Indeed, we agree that the CO2 based argument is 19th century science. Which is why it fails against Shaviv's 21st century science, much as Bryan failed against Darrow.
[FONT="]The body of evidence however clearly shows that the climate sensitivity is on the low side, about 1 to 1.5 degree increase per CO2 doubling. People in the climate community are scratching their heads trying to understand the so called hiatus in the warming. Where is the heat hiding? While in reality it simply points to a low sensitivity. The “missing” heat has actually escaped Earth already! If you look at the average global response to large volcanic eruptions, from Krakatoa to Pinatubo, you would see that the global temperature decreased by only about 0.1°C while the hypersensitive climate models give 0.3 to 0.5°C, not seen in reality. Over geological time scales, the lack of correlation between CO2 and temperature places a clear upper limit of a 1.5°C per CO2 doubling sensitivity. Last, once we take the solar contribution into account, a much more consistent picture for the 20th century climate changes arises, one in which the climate drivers (humans AND solar) are notably larger, and the sensitivity notably smaller. [/FONT][FONT="]So, how do we know that the sun has a large effect on climate? If you search on google images “oceans as a calorimeter”, you would find one of the most important graphs to the understanding of climate change which is simply ignored by the IPCC and alarmists. You can see that over more than 80 years of tide gauge records there is an extremely clear correlation between solar activity and sea level rise - active sun, the oceans rise. Inactive sun - the oceans fall. On short time scales it is predominantly heat going to the oceans and thermal expansion of the water. This can then be used to quantify the radiative forcing of the sun, and see that it is about 10 times larger than what the IPCC is willing to admit is there. They only take into account changes in the irradiance, while this (and other such data) unequivocally demonstrate that there is an amplifying mechanism linking solar activity and climate.[/FONT][FONT="]The details of this mechanism are extremely interesting. I can tell you that it is related to the ions in the atmosphere which are governed by solar activity and in fact, there are three microphysical mechanisms linking these ions to the nucleation and growth of cloud condensation nuclei. Basically, when the sun is more active, we have less clouds that are generally less white. [/FONT]