It's always interesting listening to politicians and such blab about global warming. Over here in Hawaii, we have one of the most advanced climate monitoring stations on top of Mauna Loa. Since it is so high up and access is limited, it is used to take Co2 measurements and such without having much man made interefrences in the measurements.
I've gone up to the station before with my University, and when you look at all the records of Co2 concentration in the atmosphere, there really doesn't look like a significant change up to this date. Granted, it is climbing, it has always been cycling up and down as far as all records have been taken.
I do believe that it is a natural process of warming, as well as cooling, human activities are probably just speeding them up a bit. My 2 cents...