Volcanic eruptions influence climate primarily through which mechanism?

• A. Emission of aerosols that reflect sunlight leading to cooling
• B. Release of greenhouse gases that traps heat
• C. Increasing atmospheric oxygen
• D. Decreasing atmospheric moisture

Answer: (B)

Volcanic eruptions mainly affect climate through the sheer amount of sulfur dioxide they release into the stratosphere, where it forms sulfate aerosols. These tiny particles spread around the globe and are very effective at reflecting and scattering sunlight back into space. That reduces the amount of solar energy reaching the surface, causing a cooling effect that can last for a year or two after a large eruption.

Greenhouse gases from volcanoes do contribute to warming, but the amount of CO2 released during eruptions is relatively small compared with human emissions, and the immediate, noticeable climate signal from eruptions is the cooling driven by sulfate aerosols rather than warming from CO2. So the dominant mechanism by which volcanic eruptions influence climate is the reflection of sunlight by volcanic aerosols leading to cooling.