Global warming poses a serious threat to life on earth. Although scientists are unclear about the exact implications of global climate change, most experts agree that plant communities, tropical landscapes, wildlife habitat, sea levels, weather patterns, and human mortality would be negatively impacted. Despite these findings, industrialized nations are reluctant to curb their dependence on carbon-based fuels which contribute to an intensified greenhouse effect.
The greenhouse effect describes the accumulation of greenhouse gases which regulate the temperature on earth. A greenhouse gas is any molecule that absorbs radiation in the wavelength region at which the earth radiates heat to outer space. The greenhouse gases include carbon dioxide, methane, nitrous oxide, ozone (in the troposphere), and the chlorofluorocarbons CFC-11 and CFC-12. Although transparent to sunlight, greenhouse gases, along with water vapor, absorb infrared heat. The transparency of greenhouse gases permits the relatively unimpeded passage of sunlight through the atmosphere. By absorbing heat, greenhouse gases warm the lower atmosphere and global surface while cooling the upper atmosphere (the stratosphere). Carbon dioxide is the most important contributor to the greenhouse effect, an estimated 60 percent. Methane accounts for 15 percent, nitrous oxide 5 percent, tropospheric ozone 8 percent, CFC-11 4 percent, and CFC-12 8 percent (1:54).
The greenhouse effect is so named because it operates on the same principle as a garden greenhouse works. Sunlight penetrates the transparent glass of the greenhouse roof and the humid atmosphere of the greenhouse interior. Plants and soil absorb the sun's light. The lightwaves are transformed into infrared radiation (heat) which is absorbed within the atmosphere of the greenhouse and not permitted to escape through the greenhouse roof. This physical mechanism slows down the rate of radiative cooling in th...