Monday, January 30, 2006

The Greenhouse Effect2

Before the Industrial Revolution the carbon dioxide concentration was 280-90 ppm now it is 340ppm. By 2100, if the burning of fossil fuels continues at its present level, the concentration of carbon dioxide will have doubled. Climatologists estimate that doubling the carbon dioxide concentration would increase mean temperatures by 2-3 degrees Celcius. They also predict that increase would be greatest at high latitudes(near the poles) with Russia warming up by say 3 degrees Celcius, North America by 1-2 degrees Celcius and some countries like Japan, India and Spain showing little change in temperature.

Plants take in carbon dioxide from the atmosphere to use in the photosynthesis, Unfortunately, the world's forest cover is being drastically cut. In Brazil, the Amazon rain forest once covered 3 million square miles. As the region has been developed for agriculture and mining, 20% to 25% of the forest has been destroyed and a further 20% has been seriously disturbed. When felled trees are burned to rot, carbon doxide and other greenhouse gases are released. The same kind of deforestation is going on in some African countries, Indonesia, India and the Philippines. The loss of trees may already be making the Earth warmer.

Methane is another greenhouse gase. Methane enters the atmosphere from a number of sources. A single termite mound can emit about 5 litres of methane per minute. Swamps, rice fields, leaking North Sea gas pipes and herds of cows all send methane into the atmosphere. CFC's are powerful greenhouse gases.

A temperature increase of 0.5 degree Celcius has been observed since the beginning of the century. This may not sound alarmingly but scientists expect any greenhouse warming to be masked for quite a time by the enormous capacity of the oceans to absorb heat.

To be continued.......

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