What Do We Know?
As you might imagine, there are many different greenhouse gases in the atmosphere. However, not all greenhouse gases are created equal - some are more important than others in contributing to overall atmospheric warming. The importance of a greenhouse gas depends upon three factors:
- The concentration of the gas in the atmosphere.
- The region of the IR spectrum that the gas absorbs and how strongly it absorbs IR radiation.
- The atmospheric lifetime of the gas (i.e., how long the gas stays in the atmosphere).
Why are these factors important? To answer this question, we must first gain a basic understanding of Earth’s radiation balance.