The scientific view is that the increase in global temperature should not exceed 2 °C above pre-industrial level. If the global temperature increases beyond 3 °C above the pre-industrial level, what can be its possible impact/impacts on the world? 1. Terrestrial biosphere tends toward a net carbon source. 2. Widespread coral mortality will occur. 3. All the global wetlands will permanently disappear. 4. Cultivation of cereals will not be possible anywhere in the world. Select the correct answer using the code given below.
- (a) 1 only
- (b) 1 and 2 only ✓ UPSC's answer
- (c) 2, 3 and 4 only
- (d) 1, 2, 3 and 4
Why the answer is (b)
• IPCC assessments project that beyond about 3 °C of warming the terrestrial biosphere could switch from absorbing to emitting carbon as forests die back and soils release CO2 (statement 1), and that widespread coral bleaching and mortality would occur — corals are severely hit even at 1.5–2 °C (statement 2).
• Statements 3 and 4 are exaggerations: wetlands would be degraded but not all permanently lost, and cereal cultivation would shift poleward and decline in the tropics, not become impossible everywhere.
• Hence 1 and 2 only, option (b).
Why the other options are wrong
- (a) 1 only
- Coral mortality is also a projected impact.
- (c) 2, 3 and 4 only
- Statements 3 and 4 overstate the impacts.
- (d) 1, 2, 3 and 4
- Statements 3 and 4 are exaggerations.
Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2014, held on 24 August 2014. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.