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?
Answer & explanation
Answer: (c) All three
All three activities are discussed as ways to capture and lock away carbon dioxide. Spreading crushed basalt (enhanced weathering) and adding lime to the sea (ocean alkalinity enhancement) are carbon-removal options assessed by the IPCC, and abandoned mines are listed among niche sites for underground CO2 storage.
- ✓ 1. Enhanced weathering spreads crushed silicate rock such as basalt on soil so that it reacts with atmospheric CO2. The IPCC cites estimates that spreading basalt on farmland in 12 countries could remove up to 2 GtCO2 a year by 2050.
- ✓ 2. Ocean alkalinity enhancement adds alkaline material such as lime to the sea so that it takes up and stores more CO2. The IPCC notes this idea goes back to a 1995 proposal to dissolve highly reactive lime in surface ocean water.
- ✓ 3. The IPCC's report on CO2 capture and storage names abandoned mines, along with basalts and salt caverns, as niche options for geological storage of captured CO2.
Remember · Enhanced weathering (crushed basalt on land), ocean alkalinity enhancement (lime in the sea) and storing captured CO2 underground, even in abandoned mines, are all discussed for carbon removal.
Sources
- IPCC AR6 Working Group III, Chapter 12: enhanced weathering (Cross-sectoral Perspectives) ↗ “Beerling et al. (2020) estimate that up to 2 GtCO2 yr–1 could be removed by 2050 by spreading basalt onto 35–59% (weighted mean 53%) of agricultural land of 12 countries. … The use of enhanced ocean alkalinity for carbon storage was first proposed by Kheshgi (1995) who considered the creation of highly reactive lime that would readily dissolve in the surface ocean and sequester CO2.”
- IPCC Special Report on Carbon Dioxide Capture and Storage, Chapter 5: Underground geological storage ↗ “Other geological media and/or structures – including basalts, oil or gas shale, salt caverns and abandoned mines – may locally provide niche options for geological storage of CO2.”
Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·