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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Questions per year, counted from the official papers.
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It is possible to produce algae based biofuels, but what is/are the likely limitation(s) of developing countries in promoting this industry ?
- 1. Production of algae based biofuels is possible in seas only and not on continents.
- 2. Setting up and engineering the algae based biofuel production requires high level of expertise/technology until the construction is completed.
- 3. Economically viable production necessitates the setting up of large scale facilities which may raise ecological and social concerns.
Select the correct answer using the code given below :
Answer (b) & explanation
Statements 2 and 3 are correct (b). Statement 1 is wrong because algae can be grown on land in open ponds, in closed photobioreactors, and even in wastewater, not only at sea. The real hurdles for developing countries are that setting up and engineering these plants needs high expertise and technology (2), and that making the fuel pay needs large facilities, which use land, water and nutrients and may raise ecological and social concerns (3).
Algae are third-generation biofuels: they grow fast, make oil, and do not compete with food crops the way first-generation sugarcane and maize ethanol do. Notice India's biofuel path: the National Policy on Biofuels (2018, amended 2022) and the E20 petrol target, which India reached in 2025.
Answer as per the official UPSC answer key.
In the context of mitigating the impending global warming due to anthropogenic emissions of carbon dioxide, which of the following can be the potential sites for carbon sequestration ?
- 1. Abandoned and uneconomic coal seams
- 2. Depleted oil and gas reservoirs
- 3. Subterranean deep saline formations
Select the correct answer using the code given below :
Answer (d) & explanation
All three are possible storage sites (d). Geological carbon sequestration, part of CCS (carbon capture and storage), pumps CO₂ deep underground. Unmineable coal seams absorb CO₂ onto the coal and can release methane in exchange, a method called ECBM (1). Depleted oil and gas fields once held gas safely for millions of years, and injecting CO₂ can also push out leftover oil (enhanced oil recovery) (2). Deep saline aquifers have the largest storage capacity of all (3).
Norway's Sleipner project has stored CO₂ in a saline formation since 1996. Notice India's steps: NITI Aayog's CCUS report (2022) and ONGC's EOR trials. Remember the other carbon sinks too: oceans, forests and soils.
Answer as per the official UPSC answer key.
According to the Wildlife (Protection) Act, 1972, which of the following animals cannot be hunted by any person except under some provisions provided by law ?
- 1. Gharial
- 2. Indian wild ass
- 3. Wild buffalo
Select the correct answer using the code given below :
Answer (d) & explanation
All three cannot be hunted except as the law allows (d). Section 9 of the Wildlife (Protection) Act, 1972 bans hunting any wild animal listed in the Schedules. The exceptions are narrow, such as an animal that has become dangerous to human life (Section 11), or for research and education with permission (Section 12). The gharial (1), Indian wild ass (2) and wild buffalo (3) are all Schedule I species, with the highest protection.
The 2022 amendment cut the Schedules from six to four and brought in CITES listings. Notice where these animals live: the gharial in the Chambal, the wild ass only in the Little Rann of Kutch, and the wild buffalo in Assam and Chhattisgarh, where it is the State animal.
Answer as per the official UPSC answer key.
With reference to ‘Global Climate Change Alliance’, which of the following statements is/are correct?
- 1. It is an initiative of the European Union.
- 2. It provides technical and financial support to targeted developing countries to integrate climate change into their development policies and budgets.
- 3. It is coordinated by World Resources Institute (WRI) and World Business Council for Sustainable Development (WBCSD).
Select the correct answer using the code given below :
Answer (a) & explanation
Statements 1 and 2 are correct (a). The Global Climate Change Alliance was started by the European Union in 2007 (1) and became GCCA+ in 2014. It gives technical and financial support to poor, climate-exposed countries, mainly small island states (SIDS) and least developed countries (LDCs). The aim is to help them build climate change into their development policies and budgets (2), with a focus on adaptation and disaster risk reduction. Statement 3 is wrong because WRI and WBCSD run the GHG Protocol, not the GCCA.
