Q. 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.

  • 1 only
  • 1 and 2 only
  • 2, 3 and 4 only
  • 1, 2, 3 and 4

Answer: (b) 1 and 2 only

Notes:

  • Terrestrial biosphere
    • It has an important role in regulating atmospheric composition and climate.
    • It can release or absorb the greenhouse gases, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O).
    • It regulates fluxes of energy, water and aerosols between the earth surface and atmosphere.
    • Carbon is exchanged most quickly with the atmosphere, although small amounts of carbon leave the terrestrial biosphere and enter the oceans as dissolved organic carbon.
  • If the global temperature increases beyond 3 °C above the pre-industrial level, the terrestrial biosphere tends toward a net carbon source. Taiga and temperate forests act as an important carbon sink; these forests would turn into a carbon source.
  • Corals
    • These are invertebrate animals belonging to a large group of colourful and fascinating animals called Cnidaria. 
    • Coral reefs are extremely diverse marine ecosystems hosting over 4,000 species of fish, massive numbers of cnidarians, molluscs, crustaceans, and many other animals.
    • As temperatures rise, mass coral bleaching events occur. If the temperature keeps on rising, widespread coral mortality will occur.
  • The temperate regions can still survive if the temperature increases. The temperate zones are where the widest seasonal changes occur. The vegetation can survive there.
  • The weather should be warm and moist during the early stage of growth of cereals. Hence, the cultivation of cereals would still be possible if the temperature rises.