiger reserves under the Wild Life (Protection) Act. Kuno, also in MP, is home to India's reintroduced cheetahs. India has about 75% of the world's wild tigers.
Shivpuri is near the Rajasthan border, which makes "shared" sound believable.
Answer as per the official UPSC answer key.
Consider the following statements about Rhynchostylis retusa (Foxtail orchid) :
- 1. It is an epiphytic orchid.
- 2. The species is endemic to North-east India.
- 3. It is the State flower of Arunachal Pradesh and Assam.
Which of the statements given above is/are correct ?
Answer (b) & explanation
Statements 1 and 3 are correct (b). Statement 1 is right: the foxtail orchid grows on tree trunks and branches, using the tree only for support, so it is epiphytic, not a parasite. Statement 3 is right: it is the State flower of Arunachal Pradesh and of Assam, where it is the kopou phool, worn in Bihu dances. Statement 2 is wrong: it is not endemic; it grows across South and South-East Asia. So options (a), (c) and (d) fail.
Notice the North-East's orchid wealth: Arunachal alone has over 600 orchid species, and Sikkim's state flower, the Noble Dendrobium, is also an orchid. The Tipi Orchid Research Centre is in Arunachal. All wild orchids trade under CITES Appendix II.
it is famous in the North-east, but "endemic" means found nowhere else.
Answer as per the official UPSC answer key.
At the United Nations Ocean Conference (UNOC) held in June, 2025 in France, the Food and Agricultural Organization (FAO) of the United Nations demonstrated its leading voice on marine and ocean issues, especially on sustainable fisheries and aquaculture for resilient livelihood and “Blue Transformation”. Which of the following combinations about the “Four Betters” proposed by FAO for “Blue Transformation” is correct ?
Answer (b) & explanation
The Four Betters are production, nutrition, environment and life (b). The "Four Betters" run through FAO's whole strategy (2022–31): better production, better nutrition, a better environment and a better life, leaving no one behind. Blue Transformation applies them to fisheries and aquaculture. Option (a) is wrong: "better ocean" is not one of them. Options (c) and (d) are wrong: coral reefs, estuaries and mangroves are not among the Four Betters.
Notice the link to SDG 14, "Life Below Water". The UN Ocean Conference in Nice, France (2025) pushed for 30% ocean protection, and the High Seas Treaty (BBNJ) came into force in 2026. India's own schemes include the PM Matsya Sampada Yojana.
"better ocean" fits an ocean conference, but the four Betters are FAO's general formula.
Answer as per the official UPSC answer key.
Which one of the following is the first Plan Vivo certified Reducing Emissions from Deforestation and Forest Degradation (REDD+) project in India ?
Answer (c) & explanation
The Khasi Hills Community REDD+ project was India's first (c). REDD+ pays communities for keeping forests standing, through carbon credits. Plan Vivo is a standard for community-led projects. India's first such project is the Khasi Hills Community REDD+ project around Mawphlang, Meghalaya, run by a federation of Khasi village councils (hima). Options (a), (b) and (d), the Uttarakhand, ICFRE-ICIMOD and Sikkim Mamley Kamrang projects, came later or use other routes.
Notice why Mawphlang is famous: its sacred grove, a forest protected by local beliefs. REDD+ stands for Reducing Emissions from Deforestation and forest Degradation, plus conservation and sustainable management. It is recognised under Article 5 of the Paris Agreement.
Answer as per the official UPSC answer key.
Which of the following statements with regard to Green Hydrogen is/are correct ?
- 1. It is decarbonized hydrogen obtained from natural gas reforming combined with carbon capture and storage (CCS).
- 2. It is produced using electrolysis of water with electricity generated by renewable energy.
- 3. National Green Hydrogen Mission of India aims for abatement of nearly 50 MMT of annual greenhouse gas emissions by 2030.
