Amount of CO2 isn't measured with 100% accuracy. It's VERY possible, what amount in the peaks even greater than in 2006. CO2 doesn't leavs alot of footprints and can be reduced dramatically by water.
Yes, chages ARE periodic, it's not our fault. Our Sun is "very slow pulsar" and have own heartbeat. We are investigating space and stars only last 50 years (except movement)! How we can know anything about stars? We ARE stupid children in space knowledge.
But, YES! WE ARE TURNED OUR ATMOSPHERE INTO CRAP. Thank you England and "industrial revolution"! Thank you, steam engines, converting tonns of charcoal into tons of black dust!
Our precursors and previous civilizations were much clever and lived WITH planet, rather than AGAINST. We are virus on planet's body and deserved to be removed from planet's surface (may be even from universe because of our nature of destroyers).