Greenhouse+Gases

** Greenhouse Gases ** Greenhouse gases naturally "blanket" the earth and keep it about 33 degrees Celsius warmer than it would be without the gases in teh atmosphere. It is refered to as the "Greenhouse Effect." Throughout the past century, the earth has increased in temperature by .5 degrees Celsius. Scientists believe it is an increase in concentration of the main greenhouse gases : -Carbon Dioxide -Methane -CFCs -Water Vapor -Nitrous Oxide -Ozone Layer 

** Carbon Dioxide ** Carbon dioxide is a colorless, odorless, non-flammable gas. It is the most prominent greenhouse gas in Earth’s atmosphere. It is recycled through the atmosphere by the process of photosynthesis. Photosyntheisis is the process of green plants and other organisms transforming light energry into chemical energy. Light energy is trapped and then used to convert carbon dioxide, water, and other minerals into oxygen and energy rich compounds. Carbon dioxide is emitted into the air as humans exhale, burn fossil fuels, and deforest the planet, Humans add over 30 billion tons of carbon dioxide into the atmosphere. Since 1750 it is up 30% by these processes. The United States continues to emit more than any other country in the world. It accounts for 25% of all emissions.

Fossils fuels were created by the decay of plants from millions of years ago. Fossil fuels are used for coal, oil, and natual gas to generate electricity, heat homes, power factories, and run cars. Fossil fuels contain carbon so when they are burned they combine with oxygen and form carbon dioxide. The World Energy Council reported that between 1990 and 1995 the global carbon dioxide emissions rose 12% from the burning of fossil fuels.

[]  **Methane** Methane is a colorless, odorless, flammable gas that is formed when plants decay and there is very little air. When methane is inhaled it is not toxic, but it can produce suffocation by reducing the concentration of oxygen inhaled. It is often referred to as swamp gas because it is abundant around swamps, since there is a lot of decaying matter in swamps. Methane is produced naturally by bacteria that break down organic matter in wetlands. Methane is also produced naturally by cows, sheep, goats, buffalo, termites, and camels. Since 1750 methane has doubled and potentiall could doublt again by 2050. Every year humans add 350-500 million tons of methane in the air by rising livestock, coal mining, drilling for oil and natural gas, rice cultivation, and garbage sitting in land fills. Methane stays in the atmosphere for only ten years but traps 20 times more heat than Carbon dioxide.

CFCs are several organic compounds composed of carbon, fluorine, chlorine, and hydrogen. They were developed during the 1930s and have been used for aerosol spray-propellants, refrigerants, solvents, and foam-blowing agents. Studies done in the 1970s revealed that CFCs posed a threat to the environment. The CFCs accumulate in the stratosphere, where they have a poisonous effect on the ozone layer. The stratospheric ozone layer shields living organisms from the harmful effects of ultraviolet radiation from the sun. A relatively small decrease in the stratospheric ozone concentration can result in an increased number of skin cancer in humans and in genetic damages in organisms. In the stratosphere the CFC molecules break down by the action of solar ultraviolet radiation and release their chlorine atoms. These then react with the ozone molecules, resulting in their removal.
 * CFC's **

Due to the growing concern over stratospheric ozone depletion, a ban was imposed on the use of CFCs in aerosol-spray dispensers in the 1970s by the United States and Canada. In 1990, 93 other nations agreed to end production of ozone depleting chemicals by the end of the century.

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