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.
Answer & explanation
Answer: (b) 1 and 2 only
The answer is (b), 1 and 2 only. The IPCC's Fourth Assessment Report lists the impacts expected as warming rises. These include widespread coral mortality and the terrestrial biosphere tending toward a net carbon source. The same report projects only partial losses of coastal wetlands and falling cereal productivity in some regions, not total disappearance or impossibility. So statements 1 and 2 hold, while 3 and 4 are exaggerations.
- ✓ 1. The IPCC impacts chart lists 'Terrestrial biosphere tends toward a net carbon source' at higher warming levels. This means land ecosystems begin releasing more carbon than they absorb.
- ✓ 2. The chart shows a progression as warming rises: increased coral bleaching, then most corals bleached, and then widespread coral mortality.
- ✗ 3. The IPCC projects about 30% of global coastal wetlands lost, not all wetlands. A permanent disappearance of all global wetlands is not a projected outcome.
- ✗ 4. The IPCC projects cereal productivity decreasing in low latitudes and in some regions. It does not say cereal cultivation becomes impossible anywhere in the world.
Remember · IPCC AR4: at high warming, corals face widespread mortality and the land biosphere tends toward a net carbon source. Wetland and cereal losses are partial, never total.
Sources
- IPCC Fourth Assessment Report, Synthesis Report (full report): impacts associated with global average temperature change ↗ “Increased coral bleaching Most corals bleached Widespread coral mortality Increasing species range shifts and wildfire risk Terrestrial biosphere tends toward a net carbon source as: ~15% ~40% of ecosystems affected … About 30% of global coastal wetlands lost‡ Increased water availability in moist tropics and high latitudes”
Question: UPSC Civil Services (Preliminary) 2014, General Studies Paper I. Explanation: Minimalist IAS, checked 25 Oct 2026 (how we verify). ·
