Previous Year Question
In the context of which of the following do some scientists suggest the use of cirrus cloud thinning technique and the injection of sulphate aerosol into stratosphere?
Creating artificial rains in some regions
Reducing the frequency and intensity of tropical cyclones
Reducing the adverse effects of solar wind on the Earth
Reducing the global warming
Correct Answer: D
Detailed Solution
Cirrus cloud thinning and stratospheric sulphate aerosol injection are viewed as proposed climate-intervention or geoengineering techniques for limiting global warming.
Both techniques aim to reduce temperature by changing the Earth’s radiation balance, but their mechanisms are different.
Cirrus clouds are thin clouds formed at very high altitudes and are composed mainly of ice crystals.
Cirrus clouds can trap a portion of the outgoing longwave infrared radiation and redirect it towards the Earth. Therefore, their net effect is generally warming.
Cirrus cloud thinning proposes modifying the formation and size of ice crystals with the help of suitable ice-nucleating particles.
Its objective is to reduce the lifetime or optical thickness of cirrus clouds so that more of the Earth’s longwave radiation can escape into space.
It is different from the conventional cloud-seeding process used for creating artificial rainfall.
Stratospheric sulphate aerosol injection proposes delivering sulphur dioxide or other sulphur-containing substances into the stratosphere.
These substances form sulphate aerosols in the stratosphere, which can reflect a portion of incoming solar radiation back into space.
This would reduce the amount of solar energy absorbed by the Earth and may temporarily lower the global average temperature.
This effect is considered similar to the short-term global cooling produced by sulphate aerosols following major volcanic eruptions.
These techniques do not remove carbon dioxide from the atmosphere and do not solve CO₂-related problems such as ocean acidification.
Their potential risks include changes in rainfall and monsoon patterns, effects on stratospheric ozone, regional climate inequality and rapid warming if the intervention is stopped abruptly.
They may have some effect on tropical cyclones, but reducing the frequency or intensity of cyclones is not their primary proposed objective.
These techniques have no connection with controlling the effects of solar wind.
Therefore, the proposed objective of both techniques is reducing global warming.