The gases that play a role in global warming include carbon dioxide, nitrous oxide, methane, chlorofluorocarbons and water vapor. These compounds are called greenhouse gases because their presence in the atmosphere can be compared to the actions of the glass surrounding a greenhouse.
The sun's light and heat penetrate Earth's atmosphere. Once the sun's energy reaches the Earth's surface, it gets radiated back into space. Greenhouse gases act like a blanket wrapped around the Earth; they prevent heat from escaping back into space. Because the heat is trapped by the atmosphere, global temperatures around the world start creeping up. This process is called global warming. The greenhouse gas that is the main culprit contributing to global warming is carbon dioxide.