Earth ozone layer due to the subsequent conversion of atmospheric into. The ozone layer blocks ultraviolet solar radiation, permitting life on land. Other atmospheric functions important to life include transporting water vapor, providing useful gases, causing small meteors to burn up before they strike the surface, and moderating temperature. This last phenomenon is known as the greenhouse effect: trace molecules within the atmosphere serve to capture thermal energy emitted from the ground, thereby raising the average temperature. Water vapor, carbon dioxide, methane, nitrous oxide, and ozone are the primary greenhouse gases in the atmosphere. Without this heat-retention effect, the average surface
Greenhouse and icehouse Earth years. However, this "super-greenhouse" eventually became an icehouse by the late Eocene. It was believed that the decline of CO caused this change, though there are possible positive feedbacks, or added influence that contributes to the cooling. The best record we have for a transition from an icehouse to a greenhouse period where plant life exists is during the Permian epoch that occurred around 300 million years ago. In 40 million years a major transition took place, causing the Earth to change from a moist, icy planet where rainforests covered the tropics, into a hot, dry, and windy location where