Chapter 8 · Topic 8.2 · Prelims + Mains2 of 3
Climate Change: Sinks, capture and carbon markets
Key points
- Footprint and sinks.
- Carbon capture.
- Carbon credits and markets.
10 PYQs 2017–2026
Prelims box: facts and traps
- India's NDC for 2031-35 lists a push for CCUS among its clean energy measures (PIB, 25 March 2026).
- From 2005 to 2021, an additional carbon sink of 2.29 billion tonnes of CO2 equivalent was created (PIB, 2 January 2025, citing India's Fourth Biennial Update Report).
- The Carbon Credit Trading Scheme was notified on 28 June 2023 (S.O. 2825(E)) and amended on 19 December 2023.
- The basic rules came at COP26 (2021), and COP29 (Baku, 2024) completed the remaining details on authorisation, registries and Article 6.4 standards.
- Trap (UPSC Prelims 2023): all the statements are correct.
- Trap (UPSC Prelims 2017): all the statements are correct.
On this page (3 sections)
Carbon footprint and carbon sinks
A carbon footprint is the total greenhouse gas emissions caused by a person, product, organisation or country, expressed in tonnes of CO2 equivalent. Carbon sequestration is the long-term capture and storage of CO2 in plants, soils, oceans or rock.
India’s forest and tree cover and other land use absorbed about 522 million tonnes of CO2 in 2020, equal to about 22% of the country’s CO2 emissions that year. From 2005 to 2021, an additional carbon sink of 2.29 billion tonnes of CO2 equivalent was created (PIB, 2 January 2025, citing India’s Fourth Biennial Update Report).
Blue carbon is Carbon captured by oceans and coastal ecosystems (Prelims 2021), such as mangroves, seagrass meadows and salt marshes, which lock carbon in their waterlogged soils.
What is blue carbon?
- Carbon captured by oceans and coastal ecosystems
- Carbon sequestered in forest biomass and agricultural soils
- Carbon contained in petroleum and natural gas
- Carbon present in atmosphere
Show answer
Answer: (a) · UPSC official key
Contour bunding, relay cropping and zero tillage all help store carbon in the soil (Prelims 2012: 1, 2 and 3).
Consider the following agricultural practices : 1. Contour bunding 2. Relay cropping 3. Zero tillage In the context of global climate change, which of the above helps/help in carbon sequestration/storage in the soil?
- 1 and 2 only
- 3 only
- 1, 2 and 3
- None of them
Show answer
Answer: (b) · UPSC official key
Biochar can be part of the growing medium in vertical farming, where it promotes nitrogen-fixing microbes and helps the medium hold water longer (Prelims 2020: 1, 2 and 3).
What is the use of biochar in farming ? 1. Biochar can be used as a part of the growing medium in vertical farming. 2. When biochar is a part of the growing medium, it promotes the growth of nitrogen-fixing microorganisms. 3. When biochar is a part of the growing medium, it enables the growing medium to retain water for longer time. Which of the statements given above is/are correct ?
- 1 and 2 only
- 2 only
- 1 and 3 only
- 1, 2 and 3
Show answer
Answer: (d) · UPSC official key
Carbon capture and storage technologies
Carbon capture, utilisation and storage (CCUS) captures CO2 from power plants and factories, then either uses it (in fuels, chemicals or building materials) or stores it deep underground. Direct air capture takes CO2 straight from the open air.
Potential sites for storing captured CO2 include abandoned and uneconomic coal seams, depleted oil and gas reservoirs and deep saline formations underground (Prelims 2017: 1, 2 and 3).
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 :
- 1 and 2 only
- 3 only
- 1 and 3 only
- 1, 2 and 3
Show answer
Answer: (d) · UPSC official key
Spreading crushed basalt on farms (enhanced rock weathering), adding lime to raise ocean alkalinity, and pumping industrial CO2 into old mines as carbonated water are all discussed for carbon capture and sequestration (Prelims 2023: All three).
Consider the following activities : 1. Spreading finely ground basalt rock on farmlands extensively 2. Increasing the alkalinity of oceans by adding lime 3. Capturing carbon dioxide released by various industries and pumping it into abandoned subterranean mines in the form of carbonated waters How many of the above activities are often considered and discussed for carbon capture and sequestration?
- Only one
- Only two
- All three
- None
Show answer
Answer: (c) · UPSC official key
Direct air capture can be used for carbon sequestration, can supply CO2 for plastics and food processing, and in aviation can provide carbon to combine with hydrogen for synthetic low-carbon fuel (Prelims 2025: I, II and III).
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.
