Global Warming
Our planet's atmosphere traps energy just like a greenhouse. Energy
from the Sun can enter the Earth’s atmosphere, but not all of it can
easily find its way out again.
What blocks the Sun’s energy from escaping from the Earth? Unlike a
greenhouse, the Earth does not have a layer of glass over it! Instead,
molecules in our atmosphere called greenhouse gasses absorb the heat.
Greenhouse gasses include water vapor, methane, ozone, nitrous oxide,
and carbon dioxide. There may not be much of some of these gasses in
our atmosphere, but they can have a big impact. Each greenhouse gas
molecule is made of three or more atoms that are bonded loosely
together. These molecules are able to absorb heat, which makes them
vibrate. They eventually release the heat energy and it is often
absorbed by another greenhouse gas molecule.
The greenhouse effect is useful because trapping some energy keeps the
temperatures on our planet mild and suitable for living things.
Without its atmosphere and the greenhouse effect, the average
temperature at the surface of the Earth would be zero degrees
Fahrenheit. However, too many greenhouse gases can cause the
temperature to increase out of control. Such is the case on Venus
where greenhouse gases are abundant and the average temperature at the
surface is more than 855 degrees Fahrenheit (457 degrees Celsius).
We have increased the amount of carbon dioxide in the atmosphere by
burning fossil fuels, such as coal, oil and petrol. Cows, rice fields
and rubbish rotting in landfill sites produce methane, and aerosols
and fridges use CFCs.
The removal of trees - deforestation - is also thoug...
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...warming.
The theory for these rapid rises and falls of temperature, based on
the geological records from 55 million years ago, is that gradual
global warming due to some natural cause had resulted in temperatures
5 to 7 degrees centigrade higher than average ( i.e. higher than
today's temperatures). At this point methane trapped in methane
hydrate deposits started to be released into the atmosphere and
accelerated the rate of warming. This would result in further warming
releasing more methane. As the atmosphere warmed different types of
methane deposits would start to be released and so a cycle of methane
release leading to increased warming leading to more methane release
from other areas of methane deposits elsewhere in the world would
become established as global warming effected different areas of the
world.