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Old 7th Aug 2003, 19:28
  #11 (permalink)  
Dr Dave
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HectorusRex

I'm afraid your post is over-simplifying a very complex system.

The key to increased temperatures due to changes in atmospheric composition comes from the relative transparency of the atmosphere to various types of radiation.

The Earth receives energy from the sun in the form of shortwave radiation. It re-emits it in the form of long wave radiation. For constant temperature the amount coming in must equal the amount going out.

This is basically illustrated in the following diagram
(http://www.yale.edu/ceo/images/GuideFig1.gif):



A the top, the curve on the left is the spectrum for incoming radiation, the one on the right for outgoing.

At the bottom, the wavelengths of radiation absorped by different atmospheric gases are shown. So on the far left (short wavelength) is ozone, which absorbs high energy radiation, protecting the surface.

Note that H20 appears several times, as does CO2 etc. So changing the concentrations of these gases changes the amount of energy being absorped in different parts of the spectrum.

Overall effect is that changing atmospheric chemistry probably changes the balance between incoming and outgoing radiation, and thus changes global climate.

Unfortunately CO2 and water vapour are more effeicient at trapping long wave than short wave radiation, so increasing their concentration in the atmosphere will lead to more radiation being retained than is being emitted. The effect of this is increased temperature.

The smoking gun, to coin a phrase, is the Vostok ice core, from which it was possible to determine global temperature over the last 150,000 years and, by extracting gas bubbles, to measure the atmospheric chemistry.

The two curves are plotted here (sorry can't find a way to link this):

http://www.geocraft.com/WVFossils/temp_vs_CO2.html

Given the correlation between these curves can you really argue that levels of CO2 are not linked to temperature?

By the way this core was drilled and analysed by Russian scientists before the end of Communism. Notsofantastic, I bet you didn't realise your conspiracy was so far reaching?

DrDave (rather relishing being a children's show character!)