I found this excellent ressource and I thought I’d share. The quotes below are an excerpt from the linked site, so all credit goes to the original author – I can only take credit for not buying into the CO2 hype really. The site is here CLICKY
Also pay special attention to the alternate and much more plausible explanation of the current global warming trend, as explained by Henrik Svensmark – referenced here CLICKY
So, greenhouse is all about carbon dioxide, right?
Wrong. The most important players on the greenhouse stage are water vapor and clouds. Carbon dioxide has been increased to about 0.038% of the atmosphere (possibly from about 0.028% pre-Industrial Revolution) while water in its various forms ranges from 0% to 4% of the atmosphere and its properties vary by what form it is in and even at what altitude it is found in the atmosphere.
In simple terms the bulk of Earth’s greenhouse effect is due to water vapor by virtue of its abundance. Water accounts for about 90% of the Earth’s greenhouse effect — perhaps 70% is due to water vapor and about 20% due to clouds (mostly water droplets), some estimates put water as high as 95% of Earth’s total tropospheric greenhouse effect (e.g., Freidenreich and Ramaswamy, “Solar Radiation Absorption by Carbon Dioxide, Overlap with Water, and a Parameterization for General Circulation Models,” Journal of Geophysical Research 98 (1993):7255-7264).
The remaining portion comes from carbon dioxide, nitrous oxide, methane, ozone and miscellaneous other “minor greenhouse gases.” As an example of the relative importance of water it should be noted that changes in the relative humidity on the order of 1.3-4% are equivalent to the effect of doubling CO2.
Second important snippet:
But we’re responsible for all the carbon dioxide greenhouse effect?
Gracious no! Humans can only claim responsibility, if that’s the word, for abut 3.4% of carbon dioxide emitted to the atmosphere annually, the rest of it is all natural (you can see the IPCC representation of the natural carbon cycle and human perturbation here or a simple schematic from Woods Hole here).
Half our estimated emissions fail to accumulate in the atmosphere, “disappearing” into sinks as yet undetermined. Humans’ total accumulated carbon contribution could account for perhaps a quarter of the total non-water greenhouse gases (that is, accounting for all the increase since the Industrial Revolution regardless of source and irrespective of whether warming from any cause might result in an increase in natural emission to atmosphere — we’re simply claiming the lot as anthropogenic or human-caused here).
Assuming that water vapor accounts for about 70% and clouds (mostly water droplets) accounts for another 20%, thus water in it’s various forms is 90% of the total greenhouse effect, leaving 10% for non-water greenhouse effect (we know we cited 95% above — see “important distinction“). Of this remaining 10%, mainly atmospheric carbon, humans might be responsible for 25% of the total accumulated atmospheric carbon, meaning 0.25 x 0.1 = 0.025 x 100 = 2.5% of the total greenhouse effect.
The end result is we’re about to spend a lot of time, energy and ressources on reducing CO2 emissions that in all likelyhood as a worst case scenario have a minimal effect overall.