Wednesday 4 July 2012


Global warming is the rise in temperature of the Earth's atmosphere and oceans. The causes of global warming have been investigated by scientists for many years, and research is still ongoing amidst much debate.  

Natural cycles and events influence the climate, but they cannot explain all the changes that are occurring.  However, when additional greenhouse gases produced by man are considered we get a clearer picture of what is happening.  The release of greenhouse gases, through both natural and man made activities, are responsible for warming the earth and causing global warming.

Natural causes 
The Earth naturally cycles through patterns of warming and cooling.  There are many natural things that contribute to global warming but natural process occur in a slow and measured way over many millennia.

There are natural carbon sinks on earth which have been storing carbon over many thousands of years.  These include peat bogs and the arctic tundra.  If warming temperatures cause these carbon sinks destabilise then carbon will be released into the atmosphere and can possibly cause an unstoppable catastrophic warming of the earth.

Man made causes
We are accelerating the natural climatological cycles by releasing man made greenhouse gases into the environment. There are several greenhouse gases responsible for global warming that are produced by man.  Most are produced by the burning of fossil fuels in factories, electricity production and use of cars.  Carbon dioxide is the main gas responsible for global warming, but methane, nitrous oxide and refrigeration gases also contribute. 

The build up of carbon dioxide in the environment is by far the biggest contributor to global warming, resulting mainly from the use of fossil fuels. The loss of forests also reduces the amount of carbon dioxide absorbed in the environment and so contribute to increased levels. As forests and grasslands are cleared, enormous amounts of stored carbon are released from the decaying plants and enter the atmosphere.

Methane is released from landfill sites and agriculture (grazing animals produce methane as part of their digestive process).   Nitrous oxide comes from from fertiliser, gases for refrigeration and industrial processes. 

These different gases have varying heat trapping abilities.  A molecule of methane can trap 20 times more heat than a molecule of carbon dioxide. Nitrous oxide can trap 300 times more heat than carbon dioxide.  Chlorofluorocarbons have heat trapping potential a thousand times greater than CO2.  However CO2 is the greatest contributor to global warming due to high concentrations.

In order to measure these gases simply, Greenhouse gases are measured in terms of the equivalent amount of carbon dioxide.

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