If it's the CO2 levels that really cause global warming. There were some graphs posted recently on other threads that showed no correlation between CO2 levels and temperature.
No doubt. And there are graphs showing a strong negative correlation between global warming and pirates. However, basic physics being what it is, the CO2 correlation is a bit more dependable.
the sun causes warming.
CO2, among other atmospheric components, can act to trap warmth and slow its reflection and radiation into space.
However, the primary factor has always been and shall (probably) always be the amount of solar radiation reaching Earth, so long as the system endures.
That being said - climate is not defined by temperature alone.
Free atmospheric molecular oxygen is a toxin to many organisms, and a requirement for others. Changing the compostition of the atmosphere by drastically reducing the CO2 content and raising from approximately zero percent O2 to the current @20% is a whopping big change in the environment, affecting not only mean temperature but diurnal temperature ranges, weather patterns, etc...