Oxygen is lethal in certain concentrations, you know that right?
CO2 is a proven heat trapper, you acknowledge this yes?
By putting more of it into the atmosphere than we take out, the system is changing to have more heat trapping gases in it.
Now perhaps the system can continue to function as it has for recent history (less than 10,000 years) while having millions of years worth of CO2 added to it in just under 200 years, but that would be a pretty brazen thing to assume wouldn't it?
CO2 is not the largest driver of warming. Nobody literate in the science claims it to be. The largest driver as I'm sure you know is water vapor. CO2 is the focus of climate change because it is the single biggest change occurring. We ARE dumping millions of tons more of it in to the air than is being removed.
What drives water vapor concentrations in the air? Ambient temperature.
This is called a feedback loop. The logic is quite simple. Is logic alone enough? Of course not, but studies have shown temperatures rising pretty significantly and quickly during the last 200 years. Are there anomalies like the last 10-15 years? Sure, but after 2 centuries of rapid and increasing warming, assuming that any deviation from that upward rise means it is definitely not anything serious and is going to stop is one heck of a conclusion. One not supported by any evidence.