Notice the trap: UPSC mixes up who runs which climate body. Remember these pairs: GCCA belongs to the EU, the CCAC to UNEP with partner countries, REDD+ to the UN or World Bank, and the GHG Protocol to WRI and WBCSD.
The WRI–WBCSD pairing belongs to the GHG Protocol.
Answer as per the official UPSC answer key.
Biological Oxygen Demand (BOD) is a standard criterion for
Answer (c) & explanation
BOD is used to test pollution in water (c). Biochemical (Biological) Oxygen Demand is the amount of dissolved oxygen that microbes use to break down the organic matter in a water sample, usually measured over 5 days at 20°C. A high BOD means heavy organic pollution, as from sewage or dairy waste, which takes oxygen away from fish. Clean river water has a BOD under about 3 mg/L, which is the bathing standard. It has nothing to do with blood (a), forests (b), or high altitudes (d).
COD (Chemical Oxygen Demand) measures all oxidisable matter and is always higher than BOD. Notice how the CPCB uses BOD to list polluted river stretches. Low dissolved oxygen with high BOD leads to eutrophication and fish deaths.
Answer as per the official UPSC answer key.
Which of the following best describes/describe the aim of ‘Green India Mission’ of the Government of India?
- 1. Incorporating environmental benefits and costs into the Union and State Budgets thereby implementing the ‘green accounting’
- 2. Launching the second green revolution to enhance agricultural output so as to ensure food security to one and all in the future
- 3. Restoring and enhancing forest cover and responding to climate change by a combination of adaptation and mitigation measures
Select the correct answer using the code given below.
Answer (c) & explanation
Only statement 3 is correct (c). The Green India Mission, one of the eight missions under the National Action Plan on Climate Change (2008), aims to protect, restore and enhance forest cover and respond to climate change through both adaptation and mitigation. Statement 1 is wrong: green accounting in budgets is not its aim. Statement 2 is wrong: a second green revolution in farm output is an agriculture goal, not this mission's.
The mission seeks to improve forest and tree cover on millions of hectares and boost ecosystem services. Notice how it links to India's NDC promise of an extra carbon sink of 2.5–3 billion tonnes of CO₂ equivalent.
Answer as per the official UPSC answer key.
With reference to the Agreement at the UNFCCC Meeting in Paris in 2015, which of the following statements is/are correct?
- 1. The Agreement was signed by all the member countries of the UN and it will go into effect in 2017.
- 2. The Agreement aims to limit the greenhouse gas emissions so that the rise in average global temperature by the end of this century does not exceed 2°C or even 1.5°C above pre-industrial levels.
- 3. Developed countries acknowledged their historical responsibility in global warming and committed to donate $ 1000 billion a year from 2020 to help developing countries to cope with climate change.
Select the correct answer using the code given below.
Answer (b) & explanation
Only statement 2 is correct (b). The Paris Agreement (COP21, 2015) aims to keep the rise in global temperature well below 2°C above pre-industrial levels and to try to limit it to 1.5°C (2). Statement 1 is wrong because it came into force on 4 November 2016, after the 55-country, 55%-of-emissions threshold was crossed. Not every UN member had signed it. Statement 3 is wrong because the finance goal was $100 billion a year, not $1,000 billion, and it was a collective goal, not an admission of historical blame.
At COP29 (Baku, 2024) a new goal (NCQG) of $300 billion a year by 2035 was set. Notice that countries set their own targets (NDCs). India's include net zero by 2070 and 50% non-fossil power capacity, which it reached in 2025.
Watch the zero: the goal was 100 billion dollars, not 1000.
Answer as per the official UPSC answer key.
What is/are unique about ‘Kharai camel’, a breed found in India?
- 1. It is capable of swimming up to three kilometres in seawater.
- 2. It survives by grazing on mangroves.
