Note the strong CO2 absorbance (dip) between 4-5 microns (where water does NOT absorb much). ...hence the logic problems arising as some simply say 'water vapor is a stronger GHG than CO2.'
samwik - sorry, water vapour is a stronger GHG than CO2. Just looking at the GCM output should drive that home. At 2xCO2, warming effects are estimated to be about 1.1C. It is the positive feedback processes (namely the increase in water vapour) that brings the total warming effect to be 2.5-4 degrees.
Also, the warming effect caused by CO2 increases logarithmically. This is due to IR at the CO2 absorption band already being removed to extinction (can't absorb what's not there). It is theorized that at lower pressures (higher elevations), the absorption band for CO2 will broaden, which will allow more IR to be absorbed, which is where this extra warming is supposed to happen. This is why we're supposed to see more warming at the mid-troposphere, than the lower troposphere. Yet, we see the exact opposite......apparently another "fingerprint" we're not seeing.
