GLOBAL WARMING

CO2 is a greenhouse gas that strongly absorbs infrared radiation and plays a major role in warming the lower atmosphere. CO2 has been increasing steadily in the atmosphere due to the burning of fossil fuel. However, deforestation is also adding to this increase as tropical rain forests are cut down and replaced with plants less efficient in removing CO2 from the atmosphere. Trace gases sush as methane ,nitrous oxide and chlorofluorocarbons, all of which readily absorb infrared radiation. The increase in these gases is about equal to CO2 in its ability to enhance the atmospheric greenhouse effect. Increasing concentration of greenhouse gases will result in a mean global warming of surface air between 1.4 and 5.8 C above the average surface air temperature of 1990. The most abundant greenhouse gasses will produce a positive feedback on the climate system by enhancing the atmospheric greenhouse effect and accelerating the temperature rise.

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