Given below are two statements:
Statement I: Major emission of sulfur into the atmosphere is in the form of SO₂, but the longest-lived reservoir is OCS. Statement II: Sulfur in the atmosphere leads to aerosol formation and clouds and therefore cools the planet (Negative greenhouse effect).
Choose the most appropriate answer:

Correct option is A

The correct answer is (a) Both Statement I and Statement II are correct.
· Statement I: Correct. The primary emission of sulfur into the atmosphere is sulfur dioxide (SO₂), which is produced by volcanic activity, burning fossil fuels, and industrial processes. However, the longest-lived sulfur reservoir in the atmosphere is carbonyl sulfide (OCS) because it is relatively stable and has a longer atmospheric lifetime compared to SO₂.
· Statement II: Correct. Sulfur compounds in the atmosphere, particularly sulfate aerosols, contribute to cloud formation and reflect sunlight, leading to a cooling effect (referred to as a negative greenhouse effect). This process helps counteract some of the warming caused by greenhouse gases.
Information Booster: 1. Sulfur Dioxide (SO₂): A major pollutant released from burning fossil fuels and volcanic eruptions. It converts to sulfate aerosols.
2. Carbonyl Sulfide (OCS): The most stable sulfur gas in the atmosphere, with a lifetime of 2-6 years, making it the longest-lived sulfur reservoir.
3. Aerosols: Tiny particles that reflect sunlight, contributing to a cooling effect on the Earth’s surface.
4. Negative Greenhouse Effect: The cooling effect caused by aerosols reflecting solar radiation back into space.
5. Cloud Condensation Nuclei (CCN): Sulfate aerosols act as CCN, enhancing cloud formation and increasing cloud albedo (reflectivity).
Additional Knowledge: · SO₂ and Climate: Converts to sulfuric acid (H₂SO₄) in the atmosphere, contributing to acid rain and forming sulfate aerosols.
· OCS: Naturally produced by oceans and vegetation and can reach the stratosphere, where it contributes to sulfate formation.
· Cooling Impact: Large volcanic eruptions inject SO₂ into the atmosphere, leading to temporary global cooling (e.g., Mount Pinatubo in 1991).
· Anthropogenic Sources: Industrial activities are the largest human-caused sources of sulfur emissions.