UPSC Prelims 2010 Q61: Environment & Ecology – Climate Change & Greenhouse Gases
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer: (a) 1 only
Explanation
How rice cultivation itself contributes to global warming
The question asks specifically about rice cultivation's own contribution, which points to one dominant, well-documented pathway.
| Statement | Verdict | Reason |
|---|---|---|
| 1. Anaerobic conditions in paddies cause methane emission | Correct | Flooded, waterlogged (anaerobic) rice paddies create ideal conditions for methane-producing bacteria, making methane the signature greenhouse gas directly tied to rice cultivation itself |
| 2. Nitrogen-based fertilizers release nitrous oxide | Incorrect | Nitrous oxide emission from nitrogen fertilizer is a general cropland fertilization issue, applicable to many crops — not a reason specific to rice cultivation's own distinguishing contribution to warming |
Rice cultivation's specific greenhouse gas link:
| Point | Detail |
|---|---|
| Rice-specific pathway | Methane, from anaerobic/waterlogged paddy soils |
| General cropland issue (not rice-specific) | Nitrous oxide, from nitrogen fertilizer use on any crop |
Answer: (a) 1 only.
Why each option is right or wrong
- (a) CORRECT. Methane from anaerobic paddy conditions is the pathway specifically and distinctively tied to rice cultivation.
- (b) Incorrect. Nitrous oxide from fertilizer applies broadly to many crops, not specifically to rice cultivation's distinguishing warming contribution.
- (c) Incorrect. Statement 2 is not rice-specific, so 'both' is wrong.
- (d) Incorrect. Statement 1 is accurate and rice-specific, so 'neither' is wrong.
Key point
Rice cultivation's distinctive contribution to global warming is METHANE from anaerobic, waterlogged paddy soils — nitrous oxide from nitrogen fertilizer is a general cropland issue, not specific to rice.
Remember
Rice cultivation's distinctive global warming contribution: methane from anaerobic paddy soils — not nitrous oxide, which is a general fertilizer issue.
Common mistakes
- Treating a general fertilizer-related emission (nitrous oxide) as specific to rice, when it applies to many crops.
- Missing that the question asks for what is specific to rice cultivation, not greenhouse gases from agriculture broadly.
- Not connecting anaerobic/waterlogged conditions specifically to methane-producing bacteria in paddies.
Exam tip
Rice cultivation's SPECIFIC climate link = methane (from waterlogging). Nitrous oxide from fertilizer is a general cropland issue, not rice-specific.
Sources
- Intergovernmental Panel on Climate Change — Climate Change 2007: Mitigation of Climate Change, Chapter 8 (Agriculture)
- Intergovernmental Panel on Climate Change — 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 4 (Agriculture): rice cultivation