The real inconvenient truth Al Gore doesn't want you to know is that historical CO2 has lagged behind temperature, and not the other way around. When temperatures increase, so does CO2 levels. When temperatures drop, CO2 levels decrease.
Note the CO2 curves are generally to the left of the temperature curves. This shows that temperature trends, driven by the sun and its solar cycle, drive atmospheric CO2. Yes, man has increased the levels of CO2 in the atmosphere, but there is zero evidence that the increase in CO2 by man has caused any form or global temperature changes. This relatively insignificant greenhouse gas appears able to increase and decrease with little to no effect on global temperatures.