Radiation and Global Warming

Global warming (also called the greenhouse effect)GREENHOUSE EFFECT?
describes the gradual increase of the airHuman population growth and related industrial
temperature in the earth's lower atmosphere.expansion, have led to greater air pollution and a
A greenhouse is made entirely of glass. Whenchange in the composition of the earth's
sunlight (shortwave radiation) strikes the glass,atmosphere. Some pollutants enhance the natural
most of it passes through and warms up thegreenhouse effect, resulting in increased global
plants, soil and air inside the greenhouse. As theseatmospheric temperatures.
objects warm up they give off heat, but theseDID YOU KNOW?
heat waves have a much longer wavelength than* Many nations are reluctant to commit
the incoming rays from the sun. This longwavethemselves to the costly changes necessary to
radiation cannot easily pass through glass, it is re-reduce greenhouse gas emissions in view of the
radiated into the greenhouse, causing everything inuncertainties surrounding the precise effects of
it to heat up.global warming.
THE NATURAL GREENHOUSE EFFECT* Atmospheric CO2 concentration will be double
The term greenhouse effect is used to describethe pre- industrial concentration in about 60 years
the warming effect that certain gases have ontime.
the temperature of the earth's atmosphere under* Sea levels are likely to rise 60 mm each decade
normal conditions.over the next century.
Sunlight (shortwave radiation) passes easily* Two-thirds of South Africa's population rely
through the earth's atmosphere. Once it strikesmainly on coal as an energy source. Providing
and warms the earth's surface, longwave radiationelectricity to these people will result in a nett
is given off and goes back into the atmosphere.reduction in CO2 emissions as a consequence of
While some of this longwave radiation or heatimproved overall energy efficiency.
escapes into space, most of it is absorbed or heldWHAT WE CAN DO
by carbon dioxide and other gases that exist inReduction of greenhouse gas emissions requires
small quantities in the atmosphere. Thus thesegreater energy efficiency. Industrialists and
gases form a `blanket' that keeps the earth angovernments have a key role to play here. But
average of 33 degrees centigrade warmer than itwhat can the individual do?
would be if this greenhouse effect did not occur.- Reduce electricity consumption.
Without these gases the whole planet would be- Use lift clubs, public transport, bicycles or your
an icy wasteland with an average temperature offeet for transport.
16 degrees centigrade below freezing!- Reduce, reuse, recycle, and save energy - the
HOW HAVE PEOPLE ALTERED THEmanufacture of all products requires energy.