- 3. It lives in the wild and cannot be domesticated.
Select the correct answer using the code given below.
Answer (a) & explanation
Statements 1 and 2 are correct (a). The Kharai camel ("kharai" means saline) of Kachchh, Gujarat, can swim up to about 3 km in seawater (1) to reach the islands of the Gulf of Kachchh, where it feeds on mangroves (2). Statement 3 is wrong: it is a domesticated breed, reared by Rabari and Fakirani Jat herders.
It was recognised as a distinct breed in 2015. Mangrove loss, salt pans and industry along the coast threaten its grazing grounds. Notice how this links pastoral communities, coastal ecology and breed conservation; the Marine National Park in the Gulf of Kachchh lies in the same region.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. The Sustainable Development Goals were first proposed in 1972 by a global think tank called the ‘Club of Rome’.
- 2. The Sustainable Development Goals have to be achieved by 2030.
Which of the statements given above is/are correct?
Answer (b) & explanation
Only statement 2 is correct (b). The SDGs were proposed at Rio+20 (2012), with Colombia and Guatemala pushing the idea. The UN adopted them in September 2015 as Agenda 2030: 17 goals and 169 targets to be met by 2030 (2). They replaced the eight MDGs (2000–2015). Statement 1 is wrong because the Club of Rome's 1972 report The Limits to Growth warned about resource limits but never proposed the SDGs.
In India, NITI Aayog tracks progress through its SDG India Index, and Kerala and Uttarakhand usually rank at the top. Notice the related term sustainable development, made popular by the Brundtland Report, Our Common Future (1987): meeting today's needs without harming future generations.
Answer as per the official UPSC answer key.
Recently, our scientists have discovered a new and distinct species of banana plant which attains a height of about 11 metres and has orange-coloured fruit pulp. In which part of India has it been discovered?
Answer (a) & explanation
The new banana was found in the Andaman Islands (a). Named Musa indandamanensis, it was discovered in 2014 in a remote forest on Little Andaman. It grows to about 11 metres and has unusual orange-coloured pulp. The Anaimalai forests (b), the Maikala Hills (c) and the north-east rainforests (d) were not where it was found.
The Botanical Survey of India described the species. Wild bananas are valuable as gene pools for breeding disease-resistant cultivated varieties. Notice how island ecosystems, isolated for long periods, produce high endemism, which is why the Andaman and Nicobar Islands keep yielding new species.
Answer as per the official UPSC answer key.
With reference to an initiative called ‘The Economics of Ecosystems and Biodiversity (TEEB)’, which of the following statements is/are correct?
- 1. It is an initiative hosted by UNEP, IMF and World Economic Forum.
- 2. It is a global initiative that focuses on drawing attention to the economic benefits of biodiversity.
- 3. It presents an approach that can help decision-makers recognize, demonstrate and capture the value of ecosystems and biodiversity.
Select the correct answer using the code given below.
Answer (c) & explanation
Statements 2 and 3 are correct (c). TEEB began in 2007 after a G8+5 environment ministers' meeting in Potsdam. Germany and the European Commission backed it, and it is hosted by UNEP. Statement 1 is wrong because the IMF and WEF do not host it. TEEB draws attention to the economic benefits of biodiversity (2). It also gives decision-makers a way to recognise, demonstrate and capture the value of ecosystems (3), for example through payments for ecosystem services.
The idea is that nature is lost partly because its services look "free". Notice how it connects with natural capital accounting, including the UN SEEA framework that India's MoSPI uses for its EnviStats environmental accounts.
Answer as per the official UPSC answer key.
With reference to ‘Red Sanders’, sometimes seen in the news, consider the following statements :
- 1. It is a tree species found in a part of South India.
- 2. It is one of the most important trees in the tropical rain forest areas of south India.
Which of the statements given above is/are correct?
