How much do you actually know about climate? Have you ever taken, for example, a biogeography/environmental ecology class? Do you understand about climate forcings and feedbacks? If not, then how can you be so sure that you understand how anthropogenic CO2 affects climates?
CO2 is, in fact, a trace gas. But, an analogy. If I put a couple of grams of water-soluble dye into a bathtub full of water, the dye would be a tiny percentage of the total water--but, at least for most dyes, you would have no trouble telling what color of dye it was. Why? Because the water is clear, so it has no real effect of the color that you get from adding the dye. Similarly, most of the atmosphere is essentially irrelevant to AGW.
Recent research suggests that upper stratosphere CO2 helps to block incoming thermal radiation, but a very small concentration of it is enough to do that. Beyond that, I believe there is little additional effect, since it's happening at about the atmospheric layer where the Earth radiates heat out to space. In the troposphere, CO2 has a warming effect by trapping thermal radiation coming from the Earth's surface, and since heat from the bottom of the atmosphere has to get through the entire atmosphere to leave the system, more CO2 has more of an effect.
In your second paragraph, you seem to be saying that CO2 can't cause warming because it causes so much warming that it evaporates water and forms clouds. I hope you realize how incoherent and inconsistent that sounds.
But, in any case, what warming will do to clouds, and in fact whether clouds cause warming or cooling, is... a complicated subject, that scientists haven't even quite figured out yet.
And, as someone else pointed out, the only way that you can change the amount of water vapor in the air is by, well, changing the temperature. Any excess water vapor will become precipitation within days, and if there's not enough water vapor more will evaporate from any available water source, like the oceans that cover ~70% of the planet...
So, to answer your last question, CO2 is driving temps up.
Trace gas =/= too little to have an impact. If there were too little to have an impact, it would not be able to support plant life.
Carbon dioxide absorbs infrared. For it to cool the planet would violate the laws of thermodynamics.
http://physics.about.com/od/thermodynami...
<'Water vapor' is considered by science as the dominant greenhouse gas by no less than 3 times the warming capabilities as CO2 does.>
It would have to change in order to contribute to warming temperatures. Only temperature would cause the concentration of water vapor to change. The concentration of water vapor in the atmosphere is inherently stable, or Earth would turn to this.
http://en.wikipedia.org/wiki/Venus
Warming leads to less clouds.
http://www.climate4you.com/images/CloudC...
Check my link on the laws of thermodynamics.
Current acceleration of AGW is human induced CO2, methane, Nitrous oxide. Low level Ozone which is produced when NO is exposed to sunlight and CFCs along with some trace gases. Human produced greenhouse gases have increased since the start of the industrial revolution @ 1780 and have accumulated to the point that GW will go well beyond 2100.
water vapor is indeed the largest of the greenhouse emissions. Although this is a natural phenomenon,.The combination of water and GW produce a positive feedback loop which enhances GW As waves crest, they release CO2 which in turn adds to GW, producing more CO2 as waves crest fueling more warming which produces more CO2 This is a never ending loop and one of the most significant considering @70% of the planet is covered by water
There is no cooling that is off setting AGW to any noticeable degree. CO2 indeed drives temps up
CO2 does drive temps but most of if at very low levels by 100ppm it is pretty much saturated, more warming occurs only through broadening of the frequency band.
However I feel there is self balancing effect as it seems water vapor actually reduces as temperature go up. http://c3headlines.typepad.com/.a/6a0105...
CO2 should be produced near the forest to balance the temperature.
Here is what climate science REALLY says:
U.S. National Academy of Sciences, 2010:
http://books.nap.edu/openbook.php?record...
“Climate change is occurring, is caused largely by human activities, and poses significant risks for a broad range of human and natural systems.”
http://www8.nationalacademies.org/onpine...
“Choices made now about carbon dioxide emissions reductions will affect climate change impacts experienced not just over the next few decades but also in coming centuries and millennia…Because CO2 in the atmosphere is long lived, it can effectively lock the Earth and future generations into a range of impacts, some of which could become very severe.”
http://www.physics.fsu.edu/awards/NAS/
“The Academy membership is composed of approximately 2,100 members and 380 foreign associates, of whom nearly 200 have won Nobel Prizes. Members and foreign associates of the Academy are elected in recognition of their distinguished and continuing achievements in original research; election to the Academy is considered one of the highest honors that can be accorded a scientist or engineer.”
CO2 has little to no effect on global temperatures.
Ask the planet Venus.
A resident "expert" (LOL! pegminer) here at Y/A has chosen to compel others into believing that CO2 is a driver of Global Warming temperatures even though climate science knows that it is a "trace gas" and also helps our Planet to cool itself. Our Planet has over 300,000,000 cubic miles of water and an atmospheric level of 0.04% of CO2.
'Water vapor' is considered by science as the dominant greenhouse gas by no less than 3 times the warming capabilities as CO2 does. It is also known that CO2 can cause cooling by magnifying warming to a point that it creates too much water vapor which , in effect, eventually causes clouds and cooling.
Is CO2 driving temps up or down or does CO2 have any affect on temps?
