Introduction
This article is the first in a series of articles which
will take the reader on an alphabetic journey on global
warming, commencing with A for Amazon Rainforest
The phrase global warming is a term that has been in common
usage for some time and usually refers to the warming of
Earth's atmosphere, and which also implies a man-made or
human influence.
Earth's atmosphere is comprised of many gases, oxygen,
nitrogen, carbon dioxide and water vapour to name a few.
These gases are collectively called greenhouse gases and
they keep the Earth's temperature at a comfortable 15
degrees Celsius, without them Earth would be a chilly - 18
degrees Celsius. Since pre-industrial times, usually taken
to be around 1750 we know from ice core records that Carbon
Dioxide (CO2) levels were around 280 ppm, that's 280 parts
of CO2 per million parts of air. As industrialisation got
under way mankind started to farm the land more intensely
than ever before, deforest for agriculture and settlements,
and later since around 1850 or so, burn fossil fuels for
energy and transport which have added considerably to
greenhouse gas levels, particularly Co2.
This has resulted in CO2 levels increasing to around 385
ppm, an increase of around 37% from pre-industrial levels
mainly as a result of burning fossil fuels.
How do we know this? Well, data from ice core records that
go back at least 650,000 years now show us that CO2 levels
have fluctuated naturally during this time between 280 and
300 ppm. CO2 levels have also been measured accurately from
the top of Mauna Loa Volcano in Hawaii since 1958, and
results show an increase in CO2 levels from 315 ppm to 385
ppm since that time. Therefore CO2 is now at 85 ppm more
than it has been for at least 650,000 years of Earth's
history. It is a known scientific fact that higher levels
of greenhouse gases will lead to higher temperatures, which
appears to be happening now. The world has warmed by an
average of 0.74 degrees during the last 100 years or so.
As a result of this warming, polar ice has started to
decrease and melt, and so are Earth's land based glaciers.
This in turn is causing sea levels to rise which is putting
low lying islands at risk of flooding or total submersion,
and will eventually threaten more and more of the worlds
coastal cities and regions.
As Earth's atmosphere starts to warm, the warming itself
may cause further positive feedback mechanisms to kick in.
A warmer atmosphere holds more water vapour, which is
itself a powerful greenhouse gas. This will in turn cause
further warming, and so on.
Melting ice means that more sunlight is absorbed by the
surrounding "darker" water and land, meaning further
warming, and more melting ice. Methane deposits currently
held in a frozen but stable state under the sea and under
the permafrost maybe released as the oceans warm and
permafrost melts, which will cause further warming as
methane is a potent greenhouse gas etc etc.
Where better place to start this A-Z journey on global
warming than with The Amazon Rainforest, which has an
incredibly important role to play in maintaining a balance
in the Earth's climate. The Amazon as well as other
rainforests are inextricably linked to the issue of global
warming and have a considerable influence on Earth's
climate.
Amazon Rainforest Facts
The Amazon river basin contains the largest rainforest on
Earth and covers approximately 40% of the South American
continent. The Amazon Rainforest is located within eight
countries, Brazil contains 60% of the forest, with
Colombia, Peru, Venezuela, Ecuador, Bolivia, Guyana,
Suriname and French Guyana containing the rest.
The Amazon forest is a natural reservoir of genetic
diversity, containing the largest and most species rich
tract of tropical rainforest that exists. The Amazon
contains an amazing thirty-percent of Earth's species. One
square kilometre of Amazon can contain about 90,000 tons of
living plants! It's also amazing to consider that one in
five of all the birds in the world make the rainforest
their home.
The Amazon basin is drained by the Amazon river, the worlds
second longest after the Nile and the river is essentially
the lifeline of the forest. The river is the most
voluminous on Earth.
A few hundred years ago tropical rainforests covered as
much as 12% of the Earth's land surface, but today the
figure is less than 5%. The largest stretch of rainforest
can be found in the Amazon river basin, over half of which
lies in Brazil.
Why is the Amazon Rainforest so important in the context of
global warming?
The rainforest acts as a major store of carbon and produces
enormous amounts of oxygen. The Amazon has been referred to
as "The lungs of the Earth" because of its affect on the
climate. The way this is achieved is of course through
photosynthesis, the process by which green plants/trees use
the energy from sunlight to produce food by taking CO2 from
the air and water and converting them to carbon. The
by-product of this is oxygen.
The Amazon therefore helps recycle CO2 by turning it into
oxygen, and its estimated that the Amazon produces about
20% of this essential gas for Earth's atmosphere.
Trees, plants and CO2
Levels of CO2 in the atmosphere have been measured since
1958 from a monitoring station located on Mauna Loa volcano
in Hawaii and they show sharp annual increases and
decreases in CO2 levels, similar to the tooth on a saw. The
readings almost mimic a breath of air being taken in and
out; it's almost as if the Earth is breathing. The readings
correspond to the amount of vegetation on the planet (most
of which is contained in the Northern Hemisphere, as the
landmass there is greater), taking in CO2, and giving out
oxygen. During the Northern Hemisphere summer, when the
Earth is tilted toward the sun, the Earth's vegetation is
able to photosynthesise resulting in an uptake of CO2,
causing worldwide CO2 levels to drop. During winter, when
the Earth's axis is tilted away from the sun, the opposite
happens causing CO2 levels to rise again.
When one becomes aware of the correlation between the
Earth's vegetation and CO2 levels, it is easy to understand
why the Amazon, and rainforests in general are such an
important part of Earth's ecosystem. If global warming is
to be tackled, the Amazon, and other rainforests must be
saved.
----------------------------------------------------
This article is taken from a book entitled The A-Z of
Global Warming which was published by Schmall World
Publishing on 25th September 2008. Further information can
be obtained from the following website-
http://www.a-zofglobalwarming.com
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