Tropospheric CO2 and O3 run around on a roughly 10,000 year cycle, between 150-275 ppm for CO2. This has been shown through ice cores in Antarctica, and other methods proven to give us a real look at historic atmospheric data. In the last 150 years, CO2 has gone through the roof.
In addition, global O3 concentrations used to be around 10 ppb. Currently, in the midwest region of the USA, it stands around 40 ppb. Through PopFACE and AspenFACE experiements, along with work done all over the world, it has been proven that even today's elevated O3 levels negatively impacts the ability for trees to act as a carbon sink, which then results in more CO2 in the air.
Where does this lead us? CO2 accounts for roughly 9-26% of the greenhouse effect, which is both undisputed and, overall, a Very Good Thing for life on Earth (it's what tempers the climate on the surface). In laboratory experiments, it also has been shown that in columns of air composed similarly to our atmosphere at different points in history, heat is trapped by the test atmospheres in amounts similar to what we're seeing here on the ground on earth when you crank up the CO2 levels to how we've cranked them up.
I haven't discussed models here at all. I've only discussed experiments and statistical analysis based on observational data.