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 * Global warming** is a significant increase in the Earth's climatic temperature over a relatively short period of time as a result of the activities of humans


 * What is happening?** Humans have been pouring huge amounts of harmful gases into the environment. Power plants, vehicles deforestation, excessive burning of fossil fuels are major contributors of greenhouse gases such as carbon dioxide and methane.

© **Carbon dioxide:** o A by product of combustion of organic matter. Today, human activities are pumping huge amounts of carbon dioxide into the atmosphere, resulting in an overall increase in concentration. o This increase in concentrations is considered the primary factor in global warming because carbon dioxide absorbs infrared radiation from the sun. o most energy that escapes earth’s atmosphere comes in this form, so extra carbon dioxide means more heat from the sun is absorbed, and thus increase in temperature

© **Nitrous Oxide**: o derived from large amounts of nitrogen fertilizer on crops o by product of combustion o also absorbs much more heat than carbon dioxide

© **Methane** o a combustible gas, a main component of natural gas o occurs naturally through the decomposition of organic materials and often encountered in the form of “swamp gas” o man made by § extracting it from coal § large herds of livestock (digestives gases) § bacteria from rice paddies § decomposition of garbage especially in landfills o also acts like carbon dioxide, absorbing infrared energy and heat energy on earth


 * Read more at:** http://science.howstuffworks.com/global-warming.htm!