Many aspects of Earth’s climate are dependent upon atmospheric composition and biogeochemical cycling.
- The amount of solar energy absorbed or radiated by earth is modulated by the atmosphere and depends on its composition. Greenhouse gases – such as water vapor, carbon dioxide, and methane – occur naturally in small amounts and absorb and release heat energy more efficiently than abundant atmospheric gases like nitrogen and oxygen. Small increases in carbon dioxide concentration have a large effect on the climate system.
- The abundance of greenhouse gases in the atmosphere is controlled by biogeochemical cycles that continually move these components between their ocean, land, life, and atmosphere reservoirs.
- Airborne particulates, called “aerosols,” have a complex effect on Earth’s energy balance: they can cause both cooling, by reflecting incoming sunlight back out to space, and warming, by absorbing and releasing heat energy in the atmosphere. Small solid and liquid particles can be lofted into the atmosphere through a variety of natural and manmade processes, including volcanic eruptions, sea spray, forest fires, and emissions generated through human activities.