Atmosphere of Earth development of animals. Today's atmosphere contains 21% oxygen, which is great enough for this rapid development of animals. "Air pollution" is the introduction into the atmosphere of chemicals, particulate matter or biological materials that cause harm or discomfort to organisms. Stratospheric ozone depletion is caused by air pollution, chiefly from chlorofluorocarbons and other ozone-depleting substances. The scientific consensus is that the anthropogenic greenhouse gases currently accumulating in the atmosphere are the main cause of global warming. On October 19, 2015 NASA started a website containing daily images of the full sunlit side of Earth on http://epic.gsfc.nasa.gov/. The images are taken
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