BCB311

Wednesday, March 08, 2006

GLOBAL DIMMING- SHOULD WE BE CONCERNED?

Global dimming is a relatively new phenomenon that is not fully
understood by the general public but has caused some major impacts on
the climate, global dimming is caused by having large particles or
aerosols in the atmosphere that provide sites for water to condense in
clouds, smaller particles, smaller particles can only held small amounts
of water droplets on it but the aerosols and other larger particles
allow more water droplets to form and stay in the atmosphere and reflect
incoming radiant energy from the sun, which causes a cooling affect on
the Earth, pollution particles from the burning of fossil fuels
contribute to global dimming.

Global dimming works oppositely to global warming, which increases the
surface temperature of the earth between 1960 -1990 but recent evidence
indicate that the trend reversed, both these phenomenon is caused by the
burning of fossil fuels, therefore in the theory these two phenomenon
would cancel each other out and the climate of the earth would remain in
constant temperature, but the combustion of fossil fuels releases
harmful gases that threaten human life and most first world countries
have begun to implement strategies to reduce the pollutants in the
atmosphere by using catalytic converters on cars, the use of unleaded
fuels and other methods to reduce CO2 levels and other harmful gases in
the atmosphere.

This improvement on air quality has reduced the amount of aerosols in
the atmosphere and has reduced the affect of global dimming but has
increased the effect of global warming.

It's now believed that global dimming is responsible for the 1984
Ethiopian Famine, which has been called by a BBC reporter as being :
"The closest place to hell on earth", which saw hundreds of
thousands of people dying of starvation, but how does global dimming,
which cools down the earth cause drought and famine?

The answer is that this phenomenon reduces the amount of incoming
photons from the sun to the earth and reduces the PAN evaporation rate
reducing the amount of photons hitting the ocean and replenishing the
water cycle of Ethiopia.

Today many studies are being conducted about global dimming and what
really causes it, some scientists believe that aero planes create a
blanket of aerosols over the earth and therefore creating a cooling
affect which was seen after the September 11th terrorist attacks, where
all air crafts were grounded for a week.

Global dimming is an issue that must be taken seriously because we do
not fully understand climate and the rate at which the climate is
changing over the world and the consequences of the these changes are
going to be disastrous on future generations

Reviewed by: Lee Mervin Mentoor, 2111335

Ashton Mouton
Student Number: 2432509
University of the Western Cape
Private Bag X17
Bellville 7535

E-mail: 2432509@uwc.ac.za

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