Select the answer using the code given below :
Answer (b) & explanation
Statements 2 and 3 are correct (b). Statement 2 is right: green hydrogen comes from splitting water by electrolysis, using renewable power. Statement 3 is right: the National Green Hydrogen Mission (2023) targets 5 MMT of green hydrogen a year by 2030 and about 50 MMT of avoided CO₂-equivalent emissions each year. Statement 1 is wrong: hydrogen from natural gas with carbon capture is blue hydrogen. So options (a), (c) and (d) fail.
Notice the colours: grey hydrogen from gas without capture (most hydrogen today), brown from coal, and pink from nuclear power. The mission's SIGHT programme supports electrolyser making. Uses include fertilisers, refineries, steel and shipping fuel.
1 says "decarbonized", which sounds green. Gas with CCS is blue.
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Answer as per the official UPSC answer key.
Which of the following statements in relation to NIRANTAR (National Institute for Research and Application of Natural Resources to Transform, Adapt and Build Resilience), a platform of institutions under the Ministry of Environment, Forest and Climate Change, is/are correct ?
- 1. Ecosystem Survey and Analysis is a vertical under this platform, the lead institute of which is Botanical Survey of India, Kolkata.
- 2. Research and Management of Ecosystem Service is a vertical under this platform, the lead institute of which is Central Zoo Authority, New Delhi.
- 3. Capacity Development Support is a vertical under this platform, the lead institute of which is Indian Institute of Forest Management, Bhopal.
Select the answer using the code given below :
Answer (b) & explanation
Statements 1 and 3 are correct (b). NIRANTAR groups the Environment Ministry's institutes into verticals. Statement 1 is right: Ecosystem Survey and Analysis is led by the Botanical Survey of India, Kolkata, with bodies like the FSI and ZSI. Statement 3 is right: Capacity Development Support is led by the Indian Institute of Forest Management, Bhopal. Statement 2 is wrong: Research and Management of Ecosystem Service is led by ICFRE, Dehradun; the Central Zoo Authority is only a member. So options (a), (c) and (d) fail.
Notice the purpose: pooling institutes avoids duplicate work and links research to climate adaptation and resilience. Other Ministry bodies include the Wildlife Institute of India (Dehradun) and GBPNIHE for the Himalaya.
the Central Zoo Authority does sit in that vertical, but as a member, not the lead.
Answer as per the official UPSC answer key.
Consider the following statements with reference to India’s response to climate change :
- I. India’s Long-Term Low Emission Development Strategy (LT-LEDS) is a crucial tool for achieving net-zero emissions by 2070.
- II. India’s 4th Biennial Update Report (BUR-4) submitted in December, 2024 recorded around 8% decrease in Greenhouse gas emissions in 2020 over 2019.
- III. Climate-resilient development necessarily depends on quick and short-term achievement of emission reduction targets.
Which of the following relationships among the above statements is/are correct ?
- 1. Statement I is empirically supported by statement II.
- 2. Statement III contradicts the approach implicit in statement I.
- 3. Statement I and statement III together establish the premise of long-term sustainability.
Select the answer using the code given below :
Answer (b) & explanation
Relationships 1 and 2 are correct (b). Relationship 1 is right: the LT-LEDS (2022) lays out India's path to net zero by 2070, and BUR-4 reported a fall of about 7.9% in 2020 emissions over 2019, real data in line with that path. Relationship 2 is right: Statement III wants quick, short-term cuts, while the LT-LEDS is a long, gradual plan, so III contradicts I. Relationship 3 is wrong: two contradicting statements cannot together set a premise. So options (a), (c) and (d) fail.
Notice the cause of the 2020 fall: the COVID-19 lockdowns, not a lasting trend. India's updated NDC (2022) targets cutting emissions intensity of GDP by 45% from 2005 levels by 2030. Biennial Transparency Reports now replace BURs.
"together establish" sounds positive, but two statements that clash cannot form one premise.
Answer as per the official UPSC answer key.
With respect to the Western Hoolock Gibbons, which of the following statements is/are correct ?
- 1. A Sanctuary in North-east India is home to this ape species listed as Endangered in the International Union for Conservation of Nature (IUCN) Red List.
