How strong is the water vapour feedback?

The studies reviewed by the IPCC concluded that water vapor doubles the CO2 effect, but that when interactions with yet other feedbacks are considered the water vapor effect could be 3.5 times the CO2 effect.

http://www.ipcc.ch/ipccreports/tar/wg1/268.htm

A more recent study confirmed that previous conclusions the water vapor could as much as double the CO2 effect.

http://www.sciencedaily.com/releases/2008/11/08111...

A study several years prior used Mt Pinatubo to try to measure the water vapor effect and concluded that water vapor added about +60% to CO2 (not including the amplification of other feedbacks.)

http://atoc.colorado.edu/~dcn/ATOC6020/papers/Sode...

So, the best estimate is about doubling initially, but when that doubling increases the albedo and methane feedbacks it becomes much more than that.

Effectively, the earth is a divergent sink of IR flux

resulting in a mean positive temperature gradient.

This is due to in phase feedback between the flux and

increasing CO2 and H20 particle density to name

just two. Although out of phase feedbacks are

present, they are not on average greater than positive

feedbacks.

Edit:

The data, if true, indicates that there are slowly increasing

levels of CO2 and H2O over a time scale measured in decades.

In the gas phase (and liquid) this means more kinetic and quantum potential

excited states of energy on the surface and in the atmosphere. Again, assuming

the data I've studied is correct, a simple application of quantum theory,

kinetic theory, and deductive reasoning proves the case to me beyond a reasonable

doubt. Nature has way of cycling up and down. Currently, she is on the upswing.

To answer your question directly without proof if I understand your terminology and

meaning correctly:

Water vapor has a average positive feedback that is stronger now than in the past.

Temperature is only one factor governing the maximum amount of water vapor in the atmosphere.

Temperature does not control precipitation - energy and water saturation are the two factors. Energy is dependent on the phase of the water. Precipitation requires airborne particulates to initiate condensation (which releases energy) and turbulent mixing of air (which transfers energy).

Precipitation is a phenomena of the troposphere and the lower stratosphere. CO2 affects heat retention in the mesosphere and thermosphere.

Increased water vapor is a symptom, not a cause of global warming. By definition the feedback effect is mathematically insignificant.

You are using a phenomena dependent on local conditions and trying to extrapolate globally. The rules don't apply. Microscopic and macroscopic phenomena are different.

Too many interdependent variables that are poorly quantified to draw a reliable conclusion.

More water vapor means more clouds (maybe). This can have a cooling effect (maybe). Will water vapor increase the snowfall in permanent Ice fields in Antarctica locking up this water? Will more rain fall? Less rain? Will the long term consequence be more forestation? Less? Will it affect the albedo? Which way?

No one can answer those questions with a definite answer.

We do know that it has not warmed in 16 years. The ice is growing in Antarctica and the sea level is dropping. Who predicted that?

Simple computer models diverge quickly enough. Complicated ones are a joke. The only thing that can be predicted is the speed of divergence--in that respect, the models have behaved as you would expect.

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You would have thought "yes"? But the atmosphere is (supposedly) warmer. Therefore water vapor has less of a chance of condensing.

Regarding your reply regarding clouds: Read YOUR reply carefully. Isn't "maybe" what you are saying? First you say "yes" they cool. Then you say "no" they warm.

Maybe "maybe" is correct, eh?

<<We do know that it has not warmed in 16 years.>> We do not 'know' this; even if temps were dropping, ------------------------Prima facia.

>>But please; the question is about the water vapour feedback>> OK, my bad.

>>Not quite; they both cool and warm by different mechanisms. >>

So,....we're back to 'maybe'? How can you possibly conclude (or even conjecture) that the water vapor feedbacks are positive? It seems ALL feedbacks are positive with you guys. How has the planet's climate stayed so stable when we have had all these positive feedbacks lurking? I guess that one molecule in ten thousand was the tipping point, eh?

Using NASA's average seasonal atmospheric pressure adjustment, an ~ 1.8 F increase in a warming. Will increase water vapor and trap an additional ~2watts per sq meter... Or a factor of two for warming.

Your use of (maximum) has left me befuddled: snow can bypass the liquid transition phase, which is not restricted to temperature increases. But altitude and wind, or are you literally stating a unformed constant pressure for everything or trying to apply one or more STP formulas?

There are modeling attempts concerning sea spray, aerosol salts, and BVOCs, those are usually specific studies. I couldn't with any degree of accuracy state an overall net effect. But then I'm not alone.

Ottawa Mike usually avoids mentioning the denier-blog sources he endlessly trawls, but this time he provides one link for his denier-fantasies about water vapor: non-scientist Marcel Crok. Anti-science non-scientists, like JimZ, often pretend to be scientists. Having taken some classes in geology, however, does not make someone a scientist except in the sense that everyone, even the most non-skeptical fake-skeptics, has some degree of interest in scientific questions.

Assuming the parties above who say the thing is too complicated to work out are correct you might work it out yourself using a very simply model. This sort of exercise tends to be interesting and informative.

Perhaps: A disk, the earth, has a 'law of atmospheres' atmosphere hanging above it and down through this shines parallel rays of heat. It shines back with light appropriate to its temperature.

Warm the disk and water vaporizes into the atmosphere. This increases the volume of the atmosphere - would this 'useless work' squeeze some of the water vapour in the atmosphere into liquid? - and increases its pressure, due to the partial pressure of the additional water vapour.

That sort of thing. It'll probably turn out to be vastly more complicated than it looks.

In the event you get this working, could you mail me with it?

I would go with Baccheus. His is the only answer addresses the question, makes sense, and provides credible links. Unless you think he is really missing something, I would suggest that you could stop there with no need to continue to ask further variations of this same question.

Since it isn't 100 percent humidity everywhere, obviously it could be increased simply by adding water vapor where it isn't at 100%, IMO.

srtong