Answer (a) & explanation
Only statement 1 is correct (a). Red sanders (Pterocarpus santalinus) is endemic to the southern Eastern Ghats, mainly the Seshachalam, Palakonda and Lankamala hills of Andhra Pradesh, with small extensions into Tamil Nadu and Karnataka. Statement 2 is wrong because it grows in dry deciduous forest on rocky, poor soil, not in tropical rainforest. So it is neither a rainforest tree nor one of the "most important" ones there.
Its deep red heartwood is prized in China and Japan for furniture and instruments, so it is smuggled heavily. It is Endangered on the IUCN Red List and listed in CITES Appendix II. The Pushpa films made this smuggling famous, and it is a favourite species question.
"Rain forest" is the error. Red sanders grows on dry, rocky hills.
Answer as per the official UPSC answer key.
Which of the following statements is/are correct?
Proper design and effective implementation of UN-REDD+ Programme can significantly contribute to
- 1. protection of biodiversity
- 2. resilience of forest ecosystems
- 3. poverty reduction
Select the correct answer using the code given below.
Answer (d) & explanation
All three are correct (d). REDD+ (Reducing Emissions from Deforestation and forest Degradation, plus conservation, sustainable management and enhancing carbon stocks) pays developing countries for keeping forests standing. UN-REDD, started in 2008, is run jointly by the FAO, UNDP and UNEP. If it is well designed, it brings co-benefits: standing forests protect biodiversity (1), healthy and connected forests are more resilient to climate stress (2), and payments that reach forest communities help reduce poverty (3).
The word "proper design" in the question is the clue. Badly designed REDD+ can push out tribal people. That is why safeguards on indigenous rights matter, and in India they link with the Forest Rights Act, 2006.
Answer as per the official UPSC answer key.
The term ‘Intended Nationally Determined Contributions’ is sometimes seen in the news in the context of
Answer (b) & explanation
Intended Nationally Determined Contributions were climate pledges countries set for themselves before the Paris Agreement (2015), so the term relates to combating climate change (b). Once a country ratified the Agreement, its INDC became its NDC. The term has nothing to do with refugee pledges (a), AIIB capital (c) or the SDGs (d).
India pledged to cut emissions intensity of GDP by 33–35% from 2005 levels by 2030, and raised this to 45% in 2022, along with 50% of power capacity from non-fossil sources by 2030 and net zero by 2070. Notice how Paris replaced top-down targets with nationally decided ones.
Answer as per the official UPSC answer key.
What is ‘Greenhouse Gas Protocol’?
Answer (a) & explanation
The GHG Protocol is an accounting tool (a). It was built by the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD). It is the most widely used standard for measuring and managing emissions. It sorts emissions into Scope 1 (direct), Scope 2 (purchased electricity) and Scope 3 (the value chain). It is not a UN financial incentive (b); that describes REDD+ or climate funds. It is not a treaty with a 2022 target (c), and it is not a World Bank REDD+ initiative (d), such as the Forest Carbon Partnership Facility.
Notice how this matters today. SEBI's BRSR reporting for listed companies and India's Carbon Credit Trading Scheme both rely on this kind of emissions accounting.
Answer as per the official UPSC answer key.
What is/are the importance/importances of the ‘United Nations Convention to Combat Desertification’?
- 1. It aims to promote effective action through innovative national programmes and supportive international partnerships.
- 2. It has a special/particular focus on South Asia and North Africa regions, and its Secretariat facilitates the allocation of major portion of financial resources to these regions.
- 3. It is committed to bottom-up approach, encouraging the participation of local people in combating the desertification.
Select the correct answer using the code given below.
Answer (c) & explanation
Statements 1 and 3 are correct (c). The UNCCD (1994) promotes action through national action programmes and supportive international partnerships (1). It is committed to a bottom-up, community-led approach involving local people (3). Statement 2 is wrong: its special regional focus is Africa, not South Asia and North Africa, and the Secretariat does not allocate most funds to particular regions.
