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.

The correct answer is B, because statements 1 and 2 are the ones supported by climate assessments of warming beyond 2 to 3 degrees above pre-industrial levels.

Statement 1 is correct. As warming rises, heat and drought stress cut vegetation productivity and speed up soil respiration, so the land biosphere can shift from a net carbon sink to a net carbon source. Statement 2 is also correct. Corals live close to their thermal tolerance, and sustained warming causes bleaching and widespread mortality, with severe reef loss projected well before 3 degrees.

• Statement 3 is wrong. Wetlands may shrink or change character in many regions, but the claim that all of them will permanently disappear is an overstatement that no assessment supports.
• Statement 4 is wrong. Some regions lose suitability for cereals, but shifting temperature and rainfall would move cultivation poleward and to higher altitudes. It would not vanish everywhere.

Core concept: climate feedbacks, tipping points and the carbon cycle, linked to the 1.5 to 2 degree goal of the Paris Agreement. For Mains, connect this to food security and the adaptation versus mitigation debate.

Trap: rejecting statement 2 because coral reefs seem remote from carbon or food issues, or accepting absolute words like all and anywhere without checking them.