- 2. They have specialized brachiation and can easily swing between trees.
- 3. They possess a strong and heavy build like gorillas, yet are remarkably agile tree climbers.
Select the answer using the code given below :
Answer (b) & explanation
Statements 1 and 2 are correct (b). Statement 1 is right: India's only ape, the western hoolock gibbon, is Endangered on the IUCN Red List and gives its name to the Hollongapar Gibbon Sanctuary in Assam. Statement 2 is right: gibbons move by brachiation, swinging arm over arm through the canopy. Statement 3 is wrong: they are "lesser apes", slim and light, about 6–9 kg, nothing like a heavy gorilla. So options (a), (c) and (d) fail.
Notice their habits: they live in pairs with their young and sing loud duets at dawn. They are found south of the Brahmaputra in the North-East. Rail lines cutting through Hollongapar have raised concern, and canopy bridges were proposed to help them cross.
Answer as per the official UPSC answer key.
Which of the following best explain(s) the rationale for protecting mangrove ecosystems in the context of climate resilience ?
- 1. Mangroves reduce tidal energy and store freshwater, making them ideal sites for paddy cultivation in saline estuarine belts.
- 2. Their salt-sensitive roots filter seawater, making mangroves key to converting coastal land into freshwater aquaculture zones.
- 3. By withstanding tidal surges and offering biomass resources, mangroves function both as natural bio-shields and livelihood bases for rural communities.
Select the answer using the code given below :
Answer (d) & explanation
Only statement 3 explains the rationale (d). Statement 3 is right: by withstanding tidal surges and cyclones, mangroves act as natural bio-shields, and they offer biomass, such as fish, crabs, honey and fuel, for coastal villages. Statement 1 is wrong: mangroves do not store fresh water for paddy. Statement 2 is wrong: they are salt-tolerant, not salt-sensitive. Clearing them for farms or aquaculture ponds is exactly what harms them. So options (a), (b) and (c) fail.
Notice the proof: mangroves cut deaths in the 1999 Odisha super-cyclone and the 2004 tsunami. They also store much blue carbon. India's largest mangrove forest is the Sundarbans; the MISHTI scheme (2023) aims to plant more along the coast.
statement 2 says "salt-sensitive". Mangroves live in salt water because they tolerate it.
Answer as per the official UPSC answer key.
With reference to ‘Direct Air Capture’, an emerging technology, which of the following statements is/are correct?
- I. It can be used as a way of carbon sequestration.
- II. It can be a valuable approach for plastic production and in food processing.
- III. In aviation, it can be a source of carbon for combining with hydrogen to create synthetic low-carbon fuel.
Select the correct answer using the code given below.
Answer (c) & explanation
All three statements are correct (c). Direct Air Capture (DAC) pulls CO₂ straight from the open air using chemical filters or liquids. Statement I is right: the gas can be stored underground, a way of carbon sequestration. Statement II is right: it can be used as a raw material for plastics, and in food processing and fizzy drinks. Statement III is right: joined with green hydrogen, it can make synthetic low-carbon aviation fuel. So options (a), (b) and (d) fail.
Notice the difference from carbon capture and storage (CCS) at a factory chimney, where CO₂ is far more concentrated. DAC is still very expensive and energy-hungry. The world's largest plant, Mammoth, runs in Iceland.
Answer as per the official UPSC answer key.
Regarding Peacock tarantula (Gooty tarantula), consider the following statements :
- I. It is an omnivorous crustacean.
- II. Its natural habitat in India is only limited to some forest areas.
- III. In its natural habitat, it is an arboreal species.
Which of the statements given above is/are correct?
Answer (d) & explanation
Statements II and III are correct (d). Statement II is right: the peacock tarantula (Gooty tarantula) is found only in a few forest patches of the Eastern Ghats, mainly in Andhra Pradesh. Statement III is right: it lives in tree holes, so it is arboreal. Statement I is wrong: it is a spider, an arachnid, not a crustacean, and it eats insects, not plants. So options (a), (b) and (c) fail.
