CO2, which is a miniscule component of the total greenhouse gases
From 10% to 25% depending on who you talk to. Small but not miniscule.
Miniscule palmer, you've bought into hype, not science.
http://www.eia.doe.gov/cneaf/alternate/page/environment/appd_d.html
"Carbon dioxide adds 12 percent to radiation trapping, which is less than the contribution from either water vapor or clouds. By itself, however, carbon dioxide is capable of trapping three times as much radiation as it actually does in the Earth's atmosphere. Freidenreich and colleagues[106] have reported the overlap of carbon dioxide and water absorption bands in the infrared region. Given the present composition of the atmosphere, the contribution to the total heating rate in the troposphere is around 5 percent from carbon dioxide and around 95 percent from water vapor."
In the words of Dr. Richard Lindzen MIT [contributor to IPCC second assessment, and a lead author in IPCC Working Group 1] in regard to the important role of water vapor in transport of surface heat to the upper atmosphere and subsequent re-emission in IR bands:
"If all CO2 were removed from the atmosphere, water vapor and clouds would still provide almost all of the present greenhouse effect." Res. Explor. 9, 191-200, 1993.
"The surface of the earth does not cool primarily by infrared radiation. It cools mainly through evaporation.7 Most of the evaporated moisture ends up in convective clouds (clouds with strong vertical currents carrying the air and its contents upward, as opposed to layered clouds, which form and stay at a particular level) where the moisture condenses into rain. Just as evaporation cools, the condensation of watervapor heats, and the atmosphere realizes most of this heat at altitudes >5km. It is at these heights that the atmosphere must balance the heat deposited by convection from the surface through cooling by thermal radiation. It is worth noting that, in the absence of convection, pure geenhouse warming would lead to a globally averaged surface temperature of 72oC given current conditions (Moller and Manabe 1961). Our current average temperature, 15oC, is actually much closer to the black body temperature temperature (-18oC), than to the pure greenhouse result.8 The relative ineffectiveness of the greenhouse effect is due to convection which carries heat past the bulk of watervapor (which has a characteristic scale height of about 2km), and to large-scale meridional heat transport which carries heat from the moist tropics to the less moist higher latitudes. Because of this transport, it is primarily the distribution of infared absorbers above 5km (rather than below 5km) that is important for containing the heat carried away from the earth's surface (Lindzen et al. 1982)."
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"In the meantime greenhouse effect is not nearly as straight forward as is commonly stated."
--- Richard Lindzen (1990) Some coolness concerning global warming. Bull. Amer. Met. Soc., 71, 288-299."Even if all other greenhouse gases (such as carbon dioxide and methane) were to disappear, we would still be left with over 98 percent of the current greenhouse effect." Cato Review, Spring issue, 87-98, 1992;
The work of Jack Barret provides the results of HITRAN line-by-line integration of the significance of water vapor as a green house gas in comparison to CO2, CH4 & N2O, in their respective concentrations in the atmosphere near the surface clearly supporting the above statements:
Energy & Environment, volume 16 No. 6 2005
"Greenhouse molecules, their spectra and function in the atmosphere"
by Jack Barrett, PhD (Physical chemistry, Imperial College, London)The infrared (IR) spectra of the four main GH gases over a 100 metre path length are presented in Figure 6, their concentrations being those that pertain to the atmosphere at sea-level, and in the case of water that which amounts to 45% humidity.
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Table 1: Contributions to the absorption of the Earth's radiance
by the first 100 meters of the atmosphereGHG % Absorption Absorption relative
To water vapor = 1Water Vapor 68.2 1.000 CO2 (285 ppmv) 17.0 0.249 CO2 (570 ppmv) 19.0 0.271 CH4 1.2 0.180 N2O 0.5 0.007 Total [water, CO2, CH4, N20] 86.9 Combination with 285 ppmv CO2 72.9 1.069 Combination with 570 ppmv CO2 73.4 1.076 Some idea of the relative contributions to global warming by the GHGs at the Earth’s surface may be calculated from the spectral data. Percentage absorption values are useful; they are calculated as %A = 100 – %T (T = transmission). The values for CO2 in the atmosphere in the pre-industrial era of 285 ppmv and double that value, so crucial to the IPCC arguments, are given in Table 1, together with the contributions from water vapour, N2O and methane.
The absorption values for the pre-industrial atmosphere add up to 86.9%, significantly lower than the combined value of 72.9%. This occurs because there is considerable overlap between the spectral bands of water vapour and those of the other GHGs. If the concentration of CO2 were to be doubled in the absence of the other GHGs the increase in absorption would be 1.5%. In the presence of the other GHGs the same doubling of concentration achieves an increase in absorption of only 0.5%, only one third of its effect if it were the only GHG present. Whether this overlap effect is properly built into models of the atmosphere gives rise to some scepticism.
The GHGs absorb 72.9% of the available radiance, leaving 27.1% that is transmitted of which an amount equivalent to 22.5% of the total passes through the window and the other parts of the spectral range transmit only 4.6%. For the doubled CO2 case this small percentage decreases slightly to 4.1%. These small percentage transmissions are reduced by 72.9% and 73.4% respectively by the second layer of 100 m of the atmosphere so that only ~1% in both cases is transmitted to the region higher than 200 m.
As is readily determined from Barrets results, water vapor constitutes more than 100*1/1.076 = 92% of the total radiative greenhouse effect in just the first 100meter column of air near the surface, not counting additional radiative capacity in the troposphere above that level and in its particulate form as rain and ice content of clouds.
"the direct radiative effects of doubled CO2 can cause a maximum surface warming [at the equator] of about 0.2 K, and hence roughly 90% of the 2.0-2.5 K surface warming obtained by the GCM is caused by atmospheric feedback processes described above."
--- "Increased Atmospheric CO2: Zonal and Seasonal Estimates of the Effect on the Radiation Energy Balance and Surface Temperature" (V. Ramanathan and M. S. Lian), J. Geophys. Res., Vol. 84, p. 4949, 1979.