Global Warming -The State of Play
An article on by Brian Sheen
That there have been changes in the world's climate within living
memory is indisputable. It is just the weight placed by the various
authorities on the different elements that cause these changes that is
questioned by some.
The parts we cannot influence.
Solar Output - Variations in the Solar Constant.
In 1980 NASA using the Solar Maximum Mission Satellite started to
measure the output from the Sun. Over a period of six years it declined by
0.1 % and then started to rise again. Although small in percentage terms
it is a significant factor in the Earth's climatic change and changes in
phase with the 11 year Sun Spot Cycle. We are now just past Sun Spot
Maximum.
Milankovitch Cycles.
In the 1920's Milankovitich showed that the Earth's orbit changes over
a period of time. As we know the orbit is elliptical, but over a period of
100,000 years the shape of the orbit becomes more circular before
returning to its elliptical form. Every globe shows that the Earth is
inclined at an angle of 23.5 degrees from the vertical, however over a
period of 41,000 years this varies between 21.5 and 24 degrees. A further
change is caused by the fact that the Earth wobbles on its axis like a
spinning top, this is called precession and has a period of 26,000 years.
These changes alter the amount of sunlight falling on the Earth. Although
at the time not enough was known about climate changes throughout the ages
scientists now realise that he did indeed discover the cause of at least
60% of the climatic fluctuations. His cycles have been shown to correspond
with ice ages and inter glacial periods.
Today's story.
In recent years scientists have become increasing aware that the Earth is
warming up and that the temperature increase relates directly to an
increase in the amount of carbon dioxide in the atmosphere.
A mini Ice Age?
One unexpected outcome could be a drop in temperature, a mini ice age.
This is due to the fact that the ocean currents that carry warm water from
the tropics to our shores and beyond. These could melt the Arctic Ice to
such an extent that cold water flowing south could break the Gulf Stream
or Atlantic Conveyor bringing about a dramatic drop in temperature. The
Gulf Stream transports more energy northwards every hour than would be
produced by burning five billion tonnes of coal.)
The Part we can Influence
What individuals can do, although it might appear that we are powerless to
affect the total amount of emissions we can to something to help
ourselves. We can switch off TV sets when not in use, we can run our
houses at lower temperatures, and run smaller cars and recycle rather than
dump many of our products.
However it is down to Governments to put in place policies to reverse
the sharp increase in consumption of fossil fuels and keep carbon dioxide
levels from rising.
Can anything be done? Actually a significant proportion of the excess
carbon dioxide can be locked up in plants and trees so halting our slide
to a much more stormy world.
The Challenge
The challenge facing all of us, post Bonn, in the next few years is to
persuade the governments in the wealthy parts of the world to plant enough
trees in the tropical continental countries to prevent tropical island
nations from disappearing beneath the waves. Such a policy will, however,
only give us a breathing space while we put our house in order.
For those wishing to learn more about the factors involved in to global
warming should visit the Gaia
Energy Centre in Delabole, Cornwall.
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