UPSC Prelims Practice Questions — Doubts arise over rock-based climate mitigation scheme

Question 1

In the context of carbon dioxide removal, 'enhanced rock weathering' is best described as which one of the following?

Accepted Answer

Spreading finely crushed silicate rocks such as basalt on land so their accelerated dissolution converts atmospheric CO2 into bicarbonate that is eventually stored in the ocean

Answer

Injecting captured CO2 into deep basalt formations where it permanently mineralises into solid carbonate rock underground

Answer

Using naturally occurring limestone outcrops exclusively to neutralise acidic industrial flue gases at their point of emission

Answer

Replacing chemical fertilisers with rock dust solely to raise crop yields, with no effect whatsoever on atmospheric carbon

Question 2

Consider the following: afforestation, direct air capture, enhanced rock weathering, and ocean alkalinity enhancement. How many of these are classified as carbon dioxide removal (CDR) techniques?

Accepted Answer

All four

Answer

Only two

Answer

Only three

Answer

Only one

Question 3

In research questioning enhanced weathering's efficacy, the process in which formation of secondary aluminosilicate (clay) minerals consumes alkalinity and re-releases CO2 is termed:

Accepted Answer

Reverse weathering

Answer

Carbonation

Answer

Silicification

Answer

Podzolisation

Question 4

According to the 2026 research flagging a mechanistic flaw in enhanced weathering, weathering-derived alkalinity is most significantly lost when dissolved minerals become trapped, en route from soil to sea, in which one of the following?

Accepted Answer

Secondary clay minerals

Answer

Shells of marine calcifiers

Answer

Atmospheric aerosol particles

Answer

Deep-sea manganese nodules

Question 5

The 2026 review paper titled 'Uncertainties of enhanced rock weathering for climate-change mitigation' was published in which one of the following journals?

Accepted Answer

Nature Reviews Earth & Environment

Answer

Nature Geoscience

Answer

Nature Climate Change

Answer

Nature Sustainability

Question 6

Among ocean-based carbon dioxide removal approaches, which one is generally credited with the longest carbon-storage durability (of the order of centuries to millennia)?

Accepted Answer

Ocean alkalinity enhancement

Answer

Kelp / macroalgae cultivation

Answer

Mangrove (blue carbon) restoration

Answer

Seagrass meadow restoration

Question 7

Ocean alkalinity enhancement increases the ocean's uptake of atmospheric CO2 principally by which one of the following mechanisms?

Accepted Answer

Raising seawater total alkalinity and buffering capacity, shifting carbonate equilibria toward bicarbonate

Answer

Cooling surface waters so that CO2 becomes more soluble in the sea

Answer

Fertilising phytoplankton with iron to boost photosynthetic carbon fixation

Answer

Mechanically pumping CO2-rich surface water down into the deep ocean

Question 8

In India's Long-Term Low-Emission Development Strategy (LT-LEDS), the principal route relied upon to create an additional carbon sink of 2.5–3 billion tonnes of CO2-equivalent by 2030 is:

Accepted Answer

Additional forest and tree cover

Answer

Direct air capture and storage plants

Answer

Enhanced rock weathering on croplands

Answer

Ocean alkalinity enhancement along the coast

Question 9

With reference to India's climate commitments, consider the following statements:
1. India's forest-and-tree-cover carbon-sink goal was raised from 2.5–3 billion tonnes CO2-equivalent by 2030 to 3.5–4 billion tonnes CO2-equivalent by 2035.
2. Under the Panchamrit, India committed to meet 100% of its energy requirements from renewable energy by 2030.
3. India's net-zero target year of 2070 was announced at the COP26 summit in Glasgow in 2021.
Which of the statements given above is/are correct?

Accepted Answer

1 and 3 only

Answer

1 only

Answer

2 and 3 only

Answer

1, 2 and 3

Question 10

Under the Paris Agreement (Article 4), the long-term goal of achieving a 'balance between anthropogenic emissions by sources and removals by sinks' most precisely refers to:

Accepted Answer

Reaching net-zero emissions, where residual emissions are offset by removals into sinks in the second half of this century

Answer

A binding requirement that every country eliminate all of its emissions entirely by 2050

Answer

A complete ban on all carbon dioxide removal technologies in favour of source reduction only

Answer

An obligation resting exclusively on developed countries to cut their emissions to zero

Question 11

In India, systematic assessment and mapping of rock and mineral resources such as basalt — relevant to feedstock availability for enhanced weathering — is primarily carried out by the Geological Survey of India, which functions under which one of the following ministries?

Accepted Answer

Ministry of Mines

Answer

Ministry of Earth Sciences

Answer

Ministry of Environment, Forest and Climate Change

Answer

Ministry of Coal

UPSC Prelims Practice Questions — Doubts arise over rock-based climate mitigation scheme

Q1. In the context of carbon dioxide removal, 'enhanced rock weathering' is best described as which one of the following?

Q2. Consider the following: afforestation, direct air capture, enhanced rock weathering, and ocean alkalinity enhancement. How many of these are classified as carbon dioxide removal (CDR) techniques?

Q3. In research questioning enhanced weathering's efficacy, the process in which formation of secondary aluminosilicate (clay) minerals consumes alkalinity and re-releases CO2 is termed:

Q4. According to the 2026 research flagging a mechanistic flaw in enhanced weathering, weathering-derived alkalinity is most significantly lost when dissolved minerals become trapped, en route from soil to sea, in which one of the following?

Q5. The 2026 review paper titled 'Uncertainties of enhanced rock weathering for climate-change mitigation' was published in which one of the following journals?

Q6. Among ocean-based carbon dioxide removal approaches, which one is generally credited with the longest carbon-storage durability (of the order of centuries to millennia)?

Q7. Ocean alkalinity enhancement increases the ocean's uptake of atmospheric CO2 principally by which one of the following mechanisms?

Q8. In India's Long-Term Low-Emission Development Strategy (LT-LEDS), the principal route relied upon to create an additional carbon sink of 2.5–3 billion tonnes of CO2-equivalent by 2030 is:

Q10. Under the Paris Agreement (Article 4), the long-term goal of achieving a 'balance between anthropogenic emissions by sources and removals by sinks' most precisely refers to:

Q11. In India, systematic assessment and mapping of rock and mineral resources such as basalt — relevant to feedstock availability for enhanced weathering — is primarily carried out by the Geological Survey of India, which functions under which one of the following ministries?