Notice its status: it is Critically Endangered on the IUCN Red List, mainly due to deforestation and the pet trade, valued for its bright blue colour. It is named after Gooty town, where it was first found. Its bite is painful but rarely dangerous.
"crustacean" sounds scientific. Spiders are arachnids; crabs and prawns are crustaceans.
Answer as per the official UPSC answer key.
Consider the following statements :
- I. Carbon dioxide (CO2) emissions in India are less than 0·5 t CO2/capita.
- II. In terms of CO2 emissions from fuel combustion, India ranks second in Asia-Pacific region.
- III. Electricity and heat producers are the largest sources of CO2 emissions in India.
Which of the statements given above is/are correct?
Answer (c) & explanation
Statements II and III are correct (c). Statement II is right: India is second in the Asia-Pacific region in CO₂ emissions from fuel burning, after China, and third in the world. Statement III is right: electricity and heat producers, mainly coal-based power plants, are the largest single source. Statement I is wrong: India emits about 2 tonnes of CO₂ per person, far below the world average of about 4.7 tonnes, but well above 0.5 tonnes. So options (a), (b) and (d) fail.
Notice India's targets: net zero by 2070, 50% of power capacity from non-fossil sources by 2030, a goal already reached in 2025, and cutting emissions intensity of GDP by 45% from 2005 levels.
India's per-capita figure is "low" compared with others, but not as low as 0.5 t.
Answer as per the official UPSC answer key.
Consider the following :
- I. Cigarette butts
- II. Eyeglass lenses
- III. Car tyres
How many of them contain plastic?
Answer (c) & explanation
All three contain plastic (c). Item I is right: cigarette filters are made of cellulose acetate, a plastic, and are among the most common litter on beaches. Item II is right: most spectacle lenses are polycarbonate or other plastics, not glass. Item III is right: tyres contain synthetic rubber and polymer fibres, and tyre wear is a big source of microplastics in air and water. So options (a), (b) and (d) fail.
Notice that microplastics, pieces under 5 mm, are now found in human blood, lungs and even the placenta. India banned many single-use plastic items from July 2022. Talks on a global plastics treaty have not yet reached agreement.
Answer as per the official UPSC answer key.
Consider the following statements :
- Statement I : Activated carbon is a good and an attractive tool to remove pollutants from effluent streams and to remediate contaminants from various industries.
- Statement II : Activated carbon exhibits a large surface area and a strong potential for adsorbing heavy metals.
- Statement III : Activated carbon can be easily synthesized from environmental wastes with high carbon content.
Which one of the following is correct in respect of the above statements?
Answer (a) & explanation
Both II and III are correct and both explain Statement I (a). Statement II is right: activated carbon is full of tiny pores, so one gram has a huge surface area, often over 1,000 m², on which pollutants and heavy metals stick (adsorption). That makes it work well. Statement III is right: it can be made cheaply from coconut shells, rice husk and other carbon-rich waste, which makes it attractive. Both explain Statement I, so options (b), (c) and (d) fail.
Notice the spelling: adsorption means sticking to a surface; absorption means soaking in. Activated carbon is used in water filters, gas masks, and treating poisoning in hospitals. India's coconut-growing south is a big producer.
Answer as per the official UPSC answer key.
The World Bank warned that India could become one of the first places where wet-bulb temperatures routinely exceed 35°C. Which of the following statements best reflect(s) the implication of the above-said report?
- I. Peninsular India will most likely suffer from flooding, tropical cyclones and droughts.
- II. The survival of animals including humans will be affected as shedding of their body heat through perspiration becomes difficult.
Select the correct answer using the code given below.
Answer (c) & explanation
Both statements are counted correct (c). Statement II is right: wet-bulb temperature combines heat and humidity. At about 35°C, sweat no longer evaporates, so the body cannot cool itself, threatening the survival of humans and animals. Statement I is counted too in UPSC's key: the warming that drives such heat also brings heavier floods, stronger cyclones and longer droughts to peninsular India. So options (a), (b) and (d) fail.
