Environmental Impact Modelling

Abstract

The greenhouse effect is a well known phenomenon and can be simply explained as follows. As the radiation from the sun makes contact with the earth, some of it is absorbed and some of it is reflected back into space. Surfaces such as the upper surfaces of clouds and snow are particularly efficient at reflection whereas other surfaces such as the sea and forest are not. As the earth is warmed by this radiation, it is emitted back into the atmosphere but at a longer wavelength. Some of this long wavelength radiation is absorbed and then re-emitted by trace gases. It is this transparency of trace gases to (short-wave) incoming radiation contrasting with the blocking of (long-wave) outgoing radiation by the same gases that leads to the warming, commonly called the greenhouse effect. Research indicates that without the greenhouse effect, the temperature of the earth would be 33°C less than the present. The problem now of course that mankind is pumping carbon dioxide and other gases into the atmosphere whilst eliminating large areas of equatorial forest the trees in which provide natural absorbers for these gases. Other effects such as acid rain are also important and are a consequence gaseous discharges from man’s industrial activities. Thus the greenhouse effect is enhanced and the earth is heating up. The term “global warming” is the phrase which has been popularised in the press. Most think that global warming will take place and result in an increase in the earth’s average temperature, the rate of 0.3°C per decade has been quoted.