What is the "Greenhouse Effect"? As explained
in the page on Air Pollution, carbon dioxide is
constantly removed from the atmosphere by green plants and algae during
photosynthesis. But it is also released back into the air
when plants and animals respire, when organisms decay, or when any organic material is
burned (such as in burning of forests, either accidentally or purposely). Until
recently this exchange has been in balance, with neither removal nor production being
greater. However, since 1860 scientists have discovered that the amount of carbon
dioxide in the atmosphere has increased almost 25%. Most of
this increase can be contributed to human activities like burning of fossil
fuels and the clearing of forests for development. From 1957
to 1995 alone a 15% increase in carbon dioxide has been measure in
Hawaii. During this same time frame, global temperatures have also
risen steadily.
What does this mean for our planet? While there are a
few positive effects, the majority of changes produced will be negative as indicated in
the tables below.
POSITIVE EFFECTS OF GREENHOUSE GASES
1) Fossil fuel demand in the extreme latitudes would be reduced because heating of
our homes would be reduced.
2) Some areas that are currently uninhabitable or unusable for farmland might become
suitable for these uses due to warming and weather changes. Some areas could receive much
more rainfall than they do currently. Food production could be increased.
3) There might be an increase in yield of some crops due to the increase in the
photosynthetic rate of plants to try to keep up with the increased carbon dioxide in
the atmosphere.
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NEGATIVE EFFECTS OF GREENHOUSE GASES
(Owen et al. 475)
Most scientists believe that the increase in global temperatures will
cause the polar ice caps and glaciers to begin to melt. This will cause sea
levels to rise. In the past 100 years ocean levels have already risen about one
foot. Because we have built our cities right on the coastlines, many of them would
be in peril of serious flooding – if not outright collapse.
The rise and expansion of the sea would also allow storm surges and
hurricane waves to proceed
further inland, causing more
damage.
Temperature increases can also lead to changes in weather patterns,
precipitating more frequent and severe storms. The costs to
protect ourselves from flooding and storm damage could be enormous.
Many aquifers which provide our drinking water could become contaminated
with salt water, thus decreasing the
available supply.
Weather patterns will definitely be changed by this process. Some
areas will become drier while others will become wetter. While
some areas will be able to increase (or begin) crop production, some major
crop producing areas could fail due to less favorable growing conditions.
If too much drying occurs in areas, droughts could
follow. This could lead to more disasters like the Dust Bowl days in the
prairie states of the United States earlier in our history.
The rise in temperature is occurring relatively quickly.
Many animal species cannot adapt to this sudden fluctuation. It is possible
that many species will become extinct because of this stress. Some ecosystems like
coral reefs, which are already living at the upper edge of their temperature tolerances,
are very usceptible to temperature changes. These ecosystems could suffer
severe damage or simply die out altogether.
Diseases which are currently restricted to tropical areas could spread to
other areas as they become warmer and more receptive to the agents
which carry the diseases.
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There has been no real consensus among scientists yet as to
exactly what will occur over the next 100 years as the greenhouse gases accumulate.
Yet, it is certain that the results will ultimately be detrimental to the planet.