Aerosol optical depth

Aerosols are tiny droplets, dust particles, that are suspended in the atmosphere. Examples of aerosols include dust, sea salts, volcanic ash, smoke from wildfires, and pollution from factories. Human activity has directly impacted their presence, abundance and distribution. 

Aerosols influence climate in two primary ways: by changing the amount of heat that gets in or out of the atmosphere, or by affecting the way clouds form. They also play a wider role in atmospheric chemistry and biogeochemical cycles in the Earth system, for instance, by carrying nutrients to ocean ecosystems. 

Clouds and aerosols continue to contribute the largest uncertainty to estimates and interpretations of the Earth’s changing energy budget. Better long-term observations of aerosols and aerosol-cloud interactions will help to constrain climate model uncertainty.