Well, Mickey, we do know that CO2 gas contributes to atmospheric heating, the “classic CO2″ effect I discussed on another thread. And that is proven beyond any reasonable doubt. So there is that.

All gases retain heat in certain conditions.

However, that is an average. There are cases where the CO2 increase comes first (e.g, volcanic eruption). But in general, not only is the lag negative, but the changes in CO2 concentration are minute (e.g., changes from 200-300 ppm) compared to the temperature swings (which are of order 8 C):

Whistler you are exactly right about ignoring potential negative feedback loops. See for example Roy Spencer’s web site for details on his proposed “iris mechanism”, in which he proposes (and finds evidence for) a negative feedback mechanism in the tropics that tends to stabilize the Earth’s temperature against large changes in CO2 concentration. We know such a mechanism has to exist, because otherwise a large increase in CO2 would lead to a run-away greenhouse gas effect, and there is evidence that the CO2 concentration has been twenty times it’s current value, yet… life still goes on (we haven’t turned into Venus yet).

Remember the argument isn’t whether there is enough heating from CO2 to produce the recent global warming, but whether CO2 is an important greenhouse gas. You can have the latter be true (“classic greenhouse gas effect”) without the former being true (hypothetically dominant process, the “CO2 water vapor feedback cycle”).

The mechanism is very basic, there are “windows” in the infrared portion of the absorption spectrum of the Earth’s atmosphere that get filled by CO2 excitations at 5.3 and 14.8 microns. When the Earth radiates heat, part of that heat gets traped by CO2. That’s pretty close to an unassailable argument.

A bit better picture of the absorption spectra via WIKI:

We know this happens because we can measure both the absorption properties of CO2 and other gases, and because we can measure the transmitted infrared radiation that makes it into space via satellites. So it is an empirical fact that CO2 traps heat radiated from the Earth.

On the face of it, the portion of the infrared radiation trapped by CO2 is small (I think the number is 9% of the total heat trapped via the classic greenhouse gas effect), and further the CO2 absorption is heavily saturated even at the trace levels that CO2 is found in our atmosphere, meaning that increasing the amount of CO2 changes how much heat gets absorbed logarithmically. A doubling of the CO2 does not double the greenhouse gas effect from CO2.

Having a water vapor feedback loop be important, amplifies the classic greenhouse gas effect from CO2, but the strength of the effect still varies logarithmically with CO2 atmospheric concentration.

So the question for anybody who wants to argue this point, is to find a scientist who disagrees that the classic CO2 greenhouse exists and disagrees that the CO2 greenhouse gas significantly contributes to atmospheric heating.

Again the question isn’t whether there is a classic greenhouse gas effect related to CO2, but whether an exotic mechanism, the CO2-water vapor feedback mechanism provides enough amplification of the classic greenhouse gas effect to produce significant warming effects from a 25% increase in CO2.

It is true Gloabl (sic) Warming is not an abosolute (sic) certainty and that climate will change anyway, nevertheless the hypothesis that best fits the current body of scientific evidence tells us human activity is having consequenticial (sic) climate impacts…Let us opporate (sic) on a basis of propability (sic) on this issue as we do daily, unconscienciously, (sic) with our use of devices and principles entirely owed to scientific inquiry.

Who knew that when Reason finally showed up here, it would be semi-literate?

However, that is an average. There are cases where the CO2 increase comes first (e.g, volcanic eruption). But in general, not only is the lag negative, but the changes in CO2 concentration are minute (e.g., changes from 200-300 ppm) compared to the temperature swings (which are of order 8 C):

Whistler you are exactly right about ignoring potential negative feedback loops. See for example Roy Spencer’s web site for details on his proposed “iris mechanism”, in which he proposes (and finds evidence for) a negative feedback mechanism in the tropics that tends to stabilize the Earth’s temperature against large changes in CO2 concentration. We know such a mechanism has to exist, because otherwise a large increase in CO2 would lead to a run-away greenhouse gas effect, and there is evidence that the CO2 concentration has been twenty times it’s current value, yet… life still goes on (we haven’t turned into Venus yet).

Basically they’re assuming a worse case scenario and tweaking their models to work with that. At the same time they ignore any historical evidence that the Earth can warm up and cool off on it’s own accord.

Whistler you are exactly right about ignoring potential negative feedback loops. See for example Roy Spencer’s web site for details on his proposed “iris mechanism”, in which he proposes (and finds evidence for) a negative feedback mechanism in the tropics that tends to stabilize the Earth’s temperature against large changes in CO2 concentration.

Actually Mr. Spencer’s work was why I mentioned the possibility that there is a negative feedback effect.