Final answer:
The greenhouse effect is the main factor controlling our global climate system. Greenhouse gases help maintain the Earth's average temperature by trapping heat in the atmosphere.
Step-by-step explanation:
The main factor controlling our global climate system is the greenhouse effect. The greenhouse effect is a natural process that occurs when certain gases in the atmosphere trap heat from the sun, preventing it from escaping back into space. These gases, known as greenhouse gases, include water vapor, carbon dioxide, methane, and ozone. Greenhouse gases are important in helping maintain the Earth's average temperature because they absorb and emit radiation, which traps heat in the atmosphere and prevents it from being lost to space.