Volcanic eruptions can influence climate through aerosols and gases. Which statement is correct about sulfate aerosols and CO2?

• A. They trap heat causing long-term warming
• B. They reflect sunlight causing short-term cooling
• C. They increase precipitation only
• D. They have no climate effect

Answer: (B)

When a volcano erupts, it pumps sulfur dioxide into the atmosphere, which converts into sulfate aerosols that spread around the globe in the stratosphere. These tiny particles are very effective at scattering and reflecting sunlight, which increases the Earth’s albedo and reduces the amount of solar energy reaching the surface. That creates a short-term cooling effect, typically lasting months to a few years.

CO2 released during eruptions does trap heat, contributing to warming, but its effect unfolds over longer timescales. The immediate, dominant radiative impact right after major eruptions is the cooling from sulfate aerosols, which is why this statement is the best description. The other options don’t fit because sulfate aerosols don’t cause long-term warming, they don’t imply only increased precipitation, and they certainly do have a climate effect.