Atmosphere of Earth Atmosphere of Earth The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation). By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water
Regulation of greenhouse gases under the Clean Air Act time, whether due to natural variability or as a result of human activity." In its latest assessment on climate change, the IPCC found that "warming of the climate system is unequivocal" and that the anthropogenic component of this warming over the last thirty years has likely had a discernible influence on observed changes in many physical and biological systems. The properties of greenhouse gases are such that they retain heat in the atmosphere, which would otherwise escape to space. GHGs accumulate in the atmosphere when they are emitted faster than they can be naturally removed, and that accumulation prompts changes