Notice where the risk is high: humid coastal and plains areas, like the Indo-Gangetic plains and the Odisha coast. The World Bank report was on investment in cooling. India's Heat Action Plans, first made in Ahmedabad in 2013, aim to cut heat deaths.
Answer as per the official UPSC answer key.
Consider the following statements :
- Statement I : Studies indicate that carbon dioxide emissions from cement industry account for more than 5% of global carbon emissions.
- Statement II : Silica-bearing clay is mixed with limestone while manufacturing cement.
- Statement III : Limestone is converted into lime during clinker production for cement manufacturing.
Which one of the following is correct in respect of the above statements?
Answer (b) & explanation
Both II and III are correct, but only III explains I (b). Statement I is right: cement gives about 7–8% of the world's CO₂. Statement II is right: silica-bearing clay is mixed with limestone to make cement, but that step releases no carbon. Statement III is right and is the reason: heating limestone (CaCO₃) in a kiln gives lime (CaO) and CO₂. This calcination step, plus the fuel burnt for the high heat, causes most of the emissions. So options (a), (c) and (d) fail.
Notice the fixes: blending in fly ash or slag, LC3 (limestone calcined clay cement), and carbon capture. India is the world's second-largest cement producer after China, and its carbon market covers cement.
Answer as per the official UPSC answer key.
Artificial way of causing rainfall to reduce air pollution makes use of
Answer (a) & explanation
Silver iodide and potassium iodide are used (a). Cloud seeding sprays particles into suitable clouds so that water droplets or ice crystals form around them. Silver iodide is the standard agent, as its crystal shape is close to ice, and potassium iodide is used with it. Rain then washes dust and smoke out of the air. Options (b), (c) and (d) are wrong: silver nitrate, potassium nitrate and potassium chloride are not the usual agents, though common salt is used in some warm-cloud seeding.
Notice the catch: seeding needs clouds with enough moisture; it cannot make rain from a clear sky. Delhi tried cloud seeding against smog with IIT Kanpur in 2025, with little success because the air was too dry.
Answer as per the official UPSC answer key.
Consider the following statements :
- Statement I : At the 28th United Nations Climate Change Conference (COP28), India refrained from signing the ‘Declaration on Climate and Health’.
- Statement II : The COP28 Declaration on Climate and Health is a binding declaration; and if signed, it becomes mandatory to decarbonize health sector.
- Statement III : If India’s health sector is decarbonized, the resilience of its health-care system may be compromised.
Which one of the following is correct in respect of the above statements?
Answer (c) & explanation
Only Statement III is correct and it explains Statement I (c). Statement I is right: India stayed out of the COP28 (Dubai, 2023) Declaration on Climate and Health. Statement III is right and is the reason: India worried that cutting emissions from health care now could limit the growth of its still-expanding health system and its resilience. Statement II is wrong: the declaration is voluntary, not binding; signing it would not make decarbonisation mandatory. So options (a), (b) and (d) fail.
Notice the bigger picture: COP28 also launched the Global Stocktake call to "transition away" from fossil fuels and set up the Loss and Damage Fund. India stresses equity and common but differentiated responsibilities.
"binding" is the error. COP declarations are political pledges, not treaties.
Answer as per the official UPSC answer key.
Which organization has enacted the Nature Restoration Law (NRL) to tackle climate change and biodiversity loss?
Answer (a) & explanation
The European Union enacted the Nature Restoration Law (a). The European Union adopted its Nature Restoration Law in 2024. It requires member states to restore at least 20% of the EU's damaged land and sea areas by 2030, and all ecosystems in need by 2050. Options (b), (c) and (d) are wrong: only a body that makes laws can "enact" one. The World Bank, OECD and FAO give loans, advice or technical help, but cannot pass binding laws.
Notice the link to the Kunming-Montreal Global Biodiversity Framework (2022), whose "30 by 30" target asks for 30% of land and sea to be protected by 2030. The EU law faced strong protests from farmers before it passed narrowly.
Answer as per the official UPSC answer key.