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
Atmospheric carbon cycle lifetime of about eight years. This keeps the concentration of methane in the atmosphere relatively low and is the reason that it currently plays a secondary role in the greenhouse effect to carbon dioxide, despite the fact that it produces a much more powerful greenhouse effect per volume. Carbon dioxide () has a large warming effect on global temperatures through the greenhouse effect. Although individual CO molecules have a short residence time in the atmosphere, it takes an extremely long time for carbon dioxide levels to sink after sudden rises, due to e.g. volcanic eruptions or human activity and among