EVIDENCE FOR PAST CLIMATE, IS CURRENT CHANGE HUMAN INDUCED?

Climate change is a reality and it has dominated the earths processes
since its creation. When referring to past climate changes it can be
seen that rapid climate changes such as that in Greenland, when vikings
roamed the terrain, there was no anthropogenic factors which caused
cooling and froze the once green terrain. Natural factors such as
emmision of volcanic carbon dioxide can cause a massive effect in terms
of dissallowing solar radiation to over heat the earth. Gases such as
methane, carbon dioxide, nitrous oxides, sulphates and nitrates are all
greenhouse gases which in effect heat the earth. Aerosols such as soot
and dust are also cuased by natural processes. Evidence of the much
feared ''ice age'' has been seen to have occured about about 10 000
years ago, and there was no anthropogenic disturbances then. An example
of climate change in the Western Cape is that of the reduction of fynbos
species, giving way to succulent karro. This is because of the drying
out and the rise of temperature which is sufficient for succulent
karoo.

However, as far as humans are concerned, their contribution to the
climate change is much greater. Evidence is this is the burning of
foosil fuels which emits larger amounts of gases such as carbon dioxiode
which has a negative effect. An example of this is that about during the
''ice age'' trees grew much faster, but until about 500 years ago, there
has been a reduction in tree growth rate. One hypothesis is that the
cause of drought in Ethiopa was caused by large countries such as the
U.S.A and Britain, emitting dangerous, polluted aerosols. These areas
around which droplets of water arrange themselves did'nt allow the rain
belt from producing rain in the Sahel. Another example is the aeroplane
contrails which can cause a ''pseudo'' cooling effect on the earth.

The crux of the matter is that humans and natural effects can cause
climate change. However, humans have raped the earths resources (fossil
fuels) and in so doing caused an unnatural increase in climate change.
Climate is always changing though but it is up to us to take control and
not exaggerate this deadly change. Things such as global climate models
helps us identify the causes and effects of factors which causes climate
change.One of the major problems the earth is facing today is El nino
bwhich is a disruption in the ocean-atmosphere currents which which
could have detrimental effects on the rest of the world even though it
is situated in the Pacific ocean. It is still unknown whether it is
natural or caused by anthropogenic effects.

DALE OVERMEYER

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