Convincing Campbell Brown was the easy part

Checking out the data here, I see that the Twin Cities area (Minnesota) hit a high temperature of 70 degrees yesterday, considerably short of the record of 104 set in 19-freaking-31.

Looking at the September records here, I see lots of warmth records set in the 1890s and 1920s. Looking at the "Daily Averages and Records" section here, I also see lots of warm records that are very old.

Now I know the Campbell Browns of the mainstream media may be easily fooled, but ordinary people will continue to ask: If CO2 is the primary driver of climate, why then was it so warm before World War II and so relatively cool right now?