Greenhouse
Gases & Global Warming
 Human
activities are greatly increasing the atmospheric concentrations
of carbon dioxide, a "greenhouse gas" which traps heat.
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Carbon
Dioxide in the Atmosphere
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All animals produce carbon dioxide
when they exhale while plants take in carbon dioxide during
photosynthesis.
Carbon Dioxide absorbs heat from the
surface of the Earth, and prevents it from reflecting back
into space, similar to the way a greenhouse works.
That is why carbon dioxide is called
a "greenhouse gas."
Carbon dioxide and water vapor in the
Earth's atmosphere together make the planet warm enough
for life.
Of course, too much of the greenhouse
gases can cause too much heating of the atmosphere: "global
warming."
Burning fossil fuels produces a mixture
of gases -and the principal one is carbon dioxide.
Agriculture, especially cattle raising
and rice growing, produces another greenhouse gas called
methane.
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Scientists are struggling
to determine exactly how, and to what extent, rising carbon dioxide
levels will change the earth's climate.
In general,
civilization releases about 6 billion tons of carbon (in the form
of carbon dioxide) into the atmosphere every year. But only 3 billion
tons stay there; the rest is absorbed into what are called carbon
"sinks." Half of that dissolves into the ocean; the remainder
ostensibly is taken up by vegetation.
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In order to measure changes in the global
levels of greenhouse gases, you need a site as far away from
industry and with as few animals and plants as possible.
The South Pole was chosen in 1956 as a
study site for measurement of global carbon dioxide.
This still-running series of measurements
is one of the most important carbon dioxide monitoring projects
in the world.
Concentrations of other gases which may
also be involved in global warming are also rising, and these
have been added to the analyses at the South Pole.
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Consequently,
the performance of these sinks is an important variable in how much
carbon dioxide is left in the air to trap heat and possibly raise
global temperatures. Oceans absorb about one-third of all man-made
carbon dioxide. They do so mainly in the cold regions because carbon
dioxide dissolves easily into cold water, just like a soda in the
refrigerator will stay bubbly much longer than a soda sitting in
the sun. If the oceans didn't soak up carbon dioxide, the amount
in the atmosphere would increase significantly faster.
Antarctica
and the surrounding Southern Ocean provide scientists with a unique
environment in which to study both past and present amounts of greenhouse
gases in the atmosphere. The Southern Ocean is a delicate ecosystem
where ocean current and microscopic sea organisms influence the
release and burial of vast quantities of carbon dioxide. Analysis
of biological activity and water motions suggest that rising temperatures
in Antarctic waters favor the growth of microbial plants, which
would help remove carbon dioxide from the atmosphere. On the other
hand, a warming will liberate more carbon dioxide from tropical
ocean waters, amplifying the greenhouse effect. 
In examining past climate
changes, scientists are collecting valuable ice core data and
finding clues about natural climate patterns. Using evidence from
hundreds of ice specimens, or "cores," taken far below
the surface of Antarctica, investigators can analyze traces of
air trapped within the ice cores for carbon dioxide content. From
these samples, scientists can construct realistic models of climate
change which may lead to effective solutions for the future.
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Reducing
Global Warming
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- The unrestricted use of cars, the
burning of fossil fuels, and the waste gases produced
by factories have all been shown to contribute significantly
to global warming.
- Ice Core data from the South Pole
provide a baseline for global changes in greenhouse gases
and are extremely valuable in making decisions about the
next steps to reduce global warming.
- The sampling in Antarctica has now
been extended to a large number of other sites all over
the world, providing independent checks on the rate of
change.
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