Do small particles in the air (aerosols) have a warming or cooling effect on the climate?

Aerosols are small particles or droplets that float in the air. They are emitted by both natural events and human activities. Some aerosols cool the climate, and others have a warming effect. Image credits, left to right: Saiho/Pixabay, olegkamenskij20120/Pixabay, USGS. Image design: NASA/JPL-Caltech

Both! In general, light-colored particles in the atmosphere will reflect incoming sunlight and cause a cooling effect. Dark-colored particles absorb sunlight and make the atmosphere warmer. Because different types of particles have different effects, aerosols are a hot topic in climate research.

Learn more about the climate effects of aerosols.