What is a direct effect of atmospheric aerosols on climate?

What is a direct effect of atmospheric aerosols on climate?

• A. They scatter and/or absorb sunlight, cooling or warming the surface
• B. They create precipitation directly
• C. They increase greenhouse gas concentrations
• D. They have no effect

Answer: (A)

Aerosols directly change the Earth’s energy balance by interacting with radiation. They scatter sunlight back to space, which reduces the amount of solar energy reaching the surface and tends to cool it. Some aerosols also absorb sunlight, warming the air where they reside and the surrounding atmospheric layer, which can alter temperatures aloft and affect surface climate as well. Because of these direct radiative interactions, the surface can be cooled or warmed depending on the mix of aerosol types and their distribution. This is different from other ways aerosols influence climate, such as cloud formation or precipitation processes (indirect effects) or any change in greenhouse gas concentrations. So the statement that aerosols scatter and/or absorb sunlight, cooling or warming the surface, captures the direct radiative effect.

Aerosols directly change the Earth’s energy balance by interacting with radiation. They scatter sunlight back to space, which reduces the amount of solar energy reaching the surface and tends to cool it. Some aerosols also absorb sunlight, warming the air where they reside and the surrounding atmospheric layer, which can alter temperatures aloft and affect surface climate as well. Because of these direct radiative interactions, the surface can be cooled or warmed depending on the mix of aerosol types and their distribution. This is different from other ways aerosols influence climate, such as cloud formation or precipitation processes (indirect effects) or any change in greenhouse gas concentrations. So the statement that aerosols scatter and/or absorb sunlight, cooling or warming the surface, captures the direct radiative effect.