that has (and is) resulting from the use of fossil fuels along with a number of industrial and agricultural processes. All of these lead to a buildup in earth's atmosphere of what are called "greenhouse gases" - among which the most important are carbon dioxide, nitrous oxide, a variety of chlorofluorocarbons and methane - and even water vapor (Houghton 12).
Few of us had ever heard of this problem until the last decade, and it is really only in the last half-dozen years that that problem seems to have become widely acknowledged. However, scientists have understood the potential for such global warming for over a century, since the discovery that the greenhouse gases cited above lessen the escape rate of heat (or infrared radiation) into extra-atmospheric space.
These gases, now increasingly trapped against the earth in
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