Which statement about greenhouse gases is false?

• A. They trap infrared radiation emitted by Earth's surface.
• B. They include carbon dioxide, methane, and water vapor.
• C. They are responsible for the natural greenhouse effect.
• D. They are the primary source of planetary albedo.

Answer: (D)

Greenhouse gases trap infrared radiation emitted by Earth's surface, which is the mechanism behind the natural greenhouse effect. They include carbon dioxide, methane, and water vapor, with water vapor playing a major role in absorbing heat and warming the lower atmosphere. This IR trapping keeps the surface warmer than it would be otherwise. However, they are not the primary source of planetary albedo. Albedo reflects how much solar energy is reflected back into space in the visible spectrum, and is mainly determined by clouds, ice and snow, and various surface types. Greenhouse gases are largely transparent to visible light, so they don’t drive the planet’s reflectivity.