I'd guess part of the reason he got downvoted is this: "The increased CO2 levels in recent years (slightly added to by human activities) [...]".

Pretty much all of the CO2 increase above pre-industrial levels (280 ppm) is due to human activity.

99% of the time when someone says otherwise they are going to continue with a bunch of other equally inaccurate things which they got from scientifically worthless sites and so people just flag and move on.