What is the greenhouse effect?

The greenhouse effect is a natural phenomenon that helps regulate the Earth’s temperature. Greenhouse gases (e.g., carbon dioxide, methane, nitrous oxide, chlorofluorocarbons) act like an insulating blanket, trapping solar energy that would otherwise escape into space. Without this natural "greenhouse effect," temperatures would be about 60ºF lower than they are now, and life as we know it today would not be possible. However, human activities, primarily the burning of fossil fuels and clearing of forests, have enhanced the natural greenhouse effect, causing the Earth’s average temperature to rise.