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Ozone / Global Warming Myth - 111125

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Page updated - 06 December 2011

 

With some people there seems to be some confusion with the effects of Ozone Depletion and the increase of Carbon Dioxide in our atmosphere.

 

Ozone Depletion

Ozone greatly reduces the levels of UVB wavelengths passing through our atmosphere. For the last 30 years there has been a steady decline in the Ozone concentration level in our atmosphere. The result of this Ozone Depletion would seem to be the cause for the increase in the instances of skin cancer and cataracts in human beings and but could also be causing a similar effect with many other species including a detrimental effect of plant life such as plankton. Plankton is the 'start' of the 'food chain' for a number of small ocean-living organisms on which a number of larger species depend. Land based plant life is also affected due to the reduction in micro organisms to make nitrogen available for plant growth. Crops such as rice, a staple diet in several tropical countries, will yield less and cause famine.

 

A major cause for the Ozone Depletion has been attributed to increase in the levels of Chlorofluorocarbon (CFC's) in the atmosphere. CFC's were widely used as a refrigerant in (yes you've guessed it) fridges, freezers and air-conditioners. These CFC's also were a very effective replacement for the trichloroethylene, often known as 'trike', that had been used in several industrial cleaning processes for many years. Apart from being a really good engineering cleaning liquid 'Trike' had some very 'nasty' side effects, especially if breathed in . . . and it wasn't too good to the skin either.

 

The 'advent' of CFC's seemed to satisfy many of the engineering cleaning requirements but without all the side-effects of 'trike'. Sadly, when allowed to escape into the atmosphere, sunlight causes a reaction to occur with the CFC and the resulting chemical reaction to the CFC causes a 'free' chlorine molecule to be released. In the upper atmosphere this chlorine molecule becomes a catalyst to the ozone (O3), converting it back to oxygen (O2).

 

Global Warming

This is sometimes referred to as the Greenhouse Effect and here is a brief explanation. When sunlight falls on the glass of a greenhouse (sometimes known as glasshouse), a high percentage of the red end of the visible spectrum (longer wavelengths) passes through the glass and the energy is absorbed by whatever is 'illuminated' by the sunlight. This absorbed energy increases the temperature of the contents of the greenhouse and this increased temperature is used to promote plant growth. So why doesn't the heat escape from the greenhouse at the same rate?

 

The spectral radiation (wavelength and energy) from any body follows the laws of Black Body Radiation. At higher body temperatures, such as our Sun, the maximum energy from bright sunlight, normal (square-on) to the sunlight, is about 1300watts (1.3kW) per square metre of surface. This sunlight contains more than just the full spectrum of visible light with energies in the Infra-Red, Ultra-Violet and a range of radio frequencies from long wavelengths to X-Rays. The red-end wavelengths are responsible for the majority of the heating effect on our planet.

 

At lower body temperatures the majority of the energy is still towards the red-end frequencies but there may be no visible light from the body. As an example, a hot-water central heating radiator will radiate heat but there is no visible light emitted from it. A more extreme example is the human body that can radiate enough very long wavelength energy to be detected by a PIR (passive infra red) sensor and is used to control lighting for security and energy-saving purposes.

 

So why does the inside temperature of the greenhouse increase? As the Black Body Radiation temperature decreases, more of the energy is in the longer wavelength spectrum, the glass reflects more of this wavelength energy back into the greenhouse than it allows to pass through it and the result is an increase in temperature. In our atmosphere, carbon dioxide (CO2) works in the same way as the glass in the greenhouse.

 

In Conclusion

Ozone Depletion does not cause global warming but will contribute towards skin cancer and other, not yet fully researched, plant life problems in certain areas but Global Warming is altering the weather patterns and will continue to increase the extremes of climates in all areas of the world. However with the reduction of plankton, the ability of the oceans to absorb carbon dioxide is reduced. This is increasing the concentration of carbon dioxide in the atmosphere and increases the Greenhouse Effect. So by a vicious 'twist of fate' Global Warming is increasing due to Ozone Depletion.

 

Tony - 27 Nov 2011