- I and II only
- III only
- I, II and III
- None of the above statements is correct
Show answer
Answer: (c) · UPSC official key
Mains 2025: What is Carbon Capture, Utilization and Storage (CCUS)? Mains 2025 What is the potential role of CCUS in tackling climate change? India’s NDC for 2031-35 lists a push for CCUS among its clean energy measures (PIB, 25 March 2026).
What is Carbon Capture, Utilization and Storage (CCUS)? What is the potential role of CCUS in tackling climate change?
Carbon credits and carbon markets
A carbon credit is a tradable certificate, usually for one tonne of CO2 equivalent reduced or removed. Under the Kyoto Protocol’s Clean Development Mechanism, projects in developing countries earned Certified Emission Reductions that developed countries could buy. Article 6 of the Paris Agreement now covers carbon markets between countries and non-market cooperation.
The statement that is not correct about carbon credits: Carbon credits are traded at a price fixed from time to time by the United Nations Environment Programme (Prelims 2011). Prices are set by the market.
Regarding “carbon credits”, which one of the following statements is not correct ? emission quota Programme ✓
- The carbon credit system was ratified in conjunction with the Kyoto Protocol
- Carbon credits are awarded to countries or groups that have reduced greenhouse gases below their
- The goal of the carbon credit system is to limit the increase of carbon dioxide emission
- Carbon credits are traded at a price fixed from time to time by the United Nations Environment
Show answer
Answer: (d) · UPSC official key
Article 6 of the Paris Agreement is widely discussed because it sets out principles for carbon markets between countries and also provides for non-market approaches.
On carbon markets as a climate tool, UPSC’s key held: Both Statement-I and Statement-II are correct and Statement-II is not the correct explanation for Statement-I (Prelims 2023).
Consider the following statements : Statement-I : Carbon markets are likely to be one of the most widespread tools in the fight against climate change. Statement-II : Carbon markets transfer resources from the private sector to the State. Which one of the following is correct in respect of the above statements? Statement-I ✓
- Both Statement-I and Statement-II are correct and Statement-II is the correct explanation for Statement-I
- Both Statement-I and Statement-II are correct and Statement-II is not the correct explanation for
- Statement-I is correct but Statement-II is incorrect
- Statement-I is incorrect but Statement-II is correct
Show answer
Answer: (b) · UPSC official key
India’s carbon market: the Energy Conservation (Amendment) Act, 2022 empowered the Centre to specify a carbon credit trading scheme. The Carbon Credit Trading Scheme was notified on 28 June 2023 (S.O. 2825(E)) and amended on 19 December 2023. It has a compliance mechanism, in which obligated entities must meet emission-intensity norms and earn certificates if they do better, and an offset mechanism for voluntary projects (PIB, 9 December 2024).
Mains 2014: Should the pursuit of carbon credits and clean development mechanisms set up under UNFCCC be maintained even though there has been a massive slide in the value of a carbon credit? Mains 2014 Discuss with respect to India’s energy needs for economic growth.
Should the pursuit of carbon-credits and clean development mechanisms set up under UNFCCC be maintained even though there has been a massive slide in the value of a carbon credit? Discuss with respect to India’s energy needs for economic growth.
Mains box: analysis and answer points
- Article 6 of the Paris Agreement is widely discussed because it sets out principles for carbon markets between countries and also provides for non-market approaches.
- A carbon footprint is the total greenhouse gas emissions caused by a person, product, organisation or country, expressed in tonnes of CO2 equivalent.
- Carbon sequestration is the long-term capture and storage of CO2 in plants, soils, oceans or rock.
- India's forest and tree cover and other land use absorbed about 522 million tonnes of CO2 in 2020, equal to about 22% of the country's CO2 emissions that year.
- Likely next angle: Zero tillage
- Asked: Mains 2025 (GS Paper III, 10 marks): What is Carbon Capture, Utilization and Storage (CCUS)? What is the potential role of CCUS in tackling climate change?
Practice
Practice MCQs (8)
Consider the following approaches:
1. Afforestation and reforestation
2. Stratospheric aerosol injection
3. Direct air capture with carbon storage
4. Ocean alkalinity enhancement
5. Marine cloud brightening
How many of the above are carbon dioxide removal (CDR) approaches?
Answer (b) & explanation
Three are CDR approaches. Carbon dioxide removal takes carbon dioxide out of the atmosphere and stores it: afforestation and reforestation store it in trees and soils, direct air capture with storage pumps captured carbon dioxide underground, and ocean alkalinity enhancement (adding alkaline minerals) increases the ocean's uptake and storage of carbon. Stratospheric aerosol injection and marine cloud brightening are solar radiation modification methods: they reflect sunlight but leave carbon dioxide in the air.
