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The total global environment consists of four major realms: a gaseous atmosphere, liquid hydrosphere, solid lithosphere, and living biosphere.
From space, Earth's atmosphere looks like a thin blue veil. (10k jpeg) This fragile, nearly transparent envelope of gases supplies the air that we breathe each day. It also regulates the global temperature and filters out dangerous levels of solar radiation. In recent years, scientific research has shown that the chemical composition of the atmosphere is changing because of both natural and human induced causes. There is growing concern over the impact of human activities. Mankind may be increasing levels of heat absorbing gases, thereby contributing to global warming and destroying ozone, the fragile atmospheric ingredient that shields the planet from ultraviolet (UV) radiation.
