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Prelims 2018 paper

UPSC CSE Prelims 2018 · Question 65 · Climate change & agreements

Which of the following statements best describes "carbon fertilization"?

Prelims 2018 · Q65

Climate change & agreements Easy

Which of the following statements best describes "carbon fertilization"?

Answer & explanation

Answer: (a) Increased plant growth due to increased concentration of carbon dioxide in the atmosphere

Carbon fertilization (CO2 fertilization) means plants photosynthesise more, and often grow more, when the CO2 in the air rises. CO2 acts like a nutrient for plants, so the effect is on plant growth. Whether the extra photosynthesis becomes real growth still depends on temperature, moisture and nutrients.

  • ✓ (a) The IPCC defines CO2 fertilization as the increase of plant photosynthesis and water-use efficiency in response to higher atmospheric CO2; it can lead to more plant growth and carbon storage.
  • ✗ (b) Rising temperature from extra CO2 is the greenhouse effect (global warming), a different process.
  • ✗ (c) Falling ocean pH because the sea absorbs CO2 is ocean acidification, a separate consequence of higher CO2.
  • ✗ (d) 'Fertilization' refers to boosted plant growth, not to all living things adapting to climate change.

Remember · Carbon (CO2) fertilization = more atmospheric CO2 boosts plant photosynthesis and growth; warming is the greenhouse effect and ocean pH fall is acidification.

Sources

  • IPCC AR6 Working Group I, Annex VII: Glossary ↗ “The increase of plant photosynthesis and water-use efficiency in response to increased atmospheric carbon dioxide (CO2) concentration. … A reduction in the pH of the ocean, accompanied by other chemical changes (primarily in the levels of carbonate and bicarbonate ions)”

Question and answer: UPSC's official GS Paper I (2018, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·

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