How does CO2 cause warming?

If it caused warming, natural increases would increase temperatures. CO2 would have to have a correlation for millions of years to cause warming, even if it was naturally made. We have I think ~380 ppm (parts per million) CO2 in our atmosphere. It causes the "scary" warming we see today. If this was true, then CO2 twice the amount of today would lead to higher temperatures (i.e. natural increase = temperature increase). I have never seen an article proving there has been a correlation for millions of years. Look at this:



Co2 might be high when temperatures are low, and vice versa. So how can this work? How can a light amount of 380 CO2 cause warming, if a ppm of 4500 did not 450 million years ago? No alarmist can answer that.

Lets look at the big ben. Big Ben is 316 ft high. If this was the atmosphere (using top to bottom) all CO2 is 1 1/4 inches total. Humans are responsible for 1 mm of that. Cool huh? If we took 1mm out of the big bang, or added 1mm, would it be much taller or shorter? No. It would have no visible effect. If someone argued it would lead to huge differences we would say "you are crazy" right? Same with CO2, your crazy.

CO2 is a natural cycle. If normal warming trends look like this (graph below) when why does this specific one have to be man made?


(IPCC)

Again, why does our natural normal looking trend have to be man made? it does not, because it is natural.