Quote:
Originally Posted by Barrykgerdes
Calling CO2 a “Greenhouse” gas is without scientific fact and besides making up less than four ten-thousandths part of the atmosphere it would have no effect if it were. The biggest factor in the so-called “Greenhouse” effect is water vapour mainly in the form of clouds.
The increase in CO2 is be being blamed for the warming of the planet because statistically the level in the atmosphere has increased by 30% over the last 50 years whereas other factors have varied by quite insignificant percentages. The climate change lobby blames combustion of fossil fuels, mainly carboniferous, for the increase in CO2. They have failed to take note of the fact that the sea has great amounts of CO2 dissolved in it and if the temperature of the water were raised by 1 degree it would liberate sufficient CO2 to have caused the rise in CO2 percentage level.
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I'm trying to stay out of this but I will correct the above two paragraphs.
Yes water vapour is the major greenhouse gas but suggesting that CO2 has no effect just because it is in low concentration is wrong. First, it is easy to see that CO2 should trap heat by blocking outgoing IR. Since the CO2 absorption band does not fully overlap with the H2O absorption band the absorption due to CO2 is added to that of H2O. In an ideal gas these 'bands' are discrete lines but in a real gas the lines are broadened into bands. The CO2 band is, despite the low concentration, already fully blocked at its centre and the increase in absorbance is due to band broadening as the partial pressure of CO2 increases. That is why the increase in CO2 absorbance does not scale directly with the increase in CO2 cancentration. Trying to write off CO2 because of its low concentration is a bit like trying to claim that once light has travelled all those billions of km from that galaxy a mere piece of paper can't stop it reaching your telescope.
I'm surprised anyone would attempt to deny that human activity is the cause of the increase in atmospheric CO2 concentration. Records of CO2 conc go back much further than 30 years and the temporal correlation between the increase in atm CO2 and the increase in fossil fuel use is plain to see. But there is more! Consider the carbon 13: carbon 12 ratio of atmospheric CO2. These ratios are normally expressed as a 'delta value' which reports the difference in the ratio (in permille, ie. parts per thousand) of the sample from that of an internationally accepted reference material. So for carbon we talk about the d13C on the PDB scale (the 'd' should be a Greek delta but I don't have that font available). Prior to the industrial revolution the d13C of atm CO2 was about -6 permille. The carbon in fossil fuels has a value of about -27 and that of CO2 outgassed from oceans is about 0. So if the extra CO2 comes from the ocean the value will move towards 0 and if it comes from fossil fuel it will move towards -27. What do we see? The value has moved from about -6 to about -7. (The situation is a little more complicated than this but I'll stop now - I have to calibrate some d13C results so I can tell a grad student whether or not she is happy.)