Which of the following are responsible for global cooling?

1.Halocarbons

2.Stratospheric ozone

3.Tropospheric ozone

4.Sulphate aerosols

5.Black carbon

A1, 2 & 4 only

B2 & 4 only ✓ Correct

C2, 4 & 5 only

D3 & 4 only

Correct answer: (B) 2 & 4 only

Explanation

Stratospheric ozone and sulphate aerosols exert a net cooling influence on the climate.

Statement 2 holds, as changes in stratospheric ozone contribute a net negative radiative forcing.

Statement 4 holds, since sulphate aerosols scatter incoming sunlight back to space.

Statement 1 fails, as halocarbons are strong warming agents.

Statement 3 fails, because tropospheric ozone is a warming greenhouse gas.

Statement 5 fails, since black carbon absorbs heat and warms the atmosphere.

Sulphate aerosols from major volcanic eruptions have briefly cooled global temperatures in the past.

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