India hosted COP14 in Greater Noida in 2019 and aims to restore 26 million hectares of degraded land by 2030. Notice how desertification links to food security, migration and climate change.
South Asia never had special focus. Africa is the region the treaty highlights.
Answer as per the official UPSC answer key.
With reference to ‘Agenda 21’, sometimes seen in the news, consider the following statements :
- 1. It is a global action plan for sustainable development.
- 2. It originated in the World Summit on Sustainable Development held in Johannesburg in 2002.
Which of the statements given above is/are correct?
Answer (a) & explanation
Only statement 1 is correct (a). Agenda 21 is a non-binding, global action plan for sustainable development in the 21st century. Statement 2 is wrong because it was adopted at the Rio Earth Summit (UNCED), 1992, not at Johannesburg. The World Summit on Sustainable Development, Johannesburg 2002 (Rio+10) only reviewed how it was being carried out. Rio also produced the UNFCCC, the CBD, the Rio Declaration and the Forest Principles.
Its local version, Local Agenda 21, asked city governments to make their own plans. Notice the order of events: Stockholm 1972, Rio 1992, Johannesburg 2002, Rio+20 2012 ("The Future We Want"), and then the SDGs/Agenda 2030 in 2015, which carry Agenda 21's ideas forward.
Johannesburg was the review summit. Rio 1992 is where Agenda 21 began.
Answer as per the official UPSC answer key.
In which of the following regions of India are you most likely to come across the ‘Great Indian Hornbill’ in its natural habitat?
Answer (d) & explanation
The Great Indian Hornbill needs tall evergreen and moist deciduous forest with big fruiting trees and nesting holes. In India it lives in the Western Ghats (d) and in the forests of the North-East and Himalayan foothills. The sand deserts (a), high Himalayas (b) and salt marshes of Gujarat (c) lack such forest.
It is the state bird of Kerala and Arunachal Pradesh. Hornbills are called "farmers of the forest" because they spread seeds of many trees. The Hornbill Festival of Nagaland is named after it. Notice how one bird's survival depends on old, tall trees.
Answer as per the official UPSC answer key.
‘Gadgil Committee Report’ and ‘Kasturirangan Committee Report’, sometimes seen in the news, are related to
Answer (d) & explanation
Both reports deal with protecting the Western Ghats (d). The Madhav Gadgil-led Western Ghats Ecology Expert Panel (2011) suggested treating the whole range as ecologically sensitive. It put about 64% in the strictest zones and called for a bottom-up, gram-sabha-led approach. The K. Kasturirangan high-level working group (2013) cut the area to about 37%, around 60,000 sq km, focusing on natural landscape. The reports have nothing to do with constitutional reform (a), the Ganga Action Plan (b), or river linking (c).
The Environment Ministry has issued several draft Eco-Sensitive Area notifications since 2014, and the matter came up again after the Wayanad landslides (2024). Notice that the Ghats are a UNESCO site and a global biodiversity hotspot.
Answer as per the official UPSC answer key.
Which of the following are the key features of ‘National Ganga River Basin Authority (NGRBA)’?
- 1. River basin is the unit of planning and management.
- 2. It spearheads the river conservation efforts at the national level.
- 3. One of the Chief Ministers of the States through which the Ganga flows becomes the Chairman of NGRBA on rotation basis.
Select the correct answer using the code given below.
Answer (a) & explanation
Statements 1 and 2 are correct (a). The NGRBA, set up in 2009 under the Environment (Protection) Act, treated the river basin as the unit of planning and management (1) and led river conservation at the national level (2). Statement 3 is wrong: the Prime Minister chaired it, not a rotating Chief Minister.
In 2016 it was replaced by the National Ganga Council, also headed by the PM, with the National Mission for Clean Ganga under it, which runs Namami Gange. Notice how basin-level planning recognises that a river's health depends on its whole catchment.
Answer as per the official UPSC answer key.