In climate change science, surface radiative forcing refers to the change in the balance between incoming and outgoing radiative energy at the Earth’s surface caused by some perturbation, such as greenhouse gases, aerosols, land-use change, or cloud modifications.

Understanding this concept is needed to understand the paper which follows:

• Radiative forcing (general): A measure of how a factor (like CO₂, methane, aerosols, or solar changes) alters the balance of incoming solar radiation and outgoing infrared radiation in the Earth’s climate system. Traditionally, it’s reported at the top of the atmosphere (TOA).
• Surface radiative forcing: Specifically measures how much the radiation flux (shortwave + longwave) at the Earth’s surface is perturbed.
  • Positive forcing at the surface: More net downward radiation → surface warms.
  • Negative forcing at the surface: Less net downward radiation → surface cools.

For example:

• Greenhouse gases: Increase downward longwave radiation at the surface → positive surface radiative forcing.
• Aerosols: Scatter and absorb sunlight before it reaches the ground → reduce downward shortwave radiation at the surface → negative surface radiative forcing.

This is important because surface radiative forcing directly affects surface temperature, evaporation, snow/ice melt, and ecosystems, while TOA radiative forcing is more about the global energy balance.

The following paper describes actual measurements of this phenomenon.