In carbon markets, including India's Carbon Credit Trading Scheme, one carbon credit generally represents
Answer (d) & explanation
A carbon credit is a tradable unit equal to one tonne of carbon dioxide equivalent (tCO2e) reduced, removed or avoided. India's CCTS defines it exactly this way. Using 'CO2 equivalent' allows reductions of methane, nitrous oxide or fluorinated gases to be expressed on a common scale via their global warming potentials. A unit tied to one megawatt-hour of clean power is a Renewable Energy Certificate, a different instrument.
With reference to India's Carbon Credit Trading Scheme, 2023, consider the following statements:
1. It was notified under the Energy Conservation Act, 2001, as amended in 2022.
2. The Bureau of Energy Efficiency is the Administrator of the Indian carbon market.
3. The National Steering Committee for the Indian Carbon Market is chaired by the Secretary, Ministry of Environment, Forest and Climate Change.
Which of the statements given above is/are correct?
Answer (b) & explanation
Statements 1 and 2 are correct. The Energy Conservation (Amendment) Act, 2022 empowered the Centre to specify a carbon credit trading scheme, and the CCTS was notified by the Ministry of Power on 28 June 2023. The Bureau of Energy Efficiency is the Administrator: it sets emission-intensity targets for obligated entities and issues carbon credit certificates. Statement 3 is wrong: the National Steering Committee is chaired by the Secretary, Ministry of Power, with the Secretary, MoEFCC, as co-chair.
Consider the following agricultural practices:
1. Growing cover crops between main crop seasons
2. Agroforestry, that is, integrating trees with crops
3. Adding biochar to the soil
4. Burning crop stubble in the field
How many of the above practices generally help to increase the carbon stored in agricultural soils?
Answer (c) & explanation
Three practices help. Cover crops add roots and residues that build soil organic matter; agroforestry stores carbon in tree biomass and adds litter to the soil; and biochar, made by heating biomass with little oxygen, is a stable form of carbon that can stay in soil for centuries. IPCC AR6 WGIII lists these among soil-carbon and agriculture-based removal options. Stubble burning does the opposite: it sends the residue's carbon into the air as carbon dioxide, black carbon and other pollutants.
Capturing carbon dioxide directly from ambient air (Direct Air Capture) generally needs much more energy per tonne than capturing it from the flue gas of a cement plant. The main reason is that:
Answer (d) & explanation
Direct air capture must process enormous volumes of air because carbon dioxide makes up only about 420 parts per million (about 0.04%) of the atmosphere. Flue gas from cement kilns or power plants is far richer in carbon dioxide (often in the range of about 10– 30%), so far less gas must be handled per tonne captured. Separating a dilute gas costs more energy, which is why DAC is costlier per tonne, though it can be sited anywhere and removes carbon dioxide already in the air.
Consider the following pairs: Technique — What it involves
1. Enhanced weathering — Spreading finely crushed silicate rock so that it reacts with carbon dioxide faster
2. Ocean iron fertilisation — Adding iron to iron-poor ocean waters to stimulate phytoplankton growth
3. Biochar — Burning biomass completely in excess air to produce ash for fertiliser
4. Direct air capture — Using chemical sorbents to remove carbon dioxide from ambient air
How many of the pairs given above are correctly matched?
Answer (c) & explanation
Pairs 1, 2 and 4 are correct. Enhanced weathering speeds up the natural reaction of silicate minerals (e.g. basalt) with carbon dioxide, locking carbon as bicarbonate or carbonate. Ocean iron fertilisation targets regions where iron limits plankton growth, hoping that extra plankton will sink carbon to depth (its effectiveness and side-effects remain uncertain). Direct air capture pulls carbon dioxide out of ordinary air with chemical sorbents or solvents. Pair 3 is wrong: biochar is made by pyrolysis — heating biomass with little or no oxygen — which leaves a stable, carbon-rich solid rather than ash.
Consider the following statements regarding carbon capture technologies:
1. Bioenergy with carbon capture and storage (BECCS) can in principle yield net negative emissions, because the carbon in the biomass was originally drawn from the atmosphere.
2. Fitting carbon capture and storage to a coal-fired power plant makes the plant carbon- negative.
3. Injecting captured carbon dioxide into oil fields to recover more oil (enhanced oil recovery) is one existing use of captured carbon dioxide.
Which of the statements given above are correct?
Answer (b) & explanation
Statements 1 and 3 are correct. In BECCS, plants absorb carbon dioxide as they grow; when the biomass is burnt for energy and the resulting carbon dioxide is captured and stored, the overall effect can be removal from the atmosphere, which is why IPCC AR6 lists it among carbon dioxide removal methods. Enhanced oil recovery is the oldest large-scale use of captured carbon dioxide. Statement 2 is wrong: capture on a fossil plant only reduces its emissions — capture rates are below 100% and the carbon came from underground — so the plant cannot become carbon-negative.
