Let's see, water vapor, CO2, and methane are greenhouse gasses which means that they absorb Planck black body infrared radiation from the surface of the earth.

Since we can't see those gasses, they don't absorb visible light.

There is CO2 from volcanoes. Since 70+ percent of the surface of the earth is covered by water, first-cut, ballpark 70+ percent of the volcanoes and CO2 from the volcanoes are under water, commonly 3-7 miles down. We know that ocean volcanoes are important because they are responsible for a major fraction of all the smaller islands in the oceans.

We know that there is a lot of CO2 dissolved in the oceans and that cooler water absorbs more CO2 and warmer water, less. So, first-cut, we have to suspect that warming of the surface of the oceans, from any source at all, will release CO2 into the atmosphere and cooling of the surface of the oceans will absorb CO2 from the atmosphere.

We know from the ice core samples going
back 800,000 years or so that about 800 years after the start of some significant warming, atmospheric CO2 concentrations increased.

We know that for about the last 20 years, we have been able to measure some significant increase in atmospheric CO2 concentrations but saw nearly no measurable increase in global average atmospheric temperatures. So, this time, really, higher CO2 didn't cause higher temperatures.

Clearly first-cut, if higher CO2 concentrations increase temperature, then lower CO2 concentrations will reduce temperature.

From the ice core and other historical data, both temperature and atmospheric CO2 concentrations have varied significantly. But (1) in this whole record, not once was significant cooling closely preceded by significantly lower atmospheric CO2 concentrations, and (2) only once, since the coolest part of the Little Ice Age, have significantly higher temperatures been closely preceded by significantly higher atmospheric CO2 concentrations.

Indeed, in recent years, from 1940 to 1970 CO2 concentrations, from human activities, volcanoes, ocean out gassing, or whatever increased significantly but global average atmospheric temperatures actually fell enough to be measured. So, there higher CO2 led to lower temperature, not higher.

Conclusion: The idea that changes in CO2 concentrations have been a major cause of changes in temperature are refuted. Instead, there must be other causes that in the historical record have been much, much more important, that is, caused many more temperature changes, than CO2.

For more, no one is claiming that the cooling of the LIttle Ice Age was caused by lower CO2 concentrations -- the cause of the Little Ice Age was not lower CO2. Then, sure, first-cut, the cause of coming out of the Little Ice Age, which really is the recent warming, should have been from a reversal of the cause of going into that period and, thus, not CO2, from humans or anything else.

For more, the Medieval Warm period was warmer than now without relatively high CO2 concentrations. So, current temperatures are not unique, and the last time the cause was not CO2 -- so, we have to wonder if this time current temperatures are due to CO2.

If concerned about global average atmospheric temperature, looking at CO2 is "digging in the wrong place" and is very much "the wrong stuff".

From the historical record, it's fully clear that CO2 has little or no effect on temperature.

For more, many efforts were made to model CO2 in the atmosphere and the resulting effects on global average atmospheric temperature. The models made temperature predictions for future years. Many of those models and predictions are summarized in a graph at

http://www.energyadvocate.com/gc1.jpg

By now we can compare the model predictions with actual temperatures.

Results: From nearly all the models, the temperatures predicted were way too high.

Conclusion: Nearly all the models failed to correspond to reality.

In science, we try to make predictions. When the predictions from some candidate science are badly wrong, then we junk the candidate science. So, we have to junk the techniques of the models.

Consequences: We are left with no meaningful way to predict the effects of CO2 on temperature.

As above, we already know that CO2 has from at most a minor role down to no significant role at all in global atmospheric average temperature and that other causes dominate.

In particular we have no meaningful science that says that CO2 from human activity has significantly warmed the atmosphere or will in the foreseeable future.

To have the world spend trillions of dollars on reductions in CO2 from human activities would cause massive destruction of our economies and is not justified.

For more, to consider CO2 seriously, we would have to consider volcanoes including in the oceans and CO2 in and from the oceans, and so far we have no good way to do that.

There is a theory for the cause of temperature changes that actually closely fits the historical record of temperature change. That cause is the level of sun spot activity. More sun spots cause warming. How? Clouds have a net cooling effect. A significant fraction of clouds are caused by water droplets caused by cosmic rays. More sun spots cause more solar wind which blocks cosmic rays, slows cloud formation, and causes warming.

Sorry, it would be nice to have solid science for the climate, science that would let us predict the climate accurately and, in particular, the effects on climate from various levels of CO2 from human activities. So far, first-cut, the evidence is that CO2 from human activities is having no significant effect on climate at all.

Really, it appears that to predict global average atmospheric temperatures, we should focus on predicting sun spots.

To explain the high interest in global warming, f'get about science and, instead, do something much simpler that makes much more sense, just follow the money.

The Mayans killed people to pour their blood on a rock to keep the sun moving across the sky. Lowering human sources of CO2 to slow global warming is no better founded.

I have a suggestion: Suit up Saint Laureate Al Guru and send him to the sun to do a close up, hands on, field study of sun spots. Then we will take up the subject of global warming when he returns.