With reference to carbon markets under Article 6 of the Paris Agreement, consider the following statements:
1. A 'corresponding adjustment' ensures that an emission reduction transferred abroad is not counted both by the country that sells it and by the country that uses it.
2. The remaining rules needed to operationalise the Article 6 carbon markets were finalised at COP29 in Baku (2024).
3. Only developed country Parties may host projects under the Article 6.4 mechanism.
Which of the statements given above are correct?
Answer (a) & explanation
Statements 1 and 2 are correct. When internationally transferred mitigation outcomes (ITMOs) move from one country to another, the transferring country makes a corresponding adjustment, adding the units back to its emissions balance, so that the same tonne is not claimed twice. The basic rules came at COP26 (2021), and COP29 (Baku, 2024) completed the remaining details on authorisation, registries and Article 6.4 standards. Statement 3 is wrong: the Article 6.4 mechanism, like the old CDM, is open to all Parties and is expected to host many projects in developing countries.
0 / 0 correct
Prelims PYQs on this topic (8)
Consider the following statements :
- Statement I : Article 6 of the Paris Agreement on climate change is frequently discussed in global discussions on sustainable development and climate change.
- Statement II : Article 6 of the Paris Agreement on climate change sets out the principles of carbon markets.
- Statement III : Article 6 of the Paris Agreement on climate change intends to promote inter-country non-market strategies to reach their climate targets.
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). Article 6 of the Paris Agreement lets countries work together to meet their targets. Statement II is right: Articles 6.2 and 6.4 set up carbon markets, for trading credits between countries and through a UN-run mechanism. Statement III is right: Article 6.8 covers non-market approaches, such as joint finance, technology and capacity building. Both halves are why it is discussed so much, so options (b), (c) and (d) fail.
Notice the progress: rules for Article 6 carbon markets were finally agreed at COP29 in Baku (2024). India's own Carbon Credit Trading Scheme (2023) builds a domestic market, and India has signed Article 6.2 deals, such as with Japan.
Answer as per the official UPSC answer key.
Consider the following statements :
- Statement-I : Carbon markets are likely to be one of the most widespread tools in the fight against climate change.
- Statement-II : Carbon markets transfer resources from the private sector to the State.
Which one of the following is correct in respect of the above statements?
Answer (b) & explanation
Both statements are correct but II does not explain I (b). Statement I is right: carbon markets put a price on emissions and are spreading fast, from the EU's ETS to China's national market, and the Article 6 rules under the Paris Agreement. Statement II is right: under cap-and-trade, governments sell or auction emission permits, so money moves from companies to the State. But II is not the reason for I: markets spread because they cut emissions where it is cheapest, letting firms that can cut cheaply sell their spare permits.
Notice India's own Carbon Credit Trading Scheme (2023), run by the Bureau of Energy Efficiency. It sets emission-intensity targets for heavy industries such as cement, steel and aluminium.
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.
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 :
- 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.
Mains PYQs on this topic (2)
- UPSC Mains 2025 · GS Paper III · Q7What is Carbon Capture, Utilization and Storage (CCUS) ? What is the potential role of CCUS in tackling climate change ?How to approach: Intro: definition. Body: (1) Process; (2) Role in climate action; (3) India; (4) Limits. Conclusion: CCUS is a complement, not a substitute, for renewables and…
- UPSC Mains 2023 · GS Paper III · Q18The Intergovernmental Panel on Climate Change (IPCC) has predicted a global sea level rise of about one metre by AD 2100. What would be its impact in India and the other countries in the Indian Ocean region?How to approach: Intro: IPCC AR6 projections; causes: thermal expansion, ice melt. Body: (1) India: coastal flooding of cities (Mumbai, Kolkata, Chennai), Sundarbans and deltas,…
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In 150 words, explain the significance of Climate Change with one recent example.
Flashcards (9)
Blue carbon?
Carbon captured by oceans and coastal ecosystems.
India's land sink in 2020?
About 522 Mt CO2.
Three geological CO2 storage sites?
Coal seams, depleted oil/gas fields, saline formations.
Enhanced rock weathering uses?
Crushed basalt.
One carbon credit usually equals?
1 tonne CO2e.
Who sets carbon credit prices?
The market (not UNEP).
Paris article on carbon markets?
Article 6.
CCTS notified on?
28 June 2023.
Emission intensity cut, 2005–2020?
36%.
